FOREARM MUSCLES

Dr.Lubna Nazli Asst.Prof

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OBJECTIVES

At the end of the lecture the student should know:1. Muscles of flexor compartment, their nerve supply

and action.2. Muscles of extensor compartment, their nerve

supply and action.3. Nerves related: ulnar, median & radial nerve, their

course,distribution & branches in forearm.4. Arteries related: radial & ulnar artery, their

branches in forearm.5. Applied anatomy.

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Muscles of flexor compartment

They are arranged in 2 layers.1. Superficial group. ( 5 muscles )2. Deep group. ( 3 muscles )

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Muscles of the superficial group

1. Pronator teres.2. Flexor carpi radialis.3. Palmaris longus.4. Flexor digitorum superficialis.5. Flexor carpi ulnaris.

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• Origin: Medial epicondyle of humerus and coronoid process of ulna

• Insertion: Middle portion of radius

• Action: Pronates and flexes forearm

Pronator Teres

Anterior, Superficial Layer

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• Origin: Medial epicondyle of humerus

• Insertion: Base of second metacarpal

• Action: Flexes wrist and elbow and abducts wrist

Flexor Carpi Radialis

Anterior, Superficial Layer

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• Origin: Medial epicondyle of the humerus

• Insertion: Palmar aponeurosis

• Action: Weak flexion of wrist, tenses skin of palm

Palmaris Longus

Anterior, Superficial Layer

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• Origin: Medial epicondyle of humerus, olecranon process, & posterior ulna

• Insertion: Pisiform, hamate, and fifth metacarpal

• Action: Flexes and adducts wrist

Flexor Carpi Ulnaris

Anterior, Superficial Layer

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• Origin: Medial epicondyle of humerus and coronoid process of ulna

• Insertion: Middle phalanges of fingers

• Action: Flexes fingers and wrist

Flexor Digitorum Superficialis

Anterior, Middle Layer

Revise

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Muscles of the deep group

1. Flexor digitorum profundus.2. Flexor pollicis longus. 3. Pronator quadratus.

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Flexor digitorum profundus• ORIGIN

Medial olecranon, upper three quarters of anterior and medial surface of ulna.

• INSERTIONDistal phalanges of medial four fingers.

• ACTIONFlexes distal interphalangeal joints, then secondarily flexes proximal interphalangeal and metacarpophalangeal joints and wrist

• NERVEMedian nerve (anterior interosseous) and ulnar nerve

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• Origin: Middle half of radius, interosseous membrane, coronoid process of ulna

• Insertion: Distal phalanx of thumb

• Action: Flexes thumb and wrist

Flexor Pollicis Longus

Anterior, Deepest Layer

Pronator quadratus• ORIGIN

Lower quarter of anteromedial shaft of ulna

• INSERTIONLower quarter of anterolateral shaft of radius and some interosseous membrane

• ACTIONPronates forearm.

• NERVEAnterior interosseous nerve (C8)

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Revise

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Muscles of extensor compartment

They are arranged in 2 layers.1. Superficial group. ( 7 muscles )2. Deep group. ( 5 muscles )

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The Superficial extensors

1. Brachioradialis.2. Extensor carpi radialis longus.3. Extensor carpi radialis brevis.4. Extensor digitorum. 5. Extensor digiti minimi.6. Extensor carpi ulnaris. 7. Anconeus.

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• Origin: Lateral supracondylar ridge

• Insertion: Styloid process of radius

• Action: Flexes forearm

Brachioradialis

Posterior, Superficial Layer

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• Origin: Lateral supracondylar ridge of humerus

• Insertion: Second metacarpal

• Action: Extends and abducts hand

Extensor Carpi Radialis Longus

Posterior, Superficial Layer

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• Origin: Lateral epicondyle of humerus

• Insertion: Third metacarpal

• Action: Extends and abducts hand

Extensor Carpi Radialis Brevis

Posterior, Superficial Layer

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• Origin: Lateral epicondyle of humerus

• Insertion: Into distal phalanx by 4 tendons

• Action: Extends fingers and hand

Extensor Digitorum

Posterior, Superficial Layer

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• Origin: Lateral epicondyle of humerus

• Insertion: Extensor expansion of little finger

• Action: Extends 5th digit and hand

Extensor Digiti Minimi

Posterior, Middle Layer

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• Origin: Lateral epicondyle of humerus and posterior border of ulna

• Insertion: Fifth metacarpal

• Action: Extends and adducts hand

Extensor Carpi Ulnaris

Posterior, Superficial Layer

Anconeus

• ORIGINPosterior aspect of lateral epicondyle of humerus

• INSERTIONLateral side of olecranon

• ACTIONWeak extensor of elbow. Moves (abducts) ulna in pronation

• NERVERadial nerve (C7, 8)

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Deep group

• Supinator• Abductor pollicis longus• Extensor pollicis longus• Extensor pollicis brevis• Extensor indicis

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• Origin: Lateral epicondyle of humerus, supinator crest of ulna

• Insertion: Lateral surface and posterior border of radius

• Action: Supinates forearm

Supinator

Posterior, Deepest Layer

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• Origin: Posterior surface of ulna and radius, and interosseous membrane

• Insertion: First metacarpal

• Action: Abducts thumb and hand

Abductor Pollicis Longus

Posterior, Deepest Layer

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• Origin: Middle third of ulna and interosseous membrane

• Insertion: Base of distal phalanx of thumb

• Action: Extends thumb

Extensor Pollicis Longus

Posterior, Deepest Layer

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• Origin: Middle third of radius and interosseous membrane

• Insertion: Base of proximal phalanx of thumb

• Action: Extends thumb

Extensor Pollicis Brevis

Posterior, Deepest Layer

Extensor indicis• ORIGIN

Lower posterior shaft of ulna (below extensor pollicis longus) and adjacent interosseous membrane

• INSERTIONExtensor expansion of index finger

• ACTIONExtends all joints of index finger

• NERVEPosterior interosseous nerve (C7, 8)

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Revise:

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NERVES IN FOREARM

MEDIAN NERVE:In the forearm it passes between the two heads

of the Pronator teres and crosses the ulnar artery.

It descends beneath the Flexor digitorum superficialis, lying on the Flexor digitorum profundus.

It becomes more superficial at the wrist & passes to the hand.

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Median nerve branches

The muscular branches supply all the superficial muscles on the front of the forearm, except the Flexor carpi ulnaris.   

The anterior interosseous nerve supplies the deep muscles on the front of the forearm, except the ulnar half of the Flexor digitorum profundus.

The palmar branch of the median nerve arises at the lower part of the forearm.

The median nerve then continues through the carpal tunnel into the hand.

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Ulnar nerveIt enters the forearm between the two heads of flexor

carpi ulnaris. In the forearm the nerve lies between the flexor carpi

ulnaris and the flexor digitorum profundus muscles, supplying half of the latter muscle.

Above the wrist the nerve gives off a dorsal branch which supply the dorsal skin of the medial one and one-half digits, and a small palmar cutaneous branch which runs over the flexor retinaculum to supply the medial palm.

The nerve passes into the hand over the flexor retinaculum together with the artery.

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Branches of ulnar nervearticular to the elbow-jointmuscular branches supply the

Flexor carpi ulnaris & the ulnar half of the Flexor digitorum profundus.

palmar cutaneous branch ends in the skin of the palm, communicating with the palmar branch of the median nerve.

dorsal branch which supply the dorsal skin of the medial one and one-half digits,

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Radial nerve• The nerve leaves the spiral groove and passes anteriorly

through the lateral intermuscular septum to lie between brachialis and brachioradialis.

• The nerve gives off muscular branches to the lateral part of brachialis, the brachioradialis and the extensor carpi radialis longus.

• On reaching the front of the lateral epicondyle the nerve divides into terminal superficial and deep branches.

• The superficial branch is sensory and passes to the back of the hand

• The deep branch gives off innervation to the extensor carpi radialis brevis muscle before piercing the supinator muscle to form the posterior interosseous nerve.

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Radial nerve branches muscular branches supply the

Triceps brachii, Anconeus, Brachioradialis, Extensor carpi radialis longus, and Brachialis.

cutaneous branches are two in number

superficial branch is sensory and passes to the back of the hand

deep branch continues as the posterior interosseous nerve to supply extensor muscles.

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Arteries of the forearmRadial arteryIt is the continuation of the brachial, but it is smaller in size than

the ulnar. It commences at the bifurcation of the brachial, just below the

bend of the elbow, and passes along the radial side of the forearm to the wrist.

Branches In the ForearmRadial Recurrent. Muscular.Palmar Carpal.Superficial palmar.

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The ulnar artery the larger of the two terminal branches of the brachial, begins a little below the bend of the elbow, and, passing obliquely downward, reaches the ulnar side of the forearm at a point about midway between the elbow and the wrist.

Branches In the Forearm Anterior Recurrent.Posterior Recurrent.Common Interosseous.Muscular.

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APPLIED ANATOMY

Tennis Elbow(lateral epicondylitis)

It is caused by partial tearing or degeneration of the origin of superficial extensors from the lateral epicondyle of humerus.

Symptoms: Pain, on the outside (lateral) of the elbow, is usually gradual with tenderness felt on

or below the joint's bony prominence.

Seen in tennis players,violinists & housewives.

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Golfer’s Elbow(medial epicondylitis)

It is due to degeneration of flexor muscles from medial

epicondyle.

Symptoms: Pain and tenderness are felt on the

inside (medial) of the elbow, on or around the joint's bony prominence.

Seen in golfer’s & also in person’s doing similar

movements.

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Bursitis

Seen on the back of elbowIt is often due to

excessive leaning on the joint or a direct blow or fall onto the tip of the

elbow.

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