Upper Limb Anatomy PDF

A brief TEXT BOOK OF ANATOMY Upper limbs Professor M. Koruji Iran University of Medical Sciences 1 Contents upper limbs.............................................................................................................................

A brief TEXT BOOK OF ANATOMY Upper limbs Professor M. Koruji Iran University of Medical Sciences 1 Contents upper limbs........................................................................................................................................................... 1 upper limb................................................................................................................................................................ 3 bones and joints of the upper limb................................................................................................................................... 4 muscles of the upper limb........................................................................................................................................... 26 blood vessels of the upper limb..................................................................................................................................... 42 i. Branches of the subclavian artery (figure 7.8)............................................................................................................... 42 ii. Axillary artery (see figures 7.8 to 7.9)........................................................................................................................ 44 iii. Brachial artery (see figures 7.8 to 7.9)....................................................................................................................... 46 iv. Radial artery (see figures 7.8, 7.9, and 7.20)................................................................................................................ 48 v. Ulnar artery (see figures 7.8, 7.9, and 7.20).................................................................................................................. 49 vi. Veins of the upper limb (see figure 7.4)...................................................................................................................... 51 iii. Superficial lymphatics of the upper limb.................................................................................................................... 51 nerves of the upper limb............................................................................................................................................. 53 a. Branches from the roots........................................................................................................................................... 53 b. Branches from the upper trunk.................................................................................................................................. 54 c. Branches from the lateral cord.................................................................................................................................. 54. Branches from the medial cord.................................................................................................................................... 55 e. Branches from the posterior cord............................................................................................................................. 56 2 Upper Limb The upper limb is divided into the following four parts (Fig. 1): 1. Shoulder. 2. Arm or brachium. 3. Forearm or antebrachium. 4. Hand. 3 Bones and joints of the upper limb I. Bones of the Shoulder Girdle The bones of the shoulder region are the clavicle (collar bone) and the scapula (shoulder blade). They form the shoulder girdle. A. Clavicle (Collar bone) (Figure 2) The clavicle is a long and slender bone with:  Two ends (sternal and acromial)  Two borders (anterior and posterior);  Two surfaces (superior and inferior). Sternal end connects to the sternum (axial skeleton), by articulating with the sternum at the sternoclavicular joint and acromial end connects with the acromion of the scapula at the acromioclavicular joint. The medial two-thirds of the shaft of the clavicle is cylindrical whereas the lateral third of the clavicle is flattened and has a superior and an inferior surface, limited by an anterior and a posterior border. Anterior border in lateral third of the clavicle may be marked by a small deltoid tubercle. The inferior surface presents four obvious markings (Fig.2): 1. A Costal tuberosity or costal impression near the sternal end, by a roughened oval impression, which is often depressed below the surface. Its margins give attachment to the costoclavicular ligament, which connects the clavicle to the upper surface of the first rib and its cartilage. 2. A Subclavian groove where subclavius muscle lies in a groove on the inferior surface. 3. There is a prominent conoid tubercle which gives attachment to the conoid part of the coracoclavicular ligament. 4. A narrow, roughened strip, the trapezoid line, runs forwards and laterally from the lateral side of this tubercle, almost as far as the acromial end * The coracoclavicular ligament is attached to the conoid tubercle (conoid part) and trapezoid line(trapezoid part) The superior surface is roughened in its medial and lateral part and smooth at its center where it can be felt through the skin (Fig 3A).  Muscular attachments: o Deltoid (anterior) and trapezius (posterior) are attached to the lateral third of the shaft, o pectoralis major (anterior) and sternocleidomastoid are attached to the medial half of the superior surface. Its sternal end articulates with the manubrium of the sternum at the sternoclavicular (SC) joint. Its acromial end articulates with the acromion of the scapula at the acromioclavicular (AC) joint. 4  Figure 2. Clavicle. The superior (A) and inferior (B) surfaces are shown. The muscle attachments to the clavicle are identified CLINICAL CORRELATES: clavicle Is a commonly fractured bone i n the body. It commonly fractures at the junction of its lateral one-third and medial two-third(weak point) Is the first bone to begin ossification during fetal development, but it is the last one to complete ossification, at approximately 21 years of age. Is the only long bone to be ossified intramembranously and forms from somatic lateral plate mesoderm.. Scapula (Shoulder Blade) The scapula shoulder blade) is a large, flat, triangular bone which lies on the posterolateral aspect of the chest wall, covering parts of the second to seventh ribs. It has (Figure 3):  Two surfaces: costal and dorsal surfaces,  Three borders: superior, lateral and medial borders,  Three angles: inferior, superior and lateral angles,  and three processes: the spine, its continuation the acromion and the coracoid process. Surfaces:  Posterior surface The convex posterior surface of the scapula is unevenly divided by the spine of the scapula into a small supraspinous fossa and a much larger infraspinous fossa. Muscular attachments: Supraspinatus is attached to the the supraspinous fossa and Infraspinatus is attached to the infraspinous fossa.  Costal surface: 5 It has a large subscapular fossa. Subscapularis muscle arises from this fossa. The anterior aspect of the neck is separated from subscapularis muscle by a bursal protrusion of the synovial membrane of the shoulder joint (subscapular 'bursa'). Figure 3. Scapula. A. Posterior view of right scapula. B. Anterior view of posterior surface. C. Lateral view. Angles: The lateral angle of the scapula is marked by glenoid cavity, which articulates with the head of the humerus to form the glenohumeral joint. This part of the bone may be regarded as the head. The neck of the scapula is just after the head.  The infraglenoid tubercle is located inferior to the glenoid cavity and it is the site of attachment for the long head of the triceps brachii muscle.  The supraglenoid tubercle is located superior to the glenoid cavity and is the site of attachment for the long head of the biceps brachii muscle(Fig. 4). *There is spinoglenoid notch or greater scapular notch between the lateral border of the spine and the dorsal aspect of the neck. The inferior angle lies over the seventh rib. It can be felt through the skin and the muscles which cover it. The superior angle is placed at the junction of the superior and medial borders. Borders: Superior border 6 The superior border, is the shortest. There is suprascapular notch near to the base of the coracoid process. It is bridged by the transverse scapular ligament and converted into a foramen that transmits the suprascapular nerve, whereas the suprascapular vessels pass backwards above the ligament. Lateral border The lateral border of the scapula runs from the inferior angle to the glenoid cavity. At its upper end it widens into infraglanoid tubercle. Long head of triceps, teres minor and teres major muscles are attached to lateral border. Medial border The medial border of the scapula extends from the inferior to the superior angle.  levator scapular , rhomboid minor and. Rhomboid major are attached to the border (Fig 4).  Serratus anterior are attached into a narrow strip along the ventral aspect of the medial border. Processes: 1. Spine of the Scapula Is a triangular-shaped process that continues laterally as the acromion. Divides the posterior scapula into the upper supraspinous and lower infraspinous fossae, and also provides an origin for the deltoid and an insertion for the trapezius. Its posterior border has two lips 2. Acromion Is the lateral end of the spine and articulates with the clavicle(acromioclavicular joint).. Provides an origin for the deltoid and an insertion for the trapezius. 3. Coracoid Process The coracoid process is a beak-like procress and arises from the upper border of the head of the scapula. It has base and apex. Apex provides the origin of the coracobrachialis and short head of biceps brachii, the insertion of the pectoralis minor. Fig. 4. Important muscular and ligamentous attachments to the right scapula II. BONE OF THE ARM Humerus 7 The humerus (arm bone), the largest bone in the upper limb has two expanded ends (proximal and distal ends) and a shaft. It articulates with the scapula at the glenohumeral joint and the radius and ulna at the elbow join. Proximal end The proximal end of the humerus consists of (Figure 5): 1. Head Articulates with the scapula at the glenohumeral joint. 2. Anatomical Neck Is an indentation distal to the head and provides an attachment for the fibrous joint capsule. 3. Greater Tubercle Lies just lateral and distal to the anatomic neck and with three facets(Superior, middle. And inferior) provides attachments for the supraspinatus, infraspinatus, and teres minor muscles whose tendons form parts of the rotator cuff. 4. Lesser Tubercle Lies on the anterior medial side of the humerus, just distal to the anatomic neck, and provides an insertion for the subscapularis muscle. 5. Intertubercular (Bicipital) Groove Lies between the greater and lesser tubercles, lodges the tendon of the long head of the biceps brachii muscle, and is bridged by the transverse humeral ligament. Provides insertions for the pectoralis major on its lateral lip, the teres major on its medial lip, and the latissimus dorsi on its floor. 6. Surgical Neck Is a narrow area distal to the tubercles that is a common site of fracture and is in contact with the axillary nerve and the posterior humeral circumflex artery. Fracture of the surgical neck is especially common in elderly people with osteoporosis and may injure the axillary nerve and the posterior humeral circumflex artery. Figure 5. Proximal end of right humerus 8 Shaft The shaft (body) of the humerus has prominent features: 1. Borders and surfaces: In cross-section, the shaft of the humerus is somewhat triangular with (Fig 6): anterior, lateral, and medial borders; and anterolateral, anteromedial, and posterior surfaces 2. Deltoid Tuberosity Is a rough triangular elevation on the lateral aspect of the midshaft that marks the insertion of the deltoid muscle. 3. Radial or Spiral Groove Contains the radial nerve and profunda brachii artery, separating the origin of the lateral head of the triceps above and the origin of the medial head below. Fracture of the shaft of the humerus may injure the radial nerve and deep brachial artery in the spiral groove. 4. Medial and lateral supracondylar ridges The inferior end of the humeral shaft widens as Medial and lateral supracondylar ridges. Intermuscular septa, which separate the anterior compartment from the posterior compartment, attach to the medial and lateral borders. (Fig. 6, 7). Fig. 6.The (a) anterior and (b) posterior view of the humerus. (c) The humerus with its three major related nerves—axillary, radial and ulnar—all of which are in danger of injury in humeral fractures. Distal end The distal end of the humerus consist of articular (condyle) and none articular parts (Fig. 7). 9 Figure 7. Distal end of the humerus The two articular parts of the condyle are: ICALATES 1. Trochlea Is a pulley shaped medial articular surface and articulates with the trochlear notch of the ulna. 2. Capitulum Is the lateral articular surface, globular in shape, and articulates with the head of the radius. None-articular part 1. Lateral Epicondyle Projects from the capitulum and provides the origin of the supinator and extensor muscles of the forearm. It is an attachment site for the radial collateral ligament. 2. Medial Epicondyle Projects from the trochlea and has a groove on the back for the ulnar nerve and superior ulnar collateral artery. 3. Provides attachment sites for the ulnar collateral ligament, the pronator teres, and the common tendon of the forearm flexor muscles. 4. Coronoid Fossa Is an anterior depression above the trochlea of the humerus that accommodates the coronoid process of the ulna on flexion of the elbow. 5. Radial Fossa Is an anterior depression above the capitulum that is occupied by the head of the radius during full flexion of the elbow joint. 6. Olecranon Fossa Is a posterior depression above the trochlea of the humerus that houses the olecranon of the ulna on full extension of the forearm. Supracondylar fracture is a fracture of the distal end of the humerus; it is common in children and occurs when the child falls on the outstretched hand with the elbow partially flexed and may injure the median nerve. 10  Fracture of the medial epicondyle may damage the ulnar nerve. This nerve may be compressed in a groove behind the medial epicondyle “funny bone,” causing numbness. Figuer 9. Common fractures of the humerus 11 III. BONES OF THE Forearm: A. Ulna The Upper End (proximal end) The upper end presents (Fig 10): 1. Olecranon Process Is the curved projection on the back of the elbow that provides an attachment site for the triceps tendon. 2. Coronoid Process Is located below the trochlear notch and provides an attachment site for the brachialis. 3. Trochlear Notch Receives the trochlea of the humerus. 4. Ulnar Tuberosity Is a triangular roughened prominence distal to the coronoid process that provides an attachment site for the brachialis. 5. Radial Notch Accommodates the head of the radius at the proximal radioulnar joint. 6. Supinator fossa Just inferior to the radial notch allows the radial tuberosity to change position during pronation and supination. 7. Supinator crest The posterior margin of supinator fossa Figure 10. Ulna. A. The proximal part of the ulna (B) right ulna are shown. B 12  Shaft of ulna The shaft of the ulna is broad superiorly where it is continuous with the large proximal end and narrow distally to form a small distal head (Fig. 10). Like the radius, the shaft of the ulna is triangular in cross- section and has (Fig. 11):  Three borders (anterior, posterior, and interosseous);  Three surfaces (anterior, posterior, and medial). The anterior border is smooth and rounded. It begins above at the the coronoid process, and ends below in front of the styloid process. The posterior border is sharp and palpable along its entire length. It begins above at the back part of the olecranon, and ends below at the back of the styloid process. The interosseous border is also sharp and is the attachment site for the interosseous membrane. Figure 11. Surfaces and borders of Ulna and radius. The distal end of the ulna The distal end of the ulna is small and characterized by a rounded head and the ulnar styloid process (Fig 10). 1. The head articulates with the triangular articular disk which separates it from the wrist-joint; the remaining portion, is received into the ulnar notch of the radius. 2. The ulnar styloid process rounded end affords attachment to the ulnar collateral ligament of the wrist-joint. The head is separated from the styloid process by a shallow groove for the tendon of the Extensor carpi ulnaris posteriorly. B. Radius Is shorter than the ulna and is situated lateral to the ulna. Proximal end of the radius (Fig 12) 1. Head Articulates with the capitulum of the humerus and the radial notch of the ulna and is surrounded by the annular ligament. 2. Neck Is enclosed by the lower margin of the annular ligament, and the neck and head are free 13  from capsular attachment and thus can rotate freely within the socket. 4. Radial Tuberosity Is an oblong prominence just distal to the neck and provides an attachment site for the biceps brachii tendon. Figure 12. Anterior view of the proximal end of the radius Shaft of radius The shaft of the radius is narrow proximally, where it is continuous with the radial tuberosity and neck, and much broader distally, where it expands to form the distal end (see Fig. 12& 13). Throughout most of its length, the shaft of the radius is triangular in cross-section, with:  Three borders (anterior, posterior, and interosseous) begins from the radial tuberosity  Three surfaces (anterior, posterior, and lateral). The anterior border : In the superior third of the bone, it crosses the shaft diagonally as the oblique line of the radius. It gives origin to the Flexor digitorum superficialis (FDS). The surface above the line gives insertion to the Supinator and the surface below the line gives origin to Flexor pollicis longus (FPL); The posterior border is distinct only in the middle third of the bone. The interosseous border is sharp and is the attachment site for the interosseous membrane, which links the radius to the ulna. The anterior and posterior surfaces of the radius are generally smooth, whereas an oval roughening (Pronator impression) for the attachment of pronator teres marks approximately the middle of the lateral surface of the radius. 14 Figure 13. Radius. A. Shaft and (B) distal end of the right radius Distal end of radius The Distal end of radius has expansive anterior and posterior surfaces and narrow medial and lateral surfaces. 1. Dorsal tubercle: The posterior surface of the radius is characterized by the presence of a large dorsal tubercle, which acts as a pulley for the tendon of extensor pollicis longus. 2. Ulnar notch: The medial surface is marked by a prominent facet for articulation with the distal end of the ulna which is called the ulnar notch. 3. Styloid Process Is located on the distal end of the radius and is approximately 1 cm distal to that of the ulna and provides insertion of the brachioradialis muscle (Figure 13.). Can be palpated in the proximal part of the anatomic snuffbox between the extensor pollicis longus and brevis tendons. 4. The inferior surface of distal end of the bone is marked by two facets for articulation with the proximal row of carpal bones (the scaphoid and lunate). Fractures of the radius and ulna There are three classic injuries to the radius and ulna:  Monteggia's fracture is a fracture of the proximal third of the ulna and an anterior dislocation of the head of the radius at the elbow (Figure 14). 15  Figure 14. Monteggia's fracture  Galeazzi's fracture is a fracture of the distal third of the radius associated with subluxation (partial dislocation) of the head of the ulna (distal ulna) at the wrist joint (Figure 15). Figure 15. Galeazzi's fracture  Colles' fracture is a fracture in which the distal fragment is displaced (tilted) posteriorly, producing a characteristic bump described as dinner (silver) fork deformity because the forearm and wrist resemble the shape of a dinner fork(Figure 16).  Smith fracture: the distal fragment is displaced anteriorly. This fracture may show styloid processes of the radius and ulna lineup on a radiograph. (Figure 16). Figure 16. (A)Colles' fracture. (B). Smith fracture 16. IV. BONES OF THE HAND There are three groups of bones in the hand(Figure 17& 18):  The eight carpal bones are the bones of the wrist;  The five metacarpals (I to V) are the bones of the metacarpus.  The phalanges are the bones of the digits-the thumb has only two, the rest of the digits have three. A. Carpal Bones (See Figure 17) Are arranged in two rows of four (lateral to medial): scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, and hamate (mnemonic device: Sandra Likes To Pat Tom’s Two Cold Hands). 1. Proximal Row (Lateral to Medial): Scaphoid, Lunate, Triquetrum, and Pisiform Except for the pisiform, articulates with the radius and the articular disk (the ulna has no contact with the carpal bones). The pisiform is said to be a sesamoid bone contained in the flexor carpi ulnaris tendon. 2. Distal Row (Lateral to Medial): Trapezium, Trapezoid, Capitate, and Hamate Figure 17. Bones of hand. Fracture of the scaphoid occurs on a fall on the outstretched hand, shows a deep tenderness in anatomical snuffbox, and damages the radial artery and can cause avascular necrosis of the bone and degenerative joint disease of the wrist. Fracture of the hamate may injure the ulnar nerve and artery because they are near the hook of the hamate. B. Metacarpals Are miniature long bones consisting of bases (proximal ends), shafts (bodies), and heads (distal ends). Heads form the knuckles of the fist. 17 Bennett fracture is a fracture of the base of the metacarpal of the thumb. Boxer’s fracture is a fracture of the necks of the second and third metacarpals, seen in professional boxers, and typically of the fifth metacarpal in unskilled boxers. C. Phalanges Are miniature long bones consisting of bases, shafts, and heads. The heads of the proximal and middle phalanges form the knuckles. Occur in fingers (three each) and thumb (two) JOINTS Are places of union between two or more bones. Are innervated as follows: The nerve supplying a joint also supplies the muscles that move the joint and the skin covering the insertion of such muscles (Hilton’s law). Are classified on the basis of their structural features into fibrous, cartilaginous, and synovial types. A. Fibrous Joints (Synarthroses) Are joined by fibrous tissue, have no joint cavities, and permit little movement. 1. Sutures Are connected by fibrous connective tissue and found between the flat bones of the skull. 2. Syndesmoses Are connected by fibrous connective tissue. Occur as the inferior tibiofibular and tympanostapedial syndesmoses. B. Cartilaginous Joints Are united by cartilage and have no joint cavity. 1. Primary Cartilaginous Joints (Synchondroses) Are united by hyaline cartilage and permit no movement but growth in the length. Include epiphyseal cartilage plates (the union between the epiphysis and the dia- physis of a growing bone) and sphenooccipital and manubriosternal synchon- droses. 2. Secondary Cartilaginous Joints (Symphyses) Are joined by fibrocartilage and are slightly movable joints. Include the pubic symphysis and the intervertebral disks. C. Synovial (Diarthrodial) Joints Permit a great degree of free movement and are classified according to the shape of the articulation and/or the type of movement. Are characterized by four features: joint cavity, articular (hyaline) cartilage, synovial mem- brane (which produces synovial fluid), and articular capsule. 1. Plane (Gliding) Joints Are united by two flat articular surfaces and allow a simple gliding or sliding of one bone over the other. Occur in the proximal tibiofibular, intertarsal, intercarpal, intermetacarpal, carpome- tacarpal, sternoclavicular, and acromioclavicular joints. 2. Hinge (Ginglymus) Joints Resemble door hinges and allow only flexion and extension. Occur in the elbow, ankle, and interphalangeal joints. 3. Pivot (Trochoid) Joints Are formed by a central bony pivot turning within a bony ring and allow only rotation (movement around a single longitudinal axis). 18  Occur in the superior and inferior radioulnar joints and in the atlantoaxial joint. 4. Condylar (Ellipsoidal) Joints Have two convex condyles articulating with two concave condyles. ( The shape of the articulation is ellipsoidal.) Allow flexion and extension and occur in the wrist (radiocarpal), metacarpophalan- geal, knee (tibiofemoral), and atlantooccipital joints. 5. Saddle (Sellar) Joints Resemble a saddle on a horse’s back and allow flexion and extension, abduction and adduction, and circumduction but no axial rotation. Occur in the carpometacarpal joint of the thumb and between the femur and patella. 6. Ball-and-Socket (Spheroidal or Cotyloid) Joints Are formed by the reception of a globular (ball-like) head into a cup-shaped cavity and allow movement in many directions. Allow flexion and extension, abduction and adduction, medial and lateral rotations, and circumduction and occur in the shoulder and hip joints. CLINICAL CORRELATES Osteoarthritis is a noninflammatory degenerative joint disease characterized by degeneration of the articular cartilage and osseous outgrowth at the margins. It results from wear and tear of the joints; commonly affects the hands, fingers, hips, knees, feet, and spine; and is accompanied by pain and stiffness. Rheumatoid arthritis is an inflammatory disease primarily of the joints. It is an autoimmune disease in which the immune system attacks the synovial membranes and articular structures, leading to deformities and disability. There is no cure for rheu- matoid arthritis, and its most common symptoms are joint swelling, stiffness, and pain. Gout is a painful form of arthritis and is caused by too much uric acid in the blood. Uric acid crystals are deposited in and around the joints, causing an inflammation and pain, heat, redness, stiffness, tenderness, and swelling of the joint tissues. IV. JOINTS AND LIGAMENTS OF THE UPPER LIMB A. Sternoclavicular Joint Is a double synovial seller joint united by the fibrous capsule. Is reinforced by the anterior and posterior sternoclavicular, interclavicular, and costoclavicular ligaments. Allows elevation and depression, protraction and retraction, and circumduction of the shoulder. B. Acromioclavicular Joint Is a synovial plane joint that allows a gliding movement when the scapula rotates and is rein- forced by the coracoclavicular ligament, which consists of the conoid and trapezoid ligaments. 19 Figure 18. Joints and ligaments of the clavicle C. Shoulder (Glenohumeral) Joint Is a synovial ball-and-socket joint between the glenoid cavity of the scapula and the head of the humerus. Both articular surfaces are covered with hyaline cartilage. Is surrounded by the fibrous capsule that is attached superiorly to the margin of the glenoid cavity and inferiorly to the anatomical neck of the humerus. The capsule is reinforced by the rotator cuff, the glenohumeral ligaments, and the coracohumeral ligaments. Has a cavity that is deepened by the fibrocartilaginous glenoid labrum; communicates with the subtendinous subscapular bursa; and allows abduction and adduction, flexion and extension, and circumduction and rotation May be subject to inferior or anterior dislocation, which stretches the fibrous capsule, avulses the glenoid labrum, and may injure the axillary nerve. Figure 19.Shoulder Joint 20 1. Rotator Cuff (See Figure 7.3) Is formed by the tendons of the supraspinatus, infraspinatus, teres minor, and subscapularis (SITS); fuses with the joint capsule; and provides mobility. Keeps the head of the humerus in the glenoid fossa during movements and thus stabilizes the shoulder joint. Figure 20. Rotator cuff 2. Ligaments of the shoulder joint (a) Glenohumeral Ligaments Extend from the supraglenoid tubercle to the upper part of the lesser tubercle of the humerus (superior glenohumeral ligament), to the lower anatomic neck of the humerus (middle glenohumeral ligament), and to the lower part of the lesser tubercle of the humerus (inferior glenohumeral ligament). (b) Transverse Humeral Ligament Extends between the greater and lesser tubercles and holds the tendon of the long head of the biceps in the intertubercular groove. (c) Coracohumeral Ligament Extends from the coracoid process to the greater tubercle. (d) Coracoacromial Ligament Extends from the coracoid process to the acromion. (e) Coracoclavicular Ligament Extends from the coracoid process to the clavicle and consists of the trapezoid and conoid ligaments. 21 Figure 21.Shoulder Joint and ligaments 3. Bursae around the Shoulder Form a lubricating mechanism between the rotator cuff and the coracoacromial arch during movement of the shoulder joint. (a) Subacromial Bursa Lies between the coracoacromial arch and the supraspinatus muscle, usually communicates with the subdeltoid bursa, and protects the supraspinatus tendon against friction with the acromion. (b) Subdeltoid Bursa Lies between the deltoid muscle and the shoulder joint capsule, usually communicates with the subacromial bursa, and facilitates the movement of the deltoid muscle over the joint capsule and the supraspinatus tendon. (c) subtendinous Subscapularis Bursa Lies between the subscapularis tendon and the neck of the scapula and communicates with the synovial cavity of the shoulder joint. 22 Figure 22. Bursae around the Shoulder D. Elbow Joint Forms a synovial hinge joint, consisting of the humeroradial and humeroulnar joints, and allows flexion and extension. It also includes the proximal radioulnar (pivot) joint, within a common articular capsule. Is innervated by the musculocutaneous, median, radial, and ulnar nerves. Receives blood from the anastomosis formed by branches of the brachial artery and recurrent branches of the radial and ulnar arteries. Is reinforced by the following ligaments: 1. Annular Ligament Is a fibrous band that is attached to the anterior and posterior margins of the radial notch of the ulna and forms nearly four-fifths of a circle around the head of the radius; the radial notch forms the remainder. Encircles the head of the radius and holds it in position and fuses with the radial collateral ligament and the articular capsule. 2. Radial Collateral Ligament Extends from the lateral epicondyle to the anterior and posterior margins of the radial notch of the ulna and the annular ligament of the radius. 3. Ulnar Collateral Ligament Is triangular and is composed of anterior, posterior, and oblique bands. Extends from the medial epicondyle to the coronoid process and the olecranon of the ulna. 23 Figure 23. elbow joint E. Proximal Radioulnar Joint Forms a synovial pivot joint in which the head of the radius articulates with the radial notch of the ulna and allows pronation and supination by permitting the head of radius to rotate within the encircling annular ligament. F. Distal Radioulnar Joint Forms a synovial pivot joint between the head of the ulna and the ulnar notch of the radius and allows pronation and supination. Figure 24. Radioulnar Joint joint G. Wrist (Radiocarpal) Joint Is a synovial condylar joint formed superiorly by the radius and the articular disk and inferiorly by the proximal row of carpal bones (scaphoid, lunate, and rarely triquetrum). Its capsule is strengthened by radial and ulnar collateral ligaments and dorsal and palmar radiocarpal ligaments, and it allows flexion and extension, abduction and adduction, and circumduction. H. Intercarpal Joint Forms a synovial plane joint between the proximal and distal rows of carpal bones and allows gliding and sliding movements. 24  I. Carpometacarpal Joints Form synovial saddle (sellar) joints between the carpal bone (trapezium) and the first metacarpal bone, allowing flexion and extension, abduction and adduction, and circumduction. Also form plane joints between the carpal bones and the medial four metacarpal bones, allow- ing a simple gliding movement. J. Metacarpophalangeal Joints Are condyloid joints that allow flexion and extension, and abduction and adduction. K. Interphalangeal Joints Are hinge joints that allow flexion and extension. Figure 25. joints in the hand 25 MUSCLES OF THE UPPER LIMB I. Muscles of the Shoulder Region Superficial muscles of the shoulder Muscle Origin Insertion Nerve Action superior nuchal line, posterior border of 1. Elevate the Trapezius external occipital the clavicle, medial Accessory scapula as in protuberance, margin of the nerve shrugging the ligament nuchae, acromion and upper shoulder. spine of 7th cervical lip of the spine of 2. Retract the vertebra, and spines the scapula scapula as in bracing of all thoracic back the shoulder vertebrae 3. rotates the scapula so that the arm can be abducted beyond 90°. Deltoid Lateral third of Deltoid tuberosity of Axillary Abducts, adducts, clavicle, humerus flexes, acromion, and spine extends, and rotates of arm scapula medially and laterally Transverse processes Posterior surface of Elevates the Levator of Cl-4 medial border of Branches scapula scapular scapula from directly from superior angle to anterior rami of root of spine of the scapula C3 and (4) spinal nerves and by transvers branches (CS) from the dorsal and scapular nerve Rhomboid Lower end of liga Poste rior su rface Dorsal El evates and Minor mentum nuchae and of medial border of scapular ne rve retracts the sca spinous processes scapula at the root (C4, CS) of CVI I and Tl of the spine of the verte brae sca pula Rhomboid Spinous processes of Poste rior su rface Dorsal El evates and Major TII-TV, verte brae of medial border of scapular nerve retracts the sca pula and intervening scapula fro m the supraspinous liga root of the spine of ments the sca pula to the infe rior angle 26  Posterior scapular region Muscle Origin Insertion Nerve Action Supraspinat Supraspinous fossa Superior facet of Suprascapular Abducts arm scapula greater tubercle of us of humerus Infraspinat Infraspinous fossa Middle facet of Suprascapular Rotates arm laterally tubercle greater of us humerus Teres major Dorsal surface of Medial lip of Lower Adducts and rotates angle of scapula inferior intertubercular subscapular medially arm groove of humerus Teres minor Upper portion of Lower facet of Axillary Rotates arm laterally border lateral of scapula tubercle greater of humerus Rotator (Musculotendinous) Cuff (See Figure 7.3) Is formed by the tendons of supraspinatus, infraspinatus, teres minor, and subscapularis (SITS). fuses with the joint capsule; and provides mobility. Keeps the head of the humerus in the glenoid fossa during movements and thus stabilizes the shoulder joint. Gateways to the posterior scapular region A. Suprascapular foramen The suprascapular nerve passes through it whereas the suprascapular artery and vein pass immediately superior to the superior transverse scapular ligament. B. Quadrangular Space (Figures 7.11 and 7.13) Is bounded superiorly by the teres minor and subscapularis muscles, inferiorly by the teres major muscle, medially by the long head of the triceps, and laterally by the surgical neck of the humerus. Transmits the axillary nerve and the posterior humeral circumflex vessels. C. Triangular Space Is bounded superiorly by the teres minor muscle, inferiorly by the teres major muscle, and laterally by the long head of the triceps. Contains the circumflex scapular vessels. D. Triangular interval Is formed superiorly by the teres major muscle, medially by the long head of the triceps, and 27  laterally by the medial head of the triceps. Contains the radial nerve and the profunda brachii (deep brachial) artery. E. Triangle of Auscultation Is bounded by the upper border of the latissimus dorsi muscle, the lateral border of the trapezius muscle, and the medial border of the scapula; its floor is formed by the rhomboid major muscle. Is the site at which breathing sounds are heard most clearly. II. MUSCLES OF THE PECTORAL REGION AND AXILLA Axilla (Armpit) Is a pyramid-shaped space between the upper thoracic wall and the arm. Boundaries of the Axilla Include medial wall: upper ribs and their intercostal muscles and serratus anterior muscle; lateral wall: intertubercular groove of the humerus; posterior wall: subscapularis, teres major, and latissimus dorsi muscles; anterior wall: pectoralis major and pectoralis minor muscles and clavipectoral fascia; base: axillary fascia and skin; and apex: interval between the clavicle, first rib, and upper border of the scapula. Fasciae of the axilla and pectoral regions A. Clavipectoral Fascia Extends between the coracoid process, clavicle, and the thoracic wall and envelops the subclavius and pectoralis minor muscles. Its components are (1) the costocoracoid ligament, which is a thickening of the fascia between the coracoid process and the first rib; (2) the costocoracoid membrane, which lies between the subclavius and pectoralis minor muscles and is pierced by the cephalic vein, the thoracoacromial artery, and the lateral pectoral nerve; and (3) the suspensory ligament of the axilla, which is the inferior extension of the fascia and is attached to the axillary fascia, maintaining the hollow of the armpit. B. Axillary Fascia Is contiguous anteriorly with the pectoral and clavipectoral fasciae (suspensory ligament of the axilla), laterally with the brachial fascia, and posteromedially with the fascia over the latissimus dorsi. Forms the floor of the axilla and is attached to the suspensory ligament of the axilla that forms the 28  hollow of the armpit by traction when the arm is abducted. C. Axillary Sheath Is a tubular fascial prolongation of the prevertebral layer of the deep cervical fascia into the axilla, enclosing the axillary vessels and the brachial plexus. Muscles of the Pectoral Region and Axilla Muscle Origin Insertion Nerve Action Pectoral Medial half of Lateral lip of Lateral Flexes, adducts, and is clavicle; intertubercular and medially major manubrium and body groove medial rotates arm of sternum; of humerus pectora upper six costal l cartilages Pectoral Third, fourth, and fifth Coracoid Medial Depresses scapula; minor is ribs scapula process of lateral) (and elevates ribs pectora l Subclav Junction of first rib Inferior surface Nerve Depresses lateral part ius cartilage and costal clavicle of subclav to of clavicle ius Serratu Upper eight ribs Medial border Long Rotates scapula anterior scapula of thoraci abducts upward; scapula with s c arm and it above the elevates horizontal Muscles of Anterior wall of Axilla 29 Serrates anterior muscle (Medial wall) Muscles of posteriol wall of Axilla The Muscles of the wall are subscapularis, latissimus dorsi ,teres major and the long head of the triceps brachii muscles. Muscle Origin Insertion Nerve Action Subscapula Subscapular Lesser tubercle Upper Adducts and rotates fossa humerus of subsca and medially arm ris pular Latissimus Spines of T7– Floor of Thorac lower Adducts, extends, and bicipital odorsa rotates arm medially, Dorsi T12 l groove of Elevate the pelvis, thoracolumbar humerus backward swinging of fascia, the arm iliac crest, ribs 9–12 30 III. MUSCLES OF THE ARM A. Brachial Intermuscular Septa  Extend from the brachial fascia, a portion of the deep fascia, enclosing the arm.  Consist of medial and lateral intermuscular septa, which divide the arm into the anterior compartment (flexor compartment) and the posterior compartment (extensor compartment). III. MUSCLES OF THE FOREARM B. Cubital Fossa  Is a V-shaped interval on the anterior aspect of the elbow that is bounded laterally by the brachioradialis muscle, medially by the pronator teres muscle, and superiorly by an imaginary horizontal line connecting the epicondyles of the humerus with a floor formed by the brachialis and supinator muscles.  At its lower end, the brachial artery divides into the radial and ulnar arteries, with a fascial roof strengthened by the bicipital aponeurosis.  Contains (from lateral to medial) the radial nerve, biceps tendon, brachial artery, and median nerve (mnemonic device: Ron Beats Bad Man). 31 C. Bicipital Aponeurosis  Originates from the medial border of the biceps tendon, lies on the brachial artery and the median nerve, and blends with the deep fascia of the forearm. D. Interosseous Membrane of the Forearm  Is a dense connective tissue sheet between the radius and the ulna. Its proximal border forms a gap through which the posterior interosseous vessels pass, and it is pierced (distally) by the anterior interosseous vessels.  Provides attachments for the deep extrinsic flexor, extensor, and abductor muscles of the hand. E. Characteristics of the Arm and Forearm 1. Carrying Angle  Is formed laterally by the axis of the arm and forearm when the elbow is extended, because the medial edge of the trochlea projects more inferiorly than its lateral edge. The forearm deviated (5–15 degrees) laterally from a straight line of the arm.  Is wider in women than in men and disappears when the forearm is flexed or pronated. 32 2. Pronation and Supination  Occur at the proximal and distal radioulnar joints and have unequal strengths, with supination being stronger.  Are movements in which the upper end of the radius nearly rotates within the annular ligament.  Supination: palm faces forward (lateral rotation); pronation: the radius rotates over the ulna, and thus, the palm faces backward (medial rotation, in which case the shafts of the radius and ulna cross each other). Muscles of the Anterior Forearm 33  Muscle Origin Insertion Nerve Action Superficial layer Pronator teres Medial epicondyle andMiddle of lateral side Median Pronates and flexes coronoid process of radius forearm ulna of Flexor carpi Medial epicondyle of Bases of second and Median Flexes forearm, radialis humerus metacarpals third and abducts hand flexes Palmaris longus Medial epicondyle of Flexor retinaculum, Median Flexes forearm and humerus aponeurosis palmar hand Flexor carpi Medial epicondyle Pisiform, hook of Ulnar Flexes forearm; ulnaris head); medial (humeral and base of fifth and adducts hand posterior border of hamate, olecranon, and metacarpal flexes ulna (ulnar head) Intermediate Flexor digitorum layer Medial epicondyle, Middle phalanges of Median Flexes proximal Superficialis process, coronoid oblique line of finger interphalangeal Middle (FDS) layer radius joints, hand and flexes forearm Deep layer Flexor digitorum Anteromedial surface Bases of distal Ulnar and Flexes distal Profundus(FDP) of ulna, interosseous of fingers phalanges median interphalangeal membrane joints and hand Flexor pollicis Anterior surface of Base of distal phalanx Median Flexes thumb Longus(FPL) interosseous radius, thumb of membrane, and coronoid process Pronator Anterior surface of Anterior surface of Median Pronates forearm quadratus ulna distal radius distal SMuscles of the Posterior forearm 34  Muscle Origin Insertion Nerve Action Superficial layer Brachioradiali Lateral supracondylar Base of radial styloid Radial Flexes forearm humerus process s ridge of Extensor carpi Lateral supracondylar Dorsum of base of Radial Extends and abducts radialis humerus ridge of metacarpal second hand longus Extensor carpi Lateral epicondyle of Posterior base of third Radial Extends and abducts radialis brevis humerus metacarpal hands Extensor Lateral epicondyle of Extensor expansion, Radial Extends fingers and digitorum humerus of middle and digital base hand phalanges Extensor Common extensor tendon Extensor expansion, Radial Extends little finger minimi digiti interosseous and membrane middle base ofand distal phalanges Extensor carpi Lateral epicondyle and Base of fifth Radial Extends and adducts ulnaris posterior surface of ulna metacarpal hand Anconeus Lateral epicondyle of Olecranon and upper Radial humerus posterior surface of Extends forearm ulna Deep layer Supinator Lateral epicondyle, radial Lateral side of upper Radial Supinates forearm collateral and annular of radius part ligaments, supinator fossa of crest andulna Abductor Interosseous membrane, Lateral surface of base Radial Abducts thumb and pollicis longus middle third of posterior first of metacarpal hand surfaces of radius and ulna Extensor Interosseous membrane Base of distal phalanx Radial Extends distal longus pollicis and middle third of thumb of thumb and abducts phalanx posteriorof ulna surface hand of Extensor Interosseous membrane Base of proximal Radial Extends proximal brevis pollicis posterior and surface of of thumb phalanx of thumb and abducts phalanx middle third of radius hand Extensor Posterior surface of ulna Extensor expansion of Radial Extends index finger indicis interosseous and membrane finger index Tennis elbow (lateral epicondylitis) is caused by a chronic inflammation or irritation of the origin (tendon) of the extensor muscles of the forearm from the 35 lateral epicondyle of the humerus as a result of repetitive strain. It is a painful condition and common in tennis players and violinists. Golfer’s elbow (medial epicondylitis) is a painful condition caused by a small tear or an inflammation or irritation in the origin of the flexor muscles of the forearm from the medial epicondyle. Treatment may include injection of glucocorticoids into the inflamed area or avoidance of repetitive bending (flexing) of the forearm in order to not compress the ulnar nerve. Nursemaid’s elbow or pulled elbow is a radial head subluxation and occurs in toddlers when the child is lifted by the wrist. It is caused by a partial tear (or loose) of the annular ligament and thus the radial head to slip out of position. CLINICCORRELATES Cubital tunnel syndrome results from compression on the ulnar nerve in the cubital tunnel behind the medial epicondyle (funny bone), causing numbness and tingling in the ring and little fingers. The tunnel is formed by the medial epicondyle, ulnar collateral ligament, and two heads of the flexor carpi ulnaris muscle and transmits the ulnar nerve and superior ulnar collateral or posterior ulnar recurrent artery. IV. MUSCLES OF THE HAND A. Extensor Retinaculum (Figures 7.15 and 7.16)  Is a thickening of the antebrachial fascia on the back of the wrist, is subdivided into compartments, and places the extensor tendons beneath it.  Extends from the lateral margin of the radius to the styloid process of the ulna, the pisiform, and the triquetrum and is crossed superficially by the superficial branch of the radial nerve. B. Palmar Aponeurosis  Is a triangular fibrous layer overlying the tendons in the palm and is continuous with the palmaris longus tendon, the thenar and hypothenar fasciae, the flexor retinaculum, and the palmar carpal ligament.  Protects the superficial palmar arterial arch, the palmar digital nerves, and the long flexor tendons. 36 C. Flexor Retinaculum (See Figure 7.15) Serves as an origin for muscles of the thenar eminence. Forms the carpal (osteofascial) tunnel on the anterior aspect of the wrist. Is attached medially to the triquetrum, the pisiform, and the hook of the hamate and laterally to the tubercles of the scaphoid and trapezium. Is crossed superficially by the ulnar nerve, ulnar artery, palmaris longus tendon, and palmar cutaneous branch of the median nerve. F. Fascial Spaces of the Palm Are fascial spaces deep to the palmar aponeurosis and divided by a midpalmar (oblique) septum into the thenar space and the midpalmar space. 1. Thenar Space Is the lateral space that contains the flexor pollicis longus tendon and the other flexor tendons of the index finger. 2. Midpalmar Space Is the medial space that contains the flexor tendons of the medial three digits. G. Synovial Flexor Sheaths 1. Common Synovial Flexor Sheath (Ulnar Bursa) Envelops or contains the tendons of both the flexor digitorum superficialis and profundus muscles. 2. Synovial Sheath for Flexor Pollicis Longus (Radial Bursa) Envelops the tendon of the flexor pollicis longus muscle. 37 H. Tendons of the Flexor and Extensor Digitorum Muscles The flexor digitorum superficialis tendon splits into two medial and lateral bands and inserts on the base of the middle phalanx, whereas the flexor digitorum profundus tendon inserts on the base of the distal phalanx as a single tendon. On the dorsum of the hand, a single central band of the extensor digitorum tendon inserts on the base of the middle phalanx, whereas two lateral bands of the extensor digitorum tendon join to form a single band to insert on the base of the distal phalanx. I. Extensor Expansion (Figure 7.17) Is the expansion of the extensor tendon over the metacarpophalangeal joint and is referred to by clinicians as the extensor hood. Provides the insertion of the lumbrical and interosseous muscles and the extensor indicis and extensor digiti minimi muscles. 38 J. Anatomic Snuffbox Is a triangular interval bounded medially by the tendon of the extensor pollicis longus muscle and laterally by the tendons of the extensor pollicis brevis and abductor pollicis longus muscles. Is limited proximally by the styloid process of the radius. Has a floor formed by the scaphoid and trapezium bones and crossed by the radial artery. K. Fingernails Are keratinized plates on the dorsum of the tips of the fingers that consist of the proximal hidden part or root, the exposed part or body, and the distal freeborder. Parts of the nail include the following: 1. Nail bed The skin underneath the nail is the nail bed in which sensory nerve endings and blood vessels are abundant. The matrix or proximal part of the nail bed produces hard keratin and is responsible for nail growth. 2. Other structures The root is partially covered by a fold of skin known as the nail fold. The narrow band of epidermis prolonged from the proximal nail fold onto the nail is termed the eponychium. The half-moon, or lunula, is distal to the eponychium. The hyponychium represents the thickened epidermis deep to the distal end of the nail. 39  t a b l e Muscles of the 7.6 Hand Muscle Origin Insertion Nerve Action Abductor pollicis Flexor retinaculum, Lateral side of base of Median Abducts thumb brevis scaphoid, trapezium proximal phalanx of thumb Flexor pollicis Flexor retinaculum and Base of proximal Median Flexes thumb brevis trapezium of thumb phalanx Opponens pollicis Flexor retinaculum and Lateral side of first Median Opposes thumb to trapezium metacarpal digits other Adductor pollicis Capitate and bases Medial side of base of Ulnar Adducts thumb of second and third proximal phalanx of the metacarpals (oblique thumb head); palmar surface of third metacarpal (transverse head) Palmaris brevis Medial side of flexor Skin of medial side of Ulnar Wrinkles skin on retinaculum, palmar palm side of palm medial aponeurosis Abductor digiti Pisiform and tendon of Medial side of base of Ulnar Abducts little finger minimi flexor carpi ulnaris proximal phalanx of little finger Flexor digiti minimi Flexor retinaculum and Medial side of base of Ulnar Flexes proximal brevis hook of hamate proximal phalanx of of little finger phalanx little finger Opponens digiti Flexor retinaculum and Medial side of fifth Ulnar Opposes little finger minimi hook of hamate metacarpal Lumbricals (4) Lateral side of tendons Lateral side of Median Flex flexor of digitorum expansion extensor (two metacarpophalange profundus lateral) and ulnar al joints and extend (two interphalangeal medial) joints Dorsal interossei Adjacent sides of Lateral sides of bases Ulnar Abduct fingers, flex (bipennate) (4) metacarpal bones of proximal metacarpophalange phalanges, extensor expansion al joints, extend interphalangeal joints Palmar interossei Medial side of second Bases of proximal Ulnar Adduct fingers, flex (unipennate) (3) metacarpal; lateral phalanges in same metacarpophalange sides of fourth and sides as their origins, al joints, extend fifth metacarpals extensor expansion interphalangeal joints Tenosynovitis is an inflammation of the tendon and synovial sheath, and puncture injuries cause infection of the synovial sheaths of the digits. The tendons Of the second, third, and fourth digits have separate synovial sheaths so that the infection is con- fined to the infected digit, but rupture of the proximal ends of these sheaths allows the infection to spread to the midpalmar space. The synovial sheath of the little finger is usually continuous with the common synovial sheath (ulnar bursa), and thus, infection may spread to the common sheath and thus through the palm and carpal tunnel to the forearm. Likewise, infection in the thumb may spread through the synovial sheath of the flexor pollicis longus (radial bursa). 40  Trigger finger results from stenosing tenosynovitis or occurs when the flexor tendon develops a nodule or swelling that interferes with its gliding through the pulley, causing an audible clicking or snapping. Symptoms are pain at the joints and a clicking when extending or flexing the joints. This condition may be caused by rheumatoid arthritis, repetitive trauma, and wear and tear of aging of the tendon. It can be treated by immobilization by a splint, an injection of corticosteroid into the flexor tendon sheath to shrink the nodule, or surgical incision of the thickened area. Mallet finger (hammer or baseball finger) is a finger with permanent flexion of the distal pha- lanx due to an avulsion of the lateral bands of the extensor tendon to the distal phalanx. Boutonniere deformity is a finger with abnormal flexion of the middle phalanx and hyperextension of the distal phalanx due to an avulsion of the central band of the extensor tendon to the middle phalanx or rheumatoid arthritis. 41 BLOOD VESSELS OF THE UPPER LIMB Contents of the Axilla Brachial plexus and its branches Axillary artery has many branches, including the superior thoracic, thoracoacromial, lateral thoracic, thoracodorsal, and circumflex humeral (anterior and posterior) arteries. Axillary vein is formed by the union of the brachial veins (venae comitantes of the brachial artery) and the basilic vein, receives the cephalic vein and veins that correspond to the branches of the axillary artery, and drains into the subclavian vein. Lymph nodes and areolar tissue are present. Axillary tail (tail of Spence) is a superolateral extension of the mammary gland. I. BRANCHES OF THE SUBCLAVIAN ARTERY A. Suprascapular Artery Is a branch of the thyrocervical trunk. Passes over the superior transverse scapular ligament (whereas the suprascapular nerve passes under the ligament). Anastomoses with the deep branch of the transverse cervical artery (or dorsal scapular artery) and the circumflex scapular artery around the scapula, providing a collateral circulation. Supplies the supraspinatus and infraspinatus muscles and the shoulder and acromioclavicular joints. B. Dorsal Scapular or Descending Scapular Artery Arises from the subclavian artery but may be a deep branch of the transverse cervical artery. Accompanies the dorsal scapular nerve. Supplies the levator scapulae, rhomboids, and serratus anterior muscles. C. Arterial Anastomoses around Scapular Occur between three groups of arteries: suprascapular, deep branch of transvers cervical artery, and circumflex scapular arteries; 42  C. Arterial Anastomoses shoulder (b) suprascapular, acromial branch of throcoacromial and posterior humeral circumflex arteries. 43 II. AXILLARY ARTERY Is considered to be the central structure of the axilla. Extends from the outer border of the first rib to the inferior border of the teres major muscle, where it becomes the brachial artery. The axillary artery is bordered on its medial side by the axillary vein. Is divided into three parts by the pectoralis minor muscle. A. Superior or Supreme Thoracic Artery Supplies the intercostal muscles in the first and second anterior intercostal spaces and adjacent muscles. B. Thoracoacromial Artery Is a short trunk from the first or second part of the axillary artery and has pectoral, clavicular, acromial, and deltoid branches. Pierces the costocoracoid membrane (or clavipectoral fascia). C. Lateral Thoracic Artery Runs along the lateral border of the pectoralis minor muscle. Supplies the pectoralis major, pectoralis minor, and serratus anterior muscles and the axillary lymph nodes and gives rise to lateral mammary branches. D. Subscapular Artery Is the largest branch of the axillary artery, arises at the lower border of the subscapularis muscle, and descends along the axillary border of the scapula. Divides into the thoracodorsal and circumflex scapular arteries. 1. Thoracodorsal Artery Accompanies the thoracodorsal nerve and supplies the latissimus dorsi muscle and the lateral thoracic wall. 2. Circumflex Scapular Artery Passes posteriorly into the triangular space bounded by the subscapularis muscle and the teres minor muscle above, the teres major muscle below, and the long head of the triceps brachii laterally. Ramifies in the infraspinous fossa and anastomoses with branches of the dorsal scapular and suprascapular arteries. E. Anterior Humeral Circumflex Artery Passes anteriorly around the surgical neck of the humerus. Anastomoses with the posterior humeral circumflex artery. F. Posterior Humeral Circumflex Artery Runs posteriorly with the axillary nerve through the quadrangular space bounded by the teres minor and teres major muscles, the long head of the triceps brachii, and the humerus. Anastomoses with the anterior humeral circumflex artery and an ascending branch of the profunda brachii artery and also sends a branch to the acromial arch 44. CLINICAL CORRELATES If the axillary artery is ligated between the thyrocervical trunk and the subscapular artery, then blood from anastomoses in the scapular region arrives at the subscapular artery in which the blood flow is reversed to reach the axillary artery distal to the liga- ture. The axillary artery may be compressed or felt for the pulse in front of the teres major or against the humerus in the lateral wall of the axilla. C. Axillary Lymph Nodes 1. Central Nodes Lie near the base of the axilla between the lateral thoracic and subscapular veins; receive lymph from the lateral, anterior, and posterior groups of nodes; and drain into the apical nodes. 2. Brachial (Lateral) Nodes Lie posteromedial to the axillary veins, receive lymph from the upper limb, and drain into the central nodes. 3. Subscapular (Posterior) Nodes Lie along the subscapular vein, receive lymph from the posterior thoracic wall and the posterior aspect of the shoulder, and drain into the central nodes. 4. Pectoral (Anterior) Nodes Lie along the inferolateral border of the pectoralis minor muscle; receive lymph from the anterior and lateral thoracic walls, including the breast; and drain into the central nodes. 5. Apical (Medial or Subclavicular) Nodes Lie at the apex of the axilla medial to the axillary vein and above the upper border of the pectoralis minor muscle, receive lymph from all of the other axillary nodes (and occasionally from the breast), and drain into the subclavian trunks, which usually empty into the junction of the subclavian and internal jugular veins. 45 III. BRACHIAL ARTERY Extends from the inferior border of the teres major muscle to its bifurcation in the cubital fossa. Lies on the triceps brachii and then on the brachialis muscles medial to the coracobrachialis and biceps brachii and is accompanied by the basilic vein in the middle of the arm. Lies in the center of the cubital fossa, medial to the biceps tendon, lateral to the median nerve, and deep to the bicipital aponeurosis. The stethoscope should be placed in this place when taking blood pressure and listening to the arterial pulse. Provides muscular branches and terminates by dividing into the radial and ulnar arteries at the level of the radial neck, approximately 1 cm below the bend of the elbow, in the cubital fossa. 46  A. Profunda Brachii (Deep Brachial) Artery Descends posteriorly with the radial nerve and gives off an ascending branch, which anastomoses with the descending branch of the posterior humeral circumflex artery. Divides into the middle collateral artery, which anastomoses with the interosseous recurrent artery, and the radial collateral artery, which follows the radial nerve through the lateral intermuscular septum and ends in front of the lateral epicondyle by anastomosing with the radial recurrent artery of the radial artery. B. Superior Ulnar Collateral Artery Pierces the medial intermuscular septum and accompanies the ulnar nerve behind the septum and medial epicondyle. Anastomoses with the posterior ulnar recurrent branch of the ulnar artery. C. Inferior Ulnar Collateral Artery Arises just above the elbow and descends in front of the medial epicondyle. Anastomoses with the anterior ulnar recurrent branch of the ulnar artery. CLINICAL CORRELATES If the brachial artery is tied off distal to the inferior ulnar collateral artery, sufficient blood reaches the ulnar and radial arteries via the existing anastomoses around the elbow. The brachial artery may be compressed or felt for the pulse on the brachialis against the humerus but medial to the biceps and its tendon and can be used for taking blood pressure. FIGURE 2-8. anastomoses around the elbow 47 IV. RADIAL ARTERY Arises as the smaller lateral branch of the brachial artery in the cubital fossa and descends laterally under cover of the brachioradialis muscle, with the superficial radial nerve on its lateral side, on the supinator and flexor pollicis longus muscles. Curves over the radial side of the carpal bones beneath the tendons of the abductor pollicis longus muscle, the extensor pollicis longus and brevis muscles, and over the surface of the scaphoid and trapezium bones. Runs through the anatomic snuffbox, enters the palm by passing between the two heads of the first dorsal interosseous muscle and then between the heads of the adductor pollicis muscle, and divides into the princeps pollicis artery and the deep palmar arch. Accounts for the radial pulse, which can be felt proximal to the wrist between the tendons of the brachioradialis and flexor carpi radialis muscles. The radial pulse may also be palpated in the anatomic snuffbox between the tendons of the extensor pollicis longus and brevis muscles. Gives rise to the following branches: A. Radial Recurrent Artery Arises from the radial artery just below its origin and ascends on the supinator and then between the brachioradialis and brachialis muscles. Anastomoses with the radial collateral branch of the profunda brachii artery. B. Palmar Carpal Branch Joins the palmar carpal branch of the ulnar artery and forms the palmar carpal arch. C. Superficial Palmar Branch Passes through the thenar muscles and anastomoses with the superficial branch of the ulnar artery to complete the superficial palmar arterial arch. D. Dorsal Carpal Branch Joins the dorsal carpal branch of the ulnar artery and the dorsal terminal branch of the anterior interosseous artery to form the dorsal carpal arch. E. Princeps Pollicis Artery Descends along the ulnar border of the first metacarpal bone under the flexor pollicis longus tendon. Divides into two proper digital arteries for each side of the thumb. F. Radialis Indicis Artery Also may arise from the deep palmar arch or the princeps pollicis artery. G. Deep Palmar Arch Is formed by the main termination of the radial artery and usually is completed by the deep palmar branch of the ulnar artery. Passes between the transverse and oblique heads of the adductor pollicis muscle. Gives rise to three palmar metacarpal arteries, which descend on the interossei and join the common palmar digital arteries from the superficial palmar arch Gives rise to three perforating arteries, which join the dorsal metacarpal arteries palmar digital from the from the dorsal carpal arch. 48 V. ULNAR ARTERY Is the larger medial branch of the brachial artery in the cubital fossa. Descends behind the ulnar head of the pronator teres muscle and lies between the flexor digitorum superficialis and profundus muscles. Enters the hand anterior to the flexor retinaculum, lateral to the pisiform bone, and medial to the hook of the hamate bone. Divides into the superficial palmar arch and the deep palmar branch, which passes between the abductor and flexor digiti minimi brevis muscles and runs medially to join the radial artery to complete the deep palmar arch. Accounts for the ulnar pulse, which is palpable just to the radial side of the insertion of the flexor carpi ulnaris into the pisiform bone. If the ulnar artery arises high from the brachial artery and runs invariably superficial to the flexor muscles, the artery may be mistaken for a vein for certain drugs, resulting in disastrous gangrene with subsequent partial or total loss of the hand. Gives rise to the following branches: A. Anterior Ulnar Recurrent Artery Anastomoses with the inferior ulnar collateral artery. B. Posterior Ulnar Recurrent Artery Anastomoses with the superior ulnar collateral artery. C. Common Interosseous Artery Arises from the lateral side of the ulnar artery and divides into the anterior and posterior interosseous arteries. 1. Anterior Interosseous Artery Descends with the anterior interosseous nerve in front of the interosseous membrane, located between the flexor digitorum profundus and the flexor pollicis longus muscles. Perforates the interosseous membrane to anastomose with the posterior interosseous 49  artery and join the dorsal carpal network. 2. Posterior Interosseous Artery Gives rise to the interosseous recurrent artery, which anastomoses with a middle collateral branch of the profunda brachii artery. Descends behind the interosseous membrane in company with the posterior interosseous nerve. Anastomoses with the dorsal carpal branch of the anterior interosseous artery. If the ulnar artery arises high from the brachial artery and runs invariably superficial to the flexor muscles, then when injecting, the artery may be mistaken for a vein for certain drugs, resulting in disastrous gangrene with subsequent partial or total loss of the hand. The ulnar artery may be compressed or felt for the pulse on the anterior aspect of the flexor retinaculum on the lateral side of the pisiform bone. D. Palmar Carpal Branch Joins the palmar carpal branch of the radial artery to form the palmar carpal arch. E. Dorsal Carpal Branch Passes around the ulnar side of the wrist and joins the dorsal carpal arch. F. Superficial Palmar Arch Is the main termination of the ulnar artery, usually completed by anastomosis with the superficial palmar branch of the radial artery. Lies immediately under the palmar aponeurosis. Gives rise to three common palmar digital arteries, each of which bifurcates into proper palmar digital arteries, which run distally to supply the adjacent sides of the fingers. G. Deep Palmar Branch Accompanies the deep branch of the ulnar nerve through the hypothenar muscles and anastomoses with the radial artery, thereby completing the deep palmar arch. Gives rise to the palmar metacarpal arteries, which join the common palmar digital arteries. The Allen test is a test for occlusion of the radial or ulnar artery; either the radial or ulnar artery is digitally compressed by the examiner after blood has been forced out of the hand by making a tight fist; failure of the blood to return to the palm and fingers on opening indicates that the uncompressed artery is occluded. 50 VI. VEINS OF THE UPPER LIMB A. Deep and Superficial Venous Arches Are formed by a pair of venae comitantes, which accompany each of the deep and superficial palmar arterial arches. B. Deep Veins of the Arm and Forearm Follow the course of the arteries, accompanying them as their venae comitantes. (The radial veins receive the dorsal metacarpal veins. The ulnar veins receive tributaries from the deep palmar venous arches. The brachial veins are the vena comitantes of the brachial artery and are joined by the basilic vein to form the axillary vein.) C. Axillary Vein Is formed at the lower border of the teres major muscle by the union of the brachial veins (venae comitantes of the brachial artery) and the basilic vein and ascends along the medial side of the axillary artery. Continues as the subclavian vein at the inferior margin of the first rib. Commonly receives the thoracoepigastric veins directly or indirectly and thus provides a collateral circulation if the inferior vena cava becomes obstructed. Has tributaries that include the cephalic vein, brachial veins (venae comitantes of the brachial artery that join the basilic vein to form the axillary vein), and veins that correspond to the branches of the axillary artery. FIGURE. Venous drainage of the upper limb III. SUPERFICIAL LYMPHATICS OF THE UPPER LIMB A. Lymphatics of the Finger 51  Drain into the plexuses on the dorsum and palm of the hand, which form the medial and lateral lymph vessels. B. Medial Group of Lymphatic Vessels Accompanies the basilic vein; passes through the cubital or supratrochlear nodes; and ascends to enter the lateral axillary nodes, which drain first into the central axillary nodes and then into the apical axillary nodes. C. Lateral Group of Lymphatic Vessels Accompanies the cephalic vein and drains into the lateral axillary nodes and also into the deltopectoral (infraclavicular) node, which then drain into the apical nodes. D. Axillary Lymph Nodes Lie in the axilla 52 NERVES OF THE UPPER LIMB I BRACHIAL PLEXUS Is formed by the ventral primary rami of the lower four cervical nerves and the first thoracic nerve (C5–T1). Has roots that pass between the scalenus anterior and medius muscles. Is enclosed with the axillary artery and vein in the axillary sheath, which is formed by a prolongation of the prevertebral fascia. Has the following subdivisions: A. Branches from the Roots 1. Dorsal Scapular Nerve (C5) Pierces the scalenus medius muscle to reach the posterior cervical triangle and descends deep to the levator scapulae and the rhomboid minor and major muscles. Innervates the rhomboids and frequently the levator scapulae muscles. 2. Long Thoracic Nerve (C5–C7) Descends behind the brachial plexus and runs on the external surface of the serratus anterior muscle, which it supplies. 53  CLINICAL CORRELATES Injury to the long thoracic nerve is commonly caused by a stab wound or during radical mastectomy or thoracic surgery. It results in paralysis of the serratus anterior muscle and inability to elevate the arm above the horizontal. It produces a winged scapula in which the vertebral (medial) border of the scapula protrudes away from the thorax. B. Branches from the Upper Trunk 1. Suprascapular Nerve (C5–C6) Runs laterally across the posterior cervical triangle. Passes through the scapular notch under the superior transverse scapular ligament, whereas the suprascapular artery passes over the ligament. (Thus, it can be said that the army [artery] runs over the bridge [ligament], and the navy [nerve] runs under the bridge.) Supplies the supraspinatus muscle and the shoulder joint and then descends through the notch of the scapular neck to innervate the infraspinatus muscle. 2. Nerve to Subclavius (C5) Descends in front of the brachial plexus and the subclavian artery and behind the clavicle to reach the subclavius muscle. Also innervates the sternoclavicular joint. Usually branches to the accessory phrenic nerve (C5), which enters the thorax to join the phrenic nerve. C. Branches from the Lateral Cord 1. Lateral Pectoral Nerve (C5–C7) Innervates the pectoralis major muscle primarily and also supplies the pectoralis minor muscle by way of a nerve loop. Sends a branch over the first part of the axillary artery to the medial pectoral nerve and forms a nerve loop through which the lateral pectoral nerve conveys motor fibers to the pectoralis minor muscle. Pierces the costocoracoid membrane of the clavipectoral fascia. Is accompanied by the pectoral branch of the thoracoacromial artery. 2. Musculocutaneous Nerve (C5–C7) Pierces the coracobrachialis muscle, descends between the biceps brachii and brachialis muscles, and innervates these three muscles. 3. lateral root of the Median Nerve(C5-C6) 54  Median nerve is formed by roots from both the medial and lateral cords.. Branches from the Medial Cord 1. Medial Pectoral Nerve (C8–T1) Passes forward between the axillary artery and vein and forms a loop in front of the axillary artery with the lateral pectoral nerve. Enters and supplies the pectoralis minor muscle and reaches the overlying pectoralis major muscle. 2. Medial Cutaneous Nerve of arm (C8–T1) Runs along the medial side of the axillary vein. Innervates the skin on the medial side of the arm. May communicate with the intercostobrachial nerve, which arises as a lateral branch of the second intercostal nerve. 3. Medial Cutaneous Nerve of forearm(C8–T1) Runs between the axillary artery and vein and then runs medial to the brachial artery. Innervates the skin on the medial side of the forearm. 4. Medial root of the Median Nerve (C5–T1) Median nerve is formed by roots from both the medial and lateral cords. Runs down the anteromedial aspect of the arm but does not branch in the brachium. 4. Ulnar Nerve (C7–T1) Runs down the medial aspect of the arm but does not branch in the brachium. 55 E. Branches from the Posterior Cord 1. Upper Subscapular Nerve (C5–C6) Innervates the upper portion of the subscapularis muscle. 2. Thoracodorsal Nerve (C7–C8) Runs behind the axillary artery and accompanies the thoracodorsal artery to enter the latissimus dorsi muscle. 3. Lower Subscapular Nerve (C5–C6) Innervates the lower part of the subscapularis and teres major muscles. Runs downward behind the subscapular vessels to the teres major muscle. 4. Axillary Nerve (C5–C6) Innervates the deltoid and teres minor muscles and gives rise to the lateral cutaneous nerveof arm. Passes posteriorly through the quadrangular space accompanied by the posterior circumflex humeral artery and winds around the surgical neck of the humerus (may be injured when this part of the bone is fractured). CLINICAL CORRELATES Injury to the posterior cord is caused by the pressure of the crosspiece of a crutch, resulting in the paralysis of the arm called crutch palsy. It results in the loss in function of the extensors of the arm, forearm, and hand and produces a wrist drop. 56  CLINICAL CORRELATES Injury to the axillary nerve is commonly caused by a fracture of the surgical neck of the humerus or inferior dislocation of the humerus. It results in weakness of lateral rotation and abduction of the arm (the supraspinatus can abduct the arm but not to a horizontal level). 5. Radial Nerve (C5–T1) Is the largest branch of the brachial plexus and occupies the radial groove on the back of the humerus with the profunda brachii artery. CLINICAL CORRELATES Injury to the radial nerve is commonly caused by a fracture of the midshaft of the humerus. It results in loss of function in the extensors of the forearm, hand, metacarpals, and phalanges. It also results in the loss of wrist extension, leading to wrist drop, and produces a weakness of abduction and adduction of the hand. 57  II. NERVES OF THE ARM, FOREARM, AND Hand A. Musculocutaneous Nerve (C5–C7) Pierces the coracobrachialis muscle and descends between the biceps and brachialis muscles. Innervates all of the flexor muscles in the anterior compartment of the arm, such as the coracobrachialis, biceps, and brachialis muscles. Continues into the forearm a lateral cutaneous nerve of forearm. CLINICAL CORRELATES Injury to the musculocutaneous nerve results in weakness of supination (biceps) and flexion (biceps and brachialis) of forearm and loss of sensation on the lateral side of forearm. B. Median Nerve (C5–T1) Runs down the anteromedial aspect of the arm, and at the elbow, it lies medial to the brachial artery on the brachialis muscle (has no muscular branches in the arm). Passes through the cubital fossa, deep to the bicipital aponeurosis, and medial to the brachial artery. Enters the forearm between the humeral and ulnar heads of the pronator teres muscle, passes between the flexor digitorum superficialis and the flexor digitorum profundus muscles, and then becomes superficial by passing between the tendons of the flexor digitorum superficialis and flexor carpi radialis near the wrist. In the cubital fossa, it gives rise to the anterior interosseous nerve, which descends on the interosseous membrane between the flexor digitorum profundus and the flexor pollicis longus; passes behind the pronator quadratus, supplying these three muscles; and then ends in sensory “twigs” to the wrist joint. Innervates all of the anterior muscles of the forearm except the flexor carpi ulnaris and the ulnar 58  half of the flexor digitorum profundus. Enters the palm of the hand through the carpal tunnel deep to the flexor retinaculum; gives off a muscular branch (recurrent branch) to the thenar muscles; and terminates by dividing into three common palmar digital nerves, which then divide into the palmar digital branches. Innervates also the lateral two lumbricals, the skin of the lateral side of the palm, and the palmar side of the lateral three and one-half fingers and the dorsal side of the index finger, middle finger, and one-half of the ring finger. CLINICAL CORRELATES Injury to the median nerve may be caused by a supracondylar fracture of the humerus or a compression in the carpal tunnel. It results in the loss of pronation, opposition of the thumb, and flexion of the lateral two interphalangeal joints and impairment of the medial two interphalangeal joints. It also produces a characteristic flattening of the thenar eminence, often referred to as the ape hand. C. Radial Nerve (C5–T1) Arises from the posterior cord and the largest branch of the brachial plexus. Branches in Axilla: Post cutaneous nerve of arm, a branch for Med head of triceps, a branch for long head of triceps Descends posteriorly between the long and medial heads of the triceps, after which it passes inferolaterally with the profunda brachii artery in the spiral (radial) groove on the back of the humerus between the medial and lateral heads of the triceps and innervate them. Branches in radial groove:1. a bracnchs for medial of the triceps and in continu innervate Anconeus. 2.. a 59  bracnchs for lateral of the 3.Lower lateral Cutanous nerve of forearm. 4. Posterior Cutanous nerve of forearm. Pierces the lateral intermuscular septum to enter the anterior compartment and descends anterior to the lateral epicondyle between the brachialis and brachioradialis muscles to enter the cubital fossa, where it divides into superficial and deep branches. Gives rise to muscular branches (which supply the brachioradialis and extensor carpi radialis longus), articular branches, and posterior brachial and posterior antebrachial cutaneous branches. 60  1. Deep Branch Enters the supinator muscle, winds laterally around the radius in the substance of the muscle, and supplies the extensor carpi radialis brevis and supinator muscles. Emerges from the supinator as the posterior interosseous nerve and continues with the posterior interosseous artery and innervates the extensor muscles of the forearm. 2. Superficial Branch Descends in the forearm under cover of the brachioradialis muscle and then passes dorsally around the radius under the tendon of the brachioradialis. Runs distally to the dorsum of the hand to innervate the skin of the radial side of the hand and the radial two and one-half digits over the proximal phalanx. This nerve does not supply the skin of the distal