Human anatomy Muscles of the forearm

Muscles of the Forearm  The two functional forearm muscle groups are: those that cause wrist movement, and those that move the fingers and the thumb  Most anterior muscles are flexors, and posterior muscles are extensors  The pronator teres and pronator quadratus are not flexors, but pronate the forearm.  The supinator are not extensors, but supinate the forearm.

The muscles of anterior forearm Primarily flexors of the wrist and fingers Divided for convenience of description into two groups, superficial and deep.

Superficial muscles of the front of the forearm They are five: A: pronator teres, B: flexor carpi radialis, C: palmaris longus, D: flexor carpi ulnaris, E: flexor digitorum superficialis

Pronator teres Origin: The humeral head: from the medial epicondyle of the humerus The ulnar head:medial margin of the coronoid process of the ulna. Insertion: Lateral surface of the shaft of the radius. Common flexor origin

Nerve supply: Median nerve Action: pronate of the forearm flex the elbow joint

Flexor carpi radialis Origin: Medial epicondyle of the humerus Insertion: Palmar surface of the bases of the second and third metacarpal bones.

Nerve supply: Median nerve Action: Flex the elbow and wrist. abduct the wrist

Palmaris longus Origin: Medial epicondyle of humerus Insertion: distal half of flexor retinaculum and the apex of the palmar aponeurosis.

The flexor retinaculum (transverse carpal ligament, or anterior annular ligament) is a strong, fibrous band that arches over the carpus

palmar aponeurosis The palmar aponeurosis (palmar fascia) invests the muscles of the palm, and divided into 4 band.

transverse carpal ligament

Nerve supply: Median nerve Action: Flex the wrist and make the palmar aponeurosis tense.

Flexor carpi ulnaris Two heads humeral head: medial epicondyle of the humerus ulnar head: the medial margin of the olecranon, posterior border of ulna

Insertion: pisiform, and is prolonged from this to the hamate and fifth metacarpal bones by the pisohamate and pisometacarpal ligaments. Nerve supply: Ulnar nerve Action: Flex and adduct the wrist.

Action:Flexes and abducts hand (at wrist) Innervation:Median nerve Arterial supply:Radial artery Action:Flexes and adducts hand (at wrist) Innervation:Ulnar nerve Arterial supply:Ulnar artery Flexor carpi radialisFlexor carpi ulnaris

Flexor digitorum Superficialis three heads—humeral, ulnar, and radial Humeroulnar head: medial epicondyle of humerus, ulnar collateral ligament; Ulnar head: medial side of the coronoid process Radial head: superior half of anterior border of radius

Insertion:Bodies of middle phalanges of digits Innervation:Median nerve Action:Flexes interphalangeal joints of medial four digits; also flexes metacarpophalangeal joints and wrist.

MuscleOriginInsertion pronator teresmedial epicondyle of humerus; coronoid process of ulna lateral aspect of shaft of radius flexor carpi radialismedial epicondyle of humerusbases of 2nd and 3rd metacarpal bones palmaris longusmedial epicondyle of humerusflexor retinaculum of palm of hand flexor carpi ulnarismedial epicondyle of humerus; olecranon process and posterior border of ulna pisiform, hamate base of 5th metacarpal flexor digitorum superficialis medial epicondyle of humerus; coronoid process of ulna anterior border of radius tendons split to attach to lateral sides of middle phalanges

Deep muscles of the front of the forearm

Origins: The anterior and medial surfaces of the shaft of the ulna, adjoing part of the anterior surface of the interosseus membrane. Medial surfaces of the olecranon and coronoid processe of ulna. Flexor digitorum profundus

Action: Flexes distal phalanges at distal interphalangeal joints of medial four digits; assists with flexion of wrist Nerve supply: Medial part:ulnar nerve; Lateral part: anterior interosseous branch of median nerve. Insertion: Base of the distal phalanx of digits 2 - 5

Flexor pollicis longus Origin: Anterior surface of radius and anterior surface of interosseous membrane Insertion: Base of distal phalanx of thumb Action: Flexes distal phalanges of the thumb Nerve supply: Anterior interosseous nerve from median nerve

Origin: Distal 1/4 of anterior surface of ulna. Insertion: Distal 1/4 of anterior surface of radius. Action: Pronates forearm; deep fibers bind radius and ulna together. Pronator quadratus

Nerve supply: Anterior interosseous nerve from median nerve Arterial supply: Anterior interosseous artery

Muscles of the Forearm 1. ★ Anterior group First layer 1) brachioradialis 2) pronator teres 3) flexor carpi radialis 4) palmaris longus 5) flexor carpi ulnaris

Muscles of the Forearm Second layer 6) flexor digitorum superficialis Third layer 7) flexor pollicis longus 8) flexor digitorum profundus Fourth layer 9) pronator quadratus

1 brachial A. 2 radial A 3 radial recurrent 4 superficial radial 5 deep radial 6 ulnar A 7 anterior ulnar recurrent 7 posterior ulnar recurrent 8 common interosseous 9 posterior interosseous 10 anterior interosseous A 11 superficial branch 12 deep branch Arteries of Forearm

nerves of forearm

Cubital fossa  The cubital fossa is the region of the upper limb in front of the elbow joint.  It is a triangular area with the following boundaries: laterally — brachioradialis medially — pronator teres superiorly — an imaginary line from the medial and lateral epicondyles of humerus.

Roof : formed by the deep fascia of the forearm, reinforced by the bicipital aponeurosis. Floor: formed by the brachialis muscle and supinator. Contents: from medial to lateral side--- the median nerve, brachial artery, tendon of biceps, and futher laterally the radial nerve. Cubital fossa

This region from superficial to deep venous layer  1 cephalic vein  2 basilic vein  3 median cubital vein

aponeurotic layer  1 bicipital aponeurosis  2 biceps tendon Cubital fossa

artery-nerve layer  1 brachial artery  2 median nerve Cubital fossa

muscular floor  1 supinator  2 brachialis  3 biceps tendon Cubital fossa

bony floor  1 humerus  2 radius  3 ulna Cubital fossa

Posterior muscles of the forearm

These muscles are divided for convenience of description into two groups, superficial and deep. The Superficial Group: A. Brachioradialis. B. Extensor carpi radialis longus.. C. Extensor carpi radialis brevis. D. Extensor digitorum. E. Extensor digiti minimi F. Extensor carpi ulnaris. G. Anconeus. Posterior muscles of the forearm

For the most part, the superficial groups arise from the lateral epicondyle of the humerus. We called common extensor origin. Superficial group: 1.extensor carpi radialis longus 2.extensor carpi radialis brevis 3.extensor carpi ulnaris Superficial group 1.extensor digitorum 2.extensor digiti minimi

Origin: Proximal 2/3 of lateral supracondyle ridge of humerus Insertion: lateral side of radius just above the styloid process. Brachioradialis

Action: Flexes forearm Innervation: Radial nerve Brachioradialis

Origin: common extensor origin, lateral supracondylar ridge of the humerus lateral intermuscular septum. Insertion: dorsum of the base of the 2nd metacarpal bone Extensor carpi radialis longus

 Action: Extension and abduction of the wrist.  Innervation: Radial nerve

Origin: Common extensor origin and radial collateral ligament of elbow Insertion: dorsal aspect of base of 3 rd metacarpal bones. Action: Extension and abduction of the wrist Innervation: Posterior interosseous nerve (branch of the Radial nerve) Extensor carpi radialis brevis

Origin: common extensor origin Insertion: Extensor expansions of medial 4 digits. Extensor digitorum Innervation: Posterior interosseous nerve Action: Extension of interphalangeal, metacarpophalangeal and wrist joint.

Origin: common extensor origin Insertion: Extensor expansion of 5th digit Innervation: Posterior interosseous nerve Action: Extension of interphalangeal, metacarpophalangeal joint of the little finger. Extensor digiti minimi

Origin: common extensor origin and posterior border of the ulna Insertion: The base of the 5th metacarpal bone Innervation: Posterior interosseous nerve Action: Extension and adduction the wrist joint. Extensor carpi ulnaris

Origin: posterior aspect of Lateral epicondyle of the humerus Insertion: olecranon process of ulna Innervation: radial nerve Action: Weak Extension the elbow joint. Anconeus

MuscleOriginInsertion brachioradialislateral supracondylar ridgestyloid process of radius extensor carpi radialis longus lateral supracondylar ridgebase of 2nd metacarpal extensor carpi radialis brevis lateral epicondylebase of 3rd metacarpal extensor carpi ulnaris lateral epicondyle posterior border of ulna base of 5th metacarpal extensor digitorumlateral epicondyleextensor expansion over fingers extensor digiti minimi extensor expansion over fingers extensor expansion of little finger

Deep muscles of the back of the forearm From lateral to median :  Supinator.  Abductor pollicis longus.  Extensor pollicis brevis.  Extensor pollicis longus.  Extensor indicis.

Supinator Origin: supinator crest of the ulna, lateral epicondyle of humerus, radial collateral ligament and annular ligament. Insertion: Lateral surface of proximal 1/3 of radius. Nerve supply: posterior interosseus nerve. Action: supination of forearm.

Abductor pollicis longus Origin: Posterior surfaces of ulna, radius and interosseous membrane Insertion:Base of 1st metacarpal Nerve Supply:Posterior interosseus Nerve. Action: Abduction and extension of the thumb.

Origin: Posterior surface of the radius and interosseus membrane. Insertion: Base of proximal phalanx of thumb. Nerve Supply:Posterior interosseus Nerve. Action: Extends the proximal phalanx and metacarpal of the thumb. Extensor pollicis brevis

Origin: Posterior surface of middle 1/3 of ulna and interosseous embrane Insertion:Base of distal phalanx of thumb Nerve Supply:Posterior interosseus Nerve. Action: Extension at all joints of the thumb. Extensor pollicis longus

Extensor indicis Origin: Posterior surface of ulna and interosseous membrane Insertion: Extensor expansion of 2nd digit. Nerve Supply:Posterior interosseus Nerve. Action: Extends the index finger.

Deep group 1.supinator 2.abductor pollicis longus 3.extensor pollicis brevis 4.extensor pollicis longus 5.extensor indicis

Anterior compartment Demarcated medially from the posterior compartment by the olecranon pocess and the the ulna, and is demarcated laterally by the radius and intermuscular septum.

Contain: radial and ulnar arteries and their venous concomitant median and ulnar nerve anterior interosseous vessles and nerve.

The contents of the posterior compartment posterior interosseous nerve and blood vessels.

Anatomical snuff box It is a triangular depression on the radial side of the wrist. Boundaries: Laterally, tendon of abductor pollicis longus and extensor pollicis brevis; Medially, tendon of extersor pollicis longus.

The cutaneous branches of the radial nerve cross the tendons and supply to the skin. The cephalic vein begins in the roof of the snuff- box, The radia artery lies on the floor.

Extensor retinaculum Its lateral attachment is to the anterolateral border of the radius above the styloid process. Its medial attachment is to the pisiform and triquetral bores. Nine tendons to form 6 mucous Sheaths beneath the extensor retinaculum.

(1) on the lateral side of the styloid process, for the tendons of the Abductor pollicis longus and Extensor pollicis brevis; (2) behind the styloid process, for the tendons of the Extensores carpi radialis longus and brevis; (3) about the middle of the dorsal surface of the radius, for the tendon of the Extensor pollicis longus; (4) to the medial side of the latter, for the tendons of the Extensor digitorum communis and Extensor indicis proprius; (5) opposite the interval between the radius and ulna, for the Extensor digiti quinti proprius; (6) between the head and styloid process of the ulna, for the tendon of the Extensor carpi ulnaris.