1
FOREARM
By Prof. Saeed Abuel MakaremDr. Sanaa Al-Sharawy
By the end of the lecture the By the end of the lecture the student should be able to:student should be able to:
Enumerate the different muscles of the Enumerate the different muscles of the front (flexors) and back (extensors) of front (flexors) and back (extensors) of the forearm.the forearm.
Describe in brief the attachment of Describe in brief the attachment of these group these group of muscles:of muscles:
Superficial and deep flexors; Superficial and deep flexors; Superficial and deep extensors.Superficial and deep extensors. Describe the action and nerve supply of Describe the action and nerve supply of
each of these muscle.each of these muscle.
OBJECTIVES
The forearm extends from extends from elbowelbow to to wristwrist..
It posses two bones It posses two bones radius laterally & Ulna radius laterally & Ulna medially.medially.
The two bones are The two bones are connected together connected together by the interosseous by the interosseous membrane. membrane.
This membrane This membrane allows movement of allows movement of Pronation and and Supination while while the two bones are the 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 post. subcutaneous border of the ulna . This fascial sheath, together with the interosseous membrane, radius & ulna and a fibrous intermuscular septum divides the forearm into several compartments.Each compartments have 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: are (8)•They act on the wrist & elbow joints and the fingers.•They form fleshy masses in the proximal forearm and become tendinous in the distal part of the forearm.•They are arranged in three groups:
III- Deep: 3III- Deep: 3 Flexor digitorum Flexor digitorum
profundus. profundus. UU Flexor pollicis longus. Flexor pollicis longus.
RR Pronator quadratus. Pronator quadratus. R R
& U& U
Anterior compartment -FLEXOR GROUP
Superficial FlexorsSuperficial Flexors They arise - more or They arise - more or
less- from the less- from the common flexor origin common flexor origin (front of (front of medial medial epicondyleepicondyle).).
All are supplied by All are supplied by the the medianmedian nerve nerve exceptexcept one,one, flexor flexor carpi ulnaris,carpi ulnaris, FCU FCU (ulnar n.).(ulnar n.).
All cross the wrist All cross the wrist joint joint except oneexcept 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
InsertionInsertion:: Base Base of 2of 2ndnd metacarpal metacarpal bonebone
ActionAction: Flexion & : Flexion & abduction of the abduction of the wrist.wrist.
Palmaris Palmaris LongusLongusInsertionInsertion:: into the into the
flexor flexor retinaculum & retinaculum & palmer palmer aponeurosis.aponeurosis.
ActionAction:: Flexes hand Flexes hand & tightens the & tightens the palmer palmer aponeurosisaponeurosis
May Be Absent
Flexor Carpi Flexor Carpi UlnarisUlnaris
InsertionInsertion:: Pisiform, Pisiform, hook of hook of
hamate hamate 55thth
metacarpal metacarpal bonebone
ActionAction:: Flexion and Flexion and
adduction of adduction of the hand the hand (wrist)(wrist)
Flexor Flexor Digitorum Digitorum SuperficialisSuperficialis• Origin:Origin:• Common Common
flexor origin, flexor origin, • Coronoid Coronoid
process of process of ulna;ulna;
• Anterior oblique line of radius
• InsertionInsertion::• base of base of
middle middle phalanges of phalanges of the medial 4 the medial 4 fingers.fingers.
• ActionAction:: • Flexes Flexes
middle and middle and proximal proximal phalanges of phalanges of medial 4 medial 4 fingersfingers
• Flexes the Flexes the hand (wrist).hand (wrist).
Deep FlexorsDeep Flexors One above radiusOne above radius: :
Flexor pollicis Flexor pollicis longuslongus
One above ulnaOne above ulna: : Flexor Digitorum Flexor Digitorum profundusprofundus
One above the twoOne above the two
bones:bones:
Pronator Quadratus.Pronator Quadratus.
Flexor Digitorum Flexor Digitorum ProfundusProfundus
InsertionInsertion: bases : bases of the distal of the distal phalanges of the phalanges of the medial four digitsmedial four digits
ActionAction: Flexes : Flexes distal phalanges distal phalanges of medial four of medial four digitsdigits
Flexor Pollicis Flexor Pollicis LongusLongus
InsertionInsertion: Base of : Base of distal phalanx of distal phalanx of thumbthumb
ActionAction: flexes (all : flexes (all joints of the joints of the thumb), thumb), interphalangeal, interphalangeal, metacarpophalangmetacarpophalangeal & eal & carpometacarpal carpometacarpal joints. joints.
Pronator Pronator QuadratusQuadratus• InsertionInsertion: :
distal one distal one fourth of ant. fourth of ant. surface of surface of radiusradius
• ActionAction: : pronates the pronates the forearm forearm (primover), (primover),
• Hold the two Hold the two bones bones together together
Supination and
pronation
It occurs in the superior and inferior radioulnar joints; (pivot synovial joint)
Muscles produce supination
Biceps brachii. Supinator.
Muscles produce pronation
Pronator teres. pronator quadratus.NB. Brachioradialis put the forearm in midprone-supine position, (initiates pronation and supination).
Posterior Compartment: 3 groups
Superficial group 51. Extensor carpi radialis brevis.2. Extensor digitorum .3. Extensor digiti minimi.4. Extensor carpi ulnaris.5.Anconeus .
Deep group 5 (3 to thumb+ 1 to index + supinator).Supinator.Abductor pollicis longus. Extensor pollicis brevis.Extensor pollicis longus.Extensor indices.
Origin: Common Extensor Origin (front of the lateral epicondyle).
Lateral group 21.Brachioradialis.2.Extensor carpi radialis longus.(These two muscles arises from the lateral supracondylar ridge).
Posterior compartmentPosterior compartment I- Superficial group:I- Superficial group: 7 muscles 7 muscles ( from ( from
laterallateral to medial)to medial)1.1. Brachioradialis, (BR).Brachioradialis, (BR).2.2. Extensor carpi radialis Extensor carpi radialis
longus, (ECRL).longus, (ECRL).3.3. Extensor carpi radialis Extensor carpi radialis
brevis, (ECRB).brevis, (ECRB).4.4. Extensor digitorum, Extensor digitorum,
(ED).(ED).5.5. Extensor digiti minimi, Extensor digiti minimi,
(EDM).(EDM).6.6. Extensor carpi ulnaris, Extensor carpi ulnaris,
(ECU).(ECU).7.7. Anconeus. (An).Anconeus. (An).
Superficial Superficial extensorextensor
All arises from the All arises from the commoncommon extensor originextensor origin, (, (front of front of lateral epicondylelateral epicondyle of the of the humerus), humerus), EXCEPTEXCEPT, 2 , 2 (BR (BR & EXRL).& EXRL).
All cross the wrist All cross the wrist EXCEPTEXCEPT, , one,one, (brachioradialis. (brachioradialis.
All supplied by deep branch All supplied by deep branch of radial nerve, of radial nerve, EXCEPTEXCEPT ABEABE
AA,, Anconeus Anconeus BB,, Brachioradialis Brachioradialis EE,, Extensor carpi radialis Extensor carpi radialis
longuslongus These 3 muscles are These 3 muscles are
supplied by the radial supplied by the radial nerve itselfnerve itself
BrachioradBrachioradialisialis
Origin:Origin: Lateral
supracondylar ridge of humerus
Insertion: Insertion: Base of styloid
process of radius
ActionAction:: 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 second metacarpal bone
ActionAction:: 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 by the union of the tendons of: Extensor digitorum, Extensor indicis, extensor digiti minimi, palmar interossei, 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.
May I please be excused? My brain is full” HAHH