Caracterización de la comunicación ulnar-mediano palmar profunda en una muestra con material cadavérico / Characterization of ulnar-median deep palmar communication in a sample with cadaveric material

RESUMEN: La comunicación Ulnar-Mediano Palmar Profunda (CUMPP) es la conexión entre la rama profunda del nervio ulnar (NU) y la rama del nervio mediano (NM) que inerva a los músculos tenares como la cabeza superficial del flexor corto del pulgar. Son escasos los trabajos que se ocupan de esta rama comunicante, y su prevalencia es reportada con una amplia variabilidad, en un rango del 16-77 %. Este estudio no probabilístico, descriptivo, transversal, evaluó la frecuencia y características morfológicas de la CUMPP en 106 manos de especímenes cadavéricos frescos no reclamados, a quienes se les practicó necropsia en el Instituto de Medicina Legal de Bucaramanga (Colombia). Se observó rama comunicante CUMPP en 39 especímenes (50,2 %), de los cuales 12 (44,5 %) fueron bilate- rales, 15 (55,6 %) unilaterales, con predominio unilateral derecho para 9 casos (60 %), sobre el izquierdo de tan solo 6 casos (40 %). No se evidenciaron diferencias estadísticamente significativas con relación al lado de presentación (P=0,223). En 21 especímenes (54 %) se observó el tipo IV; mientras que el tipo I fue encontrado en 4 casos (10 %). El promedio de la longitud de la rama comunicante fue de 24,67 DE 6,46 mm; mientras que la distancia del punto proximal de la CUMPP al surco distal del carpo fue de 41,4 DE 2,6 mm. Nuestros hallazgos no son concordantes con lo reportado en la mayoría de estudios previos. Diversos factores como el tamaño de las muestras, las diferentes metodologías de medición y las expresiones fenotípicas de cada grupo de población evaluado, pueden explicar la variabilidad de la CUMPP.

SUMMARY: Deep Palmar Ulnar-Medium Communication (DPUMC) is the connection between the deep branch of the ulnar nerve (UN) and the median nerve (MN) branch, that innervates the thenar muscles as the superficial head of the short flexor of the thumb. Few studies dealing with this communicating branch, and its prevalence is reported with a wide variability in the range of 16-77 %. This non-probabilistic, descriptive, cross-sectional study; evaluated the frequency and morphological characteristics of DPUMC in 106 hands of fresh unclaimed cadaveric specimens, that underwent necropsy at the Institute of Legal Medicine of Bucaramanga (Colombia). DPUMC communicating branch was observed in 39 specimens (50.2 %), of which 12 (44.5 %) were bilateral, 15 (55.6 %) unilateral, with right unilateral predominance for 9 cases (60 %), on the left of only 6 cases (40 %). There were no statistically significant differences in relation to the presentation side (P = 0.223). In 21 specimens (54%), type IV was observed; while type I was found in 4 cases (10%). The average length of the communicating branch was 24.67 SD 6.46 mm; while the distance from the proximal point of the DPUMC to the distal carpal groove was 41.4 SD 2.6 mm. Our findings are not consistent with those reported in most previous studies. Various factors such as sample size, different measurement methodologies and phenotypic expressions of each population group evaluated can explain the variability of the DPUMC.

A Morphological Study on the Anatomic Variation of the Musculocutaneous Nerve with its Clinical Implication.

Background: During surgery of the shoulder region the identification of musculocutaneous nerve (MCN) and its variation is important because it is vulnerable to injury from surgical instruments. The MCN is formed as the continuation of lateral cord of brachial plexus. The MCN travels obliquely below the coracoid process and enters the coracobrachialis (CB) muscle. The MCN supplies the muscles of front of arm, namely the CB, the Biceps brachii and Brachialis muscles. Methods: The Morphological study included 25 cadavers aged between 21 to 70 years. Both the right and the left upper limbs of each cadaver, 50 limbs were studied and documented. The MCN showed variations in their course, branching pattern and communication with MN (median nerve). Results: The lateral cord gives a direct branch to CB, then pierces the muscle in 2 cases (8%) unilaterally. MCN does not pierce the CB but communicates with median nerve in 3 cases (12%) unilaterally, whereas communication between MCN and MN seen in 5 cases (20%). Conclusion: The Knowledge of Variation in origin, course, branching pattern, termination and communication of MCN in the arm have the significance in shoulder injuries and reconstructive surgeries.

Fusion of main trunks of median and musculocutaneous nerves (an anatomic variation).

Median nerve (MN) and Musculocutaneous nerve (MCN) around their origin from brachial plexus are known to have many variations. A unilateral variation in the course of MCN in 65 years male cadaver was observed during routine dissections for medical undergraduates. In the present case, MCN was observed to be formed by its normal pattern, as the continuation of lateral cord of brachial plexus. Thereafter instead of piercing coracobrachialis, it fuses for some distance with MN and then separates out to supply all the muscles of anterior compartment of the arm. It then ends as lateral cutaneous nerve of forearm. Such a case of fusion of main trunks of MN and MCN has not been clearly reported in literature. Knowledge of this variation is important owing to its numerous clinical implications.