MUSCLES OF THE POSTERIOR COMPARTMENT OF FOREARM
OBJECTIVES
At the end of lecture,students will be able to:
Learn concept of the muscles of posterior compartment of forearm
Understand nerve supply of these muscles
Idea of actions of the muscles of posterior compartment of forearm.
muscles forming this compartment:
Superficial group:
Anconeus.
Extensor digiti minimi.
Extensor carpi ulnaris
Extensor digitorium
Extenser carpi radialis brevis.
Deep group:
Supenator.
Extenser carpi radialis longus.
Abductor pollicis longus.
Extensor pollicis longus.
Extensor pollicis brevis
Extensor indices
BRACHIORADIALIS
Origin:
Upper two third of supracondylar ridge.
Insertion:
Styloid process of radius.
Action:
flexion at elbow joint.
Nerve supply:
Radial nerve
EXTENSER CARPI RADIALIS LONGUS
Origin:
Lower third of the lateral supra- condylar ridge of humerus.
Insertion: base of second metacarpal
Action: Extensor and abductor of wrist
Nerve supply: Radial nerve
COMMON EXTENSOR ORIGIN
Arise from smooth area in front of the lateral epicondyle of humerus.
This fused tendon gives rise to:
 Extensor carpi radialis brevis.
 Extensor digitorium.
 Extensor digiti minimi.
 Extensor carpi ulnaris.
EXTENSOR CARPI RADIALIS BREVIS
Origin: common extensor origin.
Insertion:
Base of third metacarpal.
Nerve supply:
Radial nerve
Action:
W rist extensor
EXTENSOR DIGITORIUM
Origin:
common extensor origin
Insertion:
middle and distal phalanges of medial four fingers.
Action:
Extensor of the wrist, metacarpophalangeal joint and interphalangeal joints.
Nerve supply:
Radial nerve
EXTENSOR DIGITI MINIMI
Origin:
common extensor origin
Insertion:
extensor expansion of distal phalanx of little finger.
Action:
Assists extensor digitorum with extension of wrist and little finger.
Nerve supply:
Radial nerve.
EXTENSOR CARPI ULNARIS
Origin:
Arises from the common extensor origin.
Insertion: into the base of 5th metacarpal.
Nerve supply: Radial nerve.
Action: Extend and adduct hand at wrist joint.
ANCONEUS
Origin:
posterior surface of lateral epicondyle of humerus.
Insertion: lateral side of olecronon and adjacent shaft of the ulna.
Nerve supply: Radial nerve.
Action: extends elbow joint
SUPINATOR
Origin:
lateral epicondyle of humerus and annular ligament of superior radioulnar joint.
Insertion:Neck and shaft of radius.
Action:Supination of forearm.
Nerve supply: Radial nerve
ABDUCTOR POLLICIS LONGUS
Origin: Shaft of radius and ulna.
Insertion: base of first metacarpal.
Action: abduct and extend thumb.
Nerve supply: Radial nerve.
EXTENSOR POLLICIS BREVIS
Origin: Shaft of radius and interosseus membrane.
Insertion: base of proximal phalanx of thumb.
Nerve supply:Radial nerve.
Action:extends MCP joints of thumb.
EXTENSOR POLLICIS LONGUS
Origin: shaft of ulna and interosseus membrane.
Insertion: into the base of distal phalanx of thumb.
Action: extends distal phalynx of thumb.
Nerve supply: Radial nerve.
EXTENSOR INDICIS
Origin:
Shaft of ulna and interosseus membrane.
Insertion:
extensor expansion of index finger.
Action:
Extends MCP joint of index finger.
Nerve supply:
Radial nerve
ANATOMICAL SNUFFBOX
Anatomical snuffbox lies between extensor pollicis longus tendon on ulnar side and
tendons of extensor pollicis brevis and abductor pollicis longus on radial side.
EXTENSOR RETINACULUM
A band like thickening in the deep fascia of forearm.
About 2.5 cm wide.
Passes obliquely across the extensor surface of wrist.
Medially attached to pisiform and hook of hamate bones.
Laterally attached to scaphoid trapezium.
Extensor carpal tunnel is divided in to six compartments by fibrous septa passing to
bones of forearm.
Starting from lateral side.
First compartment: tendons of abductor pollicis longus and extensor pollicis brevis
pass.
Second compartment: extensor longus and brevis tendons.
Third compartment: tendon of extensor pollicis longus.
Fourth compartment: extensor digitorium and indicis tendon.
Fifth compartment: tendon of extensor digiti minimi.
Sixth compartment: tendon of extensor carpi ulnaris.
Word of thanks to following great authors of Books of Anatomy:
The reading material is taken from ,
Last’s Anatomy,
Gray’s anatomy,
Keith L Moore’s Anatomy,
Clinical Anatomy by Richard S Snell and
Atlas of human anatomy by Frank H Netter
with thanks.
The end
MUSCLES OF THE POSTERIOR COMPARTMENT OF FOREARM
OBJECTIVES
 At the end of lecture,students will be able to:
 Learn concept of the muscles of posterior compartment of forearm
 Understand nerve supply of these muscles
 Idea of actions of the muscles of posterior compartment of forearm.
 muscles forming this compartment:
Superficial group:
Anconeus.
Extensor digiti minimi.
Extensor carpi ulnaris
Extensor digitorium
Extenser carpi radialis brevis.
Deep group:
Supenator.
Extenser carpi radialis longus.
Abductor pollicis longus.
Extensor pollicis longus.
Extensor pollicis brevis
Extensor indices
BRACHIORADIALIS
 Origin:
Upper two third of supracondylar ridge.
 Insertion:
Styloid process of radius.
• Action:
flexion at elbow joint.
Nerve supply:
Radial nerve
EXTENSER CARPI RADIALIS LONGUS
 Origin:
Lower third of the lateral supra-condylar ridge of humerus.
 Insertion: base of second metacarpal
Action: Extensor and abductor of wrist
 Nerve supply: adial nerve
COMMON EXTENSOR ORIGIN
 Arise from smooth area in front of the lateral epicondyle of humerus.
 This fused tendon gives rise to:
 Extensor carpi radialis brevis.
 Extensor digitorium.
 Extensor digiti minimi.
 Extensor carpi ulnaris.
EXTENSOR CARPI RADIALIS BREVIS
 Origin: common extensor origin.
 Insertion:
Base of third metacarpal.
Nerve supply:
Radial nerve
 Action:
W rist extensor
EXTENSOR DIGITORIUM
 Origin:
common extensor origin
 Insertion:
middle and distal phalanges of medial four fingers.
 Action:
Extensor of the wrist, metacarpophalangeal joint and interphalangeal joints.
 Nerve supply:
Radial nerve
EXTENSOR DIGITI MINIMI
 Origin:
common extensor origin
Insertion:
extensor expansion of distal phalanx of little finger.
 Action:
Assists extensor digitorum with extension of wrist and little finger.
Nerve supply:
Radial nerve.
EXTENSOR CARPI ULNARIS
 Origin:
Arises from the common extensor origin.
 Insertion:into the base of 5th metacarpal.
 Nerve supply: Radial nerve.
 Action: Extend and adduct hand at wrist joint.
ANCONEUS
 Origin:
posterior surface of lateral epicondyle of humerus.
 Insertion: lateral side of olecronon and adjacent shaft of the ulna.
 Nerve supply: Radial nerve.
 Action: extends elbow joint
SUPINATOR
 Origin:
lateral epicondyle of humerus and annular ligament of superior radioulnar joint.
Insertion:
Neck and shaft of radius.
Action:
Supination of forearm.
Nerve supply: Radial nerve
ABDUCTOR POLLICIS LONGUS
 Origin: Shaft of radius and ulna.
 Insertion: base of first metacarpal.
 Action: abduct and extend thumb.
 Nerve supply: Radial nerve.
EXTENSOR POLLICIS BREVIS
 Origin:
Shaft of radius and interosseus membrane.
 Insertion: base of proximal phalanx of thumb.
 Nerve supply:
Radial nerve.
Action: extends MCP joints of thumb.
EXTENSOR POLLICIS LONGUS
 Origin: shaft of ulna and interosseus membrane.
 Insertion: into the base of distal phalanx of thumb.
 Action: extends distal phalynx of thumb.
 Nerve supply: Radial nerve.
EXTENSOR INDICIS
 Origin: Shaft of ulna and interosseus membrane.
 Insertion: extensor expansion of index finger.
 Action: Extends MCP joint of index finger.
 Nerve supply: Radial nerve
ANATOMICAL SNUFFBOX
 Anatomical snuffbox lies between extensor pollicis longus tendon on ulnar side and
tendons of extensor pollicis brevis and abductor pollicis longus on radial side.
EXTENSOR RETINACULUM
 A band like thickening in the deep fascia of forearm.
 About 2.5 cm wide.
 Passes obliquely across the extensor surface of wrist.
 Medially attached to pisiform and hook of hamate bones.
 Laterally attached to scaphoid trapezium.
 Extensor carpal tunnel is divided in to six compartments by fibrous septa passing to
bones of forearm.
 Starting from lateral side.
 First compartment: tendons of abductor pollicis longus and extensor pollicis brevis
pass.
 Second compartment: extensor longus and brevis tendons.
 Third compartment: tendon of extensor pollicis longus.
 Fourth compartment: extensor digitorium and indicis tendon.
 Fifth compartment: tendon of extensor digiti minimi.
 Sixth compartment: tendon of extensor carpi ulnaris.
Word of thanks to following great authors of Books of Anatomy:
The reading material is taken from ,
Last’s Anatomy,
Gray’s anatomy,
Keith L Moore’s Anatomy,
Clinical Anatomy by Richard S Snell and
Atlas of human anatomy by Frank H Netter
with thanks.
The end