Injury of the Deep Branch of the Ulnar Nerve: A Sonographic Diagnosis.

Teaching Point: The ulnar-palmar wrist region has a unique anatomy with some specific pathologies, easily assessed with high-frequency ultrasound.

Axonal mapping of motor and sensory components within the ulnar nerve and its branches.

OBJECTIVE: Intrinsic function is indispensable for dexterous hand movements. Distal ulnar nerve defects can result in intrinsic muscle dysfunction and sensory deficits. Although the ulnar nerve's fascicular anatomy has been extensively studied, quantitative and topographic data on motor axons traveling within this nerve remain elusive. METHODS: The ulnar nerves of 14 heart-beating organ donors were evaluated. The motor branches to the flexor carpi ulnaris (FCU) and flexor digitorum profundus (FDP) muscles and the dorsal branch (DoBUN) as well as 3 segments of the ulnar nerve were harvested in 2-cm increments. Samples were subjected to double immunofluorescence staining using antibodies against choline acetyltransferase and neurofilament. RESULTS: Samples revealed more than 25,000 axons in the ulnar nerve at the forearm level, with a motor axon proportion of only 5%. The superficial and DoBUN showed high axon numbers of more than 21,000 and 9300, respectively. The axonal mapping of more than 1300 motor axons revealed an increasing motor/sensory ratio from the proximal ulnar nerve (1:20) to the deep branch of the ulnar nerve (1:7). The motor branches (FDP and FCU) showed that sensory axons outnumber motor axons by a ratio of 10:1. CONCLUSIONS: Knowledge of the detailed axonal architecture of the motor and sensory components of the human ulnar nerve is of the utmost importance for surgeons considering fascicular grafting or nerve transfer surgery. The low number of efferent axons in motor branches of the ulnar nerve and their distinct topographical distribution along the distal course of the nerve is indispensable information for modern nerve surgery.

Innervation and vascular supply of the first dorsal interosseous muscle and palmar interosseous muscle of the index: An anatomic descriptive study.

INTRODUCTION: The first dorsal interosseous muscle (FDI) and palmar interosseous muscle of the index (P2I) are essential for the strength and mobility of the index finger. This study aims to describe the course of the deep branch of the ulnar nerve (DBUN) and the blood supply to these muscles. MATERIAL AND METHODS: An anatomical cadaver study was carried out with 14 upper limbs from fresh, non-embalmed cadavers. All limbs were filled with an equal amount, based on weight, of colored silicone and diluent that was combined and catalyzed with 5% curing agent. The location of the DBUN's termination was specified relative the carpometacarpal joint. Every artery supplying either muscle was identified and documented. RESULTS: The DBUN had a slightly convex path, distal to the hook of the hamate and penetrated the FDI muscle at an average 41% of the second metacarpal length. An average of 1.3 branches to the P2I and 2.6 branches to the FDI were found. Four artery pedicles coming from the deep palmar arch supply the FDI with an average of one consistent and exclusive pedicle to the FDI and three pedicles heading to the P2I. According to the classification of Mathes and Nahai, the FDI has a type 2 blood supply and the P2I has a type 3 blood supply. CONCLUSION: In-depth knowledge of the vascular network supplying the FDI and P2I muscles and the course of the DBUN is essential when the DBUN is damaged or when dissecting these muscles for index pollicization.

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.

Sonoanatomy of the deep branch of the ulnar nerve.

INTRODUCTION: This study evaluated the sonoanatomy of the deep motor branch of the ulnar nerve (DBUN) using high-resolution ultrasonography (HRUS). METHODS: In 60 wrists of 30 healthy adults, the gross course, cross-sectional area (CSA), and diameter of the DBUN were observed by HRUS (frequency band 3-16 MHz). Its course was assessed by using the distance from anatomical landmarks and depth from the skin. RESULTS: The DBUN was found in all subjects with HRUS, and it branched off from the ulnar nerve before reaching the hamate bone. At the hook-of-hamate level, the mean DBUN CSA was 1.5 ± 0.2 mm2 , and the mean diameter was 1.5 ± 0.2 mm. The mean distance from the hamate hook to the DBUN was 5.4 ± 1.0 mm, and the mean depth from the skin was 8.6 ± 1.6 mm. DISCUSSION: Sonoanatomy of the DBUN obtained from HRUS may be useful in detecting or preventing DBUN lesions.

Anatomy of the deep branch of the ulnar nerve.

UNLABELLED: The aim of this study was to provide a clear description of the course, precise branching pattern and distribution of the deep branch of the ulnar nerve. A total of 36 hands from 18 preserved cadavers were dissected. The vertical distance from the pisoscaphoid line to the crossing points between the deep branch of the ulnar nerve and each metacarpal was about 4 cm. The deep branch of the ulnar nerve gave off two types of muscular branches: (1) trunks that innervate more than two intrinsic hand muscles; and (2) multiple separate branches innervating only a single muscle. The median numbers of trunks and separate branches were 5 and 6, respectively. LEVELS OF EVIDENCE: N/A.

Ulnar nerve deep branch compression by a ganglion: a review of nine cases.

BACKGROUND AND AIM: Ulnar nerve compression is common at the elbow, but less common at the wrist. The purposes of this study were to report a series of nine patients with pure ulnar nerve deep branch compression by a ganglion and to evaluate the outcome following a surgical treatment. METHODS: A retrospective study was conducted with nine patients from 2000 to 2011. The patients included four male and five female patients. The mean duration of symptoms before surgery was 16 months (range, 5-32 months). Different degrees of muscular atrophy and weakness of the interossei and adductor pollicis muscles were present without sensory loss in the hand. Ganglion excision and decompression of Guyon's canal were performed in all patients. We evaluated postoperative results of this uncommon nerve lesion based on the modified Bishop's scoring system. RESULTS: The ganglion compressing the deep branch originated from the pisohamate joint in eight cases and from the midpalmar space in one case. At the mean follow-up of 23 months (range, 17-31 months), strength improvement of the grip and tip pinch was achieved in all patients. In comparison, grip strength improved from a mean of 63% of the unaffected side preoperatively to 88% of the unaffected side postoperatively. Tip pinch strength improved from a mean of 61% to 87%. According to the modified Bishop's scoring system, six patients (67%) obtained excellent results, two (22%) had good results, and only one (11%) had a fair result. CONCLUSIONS: A ganglion causing ulnar nerve deep branch compression is rare. Early surgical treatment can result in satisfactory functional recovery.

ANATOMICAL STUDY ON THE FASCIAL ARCH OF THE OPPONENS DIGITI MINIMI / 解剖学报

Objective To explore the entrapment to the deep branch of the ulnar nerve at the wrist,to assist the surgeon in diagnosis and treatment of Guyon canal syndrome.Methods Twenty fresh upper limbs were dissected on loupe(?5),to record the relationship between the ulnar nerve and the hypothenar muscles,the course of the ulnar nerve at the wrist.Results The deep branchs of the ulnar nerve go through an intermuscular space after runing out of the Guyon canal.The intermuscular space consisits of the superficial and deep head of the opponens digiti minimi and the hook of the hamate,which has one entrance and one exit.We named the intermuscular space as the hiatus of opponens digiti minimi,and named the proximal edge of the superficial head of the opponens digiti minimi as the fascial arch of the opponens digiti minimi.Conclusion We found that the fascial arch of the opponens digiti minimi can compress the deep branch of the ulnar nerve causing motor deficit of the intrinsic muscles of hands.