Anterior interosseous nerve: anatomical study and clinical implications

Abstract

ObjectiveThe goal of this study was to describe anatomical variations and clinical implications of anterior interosseous nerve. In complete anterior interosseous nerve palsy, the patient is unable to flex the distal phalanx of the thumb and index finger; in incomplete anterior interosseous nerve palsy, there is less axonal damage, and either the thumb or the index finger are affected.MethodsThis study was based on the dissection of 50 limbs of 25 cadavers, 22 were male and three, female. Age ranged from 28 to 77 years, 14 were white and 11 were non-white; 18 were prepared by intra-arterial injection of a solution of 10% glycerol and formaldehyde, and seven were freshly dissected cadavers.ResultsThe anterior interosseous nerve arose from the median nerve, an average of 5.2 cm distal to the intercondylar line. In 29 limbs, it originated from the nerve fascicles of the posterior region of the median nerve and in 21 limbs, of the posterolateral fascicles. In 41 limbs, the anterior interosseous nerve positioned between the humeral and ulnar head of the pronator teres muscle. In two limbs, anterior interosseous nerve duplication was observed. In all members, it was observed that the anterior interosseous nerve arose from the median nerve proximal to the arch of the flexor digitorum superficialis muscle. In 24 limbs, the branches of the anterior interosseous nerve occurred proximal to the arch and in 26, distal to it.ConclusionThe fibrous arches formed by the humeral and ulnar heads of the pronator teres muscle, the fibrous arch of the flexor digitorum superficialis muscle, and the Gantzer muscle (when hypertrophied and positioned anterior to the anterior interosseous nerve), can compress the nerve against deep structures, altering its normal course, by narrowing its space, causing alterations longus and flexor digitorum profundus muscles.

Fascicular constrictions above elbow typify anterior interosseous nerve syndrome

“…Anterior interosseous nerve syndrome (AINS) typically manifests as spontaneous weakness of thumb and/or index finger flexion and forearm pronation preceded by pain . AINS has been attributed to either compressive neuropathy in the proximal forearm or to Parsonage‐Turner syndrome (PTS) . PTS is a condition characterized by acute, spontaneous onset of one or more peripheral neuropathies, typically, but not exclusively, with severe prodromal pain.…”

“…[1][2][3][4][5] AINS has been attributed to either compressive neuropathy in the proximal forearm or to Parsonage-Turner syndrome (PTS). 1,[5][6][7][8] PTS is a condition characterized by acute, spontaneous onset of one or more peripheral neuropathies, typically, but not exclusively, with severe prodromal pain. Parsonage and Turner's original series of 136 patients described 6 subjects with AIN involvement.…”

Targeted Muscle Reinnervation for Symptomatic Neuromas Utilizing the Terminal Anterior Interosseous Nerve

“…The versatility of the AIN as a target for TMR has not been explored previously. The anatomy of the AIN is well described in the literature 10 and predictable in nature. Sacrifice of PQ function is well tolerated in patients with a functioning pronator teres.…”

Selective Fascicular Involvement of the Median Nerve Trunk Causing Pseudo-Anterior Interosseous Nerve Syndrome: Ultrasound and MR Imaging Features

“…It originates from the nerve fascicles of the dorsal region and the dorsolateral fascicles of the median nerve, and innervates the FPL, FDP (including the index and sometimes third fingers), and pronator quadratus muscles. 7,8 Pseudo-AINS has been found to occur in association with supracondylar fractures of the humerus, proximal radius fracture, partial damage to the median nerve in the antecubital fossa during catheterization of the brachial artery or venipuncture, median nerve entrapment by an accessory bicipital aponeurosis, nerve inflammation, or fascicular constriction/torsion of nerve. [1][2][3][4]7 Hourglass-like constrictions of peripheral nerves in the upper arm cause a rare form of neuropathy, often characterized by the sudden onset of pain in the shoulder or arm, followed by muscle weakness and atrophy, with limited sensory involvement.…”