Forearm anatomy Flashcards
Describe the course of the PIN
The posterior interosseous nerve originates as a continuation of the deep branch of the radial nerve as it passes through the supinator muscle.
It then runs in a plane between the superficial and deep muscles in the posterior compartment of the forearm, supplying branches to these muscles.
When the posterior interosseous nerve reaches the wrist joint, it terminates by supplying sensory branches to the dorsal (posterior) joint capsule.
What muscles does the PIN supply?
Superficial compartment:
Extensor digitorum
Extensor digiti minimi
Extensor carpi ulnaris
Deep compartment:
Abductor pollicis longus
Extensor pollicis longus
Extensor pollicis brevis
Extensor indicus proprius
Describe the attachments of brachioradialis
Origin: proximal lateral supracondylar ridge of the humerus
Insertion:
Distal radius, just before the radial styloid.
What is the origin and insertion of FCR?
Origin: common flexor origin, medial epicondyle.
Insertion:
Base of 2nd and 3rd metacarpal
What are the forearm compartments?
Volar
Dorsal
Mobile wad
Which muscles are in the mobile wad?
Brachoradialis
ECRL
ECRB
What are the hand compartments?
10 in total
hypothenar
thenar
adductor pollicis
dorsal interosseous (x4)
volar (palmar) interosseous (x3)
How would you perform forearm fasciotomies?
volar incision:
decompresses volar compartment and carpal tunnel
incision starts just radial to FCU at wrist and extends proximally to medial epicondyle
may extend distally to release carpal tunnel
dorsal incision:
decompresses mobile wad and dorsal compartment
dorsal longitudinal incision 2cm distal to lateral epicondyle toward midline of wrist
Describe what is in the 6 extensor compartments of the wrist
I - EPB, APL
II - ECRL, ECRB
III - EPL
IV - EDC, EIP
V - EDI
VI - ECU
Describe the compartments of the hand
hypothenar
thenar
adductor pollicis
dorsal interosseous (x4)
volar (palmar) interosseous (x3)
