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.

Flexion

Extension

Adduction / abduction at the wrist joint.

Ad-duction Ab-duction

Movements of fingers.

MCP (condyloid jts):flexion / extensionabduction / adduction

IP (hinge jts): flexion / extension

XX

Movements of the thumb – a specialized digit, occur atright angles to the fingers. Mainly at the CMC (saddle) jt.

MCP – condyloid; IP – hinge (like fingers).

Muscles of

Forearm

Anterior forearm:Flexor / pronator Compartment.

Superficial:common flexor origin - pronator teres - 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

Muscles of the Forearm

Anterior Fore Arm

PassFailPassFail

Ant Fore armWrist FlexorsFCU+FCRFDSFDPPL

Wrist AddFCU

Wrist AbdFCR

Nerve Supply

Post. ForearmSuperficial disection

Nerve Supply

Radial Nerve

Anatomical snuff box

Post. Forearm

A:Extensor DigitorumB:Extensor Carpi UlnarisC:Brachio RadialisD:Biceps BrachiiE:TricepsF:Extensor Retinaculum

Anconeus

Muscles of the Forearm Post View

Origin :Lateral epicondyle of humerus Insertion Lateral surface of olecranon andsuperior 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)

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

Deep Dissection Forearm

PostAnt

Quiz

12. Pronator Teres13. Flexor carpi radialis:14. Flexor Digitorum:15. Extensor carpi ulnaris:16. Extensor digitorum:17. Extensor carpi radialis:

Rotators of the Radius

Supinator

Pronators

Biceps Brachii

Pronation / Supination:

Occurs at radio-ulnar jts.Proximal:Head of radiusarticulates 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

• 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

Neurovasculature.

Radial nerve and its branches supplyall muscles in posterior compartment, including brachioradialis (!).

- superficial radial nerve- deep radial nerve - posterior interosseus nerve.

Posterior interosseus artery runs between superficial and deep muscles

Neurovasculature.

Lateral: radial arteryradial nerve

Midline: median nerve[supplies all muscles except flexor carpi ulnaris and medial half of flexor digitorum profundous]

Medial: ulnar arteryulnar nerve

• Medial ½ of FDP• FCU• All hand muscles except

11/2 muscle groups(lateral 2 lumbricals and thenar muscles )

Ulnar Nerve

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!