Estudio biométrico de la inervación de los músculos lumbricales de la mano humana / Biometric study of the innervation of the lumbrical muscles of the human hand

Los músculos lumbricales (ML) de la mano humana son claves en la propiocepción de la flexoextensión de los dedos. La descripción de su inervación indica que el nervio mediano (NM) inerva los dos ML laterales (L1 y L2) y el nervio ulnar (NU) los ML mediales (L3 y L4). Diversos autores han reportado una gran variabilidad de esta inervación, tanto en los nervios que entregan ramos para estos músculos, como también en la distribución de sus ramos y la presencia de troncos comunes. Por otra parte, el número de ramos que recibe cada ML y los puntos motores (Pm) de los mismos ha sido escasamente reportado. El objetivo de este estudio fue determinar número, ubicación y Pm de los ramos destinados a los ML de la mano humana. Así mismo se estableció el patrón de inervación más frecuente. Para ello se utilizaron 24 manos formalizadas, pertenecientes al laboratorio de Anatomía, de la Universidad Andrés Bello, sede Viña del Mar, Chile. Se realizó una disección convencional por planos de profundidad. En todos los casos, el ramo del músculo L1 se originó del nervio digital palmar propio lateral del dedo índice, de la misma forma, en el 100 % el L2 fue inervado por un ramo del nervio digital palmar común del segundo espacio interóseo. En relación a los ML mediales en un 100 % ambos músculos fueron inervados por ramos del ramo profundo del NU (RPNM). En el caso del L3 en un 92 % se presentó un tronco común con el segundo músculo interóseo palmar, asimismo para L4 existió un tronco común con el tercer músculo interóseo palmar en un 79 %. En el 29 %, el L3 presentó una inervación dual. Considerando como referencia la línea biestiloidea, los Pm de los ramos del NM fue de 63,96 mm para L1; 67,91 mm para L2 y 68,69 mm para L3. Para los ramos provenientes del RPNU fue de 69,87 mm para L3 y 69, 21 mm para L4. Los resultados obtenidos aportan al conocimiento anatómico de la inervación de los músculos lumbricales y es de utilidad en procedimientos de neurocirugía que busquen la restauración de la funcionalidad de la mano.

The lumbrical muscles (LM) of the human hand are key in proprioception of flexion and finger extension. The description of its innervation indicates that the median nerve (MN) innervates the two lateral LMs (L1 and L2) and the ulnar nerve (UN) the medial LMs (L3 and L4). Various authors have reported a great variability of this innervation, both in which nerve delivers branches for these muscles, as well as in the distribution of their branches and the presence of common trunks. On the other hand, the number of branches that each LM receives and the motor points (Mp) of these have been scarcely reported. The aim of this study was to determine the number, location and Mp of the branches destined for the LM of the human hand. Likewise, the most frequent innervation pattern was established. For this, 24 formalized hands, belonging to the anatomy laboratory, of the Universidad Andrés Bello, Viña del Mar, Chile, were used. Conventional depth plane dissection was performed. In all cases, the branch of the L1 muscle originated from the palmar digital nerve proper to the index finger, in the same way, in 100 % the L2 was supplied with a branch of the common palmar digital nerve from the second interosseous space. In relation to the LM, in 100 % both muscles were innervated by branches of the deep branch of the UN (DBUN). In the case of L3, 92 % presented a common trunk with the second palmar interosseous muscle. Likewise, in 79 % of the cases, there was a common trunk between the L4 and the third palmar interosseous muscle. In 29 %, the L3 presented a dual innervation. The distance between of the Mp-BEstL was 63.96 mm for L1, 67.91 mm for L2 and 68.69 mm for L3. This distance was 69.87 mm for L3 and 69, 21 mm for L4. The results obtained contribute to the anatomical knowledge of the innervation of the lumbrical muscles and is useful in neurosurgery procedures that seek to restore the functionality of the hand.

Applied anatomy of the first plantar lumbrical muscle / 中华显微外科杂志

Objective To investigate the anatomical structure of the first plantar lumbrical muscle in the foot and to measure the relevant data which could provide anatomical basis for repairing thumb and finger defects with the transplantation of toes accompanied with the first lumbrical muscle,and to explore the marphological function of the first lumbrical muscle of the foot.Methods From March,2016 to January,2018,a systematic and detailed dissection of the 50 formalin-fixed feet was performed to observe the exact position of the starting and ending points of the first lumbrical muscle,and a Vernier caloper was used to measure the relevant record data.Results The first lumbrical muscle originates from the medial portion of the flexor digitorum lungus tendon of the second toe,and the length of the ventral muscle was [55.87±8.67(79.30-41.16] mm.There were 2 endpoints in the tendon.The first one was in the medial tubercle of the proximal phalanges.The second one was aponeurosis of the dorsal toe and the tendon was divided into proximal and distal segments with the medial tubercle as the mark point.The length of the proximal segment was [15.34±4.81(5.52-25.18] mm,the width of the proximal segment was [2.31±1.12(3.28-1.21)] mm,the thickness was [0.44±0.14(0.28-0.68)] mm;the length of the distal segment was [11.51±4.06(3.46-14.90)] mm,the width was [6.10±1.44(9.36-3.70)] mm,and the thickness was [0.18±0.09(1.10-0.38)] mm.The length and thickness of the proximal segment was signifantly larger than those of the distal segment (P＜0.05).Conclusion The first lumbrical muscle has the function of maintaining the balance and stability of both the toe and the arch during movement,flexuring the metatarsophalangeal joint,extending the interosseous joint of the extensor phalangeal,adducting the second toe;also the function of preventing the second toe from pronation during foots' movement.

Variations of the Lumbrical Muscles in Hands of Koreans / 체질인류학회지

The aim of this study was to classify morphological patterns of the lumbrical muscles and their anatomical variations in the hands. The lumbricals in the hand were investigated in 70 specimens of 45 embalmed Korean adult cadavers. The shapes of the lumbrical muscles were observed in 70 specimens and the distances from the distal border of the flexor retinaculum to the origins of the lumbricals were measured using digital calipers in 52 specimens. The lumbrical muscles were classified into 3 types based on their shapes, and also into 10 types based on their insertion sites. The average distances from the distal border of the flexor retinaculum to the origins of the first, second, third, and fourth lumbricals were +1.8 mm, - 1.4 mm, +5.1 mm, and +11.2 mm, respectively. The results of this study could be useful information for better understanding the function of the lumbrical muscles and for various types of diagnoses and surgery involving the hands.