Morphological Variations of Lumbrical Muscles of Hand in Sri Lankan Cadavers

Introduction: Lumbricals are the small, worm-like, intrinsic muscles responsible for performing the precision pinch movements of the hand. These are quite unique in their position owing to movable proximal and distal tendon attachments. Purpose of the study: The aim of the study was to identify anomalies of lumbrical muscle present in the Sri Lankan people. Materials and Methods: A sample of 39 formalin preserved cadaveric human hands were subjected to the gross morphological study. Results: It was encountered that 59% of the lumbricals were normal in proximal and distal attachments whereas the rest of the lumbicals (41%) indicated the morphological variations. Among the hands, unipennate third lumbrical was seen in 7.7% (Left-15.7%: Right 0%) and unipennate fourth lumbrical was seen in 5.1% (Left10.5%: Right 0%). The bipennate second lumbrical was seen in 5.1% (Left 5.3%: Right 5.1%). The 10.3% of split insertion was encountered in third lumbricals (Left 10.5%: Right 10%) as well as in fourth lumbricals (Left 5.3%: Right 15%). The third lumbrical insertion on the medial side of the middle finger was seen in 2.5% (Left 5.3%: Right 0%). Conclusion: The left hand is having more lumbrical variations than the right hand of the subjected human cadavers. The most common variation site is the insertion site. The variants are numerous in third and fourth lumbricals. The most common type of variation is the split insertion.

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.

Anatomical Variations of the Lumbrical Muscles Causing Carpal Tunnel Syndrome

@#Many anatomical variations exist in and around the carpal tunnel. However, symptomatic anomalies causing carpal tunnel syndrome is rare. Additionally, carpal tunnel surgery is considered a simple operation commonly done by junior surgeons who are usually unaware of variations resulting in unfavorable surgical outcomes. We highlight a case of lumbrical muscle variation causing carpal tunnel syndrome. A 73-year-old male presented with numbness and pain of both hands associated with abnormal fullness over both wrists and distal forearms. Initially the right hand was numb and subsequently a year later, the left hand became numb. Physical examination was positive for Durkan, Phalen and Tinel signs at the carpal tunnel. Magnetic Resonance Imaging (MRI) showed abnormal muscle tissues in the carpal tunnel. During the carpal tunnel release and exploratory surgery, we noted an abnormally proximal origin of the lumbrical muscles in the forearm rather than the typical palmar origin. He also had lumbrical muscle hypertrophy in the left side. These two factors resulted in overcrowding within the carpal tunnel. Postoperatively the patient recovered well with pain relief and gradual improvement of his numbness. Variations in the anatomy of the lumbrical muscles is not uncommon and may result in carpal tunnel syndrome. Hence, carpal tunnel release surgeries may not be as straight forward as expected and surgeons should be aware of this possibility.

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.

Re-evaluation for quality standard of Compound Lumbrical Capsule based on enzyme activity / 中草药

Objective: The quality standard of Compound Lumbrical Capsule (CLC) was re-evaluated using blood and anti-coagulation intensity as indexes. Methods: Fibrin plate method was used to determine the strength of promoting blood circulation and anti-coagulation for CLC by selecting urokinase and thrombin as reference substances. Results: The results of urokinase concentration and transparent circle area showed a good linear relationship in 200-1 000 U/mL, r = 0.999; The results of thrombin concentration and precipitation circle area showed a good linear relationship in 8-40 U/mL, r = 0.997. The blood anti-coagulant activity of compound earthworm capsule of temporary regulations were not less than 12 840 U/g and 113 822 U/g. Conclusion: The method is rapid, simple, and accurate for determining the activity of promoting blood circulation and anticoagulation for compound lumbrical capsule, thus it can be used for the quality control of CLC.

Diagnostic Value of the Second Lumbrical-Interosseous Distal Motor Latency Comparison Test in Severe Carpal Tunnel Syndrome

OBJECTIVE: To examine the usefulness of the second lumbrical-interosseous (2L-INT) distal motor latency (DML) comparison test in localizing median neuropathy to the wrist in patients with absent median sensory and motor response in routine nerve conduction studies. METHODS: Electrodiagnostic results from 1,705 hands of patients with carpal tunnel syndrome (CTS) symptoms were reviewed retrospectively. All subjects were evaluated using routine nerve conduction studies: median sensory conduction recorded from digits 1 to 4, motor conduction from the abductor pollicis brevis muscle, and the 2L-INT DML comparison test. RESULTS: Four hundred and one hands from a total of 1,705 were classified as having severe CTS. Among the severe CTS group, 56 hands (14.0%) showed absent median sensory and motor response in a routine nerve conduction study, and, of those hands, 42 (75.0%) showed an abnormal 2L-INT response. CONCLUSION: The 2L-INT DML comparison test proved to be a valuable electrodiagnostic technique in localizing median mononeuropathy at the wrist, even in the most severe CTS patients.

Unilateral Incomplete Superficial Palwar Arch: A Case Report.

The functional importance of hand is revealed by its rich vascularity contributed by superficial and deep palmar arches (SPA and DPA).Superficial palmar arch is located superficial to flexor tendons, and deep palmar arch deep to lumbrical muscles. Variations are found more often in SPA than DPA, later being more or less constant. During routine undergraduate dissection, we observed, unilateral incomplete SPA being formed by superficial palmar branches of ulnar and radial artery in the right hand of a male cadaver. These two arteries remained independent without anastomosis forming incomplete arch (SPA).The superficial branch of ulnar artery entered hand superficial to flexor retinaculum and supplied middle, ring and little finger by three branches. The superficial branch of radial artery via its two branches supplied index finger and thumb. Classical SPA formation was seen on left side. The presence of an incomplete SPA as in this case is a potential danger in RA harvesting for CABG.Variations in SPA play a pivotal role in microvascular surgical procedures of hand, RAinterventions and arterial graft applications.

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.

Clinical relevance of morphological variations in origin and insertion of lumbricals of hand in South Gujarat population.

Background & objectives: Lumbrical muscles, though small in size, have a significantly greater role to play in the intricate movements of the fingers.The great functional significance and morphological variations of lumbrical muscles as described in the literature, prompted us to undertake a detailed study of these muscles to know more about it and its significant value in the design of surgical procedures. Methods: We dissected lumbricals of hands of 40 human adult cadavers which were available from the Department of Anatomy. In the present study, variation in origin (include architecture), insertion (include split insertions, misplaced insertions or absence of muscles), the lengths of muscle belly and tendon of all lumbricals were studied and noted. Results: We found variations were more common on the right side. The second lumbrical was bipennate in 12.5% cases. The third lumbrical showed split insertion in 15% cases. The fourth lumbrical showed misplaced insertion in 10% cases. The proximal attachment of lumbricals can extend into the carpal tunnel (specially first and second) in 15% cases. Conclusion: The study provides valuable information to surgeons thus avoiding complications from local anesthetic, surgical and other invasive procedures.