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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 headshumeral 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 radialis Flexor 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 2 - 5
Innervation:Median nerve
Action:Flexes interphalangeal joints of medial four digits; also flexes metacarpophalangeal joints and wrist.
Muscle Origin Insertion
pronator teres medial epicondyle of humerus; coronoid process of ulna
lateral aspect of shaft of radius
flexor carpi radialis medial epicondyle of humerus bases of 2nd and 3rd metacarpal bones
palmaris longus medial epicondyle of humerus flexor retinaculum of palm of hand
flexor carpi ulnaris medial epicondyle of humerus; olecranon process and posterior border of ulna
pisiform, hamatebase 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 longusOrigin: 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 ForearmMuscles 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 ForearmMuscles 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 A3 radial recurrent 4 superficial radial 5 deep radial 6 ulnar A7 anterior ulnar recurrent 7 posterior ulnar recurrent 8 common interosseous 9 posterior interosseous 10 anterior interosseous A11 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
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 3rd 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 originInsertion: 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 ulnaInsertion: The base of the 5th metacarpal boneInnervation: Posterior interosseous nerveAction: 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 nerveAction: Weak Extension the elbow joint.
Anconeus
Muscle Origin Insertion
brachioradialis lateral supracondylar ridge styloid process of radius
extensor carpi radialis longus
lateral supracondylar ridge base of 2nd metacarpal
extensor carpi radialis brevis
lateral epicondyle base of 3rd metacarpal
extensor carpi ulnaris
lateral epicondyle
posterior border of ulna
base of 5th metacarpal
extensor digitorum lateral epicondyle extensor 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 thethe 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.
