Anterior interosseous nerve
Encyclopedia
The anterior interosseous nerve (volar interosseous nerve) is a branch of the median nerve
that supplies the deep muscles on the front of the forearm
, except the ulnar half of the flexor digitorum profundus.
It accompanies the anterior interosseous artery along the anterior of the interosseous membrane of the forearm
, in the interval between the flexor pollicis longus and flexor digitorum profundus, supplying the whole of the former and (most commonly) the radial half of the latter, and ending below in the pronator quadratus
and wrist joint.
Many texts, for simplicity's sake, consider this nerve part of the median nerve
.
These muscles are in the deep level of the anterior compartment of the forearm
.
. As might be expected, the symptoms involve weakness in the muscle innervated by the AIN including the flexor digitorum profundus muscle to the index (and sometimes the middle) finger, the flexor pollicis longus muscle to the thumb and the pronator quadratus of the distal forearm. As opposed to carpal tunnel syndrome, the AIN has no sensory fibers and therefore no numbness associated with the Anterior Interosseous Syndrome. Non-surgical treatment consists of splinting, proximal tissue massage and anti-inflammatory drugs. Surgical treatment consists of releasing the compression on the nerve from surrounding structures. Pronator Syndrome is similar, but involves both the AIN as well as the median nerve proper.
Median nerve
The median nerve is a nerve in humans and other animals. It is in the upper limb. It is one of the five main nerves originating from the brachial plexus....
that supplies the deep muscles on the front of the forearm
Forearm
-See also:*Forearm flexors*Forearm muscles...
, except the ulnar half of the flexor digitorum profundus.
It accompanies the anterior interosseous artery along the anterior of the interosseous membrane of the forearm
Interosseous membrane of the forearm
The interosseous membrane of the forearm is a fibrous sheet that connects the radius and the ulna...
, in the interval between the flexor pollicis longus and flexor digitorum profundus, supplying the whole of the former and (most commonly) the radial half of the latter, and ending below in the pronator quadratus
Pronator quadratus
Pronator quadratus is a square shaped muscle on the distal forearm that acts to pronate the hand.As it is on the anterior side of the arm, it is innervated by a branch of the median nerve, the anterior interosseous nerve...
and wrist joint.
Many texts, for simplicity's sake, consider this nerve part of the median nerve
Median nerve
The median nerve is a nerve in humans and other animals. It is in the upper limb. It is one of the five main nerves originating from the brachial plexus....
.
Innervation
The anterior interosseous nerve clasically innervates 2.5 muscles:- flexor pollicis longus
- pronator quadratusPronator quadratusPronator quadratus is a square shaped muscle on the distal forearm that acts to pronate the hand.As it is on the anterior side of the arm, it is innervated by a branch of the median nerve, the anterior interosseous nerve...
- the radial half of flexor digitorum profundus (the lateral two out of the four tendons).
These muscles are in the deep level of the anterior compartment of the forearm
Anterior compartment of the forearm
The anterior compartment of the forearm contains the following muscles:* "E/I" refers to "extrinsic" or "intrinsic"....
.
Injury
A branch of the median nerve, the anterior interosseous nerve (AIN) can be affected by either direct penetrating injury or compression in a fashion similar to carpal tunnel syndrome. The compression neuropathy is referred to an Anterior Interosseous SyndromeAnterior interosseous syndrome
Anterior interosseous syndrome or Kiloh-Nevin syndrome I is a medical condition in which damage to the anterior interosseous nerve, a motor branch of the median nerve, causes pain in the forearm and a characteristic weakness of the pincer movement of the thumb and index finger.Most cases of...
. As might be expected, the symptoms involve weakness in the muscle innervated by the AIN including the flexor digitorum profundus muscle to the index (and sometimes the middle) finger, the flexor pollicis longus muscle to the thumb and the pronator quadratus of the distal forearm. As opposed to carpal tunnel syndrome, the AIN has no sensory fibers and therefore no numbness associated with the Anterior Interosseous Syndrome. Non-surgical treatment consists of splinting, proximal tissue massage and anti-inflammatory drugs. Surgical treatment consists of releasing the compression on the nerve from surrounding structures. Pronator Syndrome is similar, but involves both the AIN as well as the median nerve proper.