Anatomy Upper Limb

The clavicle has a gentle S-shaped contour, with the forward-facing convex part medial forward-facing concave part lateral. The acromial (lateral) end of the clavicle is flat and has a small oval facet on its surface for articulation with a similar facet on the medial surface of the acromion of the scapula The sternal (medial) end is more robust and somewhat quadrangular in shape. and has a much larger facet for articulation mainly with the manubrium of the sternum, and to a lesser extent, with the first costal cartilage. The inferior surface of the lateral third of the clavicle possesses a distinct tuberosity consisting of a tubercle (the conoid tubercle) and lateral roughening (the trapezoid line), for attachment of the important coracoclavicular ligament. The scapula is a large, flat triangular bone with: ■ three angles (lateral, superior, and inferior), ■ three borders (superior, lateral, and medial), ■ two surfaces (costal and posterior). ■three processes (acromion, spine, and coracoid process). The lateral angle of the scapula is marked by a shallow glenoid cavity, which articulates with the head of the humerus to form the shoulder joint. The infraglenoid tubercle is the site of attachment for the long head of the triceps brachii muscle. The supraglenoid tubercle is the site of attachment for the long head of the biceps brachii muscle. 1|Page . A prominent spine subdivides the posterior surface of the scapula into a small, superior supraspinous fossa and a much larger, inferior infraspinous fossa. The acromion, which is an anterolateral projection of the spine, arches over the glenohumeral joint and articulates, via a small oval facet on its distal end, with the clavicle. The posterior surface, the costal surface of the scapula is unremarkable, being characterized by a shallow concave subscapular fossa which is related to muscle (subscapularis), moves freely over the underlying thoracic wall. The superior border is marked on its lateral end by: ■ the coracoid process, a hook-like structure that projects anterolaterally and is positioned directly inferior to the lateral part of the clavicle; and ■ the small but distinct suprascapular notch, which lies immediately medial to the root of the coracoid process. 2|Page The head is half-spherical in shape and projects medially and somewhat superiorly to articulate with the much smaller glenoid cavity of the scapula. The anatomical neck is very short and is formed by a narrow constriction immediately distal to the head. Greater and lesser tubercles The greater and lesser tubercles are prominent landmarks on the proximal end of the humerus and serve as attachment sites for the four rotator cuff muscles of the glenohumeral joint. The greater tubercle is lateral in position. Its superior surface and posterior surface are marked by three large smooth facets for muscle tendon attachments: (SIT) ■ The superior facet is for attachment of the supraspinatus muscle. ■ The middle facet is for attachment of the infraspinatus. ■ The inferior facet is for attachment of the teres minor. The lesser tubercle is anterior in position and its surface is marked by a large smooth impression for attachment of the subscapularis muscle. A deep intertubercular sulcus (bicipital groove) separates the lesser and greater tubercles and the tendon of the long head of the biceps brachii passes through this sulcus. Roughenings on the lateral and medial lips and on the floor of the intertubercular sulcus mark sites \ for the attachment of the pectoralis major, teres major, and latissimus dorsi muscles, respectively. 3|Page The deltoid tuberosity on the lateral surface of the humerus midway along its length, which is where the deltoid muscle inserts onto the humerus. In approximately the same position, but on the medial surface of the bone, there is a thin vertical roughening for attachment of the coracobrachialis muscle. The glenohumeral joint is a synovial ball and socket articulation between the head of the humerus and the glenoid cavity of the scapula.. Joint stability is provided, instead, by the rotator cuff muscles, the long head of the biceps brachii muscle, related bony processes, and extracapsular ligaments. Movements at the joint include flexion, extension, abduction, adduction, medial rotation, lateral rotation, and circumduction. The glenoid cavity is deepened and expanded peripherally by a fibrocartilaginous collar (the glenoid labrum) which attaches to the margin of the fossa. Superiorly, this labrum is continuous with the tendon of the long head of the biceps brachii muscle, which attaches to the supraglenoid tubercle. The anterior border begins on the medial side of the bone as a continuation of the radial tuberosity. The interosseous border is sharp and is the attachment site for the interosseous membrane, which links the radius to the ulna. 4|Page An oval roughening for the attachment of the pronator teres marks approximately the middle of the lateral surface of the radius. Viewed anteriorly, the distal end of the radius is broad and somewhat flattened anteroposteriorly. The posterior surface of the radius is characterized by the presence of a large DORSAL TUBERCLE OF LISTER, which acts as a pulley for the tendon of one of the extensor muscles of the thumb (extensor pollicis longus). The medial surface is marked by a prominent facet for articulation with the distal end of the ulna. The lateral surface of the radius is diamond shaped and extends distally as a radial styloid process. The distal end of the bon e is marked by two facets for articulation with two carpal bones (the scaphoid and lunate). The small carpal bones of the wrist are arranged in two rows, a proximal and a distal row, each consisting of four bones From lateral to medial and when viewed from anteriorly, the proximal row of bones consists of: ■ the boat-shaped scaphoid, ■ the lunate, which has a crescent shape, ■ the three-sided triquetrum bone, and ■ the pea-shaped pisiform. The pisiform is a sesamoid bone in the tendon of the flexor carpi ulnaris and articulates with the 5|Page anterior surface of the triquetrum. From lateral to medial and when viewed from anteriorly, the distal row of carpal bones consists of: ■ the irregular four-sided trapezium bone, ■ the four-sided trapezoid, ■the capitate, which has a head, and ■ the hamate, which has a hook. The trapezium articulates with the metacarpal bone of the thumb. The largest of the carpal bones, the capitate, articulates with the base of metacarpal III. The hamate, which is positioned just lateral and distal to the pisiform, has a prominent hook (hook of hamate) on its palmar surface that projects anteriorly and it is in contact with base of 4th and 5th metacarpals. 6|Page The carpal tunnel is formed anteriorly by the carpal bones and the flexor retinaculum . The base of the carpal arch is formed : medially by the pisiform and the hook of the hamate and laterally by the tubercles of the scaphoid and trapezium. . (1)The four tendons of the flexor digitorum profundus (2)the four tendons of the flexor digitorum superficialis (3)the tendon of the flexor pollicis longus pass through the carpal tunnel (4)the median nerve. The flexor retinaculum holds the tendons to the bony plane at the wrist and prevents them from “bowing.” Free movement of the tendons in the carpal tunnel is facilitated by synovial sheaths, which surround the tendons. All the tendons of the flexor digitorum profundus and flexor digitorum superficialis are surrounded by a single synovial sheath A separate sheath surrounds the tendon of the flexor pollicis longus. The tendon of the flexor carpi radialis is surrounded by a synovial sheath and passes through a tubular compartment formed by the attachment of the lateral aspect of the flexor retinaculum to the margins of a 7|Page groove on the medial side of the tubercle of the trapezium. Structures passing superficial to flexor retinaculum 1)The ulnar artery 2)The ulnar nerve 3)Tendon of the palmaris longus The tendon of the palmaris longus is not surrounded by a synovial sheath. 4)Palmar cutanous branch ullnar nerve 5)Palmar cutanous branch median nerve The “anatomical snuffbox” is a term given to the triangular depression formed on the posterolateral side of the wrist and metacarpal I by the extensor tendons passing into the thumb. The base of the triangle is at the wrist and the apex is directed into the thumb. ■The lateral border is formed by the tendons of the abductor pollicis longus and extensor pollicis brevis. ■ The medial border is formed by the tendon of the extensor pollicis longus. ■ The floor of the impression is formed by the scaphoid and trapezium, and the distal ends of the tendons of the extensor carpi radialis longus and extensor carpi radialis brevis. (1)The radial artery. 8|Page (2)Terminal parts of the superficial branch of the radial nerve pass subcutaneously over the snuffbox (3) the origin of the cephalic vein from the dorsal venous arch of the hand. . The brachial plexus is a somatic nerve plexus formed by: the anterior rami of C5 to C8, and most of the anterior ramus of T1. The parts of the brachial plexus, from medial to lateral, are roots, trunks, divisions, and cords. Roots…in relations to transverse foramina cervical vertebrae Trunks…in post triangle post to subclavian Artery between ant and mid scalene muscles Divisions….Behind mid 1/3 clavicle Cords…In axilla in relation to second part Axillary artery The roots of the brachial plexus are the anterior rami of C5 to C8, and most of T1. Close to their origin, the roots receive gray rami communicantes from the sympathetic trunk . These carry postganglionic sympathetic fibers onto the roots for distribution to the periphery. The three trunks of the brachial plexus originate from the roots, pass laterally over rib I, and enter the axilla: ■ The superior trunk is formed by the union of C5 and C6 roots. ■ The middle trunk is a continuation of the C7 root. 9|Page ■ The inferior trunk is formed by the union of the C8 and T1 roots. The inferior trunk lies on rib I posterior to the subclavian artery; the middle and superior trunks are more superior in position. Each of the three trunks of the brachial plexus divides into an anterior and a posterior division : No peripheral nerves originate directly from the divisions of the brachial plexus. The three cords of the brachial plexus originate from the divisions and are related to the second part of the axillary artery: ■ The lateral cord results from the union of the anterior divisions of the upper and middle trunks and therefore has contributions from C5 to C7. it is positioned lateral to the second part of the axillary artery. ■ The medial cord is medial to the second part of the axillary artery and is the continuation of the anterior division of the inferior trunk—it contains contributions from C8 and T1. ■ The posterior cord occurs posterior to the second part of the axillary artery and originates as the union of all three posterior divisions—it contains contributions from all roots of the brachial plexus (C5 to T1). In addition to small segmental branches from C5 to C8 to muscles of the neck and a contribution of C5 to the phrenic nerve, the roots of the brachial plexus give rise to the dorsal scapular and long thoracic nerves ■ innervates the rhomboid major and minor muscles from their deep surface 10 | P a g e ■ originates from the anterior rami of C5 to C7, ■ passes vertically down the neck, through the axillary inlet, and down the medial wall of the axilla to supply the serratus anterior muscle and 11 | P a g e ■ lies on the superficial aspect of the serratus anterior muscle. The only branches from the trunks of the brachial plexus are two nerves that originate from the superior trunk (upper trunk): the suprascapular nerve and the nerve to the subclavius muscle ■ originates from the superior trunk of the brachial plexus, ■ innervates the supraspinatus and infraspinatus muscles. ) is a small nerve that: ■ originates from the superior trunk of the brachial plexus, ■ passes anteroinferiorly over the subclavian artery and vein. ■ innervates the subclavius muscle. Three nerves originate entirely or partly from the lateral cord . is the most proximal of the branches from the lateral cord. It passes anteriorly, together with the thoracoacromial artery, to penetrate the clavipectoral fascia that spans the gap between the subclavius and pectoralis minor muscles, and innervates the pectoralis major muscle. is a large terminal branch of the lateral cord. It passes laterally to penetrate the coracobrachialis muscle and pass between the biceps brachii and brachialis muscles in the arm, and innervates all three flexor muscles(BBC) in the anterior compartment of the arm, terminating as the lateral cutaneous nerve of the forearm. is the largest terminal branch of the lateral cord and passes medially to join a similar branch from the medial cord to form the median nerve . The medial cord has five branches. It receives a communicating branch from the lateral pectoral nerve and then passes anteriorly between the axillary artery and axillary vein. Branches of the nerve penetrate and supply the pectoralis minor muscle. Some of these branches pass through the muscle to reach and supply the pectoralis major muscle.. 12 | P a g e passes through the axilla and into the arm where it penetrates deep fascia and supplies skin over the medial side of the distal third of the arm. In the axilla, the nerve communicates with the intercostobrachial nerve of T2. Fibers of the medial cutaneous nerve of the arm innervate the upper part of the medial surface of the arm and floor of the axilla. originates just distal to the origin of the medial cutaneous nerve of the arm. It passes out of the axilla then continues down the arm to penetrate the deep fascia with the basilic vein, continuing inferiorly to supply the skin over the anterior surface of the forearm. It innervates skin over the medial surface of the forearm down to the wrist. passes laterally to join with a similar root from the lateral cord to form the median nerve anterior to the third part of the axillary artery. *MOTOR: It is a large terminal branch of the medial cord . The ulnar nerve passes through the arm and forearm into the hand where it innervates all intrinsic muscles of the hand (except LOAF Muscles for the three thenar muscles and the two lateral lumbrical muscles). On passing through the forearm, branches of the ulnar nerve innervate the flexor carpi ulnaris muscle and the medial half of the flexor digitorum profundus muscle. *SENSORY: The ulnar nerve innervates skin over the palmar surface of the little finger, medial half of the ring finger, and associated palm and wrist, and the skin over the dorsal surface of the medial part of the hand. Five nerves originate from the posterior cord of the brachial plexus: (ULNAR) ■ the Upper subscapular nerve, ■ the Lower subscapular nerve, ■ the thoracodorsal nerve (Nerve to Latissmus dorsi) ■ the axillary nerve ■ the radial nerve. . is short and passes into and supplies the subscapularis muscle. is the longest. of these three nerves and passes vertically along the posterior axillary wall. It penetrates and innervates the latissimus dorsi muscle. also passes inferiorly along the posterior axillary wall and innervates the subscapularis and teres major muscles. 13 | P a g e originates from the posterior cord and passes inferiorly and laterally along the posterior wall to exit the axilla through the quadrangular space with post circumflex humeral artery. It passes posteriorly around the surgical neck of the humerus and innervates both the deltoid and teres minor muscles. A superior lateral cutaneous nerve of the arm originates from the axillary nerve after passing through the quadrangular space and loops around the posterior margin of the deltoid muscle to innervate skin in that region. is the largest terminal branch of the posterior cord. It passes out of the axilla and into the posterior compartment of the arm by passing through the triangular interval between the inferior border of the teres major muscle, the long head of the triceps brachii muscle, and the shaft of the humerus. It is accompanied through the triangular interval by the profunda brachii artery, which originates from the brachial artery in the anterior compartment of the arm. The radial nerve and its branches innervate: ■ all muscles in the posterior compartments of the arm and forearm. ■ the skin on the posterior aspect of the arm and forearm, the lower lateral surface of the arm, and the dorsal lateral surface of the hand. The posterior cutaneous nerve of the arm (posterior brachial cutaneous nerve) originates from the radial nerve in the axilla and innervates skin on the posterior surface of the arm. The median nerve is formed anterior to the third part of the axillary artery by the union of lateral and medial roots originating from the lateral and medial cords of the brachial plexus. It passes into the arm laterlal then anterior to the brachial artery then medially as the most medial structure in the cubital fossa and through the arm into the forearm between two heads of pronator teres muscle , where branches innervate most of the muscles in the anterior compartment of the forearm (except for the flexor carpi ulnaris muscle and the medial half of the flexor digitorum profundus muscle, which are innervated by the ulnar nerve) (LOAF)Muscles 14 | P a g e ■ the three thenar muscles associated with the thumb. ■ the two lateral lumbrical muscles associated with movement of the index and middle fingers. ■ the skin over the palmar surface of the lateral three and one-half digits and over the lateral side of the palm and middle of the wrist. 15 | P a g e 16 | P a g e Its boundaries are formed by: ■ the inferior margin of the Teres minor muscle, ■ the surgical neck of the humerus laterally. ■ the superior margin of the teres major muscle ■ the lateral margin of the long head of the triceps brachii muscle. CONTENTS: are the axillary nerve and the posterior circumflex humeral artery and vein. Its boundaries are formed by: ■ the medial margin of the long head of the triceps brachii muscle, ■ the superior margin of the teres major muscle, and ■ the inferior margin of the teres minor muscle. CONTENTS: are The circumflex scapular artery and vein. Its boundaries are formed by: ■ the lateral margin of the long head of the triceps brachii muscle, ■ the shaft of the humerus, and ■ the inferior margin of the teres major muscle. CONTENTS: are The radial nerve and Profunda Brachii artery. 17 | P a g e erb palsy Radial aspect UppeR arm and forearm UppeR trunk (c5,6,7) MOTOR: WAITER TIP DEFORMITY -Adduction, Int rotation, Forearm extension and pronation SENSORY: arm and forearm U nar aspect ower forearm and hand ower trunk(C8,T1) MOTOR: CLAW HAND -Wasting of intrinsic muscles of the hand -Paralysis of all wrist flexors except (FCU) SENSORY: forearm and hand 18 | P a g e 19 | P a g e 20 | P a g e The anterior wall of the axilla is formed by the lateral part of the pectoralis major muscle, the underlying pectoralis minor and subclavius muscles, and the clavipectoral fascia The medial wall of the axilla consists of the upper thoracic wall (the ribs and related intercostal tissues) and the serratus anterior muscle The lateral wall of the axilla is narrow and formed entirely by the intertubercular sulcus of the humerus. The posterior wall of the axilla is complex . Its bone framework is formed by the costal surface of the scapula. Muscles of the wall are: (SLT) 1) the subscapularis muscle (associated with the costal surface of the scapula), 2)the latissimus dorsi and teres major muscles (which pass into the wall from the back and posterior scapular region), and 3)the long head of the triceps brachii muscle (which passes vertically down the wall and into the arm). Gaps between the muscles of the posterior wall form apertures through which structures pass between the axilla, posterior scapular region, and posterior compartment of the arm. Contents of the axilla : Passing through the axilla are the major vessels, nerves, and lymphatics of the upper limb. The space also contains the proximal parts of two muscles of the arm, the axillary artery and vein. The subclavian artery in the neck becomes the axillary artery at the lateral margin of the first rib becoming the brachial artery at the inferior margin of the teres major muscle. The axillary artery is separated into three parts by the pectoralis minor muscle, ■ The first part is proximal to the pectoralis minor. ■ The second part is posterior to the pectoralis minor. 21 | P a g e ■ The third part is distal to the pectoralis minor. Six branches arise from the axillary artery according to the parts: ■ FIRST PART: One branch, the superior thoracic artery. ■ SECOND PART: Two branches: the thoraco-acromial artery the lateral thoracic artery. ■THIRD PART : Three branches the sub scapular artery which gives circumflex scapular and thoracodorsal arteries the anterior circumflex humeral artery the posterior circumflex humeral artery. 22 | P a g e All lymphatics from the upper limb drain into lymph nodes in the axilla. In addition, axillary nodes receive drainage from an extensive area on the adjacent trunk, which includes regions of the upper back and shoulder, the lower neck, the chest, and the upper anterolateral abdominal wall. Axillary nodes also receive drainage from approximately 75% of the mammary gland. The 20–30 axillary nodes are generally divided posteromedial to the axillary vein receive most of the lymphatic drainage from the upper limb. occur along the inferior margin of the pectoralis minor muscle along the course of the lateral thoracic vessels and receive drainage from the abdominal wall, the chest, and the mammary gland. on the posterior axillary wall in association with the subscapular vessels drain the posterior axillary wall and receive lymphatics from the back, the shoulder, and the neck. are embedded in axillary fat and receive tributaries from humeral, subscapular, and pectoral groups of nodes (the above three stations). are the most superior group of nodes in the axilla and drain all other groups of nodes in the region. In addition, they receive lymphatic vessels that accompany the cephalic vein as well as vessels that drain the superior region of the mammary gland. The major artery of the arm, the brachial artery, is found in the anterior compartment. Beginning as a continuation of the axillary artery at the lower border of the teres major muscle, it terminates just distal to the elbow joint where it divides into the radial and ulnar arteries. In the proximal arm, the brachial artery lies on the medial side. In the distal arm, it moves laterally to assume a position midway between the lateral epicondyle and the medial epicondyle of the humerus. It crosses anteriorly to the elbow joint where it lies immediately medial to the tendon of the biceps brachii muscle. The brachial artery is palpable along its length. In proximal regions, the brachial artery can be compressed against the medial side of the humerus. (1)In the arm include those to adjacent muscles and two ulnar collateral vessels, which contribute to a network of arteries around the elbow joint. (2)Additional branches are the profunda brachii artery and nutrient arteries to the humerus, which pass through a foramen in the anteromedial surface of the humeral shaft (3)Two terminal branches:ulnar and radial arteries 23 | P a g e The profunda brachii artery, the largest branch of the brachial artery, passes into and supplies the posterior. compartment of the arm. It enters the posterior compartment with the radial nerve and together they pass through the triangular interval, which is formed by the shaft of the humerus, the inferior margin of the teres major muscle, and the lateral margin of the long head of the triceps muscle. They then pass along the radial groove on the posterior surface of the humerus deep to the lateral head of the triceps brachii muscle. 24 | P a g e supply adjacent muscles and anastomose with the posterior circumflex humeral artery. The artery terminates as two collateral vessels, which contribute to an anastomotic network of arteries around the elbow joint The radial artery originates from the brachial artery at approximately the neck of the radius and passes along the lateral aspect of the forearm. It is: ■ just deep to the brachioradialis muscle in the proximal half of the forearm, ■ related on its lateral side to the superficial branch of the radial nerve in the middle third of the forearm ■ medial to the tendon of the brachioradialis muscle and covered only by deep fascia, superficial fascia, and skin in the distal forearm. The radial artery leaves the forearm, passes around the lateral side of the wrist, and penetrates the posterolateral aspect of the hand between the bases of metacarpals I and II. Branches of the radial artery in the hand often provide the major blood supply to the thumb and lateral side of the index finger. ■ a radial recurrent artery, which contributes to an anastomotic network around the elbow joint and to numerous vessels that supply muscles on the lateral side of the forearm. ■ a small palmar carpal branch, which contributes to an anastomotic network of vessels that supply the carpal bones and joints; ■ a somewhat larger branch, the superficial palmar branch, which enters the hand by passing through, or superficial to, the thenar muscles at the base of the thumb and anastomoses with the superficial palmar arch formed by the ulnar artery. THEN gives Principes Pollicis and radialis indices arteries The ulnar artery is larger than the radial artery and passes down the medial side of the forearm. It leaves the cubital fossa by passing deep to the pronator teres muscle, and then passes through the forearm in the fascial plane between the flexor carpi ulnaris and flexor digitorum profundus muscles. In the distal forearm, the ulnar artery often remains tucked under the anterolateral lip of the flexor carpi ulnaris tendon, and is therefore not easily palpable. In distal regions of the forearm, the ulnar nerve is immediately medial to the ulnar artery. The ulnar artery leaves the forearm, enters the hand by passing lateral to the pisiform bone and superficial to the flexor retinaculum of the wrist, and arches over the palm. It is often the major blood supply to the medial three and one-half digits. ■ the ulnar recurrent artery with anterior and posterior branches, which contribute to an anastomotic network of vessels around the elbow joint. ■ numerous muscular arteries, which supply surrounding muscles; the common interosseous artery, which divides into anterior and posterior interosseous arteries and 25 | P a g e ■ two small carpal arteries (dorsal carpal branch and palmar carpal branch), which supply the wrist. The posterior interosseous artery passes dorsally over the proximal margin of the interosseous membrane into the posterior compartment of the forearm. The anterior interosseous artery passes distally along the anterior aspect of the interosseous membrane and supplies muscles of the deep compartment of the forearm and the radius and ulna. It has numerous branches, which perforate the interosseous membrane to supply deep muscles of the posterior compartment; it also has a small branch, which contributes to the vascular network around the carpal bones and joints. Perforating the interosseous membrane in the distal forearm, the anterior interosseous artery terminates by joining the posterior interosseous artery 26 | P a g e 27 | P a g e 28 | P a g e 29 | P a g e 30 | P a g e The median nerve enters the arm from the axilla at the inferior margin of the teres major muscle. It passes vertically down the medial side of the arm in the anterior compartment between two heads of pronator teres muscle and is related to the brachial artery throughout its course: ■ In proximal regions, the median nerve is immediately lateral to the brachial artery. ■ In more distal regions, the median nerve crosses to the medial side of the brachial artery and lies anterior to the elbow joint. The median nerve has no major branches in the arm. The ulnar nerve enters the arm with the median nerve and axillary artery. It passes through proximal regions medial to the axillary artery. In the middle of the arm, the ulnar nerve penetrates the medial intermuscular septum and enters the posterior compartment where it lies anterior to the medial head of the triceps brachii muscle. It passes posterior to the medial epicondyle of the humerus and then into the anterior compartment of the forearm between heads of flexor carpi ulnaris muscle. The ulnar nerve has no major branches in the arm. The radial nerve originates from the posterior cord of the brachial plexus and enters the arm by crossing the inferior margin of the teres major muscle. As it enters the arm, it lies posterior to the brachial artery. Accompanied by the profunda brachii artery, the radial nerve enters the posterior compartment of the arm by passing through the triangular interval. As the radial nerve passes diagonally, from medial to lateral, through the posterior compartment, it lies in the radial groove directly on bone. On the lateral side of the arm, it passes anteriorly through the lateral intermuscular septum and enters the anterior compartment where it lies between the brachialis muscle and brachioradialis muscle, which attaches to the lateral supraepicondylar ridge of the humerus. The radial nerve enters the forearm anterior to the lateral epicondyle of the humerus, just deep to the brachioradialis muscle. ■ Muscular branches include those to the triceps brachii, brachioradialis, and extensor carpi radialis longus muscles. The radial nerve contributes to the innervation of the lateral part of the brachialis muscle. ■ Cutaneous branches of the radial nerve that originate in the posterior compartment of the arm are the inferior lateral cutaneous nerve of the arm and the posterior cutaneous nerve of the forearm, both of which penetrate through the lateral head of the triceps brachii muscle and the overlying deep fascia to become subcutaneous 31 | P a g e The cubital fossa is an important area of transition between the arm and the forearm. : ■ the brachioradialis muscle originating from the lateral supra-epicondylar ridge of the humerus. ■ the pronator teres muscle originating from the medial epicondyle of the humerus . The base of the triangle is an imaginary horizontal line between the medial and lateral epicondyles. The bed or floor of the fossa is formed mainly by the brachialis muscle. The major contents of the cubital fossa: ((from medial to lateral)) are: 1.Median Nerve 2.Brachial Artery 3.Biceps Brachii tendon 4.Radial Nerve 32 | P a g e MBBR (1)Skin (2)Superficial Fascia containing: Median cubital vein,ant branches of medial and lateral cut nerves of the forearm and supratrochlear lymph nodes (3)Deep fascia reinforced by the bicipital aponeurosis The intrinsic muscles of the hand are the palmaris brevis, interossei, adductor pollicis, thenar, hypothenar, and lumbrical muscles. Unlike the extrinsic muscles that originate in the forearm, insert in the hand, and function in forcefully gripping (“power grip”) with the hand, the intrinsic muscles occur entirely in the hand and mainly execute precision movements (“precision grip”) with the fingers and thumb. All of the intrinsic muscles of the hand are innervated by the deep branch of the ulnar nerve except for the three thenar and two lateral lumbrical muscles, which are innervated by the median nerve(LOAF Muscles) . The intrinsic muscles are predominantly innervated by spinal cord segment T1 with a contribution from C8. 33 | P a g e are muscles between and attached to the metacarpals. They insert into the proximal phalanx of each digit and into the extensor hood and are divided into two groups, the dorsal interossei and the palmar interossei.. All of the interossei are innervated by the deep branch of the ulnar nerve. Palmar….adduction (PAD) Dorsal….abduction(DAP) The three thenar muscles (the opponens pollicis, flexor pollicis brevis, and abductor pollicis brevis muscles) are associated with opposition of the thumb to the fingers and with delicate movements of the thumb and are responsible for the prominent swelling (thenar eminence) on the lateral side of the palm at the base of the thumb. The thenar muscles are innervated by the recurrent branch of the median nerve. The hypothenar muscles (the opponens digiti minimi, abductor digi ti minimi, and flexor digiti minimi brevis) contribute to the swelling (hypothenar eminence) on the medial side of the palm at the base of the little finger. The hypothenar muscles are similar to the thenar muscles in name and in organization. Unlike the thenar muscles, the hypothenar muscles are innervated by the deep branch of the ulnar nerve and not by the recurrent branch of the median nerve 34 | P a g e . The blood supply to the hand is by the radial and ulnar arteries, which form two interconnected vascular arches (superficial and deep) in the palm. Vessels to the digits, muscles, and joints originate from the two arches and the parent arteries: ■ The radial artery contributes substantially to the supply of the thumb and the lateral side of the index. ■The remaining digits and the medial side of the index finger are supplied mainly by the ulnar artery. The ulnar artery and ulnar nerve enter the hand on the medial side of the wrist. The vessel lies between the palmaris brevis and the flexor retinaculum and is lateral to the ulnar nerve and the pisiform bone. Distally, the ulnar artery is medial to the hook of the hamate bone and then swings laterally across the palm, forming the superficial palmar arch, which is superficial to the long flexor tendons of the digits and just deep to the palmar aponeurosis. On the lateral side of the palm, the arch communicates with a palmar branch of the radial artery. One branch of the ulnar artery in the hand is the deep palmar branch to anastomose with the deep palmar arch derived from the radial artery. Branches from the superficial palmar arch include: ■ A Palmar Digital Artery to the medial side of the little finger. ■Three Large, Common Palmar Digital Arteries, which ultimately provide the principal blood supply to the lateral side of the little finger, both sides of the ring and middle fingers, and the medial side of the index finger. they are joined by palmar metacarpal arteries from the deep palmar arch before bifurcating into the proper palmar digital arteries, which enter the fingers. The radial artery curves around the lateral side of the wrist and passes over the floor of the anatomical snuffbox and into the deep plane of the palm by penetrating anteriorly through the back of the hand. It passes between the two heads of the first dorsal interosseous muscle and then between the two heads of the adductor pollicis to access the deep plane of the palm and form the deep palmar arch. The deep palmar arch passes medially through the palm between the metacarpal bones and the long flexor tendons of the digits. On the medial side of the palm, it communicates with the deep palmar branch of the ulnar artery. BRANCHES OF THE RADIAL ARTERY: Before penetrating the back of the hand, the radial artery gives rise to two vessels: ■ A Dorsal Carpal Branch, which passes medially as the dorsal carpal arch, across the wrist. 35 | P a g e ■Three Dorsal Metacarpal Arteries, which subsequently divide to become small dorsal digital arteries, which enter the fingers. ■ First Dorsal Metacarpal Artery, which supplies adjacent sides of the index finger and thumb. Two vessels, The Princeps Pollicis Artery and The Radialis Indicis Artery, arise from the radial artery in the plane between the first dorsal interosseous and adductor pollicis. The princeps pollicis artery is the major blood supply to the thumb, and the radialis indicis artery supplies the lateral side of the index finger. The deep palmar arch gives rise to: ■ Three Palmar Metacarpal Arteries, which join the common palmar digital arteries from the superficial palmar arch. ■ Three Perforating Branches, which pass posteriorly between the heads of origin of the dorsal interossei to anastomose with the dorsal metacarpal arteries from the dorsal carpal arch 36 | P a g e The hand is supplied by the ulnar, median, and radial nerves. All three nerves contribute to cutaneous or general sensory innervation. The ulnar nerve innervates all intrinsic muscles of the hand except for the three thenar muscles and the two lateral lumbricals, which are innervated by the median nerve. The radial nerve only innervates skin on the dorsolateral side of the hand. The ulnar nerve enters the hand lateral to the pisiform and posteromedially to the ulnar artery. Immediately distal to the pisiform, it divides into a deep branch, which is mainly motor, and a superficial branch, which is mainly sensory. The deep branch of the ulnar nerve passes with the deep branch of the ulnar artery. It penetrates and supplies the hypothenar muscles to reach the deep aspect of the palm, arches laterally across the palm, deep to the long flexors of the digits, and supplies the interossei, the adductor pollicis, and the two medial lumbricals. In addition, the deep branch of the ulnar nerve contributes small articular branches to the wrist joint. The ulnar nerve is most commonly injured at two sites: the elbow and the wrist. ■ At the elbow, the nerve lies posterior to the medial epicondyle. ■ At the wrist, the ulnar nerve passes superficial to the flexor retinaculum and lies lateral to the pisiform bone. Ulnar nerve lesions are characterized by “clawing” of the hand, in which the metacarpophalangeal joints of the fingers are hyper extended and the interphalangeal joints are flexed because the function of most of the intrinsic muscles of the hand is lost. Clawing is most pronounced in the medial fingers because the function of all intrinsic muscles of these digits is lost while in the lateral two digits, the lumbricals are innervated by the median nerve. Function of the adductor pollicis muscle is also lost. In lesions of the ulnar nerve at the elbow, function of the flexor carpi ulnaris muscle and flexor digitorum profundus to the medial two digits is lost as well. Clawing of the hand, particularly of the little and ring fingers, is worse with lesions of the ulnar nerve at the wrist than at the elbow because interruption of the nerve at the elbow paralyzes the ulnar half of the flexor digitorum profundus, which leads to lack of flexion at the distal interphalangeal joints in these fingers. 37 | P a g e Ulnar nerve lesions at the elbow and wrist result in impaired sensory innervation on the palmar aspect of the medial one and one-half digits. Damage to the ulnar nerve at the wrist or at a site proximal to the wrist can be distinguished by evaluating the status of function of the dorsal branch (cutaneous) of the ulnar nerve, which originates in distal regions of the forearm. This branch innervates skin over the dorsal surface of the hand on the medial side. The median nerve is the most important sensory nerve in the hand because it innervates skin on the thumb, index and middle fingers, and lateral side of the ring finger. Sensory information from the lateral three and one-half digits enables the fingers to be positioned with the appropriate amount of force when using precision grip. The median nerve also innervates the thenar muscles that are responsible for opposition of the thumb to the other digits. The median nerve enters the hand by passing through the carpal tunnel and divides into a recurrent branch and palmar digital branches. The recurrent branch of the median nerve innervates the three thenar muscles and lateral two lumbricals. Around the elbow joint the radial nerve divides into its two terminal branches—the superficial branch and the deep branch. The most common radial nerve injury is damage to the nerve in the radial groove of the humerus, which produces a global paralysis of the muscles of the posterior compartment, resulting in wrist drop. 38 | P a g e Radial nerve damage can result from fracture of the shaft of the humerus as the radial nerve spirals around in the radial groove. The palmar digital nerves cross the palm deep to the palmar aponeurosis and the superficial palmar arch and enter the digits. They innervate skin on the palmar surfaces of the lateral three and one-half digits and cutaneous regions over the dorsal aspects of the distal phalanges (nail beds) of the same digits. In addition to skin, the digital nerves supply the lateral two lumbrical muscles. The typical injury produces reduction of sensation in the cutaneous distribution, predominantly over the posterior aspect of the hand. Severing the posterior interosseous nerve (continuation of deep branch of radial nerve) (which is purely motor) may paralyze the muscles of the posterior compartment of the forearm, but the nerve supply is variable. Typically, the patient may not be able to extend the fingers. The distal branches of the superficial branch of the radial nerve can be readily palpated as “cords” passing over the tendon of the extensor pollicis longus in the anatomical snuffbox. Damage to these branches is of little consequence because they supply only a small area of skin. 39 | P a g e 40 | P a g e