Sections: Click on the link(s) to view your course **Netter: Shoulder and Arm

Anatomy Extravaganza of the Upper Extremity 4.0 contact hours or.4 AOTA CEUs Editor: Walter B. Greene, MD Illustrated by: Frank H. Netter, MD EHT Instructors: Nancy Falkenstein, OTR/L, CHT and Susan Weiss OTR/L, CHT Click on SECTIONS (below) to View your Course: Description: This course is in written format. This is a mixed level learning course teaching the clinician an abundance of upper extremity anatomy details. View amazing Netter photographs and learn anatomy biomechanics, physical exam as well as a wide array of various disorders from the shoulder to the hand. The detailed photographs in this book will increase your understanding of fractures, bone anatomy, nerve compressions, the brachial plexus, muscular structures and more. You can print the chapters out and have a wonderful anatomy reference booklet to use in the clinic. This jammed packed anatomy course is priced right making it a fantastic way to earn CEU s for less. Used with permission from Elsevier/Mosby. Objectives: *Review the pertinent basic science of the more common clinical disorders of the shoulder, elbow wrist and hand. *Review rotator cuff pathology and treatment regimes *Introduce shoulder arthritis and intervention techniques *Review nerve entrapment syndromes and brachial plexus injuries *Learn about fractures of the proximal humerus, clavicle and scapula *Review the nerves passing the elbow and the various nerve entrapments *Learn about elbow arthritis, lateral epicondylitis, medial epicondylitis, and fractures about the elbow *Introduce hand anatomy and biomechanics *Review physical examination of the hand *Introduce the student to osteoarthritis of the hand, Kienbocks s disease, tendonitis, *Dupuytren s disease, ganglia, nerve entrapments, wounds, tendon injuries and *fractures *Introduce to pediatric conditions and congenital anomalies Sections: Click on the link(s) to view your course **Netter: Shoulder and Arm **Netter: Elbow and Forearm **Netter: Hand and Wrist

Chapter 14 The purpose of this chapter is to review the pertinent basic science of the more common clinical disorders of the shoulder. ANATOMY AND BIOMECHANICS The shoulder girdle includes three bones (the scapula, clavicle, and humerus) and three joints (the glenohumeral, acromioclavicular [AC], and sternoclavicular [SC] joints). The scapulothoracic articulation is also considered part of the shoulder girdle. For every 2 of glenohumeral motion, approximately 1 of scapulothoracic motion occurs. The AC and SC joints also participate in this scapulohumeral rhythm. As a result of this coordinated movement, the shoulder has a greater range of motion than any other joint in the body. The scapula is a triangular, flat bone that is surrounded by (Figures 14-1 and 14-2). Its curved coracoid process projects anteriorly from the superior border and is the site of origin for the coracobrachialis and the short head of the biceps. The other notable scapular prominence is the acromion, a spinelike process on the posterior aspect. The coracoacromial ligament stabilizes the humeral head in the superior direction. The two coracoclavicular ligaments prevent the clavicle from riding superiorly. The clavicle is an S-shaped tubular bone that articulates with the acromion laterally and the manubrium medially. The proximal end of the humerus includes the humeral head, the greater and lesser tuberosities, and the humeral neck. The head of the humerus is retroverted, or posteriorly angled, approximately 30 to match the anterior position of the scapula as it rests on the thoracic cavity. The pear-shaped glenoid fossa articulates with the humerus in a neutral or slightly retroverted position. The glenoid labrum is a rim of fibrocartilaginous tissue that increases the surface area of the glenoid fossa and the stability of the shoulder (Figure 14-3). The deltoid is a large, powerful whose primary function is shoulder abduction. The anterior half of the deltoid elevates (flexes) the shoulder, and the posterior half provides extension. Underneath the deltoid are the four rotator cuff s: the subscapularis, located anteriorly; the supraspinatus, located superiorly; and the infraspinatus and teres minor s, located posteriorly. The deltoid provides most of the power in shoulder motion, whereas the rotator cuff s act as a force couple to fine-tune and enhance the efficiency and stability of shoulder motion by compressing, depressing, and thus maintaining the humeral head in the glenoid fossa. Other important shoulder s include the trapezius, the latissimus dorsi, the serratus anterior, and the pectoralis major. The subclavian artery passes under the clavicle and continues as the axillary artery as it traverses the anterior aspect of the shoulder joint. Anastomoses of branches of the axillary artery provide important collateral circulation to the upper extremity (Figure 14-4). The main blood supply to the humeral head is the anterior humeral circumflex artery. The nerves about the shoulder include the brachial plexus and its terminal branches, the sympathetic nerves, the supraclavicular nerves, and cranial nerve XI. Important posterior landmarks include the quadrangular space and the triangular interval (Figure 14-5). The quadrangular space is bordered by the long head of the triceps, the surgical neck of the humerus, the inferior border of the scapula, and the teres major. The axillary nerve and the posterior humeral circumflex artery fill this space. The triangular interval houses the radial nerve and the deep brachial artery. Its borders are the teres major superiorly, the long head of the triceps medially, and the lateral head of the triceps laterally. 284

Figure 14-1: Anterior View Scapula and Proximal Humerus Acromion Coracoid process Clavicle (cut) The Shoulder and Arm Anatomic neck Greater tubercle Lesser tubercle Surgical neck Intertubercular sulcus Crest of greater tubercle Crest of lesser tubercle Deltoid tuberosity Muscle attachments Origins Insertions Glenoid Head of humerus Humerus Scapula Deltoid Biceps brachii (long head) Supraspinatus Subscapularis Coracobrachialis and Biceps brachii (short head) Pectoralis major Latissimus dorsi Teres major Deltoid Coracobrachialis Superior angle Superior border Suprascapular notch Neck Medial border Subscapular fossa Lateral border Inferior angle Triceps brachii (long head) Trapezius Pectoralis minor Omohyoid Subscapularis Brachialis Serratus anterior Acromioclavicular joint capsule (incorporating acromioclavicular ligament) Acromion Coracoacromial ligament Supraspinatus tendon (cut) Coracohumeral ligament Greater tubercle and Lesser tubercle of humerus Transverse humeral ligament Intertubercular tendon sheath (communicates with synovial cavity) Subscapularis tendon (cut) Biceps brachii tendon (long head) Shoulder joint, anterior view Capsular ligaments Clavicle Trapezoid ligament Conoid ligament Coracoclavicular ligament Superior transverse scapular ligament and suprascapular notch Coracoid process Communications of subtendinous bursa of subscapularis Broken line indicates position of subtendinous bursa of subscapularis 285

Chapter 14 Figure 14-2: Posterior View Scapula and Proximal Humerus Suprascapular notch Superior border Superior angle Supraspinous fossa Spine Neck Infraspinous fossa Medial border Lateral border Clavicle (cut) Coracoid process Acromion Acromial angle Spinoglenoid notch connecting supraspinous and infraspinous fossae Greater tubercle Head of humerus Anatomic neck Surgical neck Inferior angle Supraspinatus Trapezius Scapula Humerus Deltoid tuberosity Radial groove Levator scapulae Deltoid Rhomboid minor Supraspinatus Infraspinatus Teres minor Muscle attachments Rhomboid major Infraspinatus Latissimus dorsi (small slip of origin) Teres major Triceps brachii (long head) Teres minor Triceps brachii (lateral head) Deltoid Brachialis Origins Insertions PHYSICAL EXAMINATION Begin the physical examination with an inspection of the patient s overall posture and alignment of the shoulder. Look for swelling and ecchymosis, which may indicate recent trauma. Note areas of atrophy suggestive of nerve dysfunction. Injury to cranial nerve XI results in atrophy of the trapezius, which is seen superiorly as a reduced neckto-shoulder contour. Supraspinatus nerve dysfunction causes loss of the normal posterior shoulder contour and prominence of the scapular spine and acromion. Next, palpate subcutaneous landmarks to detect deformity or tenderness. For example, with an AC separation, the distal end of the clavicle is prominent. Start at the sternoclavicular joint, and proceed laterally along the clavicle to the acromioclavicular joint. Proceed to the lateral edge of the acromion and the greater tuberosity of the proximal humerus. Also, palpate the long head of the biceps in the bicipital groove of the proximal humerus to detect subluxation or tenderness. Shoulder range of motion is assessed in four planes (Figure 14-6). The zero starting 286

The Shoulder and Arm Figure 14-3: Shoulder Joint Opened (lateral view) Acromion Supraspinatus tendon (fused to capsule) Coracoacromial ligament Coracoid process Coracohumeral ligament Subdeltoid bursa Biceps brachii tendon (long head) Infraspinatus tendon (fused to capsule) Superior glenohumeral ligament Glenoid cavity (cartilage) Subscapularis tendon (fused to capsule) Teres minor tendon (fused to capsule) Insertion of synovium (enlarged for depiction) Middle glenohumeral ligament Inferior glenohumeral ligament Figure 14-4: Axillary and Brachial Arteries Acromial branch Clavicular branch Deltoid branch Pectoral branch Superior thoracic artery Axillary artery Anterior circumflex humeral artery Posterior circumflex humeral artery Brachial artery Deep artery of arm Radial collateral artery Thoracoacromial artery Lateral thoracic artery Subscapular artery Circumflex scapular artery Thoracodorsal artery Level of lower margin of teres major is landmark for name change from axillary to brachial artery Middle collateral artery 287

Chapter 14 Figure 14-5: Posterior View of Shoulder and Arm Superficial layer Posterior cutaneous nerve of arm (from radial nerve) Acromion Supraspinatus Greater tubercle of humerus Infraspinatus Teres minor Axillary nerve and posterior circumflex humeral artery Deltoid (cut and reflected) Superior lateral cutaneous nerve of arm (from axillary nerve) Teres major Long head Lateral head Triceps brachii Tendon Medial intermuscular septum Ulnar nerve Medial epicondyle of humerus Olecranon of ulna Flexor carpi ulnaris Anconeus Extensor carpi ulnaris Posterior cutaneous nerve of forearm (from radial nerve) Brachioradialis Extensor carpi radialis longus Extensor carpi radialis brevis Extensor digitorum Teres major Capsule of shoulder joint Supraspinatus tendon Infraspinatus and Teres minor tendons (cut) Axillary nerve Posterior circumflex humeral artery Superior lateral cutaneous nerve of arm Deep artery of arm Radial nerve Deep layer Long head of triceps brachii Lateral head of triceps brachii (cut) Medial head of triceps brachii Medial epicondyle of humerus Ulnar nerve Olecranon of ulna Anconeus Middle collateral artery Radial collateral artery Inferior lateral cutaneous nerve of arm Lateral intermuscular septum Nerve to anconeus and lateral head of triceps brachii Posterior cutaneous nerve of forearm Lateral epicondyle of humerus 288

fifteen Elbow and Forearm Edward D. Wang, MD Lawrence C. Hurst, MD

Chapter 15 ANATOMY The elbow is a functional link for positioning the hand in space, a fulcrum for the forearm lever, and a load-carrying joint. As such, it requires a combination of mobility and stability. The three articulations of the elbow provide flexion and extension, as well as forearm rotation (Figure 15-1). Control and stability of flexion and extension are provided primarily through the ulnohumeral (trochlea and olecranon) articulation and secondarily through the radiohumeral (capitellum and radial head) articulation. The trochlea is shaped like a spool and fits in the wrench-shaped trochlear notch. This anatomic configuration, in conjunction with the collateral ligaments, provides a stable hinge joint that can lift heavy objects. Rotation of the forearm occurs through the proximal and distal radioulnar articulations. Distal to the radial head, the bone tapers to form the radial neck, then flares at the radial tuberosity the insertion site of the biceps tendon. Between the radius and the ulna is the interosseous membrane a thickened, ligamentous structure that connects the two Figure 15-1: Bones of Right Elbow Joint Humerus Humerus Lateral supracondylar ridge Radial fossa Lateral condyle Lateral epicondyle Capitulum Head Neck Tuberosity Radius Ulna In extension: anterior view Medial supracondylar ridge Coronoid fossa Coronoid process Radial notch of ulna Tuberosity Medial condyle Medial epicondyle Trochlea Olecranon fossa Groove for ulnar nerve Ulna Olecranon Lateral epicondyle Head Neck Tuberosity Radius In extension: posterior view Humerus Lateral epicondyle Capitulum Head Neck Radial tuberosity Humerus Medial epicondyle Capitulum Trochlea Head Neck Radial tuberosity Radius Radial notch Coronoid process Trochlear notch Olecranon In 90 flexion: lateral view of ulna Ulna Coronoid process Trochlear notch Olecranon In 90 flexion: medial view 308

Elbow and Forearm bones in a manner that provides stability while allowing forearm rotation. Muscles that cross the elbow anteriorly include the elbow flexors and the flexor-pronator forearm s that originate from the medial epicondyle (Figure 15-2). In the forearm, the volar s are arranged in three layers. The superficial group includes the pronator teres, flexor carpi radialis, palmaris longus, and flexor carpi ulnaris. The middle layer is the flexor digitorum superficialis. The deep layer comprises the supinator, flexor digitorum profundus, flexor pollicis longus, and pronator quadratus. The flexor-pronator group primarily provides wrist flexion and forearm pronation. The biceps is a secondary flexor of the elbow and a strong supinator. Immediately deep to the biceps lies the brachialis the major flexor of the elbow. Posterior elbow s include elbow extensors, wrist and finger extensors, and the supinator. Posterior forearm s are arranged in two layers. The superficial group originates from a common tendon at the lateral epicondyle and includes a lateral component (brachioradialis, extensor carpi radialis longus, and extensor carpi radialis brevis) and a medial subgroup (extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, and anconeus). The deep posterior forearm s are the supinator, abductor pollicis longus, extensor pollicis brevis, and extensor pollicis longus (see Figure 15-2). The brachial artery, the main artery of the arm and elbow, travels in the anterior compartment of the arm adjacent to the median nerve. Proximal to the elbow, it gives off collateral arteries that help form a rich plexus of vessels around the elbow. At the level of the radial head, the brachial artery bifurcates into the radial and ulnar arteries. The ulnar artery enters the forearm posterior to the pronator teres, whereas the radial artery travels between the brachioradialis and the supinator. The median nerve enters the forearm between the humeral and ulnar heads of the pronator teres and travels inferior to the flexor digitorum superficialis (Figure 15-3). The anterior interosseous nerve branches innervate the index, and sometimes, the long, finger component of the flexor digitorum profundus, the flexor pollicis longus, and the pronator quadratus. Because of the location of its fibers in the median nerve, isolated paralysis of the anterior interosseous nerve may occur with an elbow fracture. The rest of the median nerve innervates all the volar forearm s except the ulnar half of the flexor digitorum profundus (fourth and fifth fingers) and the flexor carpi ulnaris, both of which are supplied by the ulnar nerve. The ulnar nerve exits the anterior compartment of the arm, passing behind the medial epicondyle into the cubital tunnel at the elbow, then enters the forearm between the two heads of the flexor carpi ulnaris (Figure 15-4). It innervates the flexor carpi ulnaris, the ulnar half of the flexor digitorum profundus, and, ultimately, the intrinsic s of the hand. In the arm, the radial nerve travels within the posterior compartment, then enters the anterior compartment lateral to the humerus. In the antecubital fossa, the radial nerve innervates the brachioradialis and extensor carpi radialis longus before dividing into superficial (sensory) and deep (mostly motor) branches (Figure 15-5). The superficial radial nerve provides sensation to the radial dorsal wrist and hand. The deep branch innervates the remaining extensor s of the forearm. It travels deep and through the supinator and exits this as the posterior interosseous nerve. Distal to the radial tuberosity, the deep branch of the radial nerve may lie on the bone and, as such, is vulnerable to injury in fractures of the proximal radius or in operations at this site. PHYSICAL EXAMINATION Inspect the elbow for swelling and ecchymosis, and determine the carrying angle (the axial alignment of the humerus and the ulna with the elbow extended). The normal carrying angle is 10 to 20, with most studies observing slightly greater cubitus valgus in females. Angular deformities may occur secondary to previous trauma, growth distur- 309

Chapter 15 Figure 15-2: Bony Attachments of Muscles of Forearm Brachioradialis Extensor carpi radialis longus Extensor carpi radialis brevis, extensor Common digitorum, extensor extensor digiti minimi, extensor tendon carpi ulnaris s Brachialis Biceps brachii Supinator Flexor digitorum superficialis (radial head) Pronator teres Flexor pollicis longus Anterior view Ulna Brachialis Pronator teres (humeral head) Common flexor tendon Flexor digitorum superficialis (humeroulnar head) Pronator teres (ulnar head) Flexor digitorum profundus Pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, flexor digitorum superficialis (humeroulnar head) Note: Attachments of instrinsic s of hand not shown Radius Pronator quadratus Brachioradialis Abductor pollicis longus Flexor carpi radialis Flexor pollicis longus Flexor digitorum superficialis Flexor digitorum profundus Origins Insertions Pronator quadratus Flexor carpi ulnaris Extensor carpi ulnaris Flexor carpi ulnaris (humeral origin via common flexor tendon) Flexor carpi ulnaris (ulnar origin) Flexor digitorum profundus Extensor carpi ulnaris (ulnar origin) Extensor pollicis longus Extensor indicis Ulna Extensor carpi radialis longus Extensor carpi radialis brevis Extensor carpi ulnaris Extensor digitorum (central bands) Extensor digiti minimi Extensor digitorum (lateral bands) Posterior view Triceps brachii (medial head) Triceps brachii tendon Anconeus Biceps brachii Supinator Abducor pollicis longus Pronator teres Extensor pollicis brevis Radius Brachioradialis Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Extensor indicis 310

Elbow and Forearm Figure 15-3: Median Nerve Pronator teres m. (humeral head) Articular branch Flexor carpi radialis m. Palmaris longus m. Median nerve Pronator teres m. (ulnar head) Flexor digitorum superficialis m. (turned up) Flexor digitorum profundus m. (lateral portion supplied via anterior interosseous n.; medial portion by ulnar n.) Anterior interosseous n. Flexor pollicis longus m. Thenar s Pronator quadratus m. Palmar branch Abductor pollicis brevis Opponens pollicis Flexor pollicis brevis (superficial head; deep head supplied by ulnar n.) Flexor retinaculum Cutaneous innervation 1st and 2nd lumbrical mm. Anastomotic branch to ulnar n. Branches to dorsum of middle and distal phalanges Common Proper Palmar digital nn. bances, or genetic syndromes. Ecchymosis, swelling, or both about the elbow indicate a or tendon injury, fracture, or elbow sprain or dislocation. Palpate subcutaneous landmarks for sites of tenderness, deformity, or effusion that indicate the site of occult fracture, tendinosis, ligament sprain, or tendon rupture. From lateral to medial, the structures in the antecubital fossa are the biceps tendon, brachial artery, and median nerve. A palpable defect is key to diagnosing rupture of the distal biceps tendon or disruption of the triceps tendon. Joint effusion is best detected in the soft spot between the lateral epicondyle, radial head, and olecranon. Tenderness over the radial head or humeral condyles may indicate an occult fracture that is not visible on radiographs. The zero starting position for measurement of elbow motion is a straight extremity (Figure 15-6). Young children commonly extend the elbow by 10 to 15, but adults usually cannot extend the elbow past the zero starting position. The normal range of elbow flexionextension is 0 to 145. The plane of forearm rotation is pronation-supination. Pronation literally means the state of being prone or, as it relates to the forearm, the palm being turned backward. Likewise, supination literally means the state of being supine (ie, the 311

sixteen The Hand and Wrist John D. Lubahn, MD D. Patrick Williams, DO

Chapter 16 The human hand, as an extension of the brain, allows us to manipulate and interact with our environment and to perform activities as routine as opening a door or as intimate as caressing a loved one. The hand also functions as part of the sensory system, providing tactile sensation for complex hand movements without the necessity of constant visual guidance; this function is epitomized by blind people who read and musicians who entertain. An understanding and careful examination of hand anatomy and function is crucial for the student of medicine. ANATOMY AND BIOMECHANICS The carpus, or wrist, is composed of eight carpal bones that link the forearm to the hand (Figure 16-1). The proximal carpal row (scaphoid, lunate, and triquetrum) articulates with the distal radius and ulna, as well as the distal carpal row (trapezium, trapezoid, capitate, and hamate). The pisiform, also part of the proximal row, is a sesamoid bone in the flexor carpi ulnaris tendon that articulates only with the triquetrum. The bones of the hand are the metacarpals and phalanges. The carpometacarpal (CMC) joint of the thumb is saddle-shaped, a configuration that permits abduction-adduction, as well as the circumduction that permits opposition of the thumb to the fingers. The metacarpophalangeal (MP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints basically are flexion-extension hinge joints. The skin on the dorsal surface of the hand is thin and flexible to allow full flexion of the fingers, whereas the palmar surface skin is thicker and characterized by creases. The Figure 16-1: Bones and Joints of Hand Distal phalanges Head Tuberosity Shafts Base Middle phalanges Head Shafts Base Right hand: anterior (palmar) view Proximal phalanges Metacarpal bones Head Shafts Base Head Shafts Base 5 4 3 2 Sesamoid bones Carpal bones Hamate and Hook Capitate Pisiform Triquetrum Lunate 1 Trapezium and Tubercle Scaphoid and Tubercle Trapezoid Carpal bones 336

The Hand and Wrist distal volar crease of the wrist crosses the proximal scaphoid and the pisiform. The distal palmar crease of the hand corresponds to the MP joint, and the proximal finger crease is at the base of the proximal phalanx. The extrinsic s of the wrist and hand originate on the medial and lateral humeral condyles and the proximal radius and ulna (see Figure 15-2). The extrinsic extensor tendons cross the wrist and are surrounded by tendon sheaths in six compartments bounded by the extensor retinacular ligament (Figure 16-2). The extrinsic finger and thumb flexor tendons and the median nerve enter the hand through the carpal canal (Figure 16-3). The transverse carpal ligament, a thick band extending from the hamate and pisiform to the scaphoid and trapezium, forms the inelastic roof of the carpal canal. A decrease in the size of the canal or an increase in the size of its contents can cause compression of the median nerve (carpal tunnel syndrome). Intrinsic musculature includes thenar, hypothenar, and interosseous s (Figure 16-4; see also Figures 15-4 and 15-5). The thenar s are the abductor pollicis brevis, the opponens pollicis, and the superficial head of the flexor pollicis brevis. The hypothenar s are composed of the abductor digiti quinti, the opponens digiti quinti, and the flexor digiti quinti. The dorsal interossei, commonly referred to as dorsal intrinsics, abduct the fingers; the palmar interossei (palmar intrinsics) adduct the fingers. The DIP joint of the fingers is flexed by the flexor digitorum profundus (FDP). It has a separate belly for the index finger (which therefore flexes independently) but a common belly for the long, ring, and small fingers (which tend to work as a single unit). The PIP joint of the fingers is primarily flexed by the flexor digitorum superficialis (FDS). It has individual bellies for each finger, thus providing the individual finger flexion at the PIP joint that is necessary for activities such as playing a musical instrument and typing. The FDS separates into two parts before its point of insertion, and the FDP passes through the split (Figure 16-5). Both finger flexors are enclosed in a common tendon sheath. The proximity of the FDS and FDP tendon to the surrounding sheath promotes efficient movement, but adhesions from injury or infection can be problematic in this region. The interossei, along with the lumbrical s, flex the MP joints and extend the PIP and DIP joints. The lumbrical s are unique in that they originate from the profundus tendons to insert into the dorsal apparatus of the antagonistic extensor mechanism (see Figure 16-5). The interossei and the two ulnar lumbricals are innervated by the ulnar nerve, but the two radial lumbricals are innervated by the median nerve. The MP joints of the fingers are extended by the extensor digitorum longus, extensor indicis proprius, and extensor digiti quinti. When the MP joints are flexed, these s also can extend the PIP joints; otherwise, the intrinsic s extend the PIP and DIP joints. The complex arrangement of the tendons on the dorsum of the hand provides the necessary synchrony and balance between flexors and extensors during the multiple precise motions of the MP, PIP, and DIP joints working in concert. The main insertion of the extrinsic extensor tendon is through the central slip at the base of the middle phalanx. The intrinsic s join with the extrinsic extensor through the interdigitating transverse and oblique fibers of the dorsal apparatus to extend the PIP and DIP joints. Contracture or spasticity of the intrinsic s creates increased tension on the dorsal hood. A swan-neck deformity develops, with PIP joint hyperextension and MP and DIP joint flexion (Figure 16-6). Laceration of the central extensor tendon proximal to its insertion into the middle phalanx allows the lateral bands to slip volarly and produces the opposite flexion, boutonnière (French from button hole ) PIP joint deformity. The radial artery lies radial to the flexor carpi radialis tendon at the wrist (see Figure 16-3). After crossing the snuffbox (see Figure 16-2), the radial artery passes through the first intermetacarpal space to the palm as the main contributor to the deep palmar arch, 337

Chapter 16 Figure 16-2: Extensor Tendons at the Wrist Posterior (dorsal) view Extensor carpi ulnaris Compartment 6 Extensor digiti minimi Compartment 5 Extensor digitorum Extensor indicis Compartment 4 Extensor pollicis longus Compartment 3 Extensor carpi radialis brevis Extensor carpi radialis longus Compartment 2 Plane of cross section shown below Extensor retinaculum Abductor pollicis longus Extensor pollicis brevis Compartment 1 Abductor digiti minimi Intertendinous connections Radial artery in anatomical snuffbox Dorsal interosseous s Transverse fibers of extensor expansions (hoods) Cross section of most distal portion of forearm Compartment 5 Compartment 4 Extensor digiti minimi Extensor retinaculum Extensor digitorum and extensor indicis Extensor pollicis longus Compartment 3 Extensor carpi radialis brevis Extensor carpi radialis longus Compartment 2 Compartment 6 Extensor carpi ulnaris 6 5 4 3 2 1 Extensor pollicis brevis Abductor pollicis longus Compartment 1 Ulna Radius 338

The Hand and Wrist Figure 16-3: Flexor Tendons, Arteries, and Nerves at Wrist Palmar view Median duo Palmaris longus tendon Median nerve Radial artery Flexor carpi radialis Radial trio tendon Flexor pollicis longus tendon in tendon sheath (radial bursa) Palmar carpal ligament (reflected) (Synovial) tendon sheath Transverse carpal ligament Trapezium 1st metacarpal bone Opponens pollicis Abductor pollicis brevis (reflected) Flexor digitorum superficialis tendons and flexor digitorum profundus tendons Common flexor sheath (ulnar bursa) Ulnar artery Ulnar nerve Flexor carpi ulnaris tendon Pisiform Ulnar trio Abductor digiti minimi Flexor digiti minimi brevis Opponens digiti minimi Superficial palmar (arterial) arch Two tendon quartets Lumbrical s Flexor pollicis brevis (reflected) Adductor pollicis Figure 16-4: Intrinsic Muscles of Hand Palmar interosseous s Palmar view Tendinous slips to hood of extensor digitorum Deep transverse metacarpal ligament Abductor pollicis brevis Radial artery Radius Dorsal view Ulna Dorsal interosseous s Abductor digiti minimi Ulna Radius 339