By :By :

Dr. Sanaa Al-Dr. Sanaa Al-SharawySharawy

FOREARM

OBJECTIVESOBJECTIVESAt the end of this lecture, the student At the end of this lecture, the student should able to :should able to :List the List the names of the Flexors Group names of the Flexors Group of of Forearm (superficial & deep muscles).Forearm (superficial & deep muscles).Identify the Identify the common flexor origin common flexor origin of flexor of flexor muscles and their muscles and their innervation & innervation & movements.movements.Identify Identify supination & poronation supination & poronation and list and list the muscles produced these 2 movements. the muscles produced these 2 movements. List the List the names of the Extensor Group names of the Extensor Group of of Forearm (superficial & deep muscles).Forearm (superficial & deep muscles).Identify the Identify the common extensor origin common extensor origin of of extensor musles and their extensor musles and their innervation & innervation & movements.movements.

The forearm extends from extends from elbowelbow to to wristwrist..

It posses It posses two bonestwo bones radius radius laterally & laterally & Ulna Ulna medially.medially.

The two bonesThe two bones are are connected together connected together by the by the interosseous interosseous membrane.membrane.

This membrane This membrane allows movement allows movement of of Pronation and and Supination while while the the two bones are two bones are connected together.connected together.

Also it gives origin for Also it gives origin for the deep muscles.the deep muscles.

Fascial Compartments of the Forearm

The forearm is enclosed in a sheath of deep fascia, which is attached to the posterior border of the ulna .This fascial sheath, together with the interosseous membrane & fibrous intermuscular septa, divides the forearm into several compartments, each having its own muscles, nerves, and blood supply.

I-Superficial: 4I-Superficial: 4 Pronator teresPronator teres Flexor carpi Flexor carpi

radialisradialis Palmaris longusPalmaris longus Flexor carpi ulnarisFlexor carpi ulnaris

II-Intermediate: 1II-Intermediate: 1 Flexor digitorum Flexor digitorum

superficialissuperficialis

These muscles: 8 Act on the elbow & wrist joints and those of the fingers. Form fleshy masses in the proximal part and become tendinous in the distal part of the forearm.•Arranged in three groups:

III- Deep: 3III- Deep: 3 Flexor digitorum Flexor digitorum

profundusprofundus Flexor pollicis longusFlexor pollicis longus Pronator quadratusPronator quadratus

FLEXOR GROUP

Superficial FlexorsSuperficial Flexors:: They arise - more They arise - more

or less- from or less- from the the common flexor common flexor originorigin (front of(front of medial medial epicondyle).epicondyle).

All are supplied by All are supplied by median nerve median nerve exceptexcept one, one, flexor flexor carpi ulnaris,carpi ulnaris, FCU FCU (ulnar).(ulnar).

All cross the wrist All cross the wrist joint except one, joint except one, pronator teres,pronator teres, (PT).(PT).

Pronator Pronator teres teres Insertion:Insertion: middle of lat. middle of lat. surface of surface of radiusradius

ActionAction:: pronation & pronation & flexion of flexion of forearm .forearm .

Flexor Carpi Flexor Carpi Radialis Radialis

Insertion:Insertion: Base Base of 2of 2ndnd metacarpal metacarpal bonebone

ActionAction: Flexion : Flexion & abduction of & abduction of the handthe hand

Palmaris Palmaris LongusLongusInsertion:Insertion: into the into the

flexor flexor retinaculum & retinaculum & palmar palmar aponeurosis.aponeurosis.

ActionAction:: Flexes Flexes hand & tightens hand & tightens palmer palmer aponeurosisaponeurosis

Flexor Carpi Flexor Carpi UlnarisUlnaris

Insertion:Insertion: Pisiform, Pisiform, hook of hook of

hamate hamate 55thth

metacarpal metacarpal bonebone

ActionAction:: Flexion and Flexion and

adduction adduction of the hand.of the hand.

Flexor Flexor Digitorum Digitorum SuperficialisSuperficialis• Origin:Origin:• Common Common

flexor flexor origin, origin,

• Coronoid Coronoid process of process of ulna;ulna;

• Anterior surface of radius

• Insertion:Insertion:• base of base of

middle middle phalanges phalanges of medial 4 of medial 4 fingers.fingers.

• ActionAction:: • Flexes Flexes

middle and middle and proximal proximal phalanges phalanges of medial 4 of medial 4 fingers, and fingers, and the handthe hand

Deep FlexorsDeep Flexors One above ulnaOne above ulna: :

Flexor Flexor Digitorum Digitorum profundusprofundus

One above One above radiusradius: Flexor : Flexor pollicis longuspollicis longus

One above the 2One above the 2

bones:bones:

Pronator Pronator QuadratusQuadratus..

Flexor Flexor Digitorum Digitorum ProfundusProfundus

InsertionInsertion: : bases of distal bases of distal phalanges of phalanges of medial 4 digitsmedial 4 digits

ActionAction: Flexes : Flexes distal distal phalanges of phalanges of medial 4 digits.medial 4 digits.

Flexor Pollicis Flexor Pollicis LongusLongus

InsertionInsertion: Base : Base of distal phalanx of distal phalanx of thumbof thumb

ActionAction: flexes : flexes interphalangeal, interphalangeal, metacarpophalametacarpophalangeal & ngeal & carpometacarpal carpometacarpal joints of thumb. joints of thumb.

Pronator Pronator QuadratusQuadratus• InsertionInsertion: :

distal fourth distal fourth of ant. of ant. surface of surface of radiusradius

• ActionAction: : pronatespronates forearm forearm (primover), (primover), helps to helps to hold hold the bones the bones together. together.

Supination and

pronation

It occurs in the superior and inferior radioulnar joints;

Muscles produce supination

Biceps brachii. Supinator.

Muscles produce pronation

Pronator teres. Pronator quadratus.

NB. Brachioradialis put the forearm in midprone- position.

Posterior compartment: 3 groups

Superficial group (5) Extensor carpi radialis brevis Extensor digitorum Extensor digiti minimi Extensor carpi ulnarisAnconeus

Deep group (5) (3 to thumb+ 1 to index + supinator).Supinator.Abductor pollicis longus. Extensor pollicis brevis.Extensor pollicis longus.Extensor indices.

Common Extensor Origin .(front of lateral epicondyle).

Superficial Lateral group (2)BrachioradialisExtensor carpi radialis longus

Posterior Posterior compartment:compartment:

Superficial group:Superficial group: 7 muscles 7 muscles ( from ( from

lateral to medial) : lateral to medial) : Brachioradialis, (BR).Brachioradialis, (BR). Extensor carpi radialis Extensor carpi radialis

longus, (ECRL).longus, (ECRL). Extensor carpi radialis Extensor carpi radialis

brevis, (ECRB).brevis, (ECRB). Extensor digitorum, Extensor digitorum,

(ED).(ED). Extensor digiti minimi, Extensor digiti minimi,

(EDM).(EDM). Extensor carpi Extensor carpi

ulnaris, (ECU).ulnaris, (ECU). Anconeus. (An).Anconeus. (An).

Superficial Superficial extensorsextensors

All arises from the All arises from the commoncommon extensor originextensor origin, , ((front of front of lateral epicondyle of the lateral epicondyle of the humerus), humerus), EXCEPTEXCEPT, 2 , 2 (BR & (BR & ECRL).ECRL).

All cross the wrist All cross the wrist EXCEPT, EXCEPT, one, one, brachioradialisbrachioradialis..

All supplied by All supplied by deep branch deep branch of radial nerveof radial nerve, , EXCEPTEXCEPT ABEABE

A, anconeusA, anconeus B, BrachioradialisB, Brachioradialis E, Extensor carpi radialis E, Extensor carpi radialis

longuslongus These 3 muscles are These 3 muscles are

supplied by the radial nerve supplied by the radial nerve itselfitself

BrachioradBrachioradialisialis

Origin:Origin: Lateral

supracondylar ridge of humerus

Insertion: Insertion: Base of

styloid process of radius

Action:Action: Flexes

forearm; (elbow).

Rotates forearm to the midprone position

Extensor Extensor Carpi Carpi radialis radialis longuslongus

Origin:Origin: Lateral

supracondylar ridge of humerus

Insertion: Insertion: Posterior

surface of base of 2nd metacarpal bone

Action:Action: Extends and

abducts hand at wrist joint

Extensor carpi radialis brevis: base of 3rd metacarpal bone.Extensor digitorum: Extensor expansion of the medial 4 fingers.Extensor digiti minimi: Extensor expansion of the little finger.Extensor carpi ulnaris:Base of the 5th metacarpal bone.

INSERTION

II- Deep group: 5 muscles 1- Abductor pollicis longus, (APL). 2- Extensor pollicis brevis, (EPB). 3- Extensor pollicis longus, (EPL). 4- Extensor indicis (EI). 5- Supinator.•All back muscles of forearm are supplied by posterior interosseous nerve except , ABE by Radial nerve.

Dorsal Extensor Expansion

It is formed on the dorsum of medial 4 fingers by : the union of the tendons of : Extensor digitorum, Extensor digiti minimi, Extensor indicis, palmar and dorsal interossei and lumbricals muscles. All these tendons unite to form one tendon which divides into 3 slips, a median one attached to middle phalanges and 2 lateral attached to the terminal phalanges.

THANK YOUTHANK YOU

1. Which one of the following muscles contributes as powerful supinator of forearm?a. Palmaris longus.b. Pronator teres.c. Biceps brachii.d. Supinator..

2.Which muscle is supplied by median nerve ? a.Anconeus. b.Brachioradialis.c.Extensor carpi radialis longus.d.Flexor digitorum superficialis.

3.Which muscle is related to common flexor origin ?a.Flexor digitorum profundus.b.Flexor pollicis longus.c.Pronator quadratus.d.Pronator teres.