Enhance your knowledge with our comprehensive guide and curated study materials.
C7, C8 (continuation of the deep branch of the radial nerve).
Arises in the cubital fossa as the deep branch of radial nerve.
Pierces the supinator muscle (between its superficial and deep layers).
Enters the posterior compartment of forearm as the posterior interosseous nerve.
Descends on the interosseous membrane, lying between the superficial and deep extensor groups.
Terminates as a gangliform enlargement on the dorsal wrist joint, giving articular branches to the wrist and intercarpal joints.
Nerve to extensor carpi radialis brevis.
Nerve to supinator.
Muscular branches to:
Extensor digitorum
Extensor digiti minimi
Extensor carpi ulnaris
Abductor pollicis longus
Extensor pollicis longus
Extensor pollicis brevis
Extensor indicis
To wrist and intercarpal joints.
Lies deep to extensor digitorum and extensor carpi radialis brevis.
Accompanied by the posterior interosseous artery (branch of common interosseous artery).
Posterior Interosseous Nerve Palsy:
Results from compression in the supinator (arcade of Frohse).
Produces inability to extend fingers (wrist extension preserved via ECRL).
Common in rheumatoid arthritis or after radial head fracture.
Testing: Ask patient to extend middle finger; weakness indicates radial nerve lesion at this level.
Place limb prone; reflect superficial extensors (ECRL, ECRB, ED, EDM, ECU).
Identify deep branch of radial nerve as it enters supinator.
Follow it beneath supinator to posterior forearm → becomes posterior interosseous nerve.
Observe muscular branches to deep extensors and terminal articular twigs near wrist.
Note accompanying posterior interosseous artery throughout its course.
From common interosseous artery, a branch of ulnar artery in the forearm.
Arises in the upper forearm, passes posteriorly above the interosseous membrane.
Appears between supinator and abductor pollicis longus.
Descends with the posterior interosseous nerve, between the superficial and deep extensor groups.
Ends near the wrist by anastomosing with the anterior interosseous artery and dorsal carpal network.
Recurrent branch → joins middle collateral artery (from profunda brachii) in the elbow anastomosis.
Muscular branches → to extensor muscles.
Terminal branches → join anterior interosseous artery and carpal arches.
Contributes to collateral circulation around the elbow and wrist.
Injury is rare due to deep position, but important for maintaining dorsal hand perfusion after radial or ulnar occlusion.
The hand contains two main arterial arches that ensure rich anastomosis between the radial and ulnar arteries:
Superficial palmar arch
Deep palmar arch
Mainly by ulnar artery, completed laterally by the superficial palmar branch of radial artery.
Deep to palmar aponeurosis, superficial to flexor tendons.
Three common palmar digital arteries → each divides into two proper digital arteries for adjacent fingers.
One proper digital artery → supplies medial side of little finger.
Lies in line with the distal border of fully extended thumb (lower than deep arch).
Mainly by radial artery, completed medially by the deep branch of ulnar artery.
Deep to long flexor tendons, on bases of metacarpal bones and interossei.
Palmar metacarpal arteries → join common palmar digital arteries of superficial arch.
Perforating branches → connect to dorsal metacarpal arteries.
Recurrent branches → to wrist and carpal area.
Approximately at the level of the proximal border of extended thumb.
Allen’s Test:
Used to check patency of both ulnar and radial arteries before radial artery cannulation or graft harvesting.
Incomplete arches (in ~20–30%) → risk of ischemia if one artery is occluded.
Severe palmar injuries: may involve both arches → profuse bleeding requiring compression of both arteries at wrist.
Surgical Note:
Deep arch injury → bleeding controlled by compressing radial artery in anatomical snuffbox.
Superficial arch injury → compress ulnar artery proximal to pisiform.
Get the full PDF version of this chapter.
Continue with Google