Triceps and cutaneous radial nerve branches investigated via an axillary anterior arm approach: new findings in a fresh-cadaver anatomical study

Abstract

OBJECTIVE The authors sought to describe the anatomy of the radial nerve and its branches when exposed through an axillary anterior arm approach. METHODS Bilateral upper limbs of 10 fresh cadavers were dissected after dyed latex was injected into the axillary artery. RESULTS Via the anterior arm approach, all triceps muscle heads could be dissected and individualized. The radial nerve overlaid the latissimus dorsi tendon, bounded by the axillar artery on its superior surface, then passed around the humerus, together with the lower lateral arm and posterior antebrachial cutaneous nerve, between the lateral and medial heads of the triceps. No triceps motor branch accompanied the radial nerve’s trajectory. Over the latissimus dorsi tendon, an antero-inferior bundle, containing all radial nerve branches to the triceps, was consistently observed. In the majority of the dissections, a single branch to the long head and dual innervations for the lateral and medial heads were observed. The triceps long and proximal lateral head branches entered the triceps muscle close to the latissimus dorsi tendon. The second branch to the lateral head stemmed from the triceps lower head motor branch. The triceps medial head was innervated by the upper medial head motor branch, which followed the ulnar nerve to enter the medial head on its anterior surface. The distal branch to the triceps medial head also originated near the distal border of the latissimus dorsi tendon. After a short trajectory, a branch went out that penetrated the medial head on its posterior surface. The triceps lower medial head motor branch ended in the anconeus muscle, after traveling inside the triceps medial head. The lower lateral arm and posterior antebrachial cutaneous nerve followed the radial nerve within the torsion canal. The lower lateral brachial cutaneous nerve innervated the skin over the biceps, while the posterior antebrachial cutaneous nerve innervated the skin over the lateral epicondyle and posterior surface of the forearm. The average numbers of myelinated fibers were 926 in the long and 439 in the upper lateral head and 658 in the upper and 1137 in the lower medial head motor branches. CONCLUSIONS The new understanding of radial nerve anatomy delineated in this study should aid surgeons during reconstructive surgery to treat upper-limb paralysis.

Triceps paralysis with intact distal radial nerve function in partial brachial plexus injury: a unique presentation

“…Surgery was conducted through an axillary-arm incision (Bertelli et al, 2011(Bertelli et al, , 2021. The musculocutaneous nerve was observed to have a normal path, piercing the coracobrachialis muscle.…”

“…Under electrical stimulation, branches to the biceps and brachialis muscles elicited full contraction. The triceps motor branches were further dissected along the anterior portion of the radial nerve (Bertelli et al., 2021) and we identified a neuroma-in-continuity about 2.5 cm over the latissimus dorsi tendon (Figure 1). The neuroma was removed and sent for histological evaluation.…”

Axillary to Radial Nerve Transfer for Recovery of Elbow Extension After Spinal Cord Injury

“…The LHT is typically the first motor branch off of the RN followed by the upper branch of the medial head. 4,5 The posterior cutaneous branch of the arm (PCB) supplies the posterior upper arm and is most often proximal to the LHT branch but may share a common trunk. The LHT is an ideal recipient because it is the largest of the triceps heads, innervated by a single cohesive branch, which enters the proximal muscle belly just distal to the LAT tendon.…”

Combined Hyperselective Neurectomy and Fractional Lengthening Technique for Triceps Spasticity

“…Anatomic studies have shown that the MH has a separate insertion deep to the common insertion of LH and LaH on the olecranon. 19 The MH has a muscular insertion, with a smaller tendinous portion that can be identified deep to the conjoined tendons of the LH and LaH. 24 The triceps receives its innervation from the radial nerve, one of two terminal branches of the posterior cord of the brachial plexus, which is formed by the C5 to T1 cervical roots.…”

“…17 The anatomy of the radial nerve has been well-defined; however, a peripheral nerve-based procedure to address triceps spasticity has not been reported. [18][19][20][21][22][23] Given the course of the radial nerve, broad branching pattern, and variable anatomy, an entirely nerve-based procedure would require extensive exposure in the posterior arm. As such, this study aims to present our surgical technique for treating triceps spasticity, which involves combining triceps tendon lengthening of the long (LA) and lateral (LaH) heads with HSN of the medial head (MH) of the triceps through a targeted distally based incision.…”