Variations of Median Nerve in Carpal Tunnel and its Distribution in Hand

Aim of the study was to study the variations in the branching pattern of median nerve in the carpal tunnel and hand, which would form useful data for hand surgeons doing open/endoscopic carpal tunnel release. Median nerve and its branches were explored by dissection in fifty hands of twenty-five formalin fixed adult human cadavers over a period of three years. We found variations in 35 out of 50 hands. Based upon Lanz classification, frequency of variations in present series was variation in the course of thenar branch (58%), accessory branches at the distal portion of the carpal tunnel (34%), high divisions of the median nerve (8%) and accessory branches proximal to the carpal tunnel (nil). Rare variations including transligamentous median nerve and multiple thenar branches were also observed. Medial take off of thenar branch as observed in this series has special clinical significance in carpal tunnel release. Knowledge of the variable anatomy of median nerve would help to avoid incomplete decompression at operations for nerve entrapment and injury to thenar branch.     

大鱼际皮瓣的解剖学基础及临床应用

目的:介绍大鱼际皮瓣的血管解剖学基础,以及临床应用经验。方法:解剖20侧经动脉灌注红色乳胶的成人手标本,观察大鱼际皮肤的血供来源、走行、分支及吻合情况。临床切取3种不同设计的大鱼际皮瓣,修复拇指软组织缺损共计14例。结果:大鱼际皮肤的血供来源主要有4个方面:(1)由掌浅支或其发出的拇指桡侧指动脉发出的皮支;(2)来源于拇主要动脉的拇指桡侧指动脉发出的皮穿支;(3)拇指桡侧指背动脉向大鱼际桡背侧发出的皮支;(4)大鱼际深部血管发出的肌皮穿支。上述这些血管在大鱼际交织成网状,营养整个大鱼际皮肤。临床应用以掌浅支(弓)发出的拇指桡侧指动脉为血管蒂的大鱼际皮瓣4例,拇指桡侧指动脉穿支蒂皮瓣7例,大鱼际桡背侧筋膜血管蒂皮瓣4例,皮瓣全部成活,其中1例指动脉穿支皮瓣远端约4mm坏死,结痂后自行脱落。术后随访半年～2年,平均10个月,皮瓣血运、质地、弹性良好,外形美观。结论:三种皮瓣疗效可靠,是修复拇指软组织缺损的理想方法。临床上可依具体情况选择不同的方法来修复。     

The Muscular Branching Patterns of the Ulnar Nerve to the Flexor Carpi Ulnaris and Flexor Digitorum Profundus Muscles

The branching pattern of the ulnar nerve in the forearm is of great importance in anterior transposition of the ulnar nerve for decompression after neuropathy of cubital tunnel syndrom and malformations resulting from distal end fractures of the humerus. In this study, 37 formalin-fixed forearms were used to demonstrate the muscular branching patterns from the main ulnar nerve to the flexor carpi ulnaris muscle (FCU) and ulnar part of the flexor digitorum profundus muscle (FDP). Eight branching patterns were found and classified into four groups according to the number of the muscular branches leaving the main ulnar nerve. Two (Group I) and three (Group II) branches left the main ulnar nerve in 18 and 17 forearms respectively. The remaining two specimens had four (Group III) and five (Group IV) branches each. Usually one or two branches were associated with the innervation of the FCU. However, in 2 cases, three and in one, four branches to FCU were observed. The FDP received a single branch in all cases, except in four, all of which had two branches. In six forearms, a common trunk was observed arising from the ulnar nerve to supply the FCU and FDP. The distribution of the muscular branches to the revealed muscles was outlined in figures and the distance of the origin of these branches from the interepicondylar line was measured in millimeters. The first muscular branch leaving the main ulnar nerve was the FCU-branch in all specimens. The terminal muscular branch of the ulnar nerve to the forearm muscles arose at the proximal 1/3 of the forearm in all specimens. In 7 forearms, Martin-Gruber anastomosis in form of median to ulnar was observed.     

An Anatomical Study to the Branching Pattern of the Posterior Interosseous Nerve on the Dorsal Side of the Hand

Partial denervation of the wrist can benefit patients with chronic wrist pain. A complication of partial denervation is loss of proprioception and hypesthesia on the dorsal side of the hand. Our aim is to evaluate whether the sensory branches of the posterior interosseous nerve could contribute to the loss of proprioception and sensation. The branching pattern of the posterior interosseous nerve was studied in 20 cadaveric hands. The terminal branches of the posterior interosseous nerve reached the metacarpophalangeal joints in three specimens (15%), the midshaft of the metacarpals in three specimens (15%), carpometacarpal joints in 11 specimens (55%), and the scapholunate joint in three specimens (15%). The finding that terminal branches of the posterior interosseous nerve can reach the metacarpals and the metacarpophalangeal joints indicates that the posterior nerve may contribute to the proprioception and sensation of the dorsal side of the hand. Clin. Anat., 33:678–682, 2020. © 2019 Wiley Periodicals, Inc.     

Nerve supply of the brachioradialis muscle: surgically relevant variations of the extramuscular branches of the radial nerve

The brachioradialis muscle is utilized in tendon-transfer operations, carried out for a variety of purposes. The extramuscular branches of the radial nerve to the brachioradialis were dissected and studied in 43 embalmed cadaveric specimens. The number of primary and secondary branches and the spatial locations of their origins and muscle-entry points was determined for each specimen. All distances were measured relative to the lateral epicondyle. A wide anatomic variation was observed in both the nerve branching pattern as well as the number and locations of muscle-entry points. A single primary nerve branch was found in 20 specimens, or 46.5% of the cases. On an average, single primary nerve branches arose from the radial nerve 30 mm proximal to the lateral epicondyle. In 16 of these cases, the primary branch splits into two to four secondary branches, and in four cases there was only one branch entering the muscle. Seventeen specimens had two primary branches whose origin points were separated by 5 to 40 mm with an average of 15 mm. In seven of these seventeen cases one or both of the primary branches split into secondary branches. Six specimens had three primary branches; the origin points of the most proximal and the most distal branch were separated by up to 30 mm with an average of 13 mm. Excluding the four cases with extensive fanning into multiple thin branches, the number of muscle-entry points ranged from 1 to 4 (mean 2.7). The locations of the muscle-entry points for all specimens were widespread ranging from 50 mm proximal and 40 mm distal to the lateral epicondyle with an average at 6 mm proximal to the lateral epicondyle. The greatest distance between muscle-entry points was 50 mm in a single specimen. In surgical procedures involving dissection of the brachioradialis muscle more proximal than 50 mm distal to the elbow, the extramuscular branch(es) of the radial nerve branches to the brachioradialis may be at risk.     

桡动脉掌浅支为蒂的大鱼际皮瓣的显微外科解剖

目的介绍以桡动脉掌浅支为蒂的大鱼际皮瓣的显微解剖学基础,为该皮瓣游离移植修复指腹缺损提供解剖学依据。方法解剖20只成人新鲜尸体手标本,于远侧腕横纹上方约10cm处解剖出桡动脉灌注红色乳胶,桡动脉的伴行静脉及头静脉灌注蓝色乳胶,在手术显微镜下进行解剖,观察大鱼际皮肤动脉、静脉、神经来源、分支及吻合情况。其中5只标本于桡动脉掌浅支起始处灌注墨汁,测量皮肤染色范围。结果桡动脉掌浅支起始处外径为(1.40±0.22)mm,长度为(2.0±0.5)cm,皮瓣可切取面积为2cm×3cm～4cm×5cm。静脉回流有两种途径,神经支配以正中神经掌皮支为主。结论桡动脉掌浅支起始与走行恒定,口径适当,可设计以桡动脉掌浅支及其伴行静脉或浅静脉为蒂、带正中神经掌皮支的大鱼际皮瓣游离移植修复指腹缺损。     

Reexamination of the communicating branch between the sural and tibial nerves

Reexamination of communicating branches between the sural and tibial nerves ventral to the calcanean tendon was carried out on 52 legs of 26 Japanese cadavers which were used for ordinary dissection practices at the Niigata University School of Medicine. Communicating branches were found in 7 out of 52 dissections (13.5% of cases). In three of the 7 specimens, the communicating branch, the sural nerve and the tibial nerve with the deep crural fascia were removed from the legs and demonstrated by a modified Sihler's staining technique. Three types of communicating branches, Y, U and N, were distinguished on the basis of their shapes. In type Y, a medial branch from the sural nerve and a branch from the tibial nerve joined in Y-shape and become one terminal branch. In type U, the both branches formed a loop between the sural and tibial nerves. The type N communicating branch ran obliquely and medially to reach the tibial nerve distally. Only the Y type appeared in 5 specimens. Both the Y and U type and the Y and N types occurred in one specimen each. We assume that the communicating branch of the N type contains motor fibers which are derived from the sural nerve and innervate some plantar muscles, because this type is correspond to the communication type of some animals in which motor fibers have been demonstrated. Therefore, if the sural nerve biopsy is performed to examine a pure sensory nerve, removal of the more distal part of the sural nerve than a diverging point of a communicating branch is recommended. This study also indicated that the modified Sihler's staining technique is useful to examine distributions of cadaveric peripheral nerves after medical students' dissection course.     

Ileocecal adenocarcinoma with overexpression of P53 protein metastasized to the thenar muscle: report of a rare case and review of literature

Metastatic malignancies of the hand are rare and metastases to the skeletal muscle from the gastrointestinal system are even much rare. Here we present a case of metastatic ileocecal adenocarcinoma to the thenar muscle, which is the first report of thenar muscle metastasis from ileocecal adenocarcinoma with P53 mutation. To date, only two other cases of thenar muscle metastasis have been documented, one is from squamous cell carcinoma of the lung and the other is from rectal carcinoma. The present 67-year-old Chinese man of poorly differentiated adenocarcinoma of the ileocecal region developed metastatic carcinoma in the right thenar eminence, which presented with swelling and pain. Magnetic resonance imaging of the right hand revealed a well-defined enhanced mass in the right thenar muscle. It was proved to be metastatic adenocarcinoma using core needle biopsy, which was supported to be gastrointestinal origination by positive immunoreaction with CDX2. Positive immunoreaction with P53 protein indicated the poor prognosis of the patient. Further systemic evaluation including computerized tomography scans revealed extensive metastases to liver, right kidney, right abdominal wall, left axillary and right subclavicular lymph nodes, and skin of the right thigh. Treatment was given with palliative systemic chemotherapy. After 8 cycles of chemotherapy, the swelling and pain of the right thenar were ameliorated, and the patient regained full use of his right hand and his quality of life was improved. The patient died of liver metastasis 9 months after the diagnosis of the right thenar metastasis. In conclusion, here we display a case of thenar skeletal muscle metastasis from P53 mutated ileocecal adenocarcinoma, who survived 9 months after diagnosis of the rare metastasis. If an oncological patient presents an intramuscular mass, muscle metastasis must be included in the differential diagnosis. Metastatic hand tumors generally indicate systemic spread, so the treatment is usually palliative and the prognosis is poor. The primary objective of treatment is improvement of the patient’s quality of life.     

Coexistence of multiple anomalies in the carpal tunnel

We determined the frequency of anomalous structures within the carpal tunnels of 89 cadaveric forearm-hand specimens. We also examined these same specimens for variations in the branching pattern of the median nerve, and analyzed the range in length and width of the lumbricals. Many of the hands contained extra tendinous slips from the long flexors within the tunnel, subligamentous thenar branches of the median nerve, or lumbricals with bipennate origins. Only one hand had an anomalous muscle belly within the tunnel, two had persistent median arteries, two had high division of the median nerve in the distal forearm, and eight had lumbricals with lengths or widths that were greater or less than 2 standard deviations (SD) from the mean. Twenty-nine percent of all hands examined had two to five anomalies/variations per tunnel, whereas another 27% had one anomaly or variation per tunnel. More right hands (17%) than left (11%) contained two to five anomalous/variant structures per carpal tunnel. More right hands (19%) than left (8%) contained only one variant/anomalous structure per carpal tunnel. Anticipation of the frequency and multiplicity of anomalous structures and variations within this region is of importance to clinicians, particularly surgeons.     

Variations in the anatomy of the auriculotemporal nerve

The common representation of the auriculotemporal nerve is either that of a single posterior branch of the mandibular nerve or of two roots that envelope the middle meningeal artery. Our observation in the anatomy of the auriculotemporal nerve on 32 dissections (16 cadaveric heads) of the infratemporal fossa included: one specimen with four roots (3.1%), three specimens with three roots (9.4%), 12 specimens with two roots (37.5%), and 16 specimens with one root (50%). Furthermore, a connecting nerve branch was observed between auriculotemporal and inferior alveolar nerves in four specimens, and in another auriculotemporal nerve case, between the upper and lower roots. In the cadaver of a 70-year-old male, a four-rooted auriculotemporal nerve variation was found. These four branches lay to the posterior, combined at the posterosuperior of the maxillary and superficial temporal arteries and formed a ganglion-like knot. From this knot, four branches stemmed and ran to the temporomandibular joint, external acoustic meatus, zygoma, and parotid gland. The knot was larger and thicker than expected; thus, it was removed and stained with haematoxylin-eosin (H&E) and S100 for histological studies. This structure was not a true ganglion but a structure formed by fusion of nerve fibers.     

An unusual termination of the ulnar nerve in the palm.

During the dissection of the left forearm and hand of a 57-year old male cadaver fixed in 10% formalin, it has been noted that the medial proper palmar digital nerve to the little finger arose from the dorsal branch of the ulnar nerve, instead of the superficial branch of the same nerve. The dorsal branch, given off by the ulnar nerve in the forearm, coursed distally and dorsally deep to the flexor carpi ulnaris muscle. Some 2 cm proximal to the pisiform, it pierced the deep fascia on the posteromedial side of the muscle to become superficial. At this point, one of the three branches given off travelled distally on the palmar-ulnar side of the hand to the skin of the little finger. There were connections between this branch and the branches of the superficial branch of the ulnar nerve which innervated the skin of the hypothenar eminence. Further, another branch of the superficial branch of the ulnar nerve passed under the fibrous arch of the flexor digiti minimi brevis muscle origin and the opponens digiti minimi muscle to re-unite with its parent nerve.     

Distal variations of the neurovascular pedicle of the serratus anterior muscle as a flap

The serratus anterior muscle has recently been suggested as a versatile and reliable flap for reconstruction of complex craniofacial and neck lesions, extremity and sacroiliac region injuries, as well as intrathoracic and extrathoracic reconstruction procedures. The muscle has been used as a microvascular flap or a pedicled transfer and has been transferred in combination with other muscles, bones, and skin. We performed 15 dissections of adult axilla regions that were examined under ×3.5 loupe magnification to collect anatomic data regarding the neurovascular pedicle of the serratus anterior muscle. The serratus muscle and fascia were found to have a dual blood supply, with the upper part supplied by the lateral thoracic artery and the lower part by terminal branches of the thoracodorsal artery. The lateral thoracic artery was noted to supply the upper four slips but it extended into the lower serratus anterior muscle in two cases. Seven branching patterns were found in the lower serratus anterior muscle. In type I, the only branch of serrati proceeded over the long thoracic nerve. Type II had the only branch of serrati proceeding under the long thoracic nerve. In type III, double branches of serrati proceeded over the long thoracic nerve; while in type IV branches of serrati ran with a double branch under the long thoracic nerve. In type V, three serrati branches proceeded over the long thoracic nerve. Type VI serrati branches were branches of thoracodorsalis, which was hypoplastic, and the supply was maintained from the lateral thoracic artery. In type VII, one serrati branch ran over the long thoracic nerve. There was no connection between the branches of serrati and the branches of the lateral thoracic artery. The length of the long thoracic nerve, the number of motor axons and the vascular network in anatomic proximity to this nerve make it an expendable but powerful source of reconstructions of head, neck, chest wall and extremity defects. Results of this study provide an anatomic framework to improve current reconstructive or aesthetic procedures on the serratus anterior neurovascular structures.     

Size and separability of the calcaneal and the medial and lateral plantar nerves in the distal tibial nerve

The tibial nerve (TN) has three main terminal branches: the medial and lateral plantar nerves and the calcaneal branch (CB), which innervates the foot sole. The design and implantation of nerve cuff electrodes with separate channels for each of these three terminal branches would provide significant sensory information, which can be used in functional electrical stimulation systems to assist standing or to correct foot drop. Detailed quantitative anatomical data about fascicular size and separability of the terminal branches of TN are needed for the design and implantation of such cuff electrodes. Therefore, the branching pattern, the fascicular separability and the fascicular size of the TN posterior to the medial malleolar-calcaneal axis were examined in this study, using ten human TN specimens. The TN branching patterns were highly dispersed. For the CBs, multiple branches were identified in five (50%) of the specimens. For the TN, the bifurcation point was located within the tarsal tunnel in eight (80%) of the cases. The distance proximal to the medial malleolar-calcaneal axis for which the TN could be split ranged form 0 to 41 mm. Quantitative and qualitative data were obtained for the fascicular size and separability of the TN. Only the CB of the TN proved separable for a sufficient length for nerve cuff electrode implantation. The results suggest the use of a two-channel cuff with one common channel for the lateral and medial plantar nerves, having multiple electrodes for selective recording, and one channel for the CB.     

人膈肌内神经分支分布

目的：探讨人膈的神经支配和肌内神经分支分布特点。方法：改良Sihler’s肌内神经分支染色法。结果：(1)一侧膈神经入肌后一般分为3—4支(3支型4例,4支型2例),1支(前支)向前内侧走行,支配胸部,1～2支(前外侧支)向外侧走行,支配肋部,最后1支(后支)最粗大,向后下走行,分为后外侧支和后脚支,分别支配膈中心腱外侧叶后外侧的肋部和腰部,各级神经的分支在肌束中部密集排列成神经丛。(2)6例标本均未发现左侧或右侧膈神经越过中线至对侧。(3)2例带肋间肌的标本肉眼未见有肋间神经分支进入膈。结论：(1)左、右膈神经分布于膈,未见左右侧膈神经重叠支配和优势支配。(2)膈神经的终末分支在肌束中部密集排列形成似“肾形”的神经丛带。     

三角肌神经入肌点定位及肌内神经分布的研究

目的　揭示三角肌神经入肌点和肌内神经分支分布 ,为其临床应用提供较为详尽的形态学资料。方法　①用经甲醛固定 2年以上的成人尸体 (2 0～ 5 0岁 ) 12具 (男 9,女 3)共 2 4侧。以肩峰后角为骨性标志 ,测量三角肌各亚部神经支入肌点的位置。②用经甲醛固定 1年以内的童尸 3具 (3～ 10岁 )及成人尸体 2具 (2 0、4 0岁 )完整取下三角肌 ,采用Sihler′s肌内神经染色法观察肌内神经分支分布。结果　①三角肌各亚部神经入肌点的体表投影 :三角肌前亚部、中亚部、后亚部的神经入肌点分别在距肩峰后角下方 (5 7± 0 7)cm、(5 9± 0 8)cm、(4 8± 0 5 )cm处的水平线上 ,距三角肌前缘外后方 (3 6± 0 4 )cm处及距三角肌后缘外前方 (3 5± 0 6 )cm、(2 3± 0 3)cm处 ,上述三点均在肌的中 1/3部。②肌内神经分布 :三角肌前、后亚部的肌内神经支在肌内为直接横过肌纤维中部 ,沿途再发出分支与肌纤维并行走行 ;而中亚部肌内神经支在各个羽内 ,与肌纤维相交 ,行向短肌纤维的起止端。结论　①三角肌的神经入肌部位及入肌形式与该肌的形态和功能有关联 ;②三角肌的肌内神经分支分布可能与该肌的肌纤维长度及肌纤维型有关 ;③三角肌中亚部的肌内神经吻合网较宽而致密 ,推测有着更精细的神经调节。     

An anatomical study of the palmar cutaneous branch of the median nerve

We present an anatomical study of the palmar cutaneous branch of the median nerve emphasizing its frequency, origin, perforation point at the transverse carpal ligament, point of emergence in the palm, width, length, divisions and innervation territory. For this purpose, fifty cadaver hands were dissected under a stereomicroscope and/or magnifying glass. The origin of the palmar cutaneous branch (PCB) was on the average 4.56 cm proximal to conventionally named "zero point" on the most distal transverse volar wrist crease. Perforation of the aponeurosis occurred on average 0.79 cm from the mentioned point and its emergence in the palm at 0.76 cm. The nerve had an average length of 5.24 cm. PCB's divisions in the palm resulted in a medial branch in 42%, a lateral branch in 92% and an intermediate branch in 100% of the hands studied. In six specimens PCB presented a deep branch which was directed toward the thenar eminence or made communication with the superficial branch of the palmar digital nerve or still penetrated between the first or second metacarpal. In 4% of the cases there was a communicating branch between the superficial branch of the radial nerve and the PCB. These anatomical results should be considered in the evaluation of the best surgical techniques for decompression of the median nerve in the carpal tunnel.     

Number and size of motor units in thenar muscles

The number and size of motor units (MUs) in the thenar muscles of 10 fresh adult cadavers (33-74 years old) were estimated by histological methods. The average number of MUs was 161 +/- 26 and the MU size was 93 +/- 11.5. Adductor pollicis showed a significantly greater MU size. The number of MUs in our histological study was in agreement with the number reported in previous studies using multiple point stimulation, the method currently used in the clinical investigation of neuromuscular disorders.     

Ulnar nerve cutaneous distribution in the palm: Application to surgery of the hand

The ulnar nerve (UN) was classically described as supplying most of the intrinsic muscles of the hand, and the cutaneous innervation of the ulnar one and half digits, by dividing into superficial sensory and deep motor branches in Guyon's canal. Variations of this pattern have been reported in the literature. This study investigated the cutaneous distribution of the UN in the palm following the dissection of 144 cadaveric hands. The UN was examined and the distances from branching points of the superficial branch to the proximal edge of the pisiform were measured. The UN bifurcated (80.4%) into one deep trunk and one superficial trunk, which further divided distally into the proper digital (PDN) and common digital (CDN) nerves or trifurcated (19.6%) into one deep trunk, a PDN and a CDN in Guyon's canal. It received fibers from the median nerve in four cases and from the dorsal branch of the UN in six cases. A classification scheme based on the nerves contributing to the sensory innervation of the ulnar side of the palm was suggested. Understanding the cutaneous distribution of the UN in the palm and appreciating possible communicating branches can help clinicians to assess hand pathologies better and avoid injuries during surgical interventions. Clin. Anat. 28:1022–1028, 2015. © 2015 Wiley Periodicals, Inc.     

前臂桡侧头静脉-皮神经的营养血管的解剖学

目的：为前臂桡侧头静脉-皮神经营养血管远端蒂复合瓣设计提供解剖学基础。方法：动脉灌注红色乳胶成人上肢标本,解剖观测头静脉-前臂外侧皮神经下1/3段营养血管的来源、分支及其与桡骨膜血管的关系。结果：头静脉-前臂外侧皮神经下1/3段的营养血管来自：桡动脉皮支,掌浅支皮支,桡骨茎突返支皮支和桡动脉肌间隙骨皮支。上述诸支血管发皮支、筋膜支、骨膜支、神经-浅静脉营养血管,形成皮神经-头静脉血管链以及深、浅筋膜和骨膜血管网。结论：前臂桡侧缘头静脉-皮神经营养血管与肌、骨、皮营养血管同源,以桡骨茎突返支为蒂的远端蒂复合瓣,旋转轴点在腕关节平面,可用于手部远处组织缺损修复。     

正中神经返支的观测及表面解剖定位

对100侧正中神经返支的形态进行观察、计测,82±3.84%源于正中神经主干分叉处。依其形态分为多支形(85±3.57%),双支型(10±3.60%),单支型(1±0.99%)、重复型(4±1.96%)。鱼际肌群(拇收肌除外)各肌神经分布呈多源性,拇对掌肌98%由正中神经返支支配。设计自舟骨结节中点与手掌第2指胰中点连线为纵轴线,通过第1掌骨小头顶端作纵轴线垂线为横轴线,以此座标测计正中神经返支的表面Ⅰ解剖定位。采用距纵轴线尺侧10～15mm设计适于临床应用的纵行切口,可避免损伤正中神经返支。