HUMAN ANATOMY – VOLUME 1

Fig. 105. Muscles of upper limb. Anterior aspect.

1 — subscapularis; 2 — teres major;

3 — latissimus dorsi; 4 — long head of triceps brachii; 5 — medial head of triceps brachii; 6 — cubital fossa; 7 — medial epicondyle of humerus; 8 — pronator teres; 9 — flexor carpi ulnaris; 10 — palmaris longus; 11 — flexor digitorum superficialis; 12 — part of fascia of forearm; 13 — palmaris breve; 14 — hypothenar; 15 — palmar aponeurosis; 16 — thenar; 17 — tendo of abductor pollicis longus; 18 — flexor pollicis longus; 19 — flexor digitorum superficiale; 20 — flexor carpi radialis; 21 — brachioradialis; 22 — aponeurosis of biceps brachii; 23 — tendon of biceps brachii; 24 — brachialis; 25 — biceps brachii; 26 — coracobrachialis; 27 — short head of biceps brachii; 28 — long head of biceps brachii; 29 — deltoid.

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accreted with the fascia of the subclavian muscle and laminae of the cervical fascia.

The omotrapezius triangle (trigónum omotrapezoídeum) is bordered by the edge of the trapezius muscle, the interior venter of the omohyoid muscle and posterior edge of the sternocleidomastoid muscle. It contains the accessory nerve. Between the scalene muscles lie the cervical and brachial plexuses.

Questions for revision and examination

1.What groups are muscle of the neck divided into according to the derivation and location?

2.How many laminae does the cervical fascia have and for which muscles does it form sheaths?

3.Name the triangles (and their borders) of the anterior and lateral regions of the neck.

MUSCLES AND FASCIAE OF THE UPPER EXTREMITY

As an instrument of work, the arm is capable of a great variety of movements. The presence of many long and short muscles and the structural features of the shoulder and elbow joints enable the upper extremity to perform delicate, precise movements within wide amplitude.

According to the points of origin and insertion and to the joints, which are moved, the muscles of the upper extremity are divided into the muscles of the upper limb (shoulder) girdle and muscles of the free upper extremity.

MUSCLES OF THE SHOULDER GIRDLE

The muscles of the shoulder girdle originate from the clavicle and the scapula and are inserted into the humerus. These muscles cause movement in the glenohumeral, or shoulder, joint. The most superficial of these is the deltoid muscle. Deeper, beneath the deltoid muscle, lie the supraspinous and infraspinous muscles, teres major and teres minor muscles and the subscapularis muscle (Fig. 105, 106).

The deltoid muscle (m. deltoídeus) is situated directly below the skin and covers the shoulder joints from the front, back, the side and the top, forming the characteristic curve of the shoulder. It originates on the anterior edge of lateral end of clavicle, the acromion, the scapular spine and adjoining part of the infraspinous fascia. Its fascicles converge on the lateral surface of the humerus and are inserted into the deltoid tuberosity. Beneath the deltoid muscle, between the deep lamina of its fascia and the greater tubercle of the humerus, is the synovial subdeltoid bursa.

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Fig. 106. Muscles of upper limb. Posterior aspect.

1 — supraspinatus; 2 — spine of scapula (partially removed); 3 — deltoid (partially removed); 4 — brachoiradialis; 5 — extensor carpi radialis longus; 6 — lateral epicondyle; 7 — anconeus; 8 — extensor carpi radialis brevis; 9 — extensor digitorum; 10 — abductor pollicis longus; 11 — extensor pollicis brevis; 12 — tendon of extensor pollicis longus; 13 — dorsal interosseal 1st; 14 — tendon of extensor digitorum; 15 — tendon extensor digiti minimi; 16 — tendon of extensor indicis; 17 — extensor retinaculum; 18 — extensor carpi ulnaris; 19 — extensor digiti minimi; 20 — flexor carpi ulnaris; 21 — olecranon; 22 — medial epicondyle; 23 — triceps brachii; 24 — lateral head of triceps brachii; 25 — long head of triceps brachii; 26 — teres major; 27 — teres minor; 28 — infraspinatus; 29 — inferior

angle of scapula.

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F u n c t i o n: During contraction of the entire muscle the arm is abducted approximately 70 percent of possible amplitude. During contraction of its anterior (c l a v i c u l a r) f a s c i c l e s the arm is partially flexed and pronated. If the arm is raised the clavicular part of the muscle lowers it. The posterior (s p i n a l) f a s c i c l e s extends, supinates and somewhat raise the arm. The middle (a c r o m i a l) p a r t of the muscle abducts the arm.

I n n e r v a t i o n: axillary nerve.

B l o o d s u p p l y: posterior circumflex humeral artery, thoracoacromial artery.

The supraspinatus muscle (m. supraspinátus) originates from the posterior surface of the scapula, above its spine, and on the supraspinous fascia. Its fascicles stretch laterally and are inserted into the lower part of the greater tubercle of the humerus. Part of its fascicles weaves into the capsule of the shoulder joint.

F u n c t i o n: Abducts the arm and pulls the articular capsule outward, preventing it from being jammed.

I n n e r v a t i o n: suprascapular nerve.

B l o o d s u p p l y: suprascapular artery, circumflex scapular artery.

The infraspinatus muscle (m. infraspinátus) originates from the posterior surface of the scapula (beneath the spine) and from the infraspinous fascia. It stretches laterally, behind the shoulder joint, and is inserted into the greater tubercle of the humerus, below the tendon of the suprascapular muscle. Part of the fascicles of its tendon weaves into the articular capsule.

F u n c t i o n: It supinates the arm and stretches the capsule of the shoulder joint.

I n n e r v a t i o n: suprascapular nerve.

B l o o d s u p p l y: suprascapular artery, circumflex scapular artery.

The teres minor muscle (m. téres mínor) originates from the lateral margin of scapula and from the infraspinous fascia. It is inserted into the greater tubercle of the humerus, below the tendon of the infraspinous muscle. The teres minor muscle lies adjacent to the infraspinous muscle and is covered in the back by the scapular part of deltoid muscle.

F u n c t i o n: It supinates the arm and pulls the capsule of the shoulder joint outward.

I n n e r v a t i o n: axillary nerve.

B l o o d s u p p l y: circumflex scapular artery

The teres major muscle (m. téres májor) originates from the lower part of the lateral margin of the scapula and from the infraspinous fascia. Its muscle fascicles stretch along the lateral margin of the scapula, crossing the humerus on the medial side, below its surgical neck. It is inserted

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into the crest of the lesser tubercle of the humerus, more distal and to the back than the latissimus dorsi muscle.

F u n c t i o n: When the scapula is fixed it extends the shoulder and pronates it. It adducts the arm. When the humerus is fixed it pulls the inferior angle of the scapula forward and to the side.

I n n e r v a t i o n: subscapular nerve. B l o o d s u p p l y: subscapular artery.

The subscapularis muscle (m. subscapuláris) is strong and thick, and almost triangular. It originates from the entire surface of the subscapular fossa and the lateral margin of the scapula. It is inserted into the lesser tubercle of thehumerus and its crest. Beneath the tendon of this muscle there is a subtendinous bursa of subscapular muscle, which often communicates with the articular cavity of the shoulder joint.

F u n c t i o n: It pronates the arm and adducts it to the body. I n n e r v a t i o n: subscapular nerve.

B l o o d s u p p l y: subscapular artery.

MUSCLES OF THE FREE UPPER EXTREMITY

According to their topography and anatomic structure the muscles of the arm are divided into an anterior (flexor muscles) and a posterior (extensor muscles) groups. The anterior group includes the coracobrachialis, biceps brachii and brachial muscles. The posterior group consists of the triceps brachii and anconeus muscles.

Anterior muscles of the arm

The coracobrachialis muscle (m. coracobrachiális) originates from the apex of the coracoid process and is inserted into the humerus, below the crest of the lesser tubercle, at the same level with the deltoid muscle. Part of its fascicles weaves into the medial intermuscular septum of the arm.

F u n c t i o n: It flexes the arm and adducts it to the body. When the arm is pronated this muscle supinates it. When the arm is fixed it pulls the scapula forward and down.

I n n e r v a t i o n: musculocutaneous nerve.

B l o o d s u p p l y: posterior and anterior circumflex humeral arteries.

The biceps brachii muscle (m. bíceps bráchii) has a long and a short heads of origin. The l o n g h e a d originates from the supraglenoid tubercle of scapula. Its tendon stretches through the articular cavity of the shoulder joint and passes along the intertubercular groove. The s h o r t h e a d originates from the coracoid process of the scapula. The two heads

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unite at midlevel of humerus into a common venter, which continues into a tendon. This tendon is inserted into the tuberosity of the radius. Between the anteromedial surface of the tendon and the antebrachial fascia is a fibrous plate called the b i c i p i t a l a p o n e u r o s i s (Pirogoff’s fascia)

F u n c t i o n: It flexes the arm in the shoulder joint and the forearm in the elbow joint. When the forearm is pronated this muscle supinates it.

I n n e r v a t i o n: musculocutaneous nerve.

B l o o d s u p p l y: brachial artery, superior and inferior collateral ulnar arteries, radial recurrent artery.

The brachialis muscle (m. brachiális) originates from the lower two thirds of the body of the humerus, between the deltoid tuberosity and articular capsule of the elbow joint, and from the medial and lateral intermuscular septa of the arm. It attaches to the tuberosity of the ulna. Some of its fascicles weave into the capsule of the elbow joint.

F u n c t i o n: It flexes the forearm in the elbow joint. I n n e r v a t i o n: musculocutaneous nerve.

B l o o d s u p p l y: superior and inferior collateral ulnar arteries, brachial artery, radial recurrent artery.

Posterior muscles of the arm

The triceps brachii muscle (m. tríceps bráchii) covers the entire posterior surface of the humerus, forming the surface contours of the arm. It has a long, a medial (deep) and a lateral heads of origin. The l o n g h e a d originates on the infraglenoid tubercle of the scapula, and stretches downward between the teres major and teres minor muscles. Approximately at midlevel of the humerus it unites with the lateral and medial heads. The l a t e r a l h e a d originates from the lateral surface of thehumerus, between the insertion of the teres minor muscle and the radial groove, and on the back of the lateral intermuscular septum. This head stretches downward and medial, by covering the radial groove with its vessels and nerves. The m e d i a l h e a d of triceps originates from the posterior surface of humerus between the place of insertion of the teres major muscle and the olecranon fossa, and from the medial and lateral intermuscular septa, below the radial groove. The common venter of the triceps continues into a broad flat tendon, which is inserted into the olecranon process of ulna. Part of its fascicles weaves into the capsule of the elbow joint and the antebrachial fascia.

F u n c t i o n: extends the forearm in the elbow joint. The long head extends and adducts the arm in the shoulder joint.

I n n e r v a t i o n: radial nerve.

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Fig. 107. Muscles of anterior region of forearm, right.

Deep layer: 1 — supinator; 2 — flexor pollicis longus; 3 — flexor digitorum profundus; 4 — lumbricals.

B l o o d s u p p l y: posterior circumflex humeral artery, deep brachial artery, superior and inferior ulnar collateral arteries.

The anconeus muscle (m. ancóneus) is a small triangular muscle. It originates from the posterior surface of the lateral epicondyle of the humerus, and is inserted into the lateral surface of the olecranon process, the posterior surface of the ulna and the antebrachial fascia.

F u n c t i o n: It participates in extension of the forearm.

I n n e r v a t i o n: radial nerve.

B l o o d s u p p l y: recurrent interosseous artery.

The muscles of the forearm are divided into an anterior (flexors of the wrist and fingers) and posterior (extensors) groups. The muscles of the anterior group (7 flexors and 2 pronators) are situated in 4 layers (Fig. 107). The muscles of the posterior group (9 extensors and one supinator) are situated in two layers.

First (superficial) layer of the anterior muscles of the forearm

The brachioradialis muscle (m. brachioradiális) originates from the lateral supracondylar crest of humerus and the lateral intermuscular septum. It borders the olecranon fossa from the lateral side. At midlevel of the forearm its venter continues into a narrow flat tendon. This tendon passes underneath tendons of the long abductor and short extensor muscles of the thumb, and is inserted into the lateral surface of the distal end of radius.

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F u n c t i o n: It flexes the forearm in the elbow joint; sets the hand in an intermediate position between pronation and supination, turning the radius outward.

I n n e r v a t i o n: radial nerve.

B l o o d s u p p l y: radial artery, radial collateral artery, recurrent radial artery.

The pronator teres muscle (m. pronátor téres) is a short muscle with unequally sized heads. The humeral head originates from the medial epicondyle of the humerus, antebrachial fascia and medial intermuscular septum of the forearm. The lesser head has a deeper origin on the coronoid process of the ulna. This muscle stretches downward and laterally, bordering the olecranon fossa from the lateral side. Its tendon is inserted into the lateral surface of the radius, approximately at its middle.

F u n c t i o n: This muscle pronates the forearm together with the hand, acting upon the radioulnar joints. It takes part in flexion of the forearm.

I n n e r v a t i o n: median nerve.

B l o o d s u p p l y: brachial, ulnar and radial arteries.

The flexor carpi radialis muscle (m. fléxor cárpi radiális) originates on the medial epicondyle of humerus and the fascia and medial intermuscular septum of the arm. Approximately at the middle of the forearm it continues into a long narrow tendon, which passes through the carpal tunnel and is inserted into the base of the second metacarpal bone.

F u n c t i o n: It flexes the wrist in the radiocarpal joint. When contracting simultaneously with the radial extensor of the wrist, it abducts the hand.

I n n e r v a t i o n: median nerve.

B l o o d s u p p l y: brachial, ulnar and radial arteries.

The palmaris longus muscle (m. palmáris lóngus) is a thin fusiform muscle. It originates on the medial epicondyle of humerus, antebrachial fascia and upper part of its medial intermuscular septum. Its long thin tendon passes through the carpal tunnel and is inserted into the palmar aponeurosis. This muscle is sometimes absent.

F u n c t i o n: It stretches the palmar aponeurosis and participates in flexion of the hand in the radiocarpal joint.

I n n e r v a t i o n: median nerve. B l o o d s u p p l y: radial artery.

The flexor carpi ulnaris muscle (m. fléxor cárpi ulnáris) has a humeral and an ulnar heads of origin. The h u m e r a l h e a d originates on the medial epicondyle and medial intermuscular septum of the humerus.

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The u l n a r h e a d originates from the deep lamina of the antebrachial fascia, medial edge of olecranon process and posterior margin of the ulna. On the proximal part of the forearm both heads continue into a common venter. The muscle stretches along the medial edge of the forearm and is inserted with a long tendon into the pisiform bone. Part of its fascicles forms the pisiform-hamate and pisiform-metacarpal ligaments.

F u n c t i o n: Flexion of the forearm. When contracting together with the ulnar extensor of the wrist, it adducts the hand.

I n n e r v a t i o n: the ulnar nerve.

B l o o d s u p p l y: superior and inferior ulnar collateral arteries, ulnar artery.

Second layer of the anterior muscles of the forearm

The flexor digitorum superficialis muscle (m. fléxor digitórum superficiális) has a h u m e r o u l n a r and r a d i a l h e a d s, which are connected by a tendinous lamina. The humeroulnar head originates from the medial epicondyle of the humerus, antebrachial fascia, ulnar collateral ligament and medial edge of the coronoid process of the ulna. The radial head originates from the proximal two thirds of anterior edge of the radius. They form a common venter on the proximal end of the forearm. Approximately at the middle of the forearm this venter is divided into four parts, which continue into separate tendons. These tendons pass through the carpal tunnel and are inserted into palmar surfaces of the bases of the middle phalanges (fingers II–V). At midlevel of the proximal phalanges each of these tendons splits into two peduncles, beneath which pass the tendons of the deep flexor of the fingers.

F u n c t i o n: This muscle flexes the middle phalanges, thus bending the fingers, and takes part in flexion of the wrist.

I n n e r v a t i o n: median nerve.

B l o o d s u p p l y: radial and ulnar arteries.

Third layer of anterior muscles of the forearm

The flexor digitorum profundus muscle (m. fléxor digitórum profúndus) originates from the front proximal two thirds of the interosseous membrane of the forearm. Its tendons stretch together with tendons of the flexor digitorum superficialis through the carpal tunnel, then pass between the peduncles of the later and is inserted into the base of distal phalanges.

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F u n c t i o n: It flexes the distal phalanges of the fingers II-V and participates in flexion of the wrist.

I n n e r v a t i o n: median nerve, ulnar nerve. B l o o d s u p p l y: ulnar and radial arteries.

The flexor pollicis longus muscle (m. fléxor póllicis lóngus) originates from the upper anterior surface of the radius and interosseous membrane of the forearm. Its tendon passes through the lateral part of the carpal tunnel and along the palm, between the two heads of the short flexor of thethumb. It attaches on the base of the distal phalanx of the thumb.

F u n c t i o n: It flexes the distal phalanx of the thumb, thus bending it, and participates in flexion of the wrist.

I n n e r v a t i o n: median nerve.

B l o o d s u p p l y: anterior interosseous artery.

Fourth (deep) layer of the anterior muscles of the forearm

The pronator quadratus muscle (m. pronátor quadrátus) is a flat muscle, situated on the distal end of the forearm. It originates on the anterior edge and anterior lower third of the body of the ulna, stretches across and is inserted into the anterior lower third of the radius.

F u n c t i o n: This muscle pronates the forearm. I n n e r v a t i o n: median nerve.

B l o o d s u p p l y: anterior interosseous artery.

Posterior muscles of the forearm

Muscles of the posterior surface of the forearm are situated in two layers: superficial and deep. The superficial layer includes the extensor carpi radialis longus muscle, extensor carpi radialis brevis muscle, extensor digitorum, extensor digiti minimi and extensor carpi ulnaris. The deep layer includes the supinator, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, extensor indicis (Fig. 108).

Superficial layer of the posterior muscles of the forearm

The extensor carpi radialis longus muscle (m. exténsor carpi radiális lóngus) originates on the lateral intermuscular septum of the arm and lateral epicondyle of the humerus. Its beginning part lies adjacent to the lateral side of the elbow joint. On the forearm this muscle lies to the front of the extensor carpi radialis brevis and behind the brachioradial muscle. At midlevel of the forearm, its venter continues into a flat tendon, which

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