POSTERIOR (EXTENSOR) POSTERIOR (EXTENSOR)
ASPECT OF FOREARM ASPECT OF FOREARM
Prof. Dr. Selda Önderoğlu
Structures from superficial to deep
• Skin
• Superficial fascia- superficial vessels and nerves
Skin innervation-mainly by the posterior cut. n. of forearm( radial nerve)
. Deep fascia ( extensor retinaculum)
. Muscles
SKIN INNERVATION
Superficial veins:
Beginning of the Cephalic and basilic veins
Deep fascia
mm. On the post.aspect of forearm
Two groups:
A- Superficial B- deep
Muscles-SUPERFICIAL GROUP
1-
Brachioradialis m.
2-Extensor carpi radialis longus 3-Extensor carpi radialis brevis 4-Extensor carpi ulnaris
5-Extensor digitorum
6-Extensor digiti minimi
7-Anconeus (?)
Muscles-DEEP GROUP
1-Supinator ( pierced by radial n.) 2-Abductor pollicis longus
3-Extensor pollicis longus 4-Extensor pollicis brevis
5-Extensor indicis (/ext.indicis proprius)
BRACHIORADIALIS MUSCLE
• The most superficial muscle.
• Forms the lateral border of the cubital fossa.
• Or:supracondylar ridge+lat.intermuscular septum
• Ins:lateral side of radius (above styloid process)
• n.: radial nerve (itself!)
• F.: flexor of forearm(flexes better when forearm is
pronated)
EXTENSOR
CARPI RADIALIS LONGUS
or: supracondylar ridge ins:second metacarpal
bone
N: radial nerve ( itself!) F:extention of forearm
and hand
COMMON EXTENSOR TENDON
• Lateral epicondyle of humerus
The extensor mm. Also orginate from:
• Radial collateral lig. Of elbow joint
• intermuscular septa.
• N.: all the muscles except the brachioradialis
and ext. carpi rad. Longus are innervated by
the deep branch of the radial nerve ( posterior
interosseus nerve)
Muscles originating from the common extensor tendon
• Extensor carpi radialis brevis m.
ins: 3rd metacarpal bone
• Extensor digitorum m.
ins:dorsal digital expansion
• Extensor digiti minimi m.( ext. Quinti proprius m.)
ins:dorsal digital expansion
• Extensor carpi ulnaris m.
ins: 5th metacarpal bone
Anconeus m.
At the back of elbow joint
Helps the extension of forearm
DORSAL DIGITAL EXPANSION (EXTENSOR EXPANSION)
• Small aponeurosis which covers the dorsum of the phalanges except the thumb.
• Triangular in shape.
• Base: covers the dorsal aspect of the metacarpophalangeal joint.
• then divides into 3 slips:
• Intermediate slip: attach to the base of second phalanx
• 2 lateral slips: unite and attach to the base of the distal
phalanx.
muscles Attaching to
the dorsal digital expansion
• Extensor digitorum m
.,(superf.m.of forearm)• Extensor digiti minimi m.
(superf.m.of forearm)• Extensor indicis proprius m.
(deep m. Of forearm)• interossei mm.(
hand)
• Lumbrical mm.(
hand)
INSERTIONS!
• Base of first metacarpal bone: abductor pollicis longus m.
• Base of second metacarpal bone:
extensor carpi radialis longus m.
• Base of third metacarpal bone: extensor carpi radialis brevis m.
• Base of fifth metacarpal bone:extensor
carpi ulnaris m.
Muscles-DEEP GROUP
• Supinator ( pierced by radial n.)
• Abductor pollicis longus
• Extensor pollicis longus
• Extensor pollicis brevis
• Extensor indicis proprius
Supinator m.:
Or: lat.epicondyle and supinator crest of ulna
ins: ant,lat,and post aspect of radius
n.: deep br. Of radial n
F:supination of forearm and hand
Deep group of extensors
• O:
from radius,ulna and interosseus membrane according to its position (medial or lateral)• I:
abd.poll.longus:1st metacarpal bone ext.poll.brevis:prox. Phalanx of thumb Ext. indicis: dors.digital expansionfunctions: ??
Deep branch of radial n.
(post.interooseus nerve) Pierces the supinator m.
Posterior interooseus artery Gives the blood supply to the extensor aspect of forearm Courses together with the post.inteross. N.
