Muscles of the Forearm Dr.Nivin Sharaf MD

Objectives -Describe the function of the muscles in the anterior and posterior compartment of the forearm. -Name and identify the muscles in the anterior (flexor/pronator) and posterior (extensor/supinator) compartments of the forearm, noting their relations. -Name and identify the neurovascular structures in the anterior) and posterior compartments of the forearm, noting their relations.

Functional organization of Anterior and posterior forearm.

Names of the Muscles of forearm Many of them Long names: good guide to location and function Location: ie. superficial / deep radial / ulnar (which side is the thumb on??) Function: ie. flexor / extensor adductor / abductor Does it act on the thumb (pollux) or the fingers (digits)?

Functional Organization Anterior compartment – flexor / pronator Posterior Compartment – extensor / supinator Flex the wrist ………[flexor] Extend the wrist ……..[extensor] Pronate the forearm ……..[pronator] Acting on wrist (carpus) only ……[carpi] Acting on fingers ……..[digiti / digitorum] Acting on thumb (pollux) ……[pollicus]

Flexion / Extension at the wrist joint.

Adduction / abduction at the wrist joint.

X X Movements of fingers. MCP (condyloid jts): flexion / extension abduction / adduction IP (hinge jts): flexion / extension X X

Movements of the thumb – a specialized digit, occur at right angles to the fingers. Mainly at the CMC (saddle) jt. MCP – condyloid; IP – hinge (like fingers).

Muscles of Forearm

Flexor / pronator Compartment. Anterior forearm: Flexor / pronator Compartment. Protonator teres Superficial: common flexor origin pronator teres flexor carpi radialis palmaris longus flexor digitorum superficialis, flexor carpi ulnaris Brachioradialis flexor carpi radialis palmaris longus flexor digitorum superficialis flexor carpi ulnaris

Functional organization: Only flex at the wrist. Flexor carpi radialis Palmaris longus Flexor carpi ulnaris Flexor Carpi Radialis Palmaris Longus Flexor Carpi ulnaris

Muscles of the Forearm

Anterior Fore Arm Pass Fail

Ant Fore arm Wrist Flexors FCU+FCR FDS FDP PL Nerve Supply Wrist Add Wrist Abd FCR Nerve Supply

Post. Forearm Superficial disection Nerve Supply Radial Nerve Anatomical snuff box

Post. Forearm A: Extensor Digitorum B: Extensor Carpi Ulnaris C: Brachio Radialis D: Biceps Brachii E: Triceps F: Extensor Retinaculum

Muscles of the Forearm Post View Origin :Lateral epicondyle of humerus Insertion Lateral surface of olecranon and superior part of posterior surface of ulna Action Assists triceps in extending forearm; stabilizes elbow joint; abducts ulna during pronation Innervation Radial nerve (C7, C8 and T1) Anconeus Origin :Lateral epicondyle of humerus Insertion Lateral surface of olecranon and superior part of posterior surface of ulna Action Assists triceps in extending forearm; stabilizes elbow joint; abducts ulna during pronation Innervation Radial nerve (C7, C8 and T1) Arterial Supply Middle collateral branch of deep brachial artery Recurrent interosseous artery Radial nerve innervates the BEST.  Brachioradialis  Extensors  Supinator  Triceps

Deep posterior compartment. - abductor pollicis longus - extensor pollicis brevis - extensor pollicis longus - extensor indicis - supinator Functional organization: extend hand at wrist extend / abduct thumb extend index finger supinate abductor pollucis longus extensor pollicis brevis extensor pollicis longus extensor indicis

Deep Dissection Forearm Post Ant

Quiz 12. Pronator Teres 13. Flexor carpi radialis: 14. Flexor Digitorum: 15. Extensor carpi ulnaris: 16. Extensor digitorum: 17. Extensor carpi radialis:

Rotators of the Radius Pronators Supinator Biceps Brachii

Pronation / Supination: Occurs at radio-ulnar jts. Proximal: Head of radius articulates with radial notch of ulna (pivot jt). It is held in place by the annular ligament. Distal – Radius pivots around the fixed distal end of ulna (pivot jt). Radio-ulnar articulation is stabilized by interosseus membrane.

Common Extensor Origin

Course of radial and ulnar arteries in forearm Axillary vein: continuation of basilic vein

Neurovasculature (deep). Lateral: radial artery radial nerve Midline: median nerve anterior interosseus a. anterior interosseus n. (deep branch of median) Medial: ulnar artery (gives off common interosseus artery divides into anterior and posterior branches) ulner nerve radial n ulnar a radial a. ulnar n median n anterior interosseus a + n

Radial nerve and its branches supply Neurovasculature. Radial nerve and its branches supply all muscles in posterior compartment, including brachioradialis (!). - superficial radial nerve - deep radial nerve - posterior interosseus nerve. Posterior interosseus artery runs between superficial and deep muscles Brachioradialis Deep branch posterior interosseus branch Superficial branch

Lateral: radial artery radial nerve Midline: median nerve Neurovasculature. Lateral: radial artery radial nerve Midline: median nerve [supplies all muscles except flexor carpi ulnaris and medial half of flexor digitorum profundous] Medial: ulnar artery ulnar nerve radial n. Brachioradialis radial a ulnar n. ulnar a. median n.

Ulnar Nerve Medial ½ of FDP FCU All hand muscles except 11/2 muscle groups(lateral 2 lumbricals and thenar muscles )

References Grey’s Anatomy Netter Keith Moore www.maestro.uottawa.ca Recommended reading: Clinically Oriented Anatomy,6th edition Keith Moore Pages:744-771

Thank you!