THE UPPER LIMB

LIST OF TOPICS:

Mammary gland, pectoral region, axillary fossa

Superficial back

Posterior triangle of the neck

Scapular region

Arm and cubital fossa

Volar forearm and palmar hand

Extensor forearm and dorsum of hand

Joints of the upper limb

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Mammary gland, pectoral region, axillary fossa

The sternum (Clemente 104-105; Grant p. 10 & 12; Netter 3e 178-179; 4e 185-186)

• The sternoclavicular joint joins the clavicle to the sternum.
• The sternum is divided from superior to inferior into :
  • the manubrium,
  • the body
  • and the xiphoid process.
• The sternal angle (of Louis) joins the manubrium and body of the sternum.
• The sternum articulates with the clavicle and 7 ribs (R1 to R7).

The bones of the upper limb

• The clavicle holds the scapula away from the trunk by the coracoclavicular ligament (Clemente 78; Grant, p. 532, fig. 6.42B; Netter 3e 406; 4e 423)
• The acromion of the scapula and the coracoacromial ligament prevent superior dislocation of the humerus (Clemente 78; Grant, p. 532, fig. 6.42A; Netter 423)
• The humerus articulates with the scapula at the glenoid cavity (Clemente 78-79; Grant p. 536-537; Netter 3e 403-406; 4e 422-423).
• Compare the radius to the ulna: the ulna is larger at the elbow and the radius is larger at the wrist (Clemente 84-85; Grant p. 545 & 551; Netter 3e 422; 4e 437-439). They are united by a strong interosseous membrane.
• 8 carpal bones (Clemente 89-93; Grant p. 588-590; Netter 3e 435-6, 439-440; 4e 452-457)
• 5 metacarpal bones
• 14 phalanges

The axilla

The anterior wall is formed by the:

• mammary gland,
• pectoralis major muscle (Clemente 2-4, 11-14; Grant p. 494-497, Netter 3e 407; 4e 181, 183-184, 188),
• pectoralis minor and subclavius muscles (Clemente 15, 21; Grant p. 498, fig. 6.17 B & C; Netter 3e 183 & 411; 4e 188-189).

The posterior wall is formed by the:

• Scapula,
• subscapularis, (Clemente 22; Netter 4e 425-426)
• teres major
• and latissimus dorsi (Clemente 328; Grant p. 503 & 510; Netter 3e 409 & 412; 4e 424).

The medial wall is formed by:

• ribs 2 to 6
• and serratus anterior (Clemente 14; Grant p. 496 & 511; Netter 3e 182-183; 4e 424, 426).

The lateral wall is formed by:

• the intertubercular sulcus of the humerus
• and the tendon of the long head of the biceps brachii (Clemente 32-33; Grant p. 506; Netter 3e 392, 397, 402, 404; 4e 425).

The base is formed by the skin and fascia of the armpit (Clemente 1-3; Grant p. 497; Netter 4e 181).

The apex is a triangular space bounded by the clavicle, the upper border of the scapula and rib 1 (Clemente 83; Grant p. 502; Netter 3e 178; 4e 185).

The Pectoralis major muscle

• has clavicular and sternal attachments (Clemente 15; Grant p. 498, fig. 6.17A; Netter 3e 407; 4e 188).
• attaches to the lateral lip of the bicipital groove on the humerus (Clemente 32).
• is innervated by the medial (C8-T1) and lateral (C5-C7)pectoral nerves (Clemente 15, 19; Grant p. 500; Netter 3e 412; 4e 429).
• adducts, medially rotates and flexes the arm.

The Pectoralis minor muscle (Clemente 15, 21; Grant p. 498 & 508; Netter 3e 183; 4e 428-429)

• attaches from ribs (2), 3, 4, 5, and (6) to the coracoid process of the scapula.
• is innervated by the medial pectoral nerve (C8-T1).
• protracts the scapula.

The deltopectoral triangle (Clemente 15; Grant p. 492, 494, 500; Netter 3e 182; 4e 424-428)

• is formed by the pectoralis major, the deltoid and the clavicle.
• transmits the cephalic vein which pierces the deltopectoral triangle and the costocoracoid membrane to join with the axillary vein.

The clavipectoral fascia (Clemente 15; Grant p. 492 & 500; Netter 3e 411; 4e 428)

• The costocoracoid membrane is part of the clavipectoral fascia which encloses the subclavius and the pectoralis minor.
• Below the pectoralis minor, the clavipectoral fascia becomes the suspensory ligament which attaches to the base of the axilla and produces the axillary fossa.

The medial triangular space (Clemente 22, 38; Grant p. 528; Netter 3e 409; 4e 431-432)

is formed by:

• the subscapularis
• the teres major
• and the long head of the triceps brachii.

The lateral quadrangular space (Clemente plate 38; Grant p. 510, 527-528; Netter 3e 409; 4e 426-427)

is formed by:

• the surgical neck of the humerus
• the subscapularis
• the teres major
• the long head of the triceps

The serratus anterior muscle (Clemente 14-15, 20-21; Grant p. 498, 511; Netter 3e 182-183, 185; 4e 426)

• attaches from ribs 1 to 8, to the medial border of the scapula.
• is innervated by the long thoracic nerve (C5-7)
• protracts and assists in rotation of scapula.
• Paralysis of this muscle results in a "winged scapula": because this muscle protracts the scapula by applying it firmly against the rib cage, paralysis of the muscle results in protrusion of the scapula on the lesioned side when the patient is asked to push against the wall with both arms extended.

The upper limb arterial trunk (Clemente plate 16-17; Grant p. 504; Netter 3e 410; 4e 427)

1.  The subclavian artery runs to the inferior border of rib 1 and becomes
2.  The axillary artery:

• is enclosed in the axillary sheath (which is continuous with the prevertebral fascia of the neck).
• is divided into 3 parts.

3.  The brachial artery begins at the lower border of teres major and continues to the cubital fossa (Clemente 16-17; Grant p. 471 fig. 6.11C; Netter 3e 417; 4e 434).

The subclavius muscle (Clemente plate 15; Grant p. 498, fig. 6.17C, 508-510; Netter 3e 183; 4e 428-429)

• attaches from the costochondral junction of rib 1 to the subclavian groove.
• is innervated by the nerve to subclavius from C5(6)
• prevents subclavian artery from being compressed between clavicle and rib 1.
• stabilizes clavicle during movements of distal portions of upper limb.

The axillary artery is divided into 3 parts and the branches have the following arrangement:

• One branch emerges from the first part: the supreme (superior) thoracic artery (Clemente 16; Grant p. 504, 509; Netter 410, 412, 417; 4e 427, 429)
• Two branches emerge from the second part. They arise posterior to the pectoralis minor muscle, where the axillary artery is enclosed by the three parts of the brachial plexus (Clemente 16; Grant p. 504, 508-509; Netter 3e 410, 412, 417; 4e 427, 429). The 2 branches are:
  • the thoracoacromial artery, which has clavicular, acromial, humeral and pectoral branches.
  • and the lateral thoracic artery which supplies mainly the breast.
• Three branches emerge from the third part (Clemente 16, ; Grant p. 504, 508-509; Netter 3e 410, 412, 417; 4e 427, 429):
  • the subscapular artery
  • the posterior humeral circumflex artery
  • and the anterior humeral circumflex artery

The axillary vein (Clemente 14, 20-21; Grant p. 501; Netter 3e 183, 248, 411; 4e 428-429)

• is enclosed by the axillary sheath only in its first part. The second and third parts are free to expand.
• lies medial to the artery
• is a continuation of the basilic vein
• becomes the subclavian vein at the level of rib 1
• is joined by the cephalic vein and the venae comitantes from the brachial and axillary arteries.

The brachial plexus (Clemente 18, 19, 29; Grant p. 506-510; Netter 3e 413; 4e 429, 430)

• is formed by 5 ventral nerve rami or roots (Cervical 5 - 8, Thoracic 1) from the spinal cord
• The 5 ventral nerve rami (roots) unite into 3 trunks in the neck:
  • a superior trunk (C5, 6)
  • a middle trunk (C7)
  • and an inferior trunk (C8, T1)

Each trunk divides into an anterior and a posterior division behind the clavicle:

• the anterior divisions supply the flexor (anterior) compartment of the upper limb
• the posterior divisions supply the extensor (posterior) compartment of the upper limb

Three cords (lateral, posterior and medial) are formed behind the pectoralis minor muscle:

• the anterior divisions of the superior and middle trunks unite to form the lateral cord.
• the anterior division of the inferior trunk form the medial cord.
• the posterior divisions of all 3 trunks unite to form the posterior cord.

The brachial plexus gives rise to terminal branches, distal to the pectoralis minor muscle. These branches are divided into supraclavicular and infraclavicular groups.

Supraclavicular branches (4)

• The dorsal scapular nerve (C5), posterior to the roots
• The nerve to subclavius (C5, 6), anterior to the roots
• The long thoracic nerve (C5, 6, 7) posterior to the roots
• The suprascapular nerve (C5, 6)

Infraclavicular branches (13)

3 branches from the lateral cord:

• The lateral pectoral nerve (C5, 6, 7)
• The musculocutaneous nerve (C5, 6, 7)
• The lateral head of the median nerve (C5, 6, 7)

5 branches from the medial cord:

• The medial pectoral nerve (C8, T1)
• The medial head of the median nerve (C8, T1)
• The ulnar nerve (C7, 8, T1)
• The medial cutaneous nerve of the arm (or medial brachial cutaneous nerve; C8, T1)
• The medial cutaneous nerve of the forearm (or medial antebrachial cutaneous nerve; C8, T1)

5 branches from the posterior cord:

• The upper subscapular nerve (C5, 6)
• Thoracodorsal nerve (C5, 6, 7)
• Lower subscapular nerve (C5, 6)
• Axillary nerve (C5, 6)
• Radial nerve (C5, 6, 7, 8, T1)

The typical spinal nerve (Clemente 8, 326-327; Grant p. 343; Netter 3e 187; 4e 170, 180)

• The ventral root (efferent) and dorsal root (afferent) join to form a spinal (mixed) nerve. The dorsal root ganglion lies in the the dorsal root.
• The spinal nerve divides into:
  • a ventral (anterior primary) ramus, which supplies muscles and skin of the anterior 3/4 of the body wall; for example: the intercostal nerve with lateral cutaneous and anterior cutaneous branches (Clemente 8; Grant p. 20; Netter 3e 187; 4e 192).
  • a dorsal (posterior primary) ramus supplying muscles acting on the spinal column and the overlying skin).

The mammary gland

• Lies in the superficial fascia (Clemente 3-6; Grant p. 4-6; Netter 3e 175-176; 4e 182-183)
• consists of 15-20 units of glandular tissue (Clemente plate 6; Grant p. 5; Netter 3e 167; 4e 182)
• extends:
  • from ribs 2 to 6 vertically.
  • from the side of the sternum to the midaxillary line horizontally.
• is connected to the skin by the suspensory ligaments (of Cooper; Clemente plate 6; Grant p. 5, Netter 3e 175). These atrophy with age and thus the breast droops. They may become contracted from fibrosis around a carcinoma and produce a characteristic pitting of the skin of the breast ("peau d'orange").

The mammary gland

• is innervated by intercostal nerves 2 to 6 via lateral and anterior cutaneous branches.
• receives a sympathetic innervation via the intercostal nerves or vessels.
• is vascularized by (Clemente 9; Grant p. 8; Netter 3e 176; 4e 183):
  • 2 to 3 perforating branches of the internal thoracic artery (internal mammary artery)
  • 2 branches from the lateral thoracic artery
  • twigs from the intercostal arteries
  • and the pectoral branch of the thoracoacromial artery

Lymph drainage of the mammary gland

• The main lymph vessels converge on the nipple (Clemente 7; Grant p. 9; Netter 3e 177; 4e 184).
• The superficial portion of the breast drains into the subareolar plexus.
• The deep portion of the breast drains to the submammary plexus.

The axillary lymph nodes (Clemente 7; Grant p. 9, 489; Netter 3e 177; 4e 184)

• Apical (subclavian, infraclavicular) nodes
• Central axillary nodes
• Brachial (lateral axillary) nodes
• Pectoral (anterior axillary) nodes
• Subscapular (posterior axillary ) nodes

A more recent nomenclature system has simplified the naming of lymph nodes surrounding the mammary gland:

• Level 1 or low nodes lie below the inferior border of the pectoralis minor muscle.
• Level 2 or middle nodes lie deep to the level of the pectoralis minor muscle.
• Level 3 or upper (apical) nodes lie between the upper border of the pectoralis minor and the lower border of the clavicle.
• In addition, Rotter's nodes (1 or 2) lie between the pectoralis minor and major muscles and are also called interpectoral nodes.

updated 8/03/2008

Superficial Back

Bony landmarks on the skull (Clemente plates 515-516; Grant p. 613-614; Netter 3e & 4e 4, 7):

• The mastoid process of the temporal bone
• The parietal bones
• The occipital bone with the external occipital protuberance (or inion), the superior nuchal line and the external occipital crest.
• The lambda point on the skull is formed by the joining of the sagittal and lambdoid sutures.
• The nuchal (back of the neck) region includes parts of the parietal, occipital and temporal bones.

Bony landmarks on the vertebral column

• Unlike most vertebrae, the C1 vertebra or Atlas has no posterior spinous process but only a posterior tubercle (Clemente 342; Grant p. 294, 296-297; Netter 3e 15; 4e 17). The lack of the posterior spinous process allows for a greater range of head extension.
• The cervical vertebrae C2 to C6 have bifid posterior spines, which will serve as attachment points for parallel sets of neck muscles.
• The last cervical vertebra C7 is also called the vertebra prominens, but, in reality, is less prominent than T1.
• In the living, palpable vertebral spines are C6 to L5 (Clemente 325, 328; Grant p. 286; Netter 3e 142; 4e 152-153).
• The ligamentum nuchae (nuchal ligament) attaches to cervical spines. Superiorly it attaches to the inion and the external occipital crest (Clemente 328, 330-333; Grant p. 322, Netter 3e 17; 4e 152).

Bony landmarks on the scapula (Clemente 76; Grant p. 478-479; Netter 3e 403-405; 4e 420-421)

• has costal and dorsal surfaces.
• is triangular in shape.
• has 3 borders (superior, medial or vertebral, and lateral or axillary).
• has 3 angles (superior, inferior and lateral).
• has 2 processes (coracoid and spine)
• 3 fossae (supraspinous, infraspinous and subscapular). The supraspinous and infraspinous fossae communicate at the spinoglenoid notch.
• The suprascapular notch is closed off superiorly by the superior transverse scapular (suprascapular) ligament; Clemente 23, 25; Grant p. 517, 529; Netter 3e 406, 409; 4e 423, 425-427).
• The suprascapular vessels cross superior to the ligament and the suprascapular nerve inferior to the ligament.
• To detect fractures of the scapula, manipulate the scapula between the coracoid process and the inferior angle.

Bony landmark on the ribs (Clemente 103; Grant p. 13, 323; Netter 3e 168; 4e 186)

The angles of the ribs (costal angles) are marked by attachment points of the iliocostalis muscle.

The iliac crest on the pelvic bone

• serves posteriorly as the attachment point for the erector spinae muscles.

Cutaneous innervation of the back:

• A dermatome is the area of skin supplied by sensory terminal branches of both dorsal and ventral primary rami of a single spinal nerve (Clemente 8, 326; Grant p. 99, 348; Netter 3e 157; 4e 164, 180).
• The dorsal ramus of the typical spinal nerve divides into medial and lateral branches. Both supply muscles, then one or the other becomes cutaneous (Clemente 326; Grant p. 20, 323, Netter 3e 163, 170; 4e 177, 180).

Branches of the dorsal rami of the typical spinal nerve

• Above the mid-thoracic region, the medial branches become cutaneous close to the median plane.
• Below the midthoracic region, the lateral branches become cutaneous close to the median plane.
• The longest of the dorsal rami is the cutaneous branch of T2 which extends to the shoulder area.

The back is arranged into 3 layers of muscle:

• Superficial
• Intermediate
• Deep

The superficial muscle layer of the back acts on the upper limb and is composed of the following muscles (Clemente 328; Grant p. 321; Netter 3e 167; 4e 174):

• Latissimus dorsi
• Trapezius
• Levator scapulae
• Rhomboidei (major and minor)

The latissimus dorsi

• attaches from:
  • the aponeurosis (thoracolumbar fascia) of the inferior 6 thoracic, all lumbar and sacral spinous processes
  • the outer lip of the iliac crest
  • ribs 9 to 12
• to the floor of the bicipital groove (intertubercular sulcus) on the humerus
• is innervated by the thoracodorsal nerve (C6, 7, 8) from the posterior cord of the brachial plexus.
• Extends, medially rotates and adducts the humerus

The trapezius

• attaches from:
  • the skull,
  • all the spinous processes of the cervical vertebrae, including the ligamentum nuchae, and the thoracic vertebrae.
• to:
  • the lateral 1/3 of the clavicle (superior fibers)
  • the acromion and crest of the spine of the scapula (intermediate fibers)
  • the tubercle on the inferior lip of the crest of the spine of the scapula
• is innervated by the accessory nerve (the spinal portion of cranial nerve XI derived from C1-5 spinal roots provides the motor innervation) and C3-4 ventral rami (sensory innervation)
• adducts scapula and elevates the shoulder
• acts as suspensory muscle of the shoulder girdle.
• The inferior fibers assist the superior fibers in rotation of the scapula.

The levator scapulae

• attaches from the transverse processes of C1-4 (posterior tubercles only)
• to the medial border of the scapula
• is innervated by direct branches from C3, 4 and a branch of the dorsal scapular nerve (C5)
• elevates the scapula

Rhomboidei

• attach from the ligamentum nuchae, and spinous processes of the cervical and T1-4 vertebrae.
• to the medial border of the scapula
• is innervated by the dorsal scapular nerve (C5)
• adduct the scapula

The triangle of auscultation (Clemente plate 328; Grant p. 321; Netter 3e 246; 4e 174, 254)

• is formed by the vertebral border of the scapula, the superior border of the latissimus dorsi and the lateral border of the trapezius.
• covers the intercostal space between ribs 6 and 7 and rib 7.
• lies superficial to the cardiac orifice of the stomach on the left side.

The lumbar triangle (of Petit; Clemente 328; Grant p. 514; Netter 3e 246; 4e 254)

• is formed by the posterior border of the external oblique, the superior border of the iliac crest and the lateral border of the latissimus dorsi.

updated 8/023/2009

Posterior triangle of the neck

Boundaries of the posterior triangle of the neck (Clemente plate 471; Grant p. 748, 752-753; Netter 3e 23; 4e 27)

• The base is formed by the middle 1/3 of the clavicle.
• The anterior border is formed by the posterior edge of the sternocleidomastoideus.
• The posterior border is formed by the anterior edge of the trapezius.
• The apex is formed by the superior nuchal line on the occipital bone (Clemente 516; Grant p. 616, Netter 3e 8; 4e 8).
• The roof is the investing layer of deep cervical fascia (Clemente 474; Grant p. 747; Netter 3e 22; 4e 28, 35).
• The floor is the prevertebral fascia (Clemente 474; Grant 747; Netter 3e 31; 4e 35).

Sternocleidomastoideus (Clemente 477-478; Grant p. 753; Netter 3e 23-24; 4e 27-28)

• attaches:
  • from the mastoid process
  • to the medial 1/3 of the clavicle and the sternum.
• is innervated by the accessory nerve (cranial nerve XI)
• Bilateral contraction of the sternocleidomastoidei flexes the head
• Ipsilateral contraction turns the head contralaterally and at maximum contraction elevates the chin.
• This muscle also acts as an accessory muscle of respiration.

Trapezius (Clemente 328-329; Grant p. 753; Netter 3e 167; 4e 174)

• attaches:
  • from the superior nuchal line.
  • to the lateral 1/3 of the clavicle, the acromion and the spine of the scapula.
• is innervated by the accessory nerve (cranial nerve XI).
• The upper fibers elevate the shoulder girdle and supports the weight of the upper limb.
• The lower fibers draw (adduct) the scapula towards vertebral column.

The accessory nerve or cranial nerve XI (Clemente 476-481; Grant p. 752, 754-756; Netter 3e 28; 4e 32)

• In the posterior triangle of the neck, the cranial nerve XI lies in the roof, passing posteroinferiorly from the sternocleidomastoideus to the trapezius.
• In this position, it lies deep to the skin and platysma within the investing layer of the deep cervical fascia and is vulnerable.
• The cranial nerve XI divides the roof of the posterior triangle into a superior (carefree) portion and an inferior (careful!) region containing the cervical plexus.

The investing layer of deep cervical fascia covers sternocleidomastoideus, the posterior triangle of the neck and trapezius (Clemente 474; Grant p. 723; Netter 3e 22, 31; 4e 31, 35).

Contents of the posterior triangle (Clemente 476-481; Grant p. 748; Netter 3e 28; 4e 31-32)

• The accessory nerve (cranial nerve XI).
• The cutaneous cervical branches.
• The omohyoid muscle.
• The external jugular vein.
• The occipital and supraclavicular (inferior deep cervical) lymph nodes (Clemente 486; Grant 9, 321, 716; Netter 3e 68; 4e 72).

Cutaneous cervical branches appear from the posterior border of sternocleidomastoideus and penetrate the investing fascia over the posterior triangle. They are derived from the anterior rami of C2, 3, and 4.

Cervical plexus (Clemente 476-478; Grant p. 754-755; Netter 3e 20; 4e 24, 31, 32)

From superior to inferior, branches of the cervical plexus are:

• The lesser occipital nerve (C2), innervating the skin posterior to the ear and superficial to the mastoid process.
• The great auricular nerve (C2, 3), innervating the skin over the upper aspects of sternocleidomastoideus, the ear lobe and the fascia over the parotid gland.
• The transverse cervical nerve (C2, 3), innervating the skin over the Adam's apple.
• The supraclavicular nerves (C3, 4) overlap with cutaneous branches from the upper thoracic intercostal nerves. They may exhibit referred pain from the area of the diaphragm, since they have similar origins from the spinal cord as the phrenic nerves (C3, 4, 5).
• The sensory nerve to the trapezius (C3, 4).

Lymph nodes of the posterior triangle

• The supraclavicular (inferior deep cervical) lymph nodes
• The occipital nodes, found at the apex of the posterior triangle, are enlarged with german measles or scalp infection.

The floor of the posterior triangle of the neck (Clemente 475; Grant p. 748, 756; Netter 3e 23; 4e 27)

The following structures form the floor of the posterior triangle of the neck. They are listed from superior to inferior:

• The semispinalis capitis lies at the very apex of the triangle and may be difficult to see.
• The splenius capitis.
• The levator scapulae which lies under cranial nerve XI (the accessory nerve).
• The scalene muscles (posterior, middle and inferior)
• The superior fibers of the serratus anterior may sometimes be observed in the most inferior part of the triangle.

Scalene muscles (Clemente 481, 488; Grant p. 756-757; Netter 3e 23, 26 ; 4e 27, 30)

• The middle and posterior scalenes form the scalene mass. They arise from the posterior tubercles of the cervical vertebrae and attach to ribs 1 and 2, posterior to the subclavian artery.
• The scalene anterior arises from the anterior tubercles of the transverse processes of cervical vertebrae C3-6. It attaches to the scalene tubercle of rib 1, separating the subclavian artery from the subclavian vein.

Osteology of cervical vertebrae: C3, 4, 5, 6 and 7 vertebrae have significant anterior tubercles (Clemente 342; Grant p. 294; Netter 3e 16; 4e 18-19).

The prevertebral fascia (Clemente 474; Grant p. 747; Netter 3e 31; 4e 35)

• covers the vertebral column, the prevertebral and postvertebral muscles of the neck.
• covers the floor of the posterior triangle of the neck, the subclavian artery, the 3 trunks of the brachial plexus and the loops of the cervical plexus.
• is drawn into the axilla as the axillary sheath and forms an infection route from the posterior compartment of the neck to the axilla, producing upper exremity signs and symptoms.
• Deep to the prevertebral fascia lie the nerves to the levator scapulae, to the rhomboids (C5), to the serratus anterior (C5, 6, 7) and the phrenic nerves (C3, 4, 5; Clemente 478-481; Grant p. 755; Netter 3e 28; 4e 32).

Lymph nodes

The lateral group of inferior deep cervical lymph nodes drain the back of the scalp and the neck into the jugular lymphatic trunks. Most of the lymph nodes are associated with the internal jugular vein deep to sternocleidomastoideus (Clemente 486-487; Grant p. 805; Netter 3e 68; 4e 72-73).

Blood vessels of the posterior triangle

• The subclavian vein
• The subclavian artery

The subclavian vein (Clemente 481, 483; Grant p. 748, 757; Netter 3e 29, 66; 4e 30, 33, 70)

• is a medial continuation of the axillary vein.
• begins at the lateral border of rib 1 and ends medial to the scalene anterior muscle.
• joins with the internal jugular vein to form the brachiocephalic vein.
• lies posteroinferior to the clavicle and can be catherized at this point.

The subclavian artery (Clemente 481-483; Grant p. 764-765; Netter 3e 29, 67; 4e 33, 69)

• enters the posterior triangle behind the insertion point of scalenus anterior.
• becomes the axillary artery at the lateral border of rib 1.
• may be compressed on rib 1 for control of bleeding in the axilla or upper limb.
• may give a dorsal scapular branch (variable) to supply the vertebral border of scapula and rhomboidei (ordinarily supplied by the transverse cervical artery) (Clemente 21, 481; Grant p. 764, Netter 3e 29; 4e 33).

Relationships of the subclavian artery (Clemente 18; Grant p. 757; Netter 3e 29; 4e 33)

• Inferior to the artery lie rib 1 and the pleura of the apex of the lung.
• The scalenus medius and the lower trunk of the brachial plexus are posterior to the artery.
• The scalenus anterior is in front of the artery.

Branches from the subclavian artery (Clemente 491; Grant p. 737; Netter 3e 29; 4e 33)

The following 2 branches arise from the first part of the subclavian artery, medial to scalenus anterior. They cross the lower part of the posterior triangle, just above the clavicle.

• The suprascapular artery supplies the supraspinous and infraspinous fossae, and their contents (Clemente 25; Grant p. 487 fig. 6.7B; Netter 3e 29, 409-410; 4e 33, 426).
• The transverse cervical artery supplies the posterior surface of trapezius by a superficial branch which runs over levator scapulae.
  • Deep branches of the transverse cervical artery (or dorsal scapular artery; Grant p. 487) supply the rhomboidei and the medial border of the scapula, running deep to levator scapulae. They may be replaced by the dorsal scapular artery (see above).

Nomenclature of spinal nerves (Clemente 356; Grant p. 344; Netter 3e 154; 4e 161)

• In the cervical region, the spinal nerves are named for the vertebrae lying below them: C1 nerve lies above the C1 vertebra.
• In the thoracic, lumbar and sacral regions, spinal nerves are named for the vertebrae lying above them: T1 nerve lies below T1 vertebra.

updated 8/23/2009

Scapular region

The clavicle (Clemente 78, 104; Grant p. 530, 532; Netter 3e 402, 406; 4e 419, 423)

• pivots on its sternal attachment, resulting in extensive movement of the scapula on the chest wall.
• has the following attachments:
  • the sternoclavicular joint
  • the coracoclavicular ligament
  • the acromioclavicular joint
• keeps the scapula and humerus lateral with the help of the coracoclavicular ligament and the medial articular disc.

The sternoclavicular joint

• is formed by the sternal end of the clavicle, the superolateral angle of the manubrium of the sternum and part of the first costal cartilage.
• The articular disc divides the joint into two and prevents medial displacement of the clavicle.
• Anterior and posterior sternoclavicular ligaments strengthen the joint.

The costoclavicular ligament

• attaches from the costal cartilage of rib 1 to the clavicle.

The coracoclavicular ligament (Clemente 78; Grant p. 532; Netter 3e 406; 4e 423)

• is formed by conoid and trapezoid portions.
• is classified as a syndesmosis (2 bones attached together by ligament).
• prevents the scapula from being driven medially.
• Partial dislocation (subluxation) may occur between the two bones, but as long as the coracoclavicular ligament is intact, the acromion will not be driven below the clavicle.

The acromioclavicular joint

• has a capsule formed by strong parallel fibers.
• contains a small articular disc.
• allows the scapula to move vertically on the thoracic cage (shrugging the shoulder).
• Allows anterior and posterior movement of the scapula on the thoracic cage.

Movements of the shoulder girdle

• Elevation of the scapula
• Depression of the scapula
• Elevation with superior rotation of the glenoid cavity
• Depression with inferior rotation of the glenoid cavity
• Protraction of scapula
• Retraction of scapula

The proximal half of the humerus (Clemente 77; Grant p. 518-519; Netter 3e 403-404; 4e 420)

• Has a rounded head with a smooth articular surface.
• The anatomical neck serves as the attachment point for the fibrous articular capsule (Clemente 80; Grant p. 532-533; Netter 3e 406; 4e 423)
• The lesser tubercle is directed anteriorly in the anatomical position and is separated from the greater tubercle by the intertubercular (bicipital) groove.
• The surgical neck is located inferior to both tubercles.
• The deltoid tuberosity is located laterally on the shaft of the humerus.
• The spiral groove for the radial nerve is located on the posterior aspect of the shaft.

The deltoid muscle (Clemente 29, 40; Grant p. 524; Netter 3e 407; 4e 424)

• attaches from the lateral 1/3 of the clavicle, the lateral border of the acromion and the spine of the scapula, to the deltoid tuberosity on the humerus.
• is innervated by the axillary nerve (C5, 6) from the posterior cord of the brachial plexus.
• abducts the humerus by its intermediate fibers.
• flexes the humerus by its anterior fibers.
• extends the humerus by its posterior fibers.

The quadrangular space (Clemente plates 38, 41, 43; Grant p. 527-528; Netter 3e 409; 4e 432)

• Its superior border is formed by the lateral border of the scapula and the capsule of the shoulder joint.
• Its lateral border is the surgical neck of the humerus.
• Its inferior border is formed by the teres major muscle.
• Its medial border is the long head of the triceps brachii, which attaches to the infraglenoid tubercle of the scapula.

Contents of the quadrangular space:

The following structures pass from anterior to posterior through the quadrangular space:

• The axillary (circumflex) nerve is bounded by the capsule of the joint superiorly and the surgical neck of the humerus laterally. It innervates the capsule, the teres minor muscle, the deltoid muscle and the overlying skin.
• The posterior humeral circumflex vessels.

The (medial) triangular space

The circumflex scapular artery, a branch of the subscapular artery, grooves the axillary border of the scapula. It runs through the triangular space to the infraspinous fossa.

Shoulder bursae

• Below the acromion lie the tendons of the supraspinatus, infraspinatus and teres minor muscles which attach to the greater tubercle of the humerus.
• The subacromial bursa lies between the acromion and supraspinatus tendon. It extends laterally as the subdeltoid bursa (Clemente 82; Grant p. 531-532; Netter 3e 406; 4e 423, 431).
• The greater tubercle passes completely under the acromion in full abduction.

The rotator cuff (Clemente 22-25, 32-35, 38; Grant p. 516-517, 527-530; Netter 3e 408-409; 4e 425)

is formed by the following muscles which are important in the treatment of shoulder dislocation:

• Subscapularis
• Supraspinatus
• Infraspinatus
• Teres minor
• (Teres major)

The subscapularis

• attaches from the subscapular fossa to the lesser tubercle and the medial lip of the bicipital groove on the humerus
• is innervated by the upper and lower subscapular nerves from the posterior cord of the brachial plexus.
• medially rotates the humerus

The serratus anterior (Clemente 20-21; Grant p. 511; Netter 3e 407; 4e 426)

• is found between the subscapularis and the thoracic cage.
• keeps the scapula protracted.

The teres major (Clemente 24-25; Grant p. 527-528; Netter 3e 407, 409; 4e 427)

• attaches from an oval area on the dorsum of the inferior angle of the scapula and on the lateral border of the scapula, to the medial lip of the bicipital groove,
• is innervated by the lower subscapular nerve (C5, 6)
• medially rotates the humerus.

The teres minor

• attaches from the scapular area superior to the attachment of teres major to the posterior portion of the greater tubercle of the humerus.
• is innervated by the axillary nerve (C5, 6).
• laterally rotates the humerus.

The supraspinatus (Clemente 24-25; Grant p. 497, 516-517; Netter 3e 408; 4e 425)

• attaches from the supraspinous fossa to the greater tubercle of the humerus.
• is innervated by the suprascapular nerve (C5, 6) from the upper trunk of the brachial plexus.
• begins abduction of the humerus

The infraspinatus

• attaches from the infraspinous fossa to the greater tubercle of the humerus
• is innervated by the suprascapular nerve (C5, 6).
• laterally rotates the humerus.

Collateral circulation around the scapula

• Anastomoses on and around the scapula join the first part of the subclavian artery to the 3rd part of the axillary artery (Clemente 25; Grant p. 504; Netter 3e 410; 4e 427).

The "tip-taking position"

• results from damage to the upper trunk of the brachial plexus (C5, 6) due to a fall on the shoulder or being born shoulder first.
• C5, 6 control flexion (deltoid, supraspinatus, clavicular head of pectoralis major), abduction (deltoid and supraspinatus) and lateral rotation ( posterior fibers of deltoid, infraspinatus and teres minor) of the humerus.
• If C5, 6 are damaged, the upper limb takes on an extended, adducted and medially rotated position.

updated 8/23/2009

The distal half of the humerus (Clemente 77; Grant p. 518-519, 544; Netter 3e 403-404; 4e 420-421)

• has 2 distinct articular surfaces: the capitulum (lateral) and the trochlea (medial).
• has non-articular surfaces: the more prominent medial and the smaller lateral epicondyles, with medial and lateral supracondylar ridges respectively. These ridges serve as attachments for the intermuscular septa.

  *The lateral supracondylar ridge ascends to the spiral (radial) groove.

• has 3 fossae: the posterior olecranon fossa, and the anterior coronoid and radial fossae (Clemente 77; Grant p. 544; Netter 3e 403-404, 419; 4e 420-421)

The fascia of the arm

• envelops all muscles;
• is divided into anterior and posterior compartment by the medial and lateral intermuscular septa (Clemente 94; Grant p. 521; Netter 435).

Muscles of the arm

Three muscles are found in the anterior compartment (Clemente 34-37; Grant p. 520; Netter 3e 414; 4e 431):

• the coracobrachialis
• the biceps brachii
• the brachialis

All are innervated by the musculocutaneous nerve (C5, 6) from the lateral cord of the brachial plexus.

One muscle is found in the posterior compartment:

• the triceps brachii (Clemente 38-43; Grant p. 520; Netter 3e 415; 4e 432)

It is innervated by the radial nerve (C5-8, T1) from the posterior cord of the brachial plexus.

The coracobrachialis (Clemente plates 35; Grant p. 523; Netter 3e 414; 4e 431)

• attaches from the tip of the coracoid process to half way down the shaft of the humerus.
• flexes the arm.

The biceps brachii (Clemente 34; Grant p. 522; Netter 3e 414; 4e 431)

• attaches proximally by its short head to the coracoid process and by its long head to the supraglenoid tubercle. The long head runs in the bicipital groove.
• attaches distally by a strong tendon to the tuberosity of the radius. A bursa exists between this tendon and the tuberosity of the radius. The biceps brachii also attaches to the ulna by a secondary attachment called the bicipital aponeurosis (Clemente 34; Grant p. 522, Netter 3e 414; 4e 431)
• supinates the radius, flexes the arm and forearm ("The biceps brachii puts in the corkscrew AND pulls out the cork")

The brachialis

• attaches from the anterior aspect of the distal half of the humerus and from the intermuscular septa (Clemente 35; Netter 3e 414; 4e 431)
• attaches to the anterior aspect of the coronoid process of the ulna (Clemente 47; Grant p. 523; Netter 3e 419; 4e 431)
• flexes the forearm

The triceps brachii (Clemente 38-43; Grant p. 524, 527; Netter 3e 415; 4e 432)

• attaches superiorly by its long head to the infraglenoid tubercle
• attaches by its medial head to the posterior surface of the humerus and, below the spiral groove, to the intermuscular septa.
• attaches by its lateral head along a line to the posterior margin of the deltoid tuberosity
• attaches to the olecranon process of the ulna (Clemente 40; Grant p. 524; Netter 3e 419; 4e 432)
• extends the elbow joint

The cubital fossa (Clemente 46-47, 50; Grant p. 539; Netter 3e 416, 429; 4e 433)

• has for its lateral border the brachioradialis.
• has for its medial border the pronator teres.

contains:

• the biceps tendon
• the brachial artery and its terminal branches
• the median nerve
• the radial nerve, hiding inferior to the brachioradialis (Clemente 50-51; Grant p. 540; Netter 3e 430; 4e 447)

The brachial artery (Clemente 17; Grant p. 486, 487C; Netter 3e 416-417; 4e 473)

Throughout the arm, it lies anterior to the triceps brachii and then the brachialis. It divides at the neck of the radius into ulnar and radial arteries (Clemente 17; Grant p. 540; Netter 3e 417; 4e 447, 448). Venae comitantes accompany the artery and join the axillary vein (Grant p. 501, 539).

Branches of the brachial artery are:

1. The profunda brachii artery

2. The superior ulnar collateral artery

3. The inferior ulnar collateral artery

4. Muscular branches

5. The nutrient artery to the humerus

The profunda brachii artery

• arises just distal to teres major. It is the companion artery of the radial nerve.
• brings the axillary artery in communication with the radial and ulnar arteries by anastomoses.

The musculocutaneous nerve

• arises from the lateral cord of brachial plexus (C5, 6, 7; Clemente 29; Grant p. 480, 506; Netter 413)
• pierces the coracobrachialis, continues between the biceps brachii and brachialis, supplying all 3 muscles (Clemente 35-37; Grant p. 510; Netter 414).
• at the lateral border of the biceps brachii, it terminates as the lateral cutaneous nerve of the forearm (Clemente 27, 29, 30, 37; Grant p. 484; Netter 3e 414, 429, 464; 4e 431, 474, 481)

The ulnar nerve

• arises from the medial cord of the brachial plexus (C (7), 8, T1), it runs medial to the brachial artery to the middle of the arm and then posterior to the medial intermuscular septum, against the medial head of the triceps brachii. It has no branch in the arm (Clemente 29, 36; Grant p. 480, 525; Netter 3e 413, 416; 4e 475-476).
• at the elbow, it runs posterior to the medial epicondyle of the humerus and into the forearm. It is accompanied by the superior ulnar collateral artery (Clemente 36; Grant p. 525; Netter 3e 416; 4e 445) and the ulnar collateral nerve (a branch of the radial nerve innervating the medial head of the triceps).

The median nerve

• is derived from C(5), 6-8, T1, from the lateral and medial cords of the brachial plexus (Clemente 37; Grant p. 506; Netter 3e 413; 4e 475), which unite in the axilla lateral to the brachial artery (Clemente 37; Grant p. 525; Netter 3e 416; 4e 473)
• crosses over the brachial artery and lies medial to it in the cubital fossa (Clemente 37; Grant p. 539; Netter 3e 416; 4e 473).
• It has no branch in the arm but may receive or give a branch to the musculocutaneous nerve.

The radial nerve

• is a continuation of the posterior cord (C 5-8, T1; Clemente 19; Grant p. 506; Netter 3e 413; 4e 430)
• runs posterior to the axillary then the brachial artery (Clemente 43; Grant p. 509; Netter 3e 456; 4e 432); runs anterior to the long head of the triceps into the posterior compartment of the arm (Clemente 42; Grant p. 510; Netter 3e 460; 4e 477); runs in the spiral groove and then into the anterior compartment between the brachioradialis and the brachialis (Clemente 50-53; Grant p. 540; Netter 3e 430; 4e 478).
• lying on the capsule of the elbow joint and then the supinator muscle, it divides into a superficial radial nerve (sensory) and the posterior interosseous nerve (deep radial nerve - mostly motor).

Collateral branches of the radial nerve are:

• muscular branches to the three heads of the triceps brachii (including the ulnar collateral nerve).
• the inferior lateral cutaneous nerve of the arm (Clemente 326; Grant p. 484; Netter 3e 461; 4e 477).
• the posterior cutaneous nerve of the forearm.
• muscular branches to the brachioradialis and extensor carpi radialis longus (radial nerve; Clemente 50-52; Grant p. 540, Netter 3e 461; 4e 478)
• muscular branches to the extensor carpi radialis brevis and the supinator. These branches are distributed by the deep radial nerve or posterior interosseous nerve)

updated 8/14/2008

RADIUS

• Bony landmarks at the proximal end include the head, neck and radial tuberosity (Clemente 84-87; Grant p. 544-547; Netter 3e 419-420; 4e 436-437)
• Bony landmarks at the distal end include the inferior articular surface, ulnar notch, styloid process (Clemente 88-89; Grant p. 551; Netter 3e 422; 4e 439) and the dorsal radial tubercle (of Lister; Grant p. 574; Netter 3e 422; 4e 439).

ULNA

• Bony landmarks at the proximal end include the olecranon and coronoid processes; the trochlear and radial notches; and the ulnar tuberosity (for attachment of the brachialis; Clemente 84-88; Grant p. 544-547; Netter 3e 419-420; 4e 436-439).
• Bony landmarks at the distal end include the head, the styloid process (Clemente 88-90; Grant p. 551; Netter 3e 422; 4e 439), the pit for the articular disc (Clemente 93; Grant p. 590; Netter 3e 438; 4e 455), the groove for the tendon of the extensor carpi ulnaris (Clemente 63; Grant p. 587; Netter 3e 424; 4e 441).

Muscles of the flexor region

are arranged into 3 layers (Clemente 95-96; Grant p. 553; Netter 3e 429-431; 4e 435, 449):

• Superficial
• Intermediate
• Deep

The superficial layer of muscles (Clemente 46; Grant p. 554; Netter 3e 429; 4e 446)

• has a common origin from the anterior portion of the medial epicondyle of the humerus.
• contains the:
  • pronator teres
  • flexor carpi radialis
  • palmaris longus
  • flexor carpi ulnaris

The intermediate layer (Clemente 47; Grant p. 555; Netter 3e 430; 4e 447) consists of the:

• flexor digitorum superficialis (sublimis)
  • arises from humerus, ulna and radius
    • the tendons run two-deep going into the carpal tunnel: tendons to digits 3 and 4 lie superior, tendons to digits 2 and 5 lie inferior (Clemente 98; Grant p. 605; Netter 3e 430; 4e 461).
    • after the flexor retinaculum, the tendons lie side-by side (Clemente 98; Grant p. 606; Netter 3e 444; 4e 462).
  • attaches to the middle phalanges and flexes the proximal interphalangeal joints (Clemente 69; Grant p. 569; Netter 3e 447; 4e 462).
  • the median nerve runs deep to this muscle.

The ulnar artery (Clemente 17, 52; Grant p. 487, 550; Netter 3e 431; 4e 434, 473)

has the following branches:

• The anterior and posterior ulnar recurrent arteries
• The common interosseous artery further divides into (Clemente 52; Grant p. 550; Netter 3e 428-431; 4e 434):
  • The anterior interosseous artery (Clemente 52; Grant p. 550-551, 557; Netter 3e 431; 4e 448) has:
    • a median branch (following the nerve), nutrient arteries to the radius and ulna, muscular branches, an anterior communicating and terminal branches.
  • The posterior interosseous artery (Clemente 60-61; Grant p. 550, 573, 557; Netter 3e 428; 4e 445) has:
    • recurrent and terminal branches
    • Muscular branches
    • Palmar and dorsal ulnar carpal arteries

Branches of the radial artery are the (Clemente 50-53; Grant p. 535, 553, 577; Netter 3e 430, 449; 4e 447):

• Radial recurrent artery
• Muscular branches
• Palmar (anterior) branch forming the deep palmar arch
• Carpal branches joining with the carpal arch and dorsal carpal rete
• Superficial palmar branch joining with the superficial palmar arch

The deep layer of muscles:

1. Pronator quadratus (Clemente 59; Grant p. 553, 571; Netter 3e 431; 4e 440, 448)

2. Flexor pollicis longus (Clemente 51-52; Grant p. 553, 557; Netter 3e 430-431; 4e 443)

3. Flexor digitorum profundus flexes the distal interphalangeal joints.

• The anterior interosseous nerve (a branch from the median nerve) innervates the pronator quadratus, the flexor pollicis longus and half of of the flexor digitorum profundus (muscle bellies to digits 2 and 3)
• The ulnar nerve innervates the other half of of the flexor digitorum profundus (muscle bellies to digits 4 and 5).

The ulnar nerve (Clemente 52-53; Grant p. 480, 556; Netter 3e 431, 459; 4e 448)

• Innervates the :
  • medial half of the flexor digitorum profundus
  • flexor carpi ulnaris
  • elbow joint
• Palmar and dorsal cutaneous branches arise proximal to the wrist.
• The ulnar artery accompanies ulnar nerve in most of the forearm.

The superficial radial nerve (Clemente 50- 53; Grant p. 556, 559, 578; Netter 3e 456, 461; 447)

• is the sensory continuation of the radial nerve distal to the origin of the posterior interosseous nerve
• lies deep to brachioradialis
• runs with the radial artery
• becomes cutaneous about 5 cm proximal to the styloid process of the radius (Clemente 60, 75; Grant p. 582; Netter 3e 461; 4e 467)

The median nerve

• runs deep to the flexor digitorum superficialis (Clemente 51-52; Grant p. 555; Netter 3e 458; 4e 447-448) and then deep to the flexor retinaculum (Clemente 70; Grant p. 554, 556; Netter 3e 443; 4e 447).
• innervates the elbow, wrist joint and all flexor muscles of the forearm, except the flexor carpi ulnaris and the medial 1/2 of flexor digitorum profundus.

An internervous line exists between the flexor digitorum superficialis and the flexor carpi ulnaris.

Neurovascular pattern in the forearm

• A nerve runs down each border (radial and ulnar nerves; Clemente 52; Grant p. 556, Netter 3e 430-431; 4e 447-448)
• The brachial artery divides into 2 branches: radial and ulnar arteries which approach the nerves but never cross them.
• The median nerve, deep to the flexor digitorum superficialis, crosses the ulnar artery and lies between the 2 arteries.
• The arterial supply of the forearm comes from the common interosseous branch of the ulnar artery (Clemente 17, 52; Grant p. 550-551, Netter 3e 431; 4e 434, 448). This divides into the anterior and posterior interosseous arteries. The posterior interosseous artery is assisted by piercing branches from the anterior interosseous artery but as it fails, the anterior interosseous artery pierces the membrane and suplies the extensor compartment.
• The anterior (from the median nerve) and posterior (from the radial nerve) interosseous nerves remain in their own compartment and supply muscles, periosteum and carpal ligaments. They do not reach skin.
• 3 nerves share in the supply of the forearm and each nerve passes between 2 heads of muscle
  • Nerve supply of the flexor compartment
    • The median nerve passes between the 2 heads of pronator teres.
    • The ulnar nerve passes between the 2 heads of flexor carpi ulnaris (Clemente 53; Grant p. 543, 556; Netter 3e 428; 4e 476).
  • Nerve supply of the extensor compartment
    • The posterior interosseous nerve (a branch from the radial nerve) passes between the 2 layers of the supinator; (Clemente 53; Grant p. 577; Netter 3e 428; 4e 478).
• Radial and ulnar arteries supply the hand by forming the deep and superficial palmar arches respectively (Clemente 70-73; Grant p. 573; Netter 3e 449; 4e 466).

The carpal flexor tunnel

• 8 bones of the wrist:
  • proximal (from lateral to medial): scaphoid , lunate, triquetrum, pisiform.
  • distal (from lateral to medial): trapezium, trapezoid, capitate, hamate.
• The flexor retinaculum is attached from the scaphoid and the trapezium on the radial side to the hook of the hamate and the pisiform on the ulnar side (Clemente 65; Grant p. 571, 588-590; Netter 3e 437-440; 4e 460-461).

The carpal flexor tunnel contains the (Clemente 98; Grant p. 602; Netter 3e 444; 4e 461):

• Flexor digitorum superficialis tendons (lying 2 by 2)
• Flexor digitorum profundus tendons (lying side by side).
  • Long flexor tendons share the same synovial sheath, referred to as the ulnar bursa (Clemente 65, 67; Grant p. 568; Netter 3e 445; 4e 460-463).
• Flexor pollicis longus tendon has its own synovial sheath, named the radial bursa.
• Median nerve.
• Flexor carpi radialis tendon.

Carpal tunnel syndrome

• is caused by compression of the median nerve in the carpal tunnel.
• manifests as:
  • weakness and wasting of thenar muscles, and loss of opposition of the thumb
  • anesthesia over 3.5 digits on the thumb side of the hand.
• may be treated by cutting the flexor retinaculum to relieve symptoms.
• The skin over the thenar area is not involved because it is supplied by the palmar cutaneous branch of the median nerve (Clemente 64; Grant p. 559; Netter 3e 442; 4e 459) or the lateral cutaneous nerve of the forearm which enters the palm superficial to the flexor retinaculum.
  

Palm of the hand

is organized into 4 layers (Clemente 98; Grant p. 561-571; Netter 3e 442-445; 4e 462)

• The palmar aponeurosis
• The short muscles of thumb and digit 5 (for position adjustment and fine movement)
• The long flexor tendons (giving power to the grip)
• The adductor of the thumb

Suface anatomy of the hand

• The skin of the palm of the hand is ridged and furrowed (fingerprints) for gripping.
• Skin creases are due to hand movements.
• Digital size formula: 3>4>2>5>1 (with 4 = 2 or 4 < 2 variations).
• The axial line is the line drawn through the middle finger, capitate and middle metacarpal .
• The thumb is set at right angle to the 4 fingers.

Bones of the wrist and hand:

• 8 carpal bones (divided into 4 proximal and 4 distal).
  • 4 proximal: scaphoid, lunate, triquetrum (these 3 articulate with the radius at the wrist joint; Clemente 89-93; Grant p. 588-590; Netter 3e 435-440; 4e 452-457), pisiform.
  • 4 distal: trapezium, trapezoid, capitate, hamate.
• 5 metacarpal bones (Clemente 90-91; Grant p. 588-589; Netter 3e 439-440; 4e 456)
• 14 phalanges: 3 on each finger, 2 for the thumb.
  • On each finger, proximal phalanx= phalanx 1, middle phalanx = phalanx 2, and distal phalanx = phalanx 3.

THE FLEXOR RETINACULUM

• forms the carpal tunnel with the carpal bones
• prevents the long flexor tendons from moving anteriorly
• and gives origin to the thenar and hypothenar muscles.

3 THENAR MUSCLES (Clemente 65; Grant p. 564, 566-567; Netter 3e 443, 448; 4e 460, 465)

• originate from the flexor retinaculum and the tubercles of the scaphoid and trapezium.
  • Abductor pollicis brevis lies most superficial and attaches to the proximal phalanx of digit 1
  • Opponens pollicis attaches to the lateral border of metacarpal 1
  • Flexor pollicis brevis attaches to the base of proximal phalanx of digit 1
• are innervated by median nerve (C8, T1) and the deep branch of ulnar nerve ( innervating the deep part of flexor pollicis brevis)

The branch from the median nerve is the recurrent branch of the median nerve running around the distal border of flexor retinaculum (Clemente 70; Grant p. 566-567; Netter 3e 443; 4e 460-465). Variations in the course of this nerve can be disastrous in carpal tunnel surgery. It may curve around the flexor pollicis brevis.

Adductor pollicis lies deep to the thenar muscles (Clemente 70-71; Grant p. 564, 570; Netter 3e 444; 4e 460-466)

• attaches from the middle metacarpal and capitate
• to the base of 1st phalanx.
• is innervated by the ulnar nerve.

3 HYPOTHENAR MUSCLES (Clemente 65-67; Grant p. 564; Netter 3e 443-444; 4e 460-465)

• have a common origin from the flexor retinaculum, pisiform and hook of hamate.
  • Abductor digiti V or minimi attaches to the base of the proximal phalanx of digit 5 (Clemente 65; Grant p. 564, 567; Netter 3e 444, 448; 4e 461-465)
  • Flexor brevis digiti V or minimi attaches to the base of proximal phalanx of digit 5
  • Opponens digiti V or minimi attaches to the 5th metacarpal bone.
• are innervated by the deep branch of the ulnar nerve.

The ulnar nerve, in the hand (Clemente 70-71; Grant p. 566-567; Netter 3e 459; 4e 465-466):

• passes between the pisiform and hook of the hamate, in front of flexor retinaculum and pisohamate ligament;
• divides into deep and superficial branch;
• is covered by deep fascia and then by palmaris brevis (cutaneous muscle)
  • 1) Superficial branch gives cutaneous branches to medial 1 1/2 fingers (Clemente 70; Grant p. 567; Netter 3e 459; 4e 466) and motor branch to palmaris brevis. It communicates with the median nerve.
  • 2) Deep branch supplies 3 hypothenar muscles and all short muscles of hand, except for the 5 muscles innervated by median nerve.

The median nerve

• runs through the carpal tunnel, in the midline of the skin crease of the hand, on the deep surface of the flexor retinaculum.
• in the palm, it is deep only to the palmar aponeurosis (Clemente 70; Grant p. 566, 605; Netter 3e 444, 458; 4e 466)
• divides into "recurrent" and digital branches
• innervates 5 short muscles of the hand, the skin of the 3 1/2 lateral digits, the joints of the digits and local vessels.

Motor branches are carried by the recurrent branch and innervate:

• Abductor pollicis brevis
• Opponens pollicis
• Flexor pollicis brevis (superficial part)
• 1st and 2nd lumbricals by digital branches

PALMAR APONEUROSIS (Clemente 64; Grant p. 554; Netter 3e 442; 4e 459)

• The palmaris longus tendon adheres to the flexor retinaculum, enters the palm and divides into 4 bands which, distally, send dorsal fibrous bands to the palmar ligaments and to the deep fascia.

Fibrous sheaths of digits (Clemente 69; Grant p. 569; Netter 3e 447; 4e 464):

• To each finger are distributed a tendon from the flexor digitorum superficialis and from the flexor digitorum profundus.
  • The tendon of the flexor digitorum profundus attaches to the base of the distal phalanx.
  • The tendons of the flexor digitorum superficialis split in front of proximal phalanx into medial and lateral halves and attach to the margins of the middle phalanx.

4 Lumbricals (Clemente plate 66; Grant 565-68; Netter 3e 446; 4e 463)

• arise from the tendons of the flexor digitorum profundus
• lie deep to the digital vessels and nerves
• lie on the radial side of the fingers
• insert into the dorsal extensor expansions beyond the interossei
• are innervated by the ulnar nerve (medial 2 lumbricals) and by the median nerve (lateral 2 lumbricals).
• flex the metacarpophalangeal joints.

3 PALMAR POTENTIAL SPACES (Clemente 65; Grant p. 562; Netter 3e 446; 4e 463):

• Thenar space
• Central (triangular) space lying behind the adductor pollicis
• Hypothenar space

ARTERIES OF THE HAND

are organized into 4 arterial arches:

1. The superficial palmar arch

• lies deep to the palmar aponeurosis (Clemente 70; Grant p. 566; Netter 3e 449; 4e 460)
• is the continuation of the ulnar artery with a variable superficial palmar branch from the radial artery.
• supplies the medial 3 1/2 digits (The lateral 1 1/2 is supplied by the deep palmar arch).

2. The deep palmar arch (Clemente 71; Grant p. 570, 572-573; Netter 3e 449; 4e 466)

• The radial artery gives off the palmar radial carpal and superficial palmar arteries, then runs lateral to the wrist, through the anatomical snuffbox (Clemente 75; Grant p. 576; Netter 3e 450; 4e 467), into the 1st metacarpal space, through the dorsal interosseous muscle and becomes the deep palmar arch.
• is completed by the deep branch of the ulnar artery (Clemente 73; Grant p. 572; Netter 3e 449; 4e 466).
• gives 2 palmar digital branches (the princeps pollicis and the radialis indicis) to the lateral 1 1/2 digits (Clemente 72-73; Grant p. 572-573; Netter 3e 449; 4e 466) from the radial artery
• gives 3 palmar metacarpal arteries supplying the interosseous muscles and the metacarpals, and form anastomoses with the palmar digital branches

3. The dorsal carpal arch is applied to dorsal surface of carpal bones (Clemente 63, 73; Grant p. 573; Netter 3e 452; 4e 469).

4. The ventral (palmar) carpal arch is a network formed by palmar carpal branches of the ulnar and radial arteries, and twigs from the forearm and from the deep palmar arch (Clemente 71-73; Grant p. 573; Netter 3e 448-449; 4e 466).

updated 8/23/2009

Extensor forearm and dorsum of hand

BOUNDARY LINES (no motor nerve crosses these lines).

• The medial boundary line is the subcutaneous border of the ulna and the ulnar border of the hand (Clemente 52; Grant p. 587; Netter 3e 427; 4e 473).
• The lateral boundary is the radial artery in the forearm and the radial border of the hand (Clemente 52; Grant p. 585; Netter 3e 427; 4e 473)

THE ANATOMICAL SNUFFBOX (Clemente 62, 75; Grant p. 584-585; Netter 3e 450; 4e 467-468):

• is formed between the tendon of the extensor pollicis longus and those of the extensor pollicis brevis and abductor pollicis longus.
• The cephalic vein and superficial radial nerve cross superficial to the anatomical snuffbox.

GENERAL ORGANIZATION OF MUSCLES IN THE EXTENSOR FOREARM:

• 3 "outcropping muscles" to the thumb divide the forearm extensors into lateral and posterior groups, each with its own nerve supply.
• An internervous line separates each group of muscles.

SUPINATOR(Clemente 53, 56, 58; Grant p. 577; Netter 3e 423, 428; 4e 440, 445)

• attaches from the lateral epicondyle of the humerus, the radial collateral ligament, the annular ligament and the ulna
• inserts into the lateral surface of the proximal third of the radius between the anterior and posterior oblique lines.
• The posterior interosseous nerve (C6, 7) passes between its 2 origins and supplies it.
• fixes forearm in supination, when forearm is flexed (biceps is the stronger supinator).
• weakly supinates forearm when forearm is extended.

POSTERIOR INTEROSSEOUS NERVE (DEEP RADIAL NERVE)

• This branch of the radial nerve is a motor nerve.
• It runs from the anterior aspect of the capsule of the elbow joint, deep to the brachioradialis.
• It runs around the radius, through the supinator and supplies it (Clemente 53; Grant p. 577; Netter 3e 428; 4e 445)
• supplies 3 muscles of the lateral group of the extensor forearm in conjunction with the radial nerve: brachioradialis, extensor carpi radialis longus and extensor carpi radialis brevis.

FOREARM EXTENSORS

• arise from the common extensor tendon attached to the front of the lateral epicondyle, the adjacent fascia and the supracondylar ridge.

THE LATERAL GROUP:

The tendons of the extensor carpi muscles cross the snuffbox and pass to the bases of the 2nd and 3rd metacarpals, respectively (Clemente 75; Grant p. 581; Netter 3e 453; 4e 469-470).

1.  Brachioradialis (Clemente 46-48; Grant p. 576-577; Netter 3e 427-430; 4e 446-447)

• arises from the superior part of the lateral supracondylar ridge and the intermuscular septum (the radial nerve lies deep to this muscle).
• attaches to the base of the styloid process of the radius.
• The radial artery and superficial radial nerve lie deep to this muscle in the forearm.
• is innervated by the radial nerve (C5, 6)
• acts as a flexor although it is innervated by an "extensor" nerve (The radial nerve).

2.  Extensor carpi radialis longus (Clemente 55; Grant p. 576-577; Netter 3e 424; 4e 441, 444-446)

• arises from the inferior 1/3 of the supracondylar ridge and the lateral intermuscular septum.
• is innervated by the radial nerve (C6, 7).

3.  Extensor carpi radialis brevis

• has bursae at either end
• arises from the common extensor tendon, the adjacent capsule and septa
• is innervated by the posterior interosseous nerve (C6, 7)

THE POSTERIOR GROUP (Clemente 54-58; Grant p. 576; Netter 3e 424, 427; 4e 441, 444-445)

1.  Extensor digitorum (communis)

• is innervated by the posterior interosseous nerve (C7, 8).

2.  Extensor digit V or minimi

3.  Extensor carpi ulnaris

• inserts into the base of the 5th metacarpal
• is innervated by the posterior interosseous nerve (C6, 7)

All 3 muscles arise from the common extensor tendon, the deep fascia and intermuscular septa.

Anconeus (Clemente 54-58; Grant p. 577; Netter 3e 427-428; 4e 54-58)

• arises from the posterior aspect of the lateral epicondyle,
• inserts into the lateral surface of the olecranon and adjacent ulna.
• is innervated by the radial nerve (C7, 8)
• is a weak extensor of the elbow.

THE "OUTCROPPING MUSCLES" TO THE THUMB (Clemente 54-58; Grant p. 577; Netter 3e 427-428; 4e 441, 444-445)

1.  Abductor pollicis longus

• arises from the radius and ulna
• attaches to the base of metacarpal I
• is innervated by the posterior interosseous nerve (C6, 7)

2.  Extensor pollicis brevis

• arises from the radius
• attaches to the proximal phalanx of digit I
• is innervated by posterior interosseous nerve (C7, 8)

3.  Extensor pollicis longus

• arises from the ulna
• attaches to the distal phalanx of digit I
• is innervated by posterior interosseous nerve (C7, 8)

Extensor indicis (Clemente plate 54; Grant p. 577; Netter 3e 428; 4e 441, 445)

• arises from the ulna just distal to the extensor pollicis longus
• joins the dorsal expansion of digit 2
• is innervated by the posterior interosseous nerve (C7, 8)

The posterior interosseous artery

• is a terminal branch of the common interosseous artery
• passes over the upper border of the interosseous membrane (Clemente 17, 60, 61; Grant p. 486-487, 550-551, 573; Netter 3e 417, 428; 4e 448, 445)
• Descends between the superficial and deep muscles, supplies them and also anastomoses at the elbow and at the wrist.

The extensor retinaculum (Clemente 62; Grant p. 581; Netter 3e 450-453; 4e 445, 470)

• is attached by septa to the radius and medial carpals (pisiform and triquetrum), forming tunnels (6 lubricated by synovial sheaths).

Extensor tunnels (6)

From lateral to medial

1. Abductor pollicis longus and extensor pollicis brevis

2. Extensor pollicis longus

3. Extensor carpi radialis longus and brevis

4. Extensor digitorum communis and extensor indicis

5. Extensor digiti minimi

6. Extensor carpi ulnaris

EXTENSOR EXPANSIONS (DORSAL EXPANSIONS)

• 4 tendons of extensor digitorum traverse wrist tunnel and pass to the fingers (Clemente 63, 69; Grant p. 581-582; Netter 3e 453; 4e 470).
• Joined by extensor indicis and extensor digiti V tendons near knuckles.
• Oblique bands (vinculae) unify the 4 tendons proximal to the knuckles, resulting in a lesser independent action of the fingers.

Dorsal (extensor) expansion:

• Each dorsal (extensor) expansion wraps around the dorsum and sides of metacarpal head and proximal phalanx (Clemente 69; Grant p. 583; Netter 3e 447; 4e 464).
• The hood around the metacarpal head is anchored on each side to palmar ligament (Grant p. 583) and attached to the base of the proximal phalanx by a fibroareolar ribbon.
• On the proximal phalanx, the expansion divides into a median band (passing to the base of middle phalanx) and into 2 side bands (passing to the base of the distal phalanx).
• The extensor tendon pulls mostly on the median band
• Side bands are pulled on by tendons of interossei muscles and distally, on the radial side, by a lumbrical tendon.
  • Lumbricals and interossei also flex the intermetacarpophalangeal joint, abduct and adduct at the metacarpophalangeal joint (when extended by long extensors), and extend both proximal and distal interphalangeal joints.

INTEROSSEI MUSCLES (Clemente 68; Grant p. 571; Netter 3e 448; 4e 465)

• is innervated by the deep ulnar nerve
• 4 dorsal interossei (seen on the dorsal aspect) arise by double heads from the facing sides of the bodies of the 5 metacarpals. They are abductors (Dorsal ABduct = DAB).
• 3 palmar interossei arise by single heads from the anterior borders of metacarpals 2, 4 and 5, each adducting its own metacarpophalangeal joint (Palmar ADduct = PAD).
• The interossei insert into the bases of proximal phalanges and into extensor expansions.

The cutaneous innervation of the dorsum of the hand by the radial nerve (Clemente 62; Grant p. 484, 578-579; Netter 3e 455-461; 4e 468, 472)

• runs just short of the nail beds, which are usually innervated by the median nerve (lateral 3 1/2) and ulnar nerve (medial 1 1/2)
• The ulnar nerve innervates the medial 1 1/2 digit by the dorsal cutaneous branch.
• The radial nerve innervates the lateral 3 1/2 digits.

The dorsal venous arch (Clemente 62; Grant p. 488, 584, 587; Netter 3e 451, 463; 4e 468)

• is subcutaneous
• is formed by companion veins
• drains into the cephalic and basilic veins

updated 08/23/2009

Joints of the upper limb

The shoulder joint (articulatio humeri or glenohumeral joint)

• is a multiaxial ball (head of humerus) and socket (glenoid cavity on scapula) joint (Clemente 79; Grant p. 518; Netter 3e 403-405, 4e 421-422).
• The glenoid labrum (fibrocartilage) runs around the rim of the cavity (Clemente 80; Grant p. 535; Netter 3e 406, 4e 423)
• Flexes, extends, adducts and abducts (circumducts)
• Medially and laterally rotates

The capsule of the joint (Clemente 80-82; Grant p. 532, 536; Netter 3e 406, 4e 423)

• is very loose: if C5 and 6 are lesioned, then the head of the humerus is held only by ligaments and the capsule can be pulled away from the glenoid cavity by 1 cm.
• stretches from the margin of the glenoid cavity to the anatomical neck of the humerus superiorly and to the surgical neck of the humerus inferiorly. The inferior portion folds when the arm is adducted.
• The synovial membrane lines the fibrous capsule but NEVER the articular heads of bone which are covered with hyaline cartilage.

Important ligaments of the shoulder joint (Clemente 80-82; Grant, p. 532-535; Netter 3e 406, 4e 423)

• The coracohumeral ligament .
• The transverse humeral ligament
• The superior, middle and inferior glenohumeral ligaments.

The coracohumeral ligament

• is attached from the lateral border of the coracoid process to the anterior portion of the anatomical neck of the humerus.
• holds the humeral head in the adducted position.
• prevents inferior dislocation.
• limits lateral rotation.

The locking mechanism to prevent inferior dislocation:

1) Slope of the glenoid fossa

2) Tight upper part of the joint capsule and the coracohumeral ligament.

3) Supraspinatus activity

4) The superior, middle and inferior glenohumeral ligaments.

The transverse humeral ligament holds the long head of the biceps in the intertubercular groove (Grant p. 532; Netter 3e 406, 4e 423).

The strength of the shoulder joint depends on the :

1) Bony formation

2) Ligaments (coracohumeral ligament)

3) Muscles (rotator cuff/accessory dynamic ligaments):

• Supraspinatus
• Infraspinatus and teres minor
• Subscapularis

Bursae of the shoulder joint (Clemente 82; Grant p. 531-532; Netter 3e 406, 4e 423)

• Subscapularis bursa.
• Subacromial bursa.

A synovial sheath for the long head of the biceps lies in the intertubercular sulcus.

The coracoacromial arch prevents superior displacement (Clemente 78; Grant p. 532; Netter 3e 406, 4e 423). It is formed by the :

1) Coracoid process

2) Coracoacromial ligament

3) Acromion

Motor innervation of the shoulder joint (Grant p. 482):

• C5: flexion, abduction and lateral rotation
• C6, 7, 8: extension, adduction and medial rotation
  • C5, 6 lesion due to trauma to the shoulder will result in the "tip-taking" position.

Sensory nerves to the shoulder joint are from the:

• suprascapular nerve,
• axillary nerve,
• lateral pectoral nerve,
• and the posterior cord (C5, 6)

The elbow joint (articulatio cubiti; Clemente 85-87; Grant p. 546-547; Netter 3e 419-421, 4e 436-438)

• Hinge (ginglymus) joint
• The capsule is loose anteriorly and posteriorly for flexion and extension.
• The collateral ligaments prevent medial and lateral displacement (Clemente 86-87; Grant p. 546-547; Netter 3e 421, 4e 438).

Distal end of the humerus (Clemente 87; Grant p. 544; Netter 3e 419, 4e 436):

• trochlea and capitulum
• coronoid fossa (anteriorly) and olecranon fossa (posteriorly)

Proximal end of the ulna:

• coronoid process (with the radial notch laterally and the tuberosity anteriorly for attachment of the brachialis tendon)
• olecranon process (with a subcutaneous olecranon bursa; Grant p. 544)
• trochlear (semilunar) notch

Proximal head of the radius is disc-shaped and rotates on the capitulum (Clemente 87; Grant p. 524-527; Netter 3e 419-420, 4e 438).

Proximal radioulnar joint

The head of the radius is held by the annular ligament attached to the radial notch (Clemente 87; Grant p. 544-545; Netter 3e 421, 4e 438).

Ligaments at the elbow (Clemente 86-87; Grant p. 546-547; Netter 3e 421, 4e 438)

a) Radial collateral ligament (lateral ligament): from the lateral epicondyle to the side of the annular ligament, strengthening the latter. This also serves as the partial origin for the supinator and extensor carpi radialis.

b) Ulnar collateral ligament (medial ligament): from the medial epicondyle to the medial margin of the trochlear notch. The anterior fibers attach to the coronoid process and form the partial origin of the flexor digitorum superficialis.

The fibrous capsule extends to the upper margins of the coronoid and radial fossae anteriorly. Distally, it attaches to the margins of the trochlear notch and annular ligament.

A synovial fat pads exist between the fibrous capsule and synovial membrane (Clemente 86; Grant p. 544; Netter 3e 421, 4e 438).

The synovial capsule droops below the lower margin of the annular ligament and attaches to the neck of the radius to allow for rotation of the head of the radius (Clemente 86; Grant p. 548; Netter 3e 421, 4e 438).

The intermediate radioulnar joint

is formed by the interosseous membrane between the radius and the ulna (Clemente 88; Grant p. 551; Netter 3e 422, 4e 439).

The distal radioulnar joint

• The head of the ulna has a semicircular surface for the ulnar notch of the radius and a distal semilunar surface for the triangular articular disc attached to the fovea, at the base of the styloid process. This articular disc separates the distal radioulnar joint from the radiocarpal joint (Clemente 88, 93; Grant p. 590; Netter 3e 438, 4e 439, 455).

The wrist (radiocarpal) joint

is formed by the inferior articular surface of the radius and the articular disc.

Scaphoid, lunate and triquetrum (note their respective positions in radial and ulnar deviations of the hand; Clemente plate 83; Grant p. 592; Netter 3e 436, 4e 453).

Ligaments (Clemente 92-93; Grant p. 590-591; Netter 3e 424, 425, 4e 437-438, 4e 454-455).:

• Palmar and dorsal radiocarpal ligaments (from the radius to the proximal carpals and capitate, anteriorly and posteriorly)
• The radial and ulnar collateral ligaments (from the styloid processes to the scaphoid and triquetrum respectively)

The midcarpal (transverse carpal) joint (Clemente 93; Grant p. 593; Netter 3e 438, 4e 455)

• between the proximal and distal rows of the carpal bones
• flexion of the wrist is performed mostly at this joint

Intercarpal ligaments are dorsal and palmar bands radiating from the capitate and interosseous ligaments.

A slight gliding movement is possible between the carpal bones.

Carpometacarpal joints (Clemente 93; Grant p. 590, 594; Netter 3e 436-438, 4e 455)

• Trapezium and metacarpal 1 (saddle joint)
• Metacarpal 2 is wedged between the trapezium, trapezoid and the capitate.
• Metacarpal 3 articulates with the distal surface of the capitate
• The hamate articulates with metacarpals 4 and 5

The sides of the metacarpals articulate with one another.

Metacarpophalangeal joints (Clemente 93; Grant p. 595; Netter 3e 440-441, 4e 457-458)

• can flex and extend.
• the collateral ligaments are taut on flexion and slack on extension.
• can abduct and adduct only when the joint is extended.

The extensor expansions serve dorsally as ligaments (Clemente 69; Grant p. 583; Netter 3e 447, 4e 464-470).

The palmar ligaments or plates (volar accessory ligaments; Clemente 92; Grant p. 571, 595; Netter 3e 441, 4e 458).

• are formed by a thickening of the capsule.
• are united by the deep transverse metacarpal ligaments
• prevent the metacarpals from spreading.

The digital bands of the palmar aponeurosis are attached to the transverse ligaments anteriorly. (Clemente 64; Grant p. 561; Netter 3e 442, 4e 459).  The slips from the extensor expansions are attached to them posteriorly.

The carpometacarpal joint of the thumb allow for flexion, extension, abduction, adduction and some rotation.

Interphalangeal joints are hinge joints.

updated 08/23/2009

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