Medial antebrachial cutaneous nerve: anatomical relationship with the medial epicondyle, basilic vein and brachial artery / Nervio cutáneo antebraquial medial: relación anatómica con el epicóndilo medial, vena basílica y arteria braquial

Medial antebrachial cutaneous nerve (MACN) courses in the medial arm to provide sensory innervation to the medial forearm. Its anatomy has been partly described since data regarding its branching pattern and distances to adjacent landmarks are still lacking. The purpose of this study was to provide morphometric anatomy of the MACN with comparisons between sides and sexes. Ninety-six upper extremities from 26 males and 22 females were dissected. We found that up to 5 branches of MACN pierced the deep fascia with the maximum of 4 reaching the interepicondylar line (IEL). Presence of 2 and 3 branches was found in the majority of cases (> 80%). The distances from these branches to the landmarks varied considerably. In case of no branch, the mean distances to the medial epicondyle (ME) and brachial artery (BA) were approximately 1.5 cm while those to the basilic vein (BV) were 0.7 cm in both sexes. Regardless of the branching pattern, the MACN could pass over or close (within 0.5 cm) to the ME, BV and BA. Asymmetry in the branching pattern was found in 50% of specimens. Sex but not side differences were observed in some measurement parameters. These data are crucial for not only localizing the MACN during nerve block and graft harvest but also avoiding the nerve injury during surgical procedures.

El recorrido del nervio cutáneo antebraquial medial (NCAM) proporciona la inervación sensorial medial del antebrazo. Su anatomía se ha descrito en parte, porque los datos relativos a su patrón de ramificación y distancias a puntos de referencia adyacentes son insuficientes. El propósito de este estudio fue proporcionar datos morfométricos sobre la anatomía del NCAM, comparando entre lados y sexos. Se disecaron 96 miembros superiores de 26 hombres y 22 mujeres. Se encontró que 5 ramos del NCAM traspasaron la fascia profunda y llegaron 4 hasta la línea interepicondilar (LIE). Presencia de 2 y 3 ramos se encontró en la mayoría de los casos (>80%). Las distancias de estos ramos a los puntos anatómicos variaron considerablemente. En caso de ausencia de ramos, la distancia medial al epicóndilo medial (EM) y arteria braquial (AB) fueron de aproximadamente 1,5 cm, mientras que a la vena basílica (VB) fueron 0,7 cm en ambos sexos. Independientemente del patrón de ramificación, el NCAM podría pasar sobre o cerca (a menos de 0,5 cm ) del EM, VB y AB. Asimetría en el patrón de ramificación se encontró en 50% de las muestras. Diferencias en algunos de los parámetros de medición se observaron según sexo, pero no por lado. Estos datos son relevantes para localizar el NCAM durante el bloqueo del nervio y la toma de injertos, sino también para evitar la lesión del nervio durante los procedimientos quirúrgicos.

Determination of an Ideal Stimulation Site of the Medial Antebrachial Cutaneous Nerve Using Ultrasound and Investigation of the Efficiency

OBJECTIVE: To determine an ideal stimulation site of the medial antebrachial cutaneous nerve (MACN) using ultrasound measurement and to compare the efficiency of the new stimulation site with the conventional stimulation site on the nerve conduction study. METHODS: Both arms of 15 healthy participants were measured using ultrasound. The MACN was identified in the transverse view at each 0, 2, 4, 6, and 8 cm proximal sites from the medial epicondyle, and the distances to the median nerve and to the skin from the MACN were measured. The ideal stimulation site should be located at the level which can give the shortest distance from the skin and the longest distance from the median nerve in terms of volume conduction. To confirm the efficiency of the ideal site, we measured the amplitude of the MACN conduction study at the ideal site against one at the 4 cm proximal to the medial epicondyle (conventional site). RESULTS: The ultrasound showed the ideal stimulation site for the MACN could be the elbow crease line. However, the nerve conduction study revealed that the amplitudes of the MACN were significantly larger at the 4 cm proximal to the medial epicondyle compared with ones at the ideal site. CONCLUSION: The ideal stimulation site based on the ultrasound did not permit better stimulation site for the nerve conduction study of the MACN compared with the conventional site. Careful adjustment of the stimulation site on the basis of this study would contribute to an accurate conduction study of the MACN.

Anatomical Distribution of Branches of the Medial Antebrachial Cutaneous Nerve during Cubital Tunnel Surgery

PURPOSE: The purpose of this prospective study is to examine the anatomical variations of the branches of the medial antebrachial cutaneous nerve in Koreans encountered during cubital tunnel surgery. METHODS: Ninety two patients with cubital tunnel syndrome were treated with a standard approach from December 2008 to July 2012. The position of the branches of medial antebrachial cutaneous nerve was evaluated based on the medial humeral epicondyle with the elbows fully extended. RESULTS: At least one medial antebrachial cutaneous nerve branch was found during the surgeries in all patients. The average number of crossing medial antebrachial cutaneous nerve branches per patient was 1.6. Thirty-eight percent of the cases showed that the medial cutaneous nerve branches cross proximal to the medial humeral epicondyle within 1 cm. Eighty-two percent showed that the medial antebrachial cutaneous nerve branches cross distal to the medial humeral epicondyle within 1.9 cm. CONCLUSION: When using standard approach during cubital tunnel surgery, more than one medial forearm cutaneous nerve is found. Therefore, understanding the general position of medial antebrachial cutaneous nerve branches helps avoid iatrogenic damage to this nerve during cubital tunnel surgery.

Anatomical Considerations of Lateral and Medial Antebrachial Cutaneous Nerves

OBJECTIVE: To evaluate the anatomic course of the lateral antebrachial cutaneous nerve (LABCN) and medial antebrachial cutaneous nerve (MABCN) in the forearm. METHOD: We dissected 29 upper extremities of 16 cadavers for LABCN and 20 upper extremities of 15 cadavers for the MABCN. We measured the distance (BT_L) between the biceps tendon (BT) and LABCN on the intercondylar line. The BT is the point at which biceps tendon crosses intercondylar line. The distance (L12) between LABCN and the point of 12 cm distal to BT on the line between BT and radial artery at wrist was measured. The distance (ME_M) between MABCN and medial epicondyle on the intercondylar line was measured. M8 and M10 are the distances between MABCN and the points 8 cm and 10 cm distal to BT on the line from BT to mid-point of flexor carpi radialis and palmaris longus at the wrist respectively. RESULTS: BT_L and L12 were 1.4+/-3.7 mm and 4.4+/-3.7 mm respectively. ME_M, M8 and M10 were 28.6+/-6.9 mm, 18.9+/-8.9 mm and 18.3+/-8.2 mm respectively. The thickness of LABCN and MABCN was 19.1+/-4.9 mm and 13.2+/-4.2 mm respectively. CONCLUSION: The LABCN was emerge just lateral to biceps tendon at the elbow and ran down to radial artery. The anatomic course of MABCN was variable at the elbow and forearm.