The surgical anatomy of ulnar and median nerve communications in the palmar surface of the hand

OBJECT: Sensation in the palmar surface of the digits is supplied by the median and ulnar nerves, with the boundary classically being the midline of the ring finger. Overlap and variations of this division exist, and a communicating branch between the ulnar and median nerve could potentially explain further variations in digital sensory innervations. The aim of this study was to examine the origin and distribution of the communicating branch between the ulnar and median nerves and to apply such findings to the risk involved in surgical procedures in the hand. METHODS: The authors grossly and endoscopically examined 200 formalin-fixed adult human hands obtained in 100 cadavers, and a communicating branch was found to be present in 170 hands (85%). Of the specimens with communicating branches, the authors were able to identify four notable types representing different points of connections of the branches. The most common, Type I (143 hands, 84.1%), featured a communicating branch that originated proximally from the ulnar nerve and proceeded distally to join the median nerve. Type II (12 hands, 7.1%) designated a communicating branch that originated proximally from the median nerve and proceeded distally to join the ulnar nerve. Type III (six hands, 3.5%) designated a communicating branch that traversed perpendicularly between the median and ulnar nerves in such a way that it was not possible to determine which nerve served as the point of origin. Type IV (nine hands, 5.3%) designated a mixed type in which multiple communicating branches existed, arising from both ulnar and median nerves. CONCLUSIONS: According to the origin and distribution of these branching patterns, the investigators were able to define a risk area in which the communicating branch(es) may be subject to iatrogenic injury during common hand procedures.     

Internal anatomy of the communicating branch between the ulnar and median nerves in the hand and its relevance to volar digital sensibility.

We studied the microanatomy of the communicating branch between the ulnar and median nerves in 26 adult cadaver hands to explain diminished sensibility in the fourth and fifth fingers we had observed in 2 patients after complete transection of the median nerve. Two new variations of the communicating branch were observed. In the first variation the communicating branch originated proximally from the third common digital nerve to distally join the ring finger ulnar digital nerve and the small finger radial digital nerve. In the second variation the ramus communicans traversed perpendicularly between the third and fourth common digital nerves with a crossover of nerve fibers.     

How to avoid operative injury to Martin-Grüber communicating branch in the transmuscular medial approach of the elbow?

The incidence of Martin-Grüber medio-ulnar communicating branch (MUCB), from median nerve to ulnar nerve, is about 20%. To avoid operative injury to MUCB, the authors suggest some modifications to the medial approach of the elbow. They suggest medial aponeurotomy of the anterior compartment of the forearm, disinsertion of the medial epicondylar muscles with dissection between the flexor carpi ulnaris (FCU) and the other medial epicondylar muscles, not exceeding 3 cm distally. This allows a valuable exposure of the elbow joint through a medial approach, with FCU disinsertion and ulnar nerve transposition preserving the ulnar nerve vascularization, without injury to the MUCB.     

Unusual anatomic variation of palmar sensory branches of the ulnar nerve: a case report.

Variant sensory branches of the ulnar nerve were encountered during a routine dissection of the palmar aspects of a cadaver hand. The variant branches were distributed to the ulnar half of the index, ulnar half of the middle, and radial half of the ring fingers. The communicating branch between the superficial ulnar branch and the third common digital branch of the median nerve was absent. Distribution of the median nerve sensory branches was normal. The clinical significance of this variation is discussed.     

Anatomic variations in sensory innervation of the hand and digits

Anatomic dissections under microscopic magnification were performed on 30 fresh cadaveric hands to depict the course and interconnections of the sensory nerves to the digits. The dissections included the median nerve, the ulnar nerve, the superficial branch of the radial nerve, the dorsal branch of the ulnar nerve, and the dorsal branch of the proper digital nerve. The communicating branches between the median and ulnar nerves in the palm were found in 20 of the 30 (67%) specimens. The dorsal branch of the proper digital nerve was found to arise at or proximal to the A1 pulley zone in 62% of the long digits, more proximally than previously reported. The dorsal sensory nerves (the terminal branch of radial or ulnar sensory nerves) extending to the nail bed area were found in 46% of the digits, thus confirming that sensory supply to the dorsum of the distal phalanx and nail bed also arises from the dorsal sensory nerves. Four types of palmar-dorsal interconnections, located in the middle of the proximal phalanx, were found in the digits but not in the thumb. The presence of these branches indicates dual innervation of the dorsal and palmar side of the distal areas of the digits. These anatomic findings may help hand surgeons interpret discrepancies in sensory loss after either dorsal or palmar injuries.     

Multiple neurilemmomas of the median and ulnar nerves with a communicating branch in the same upper extremity.

A 30-year-old woman presented with multiple neurilemmomas in the same upper extremity. One originated from the main trunk of the ulnar nerve and two others from the sensory branch of the median nerve. A communicating branch in the palm from the ulnar nerve to the median nerve was confirmed. All the tumours were successfully enucleated and she made a satisfactory recovery.     

Multiple Neurilemmomas of the Median and Ulnar Nerves with a Communicating Branch in the Same Upper Extremity

A 30-year-old woman presented with multiple neurilemmomas in the same upper extremity. One originated from the main trunk of the ulnar nerve and two others from the sensory branch of the median nerve. A communicating branch in the palm from the ulnar nerve to the median nerve was confirmed. All the tumours were successfully enucleated and she made a satisfactory recovery.     

正中神经指浅屈肌肌支移位修复尺神经运动支的应用解剖

目的 通过对正中神经指浅屈肌肌支和尺神经运动支的解剖学研究,为正中神经指浅屈肌肌支移位修复尺神经运动支,恢复手内在肌功能的临床应用提供解剖学基础.方法 选用20例40侧近期经福尔马林浸泡固定的成人上肢标本,暴露正中神经、尺神经,测量正中神经指浅屈肌肌支各项解剖学数据;应用图像分析系统对组织切片做定量分析,测算该肌支有髓神经纤维数目.临床模拟操作正中神经指浅屈肌肌支移位修复尺神经运动支.结果 正中神经第4肌支发出部位距离桡骨茎突和尺骨茎突连线(48.4±2.4)mm,入肌部位距离桡骨茎突和尺骨茎突连线(21.4±1.8)mm,可分离长度(27.1±1.2)mm,横径(1.2±0.2)mm,前后径(0.7±0.1)mm;尺神经的运动支和感觉支之间自然分束无损伤分离.长度为(7.1±0.70)cm;组织切片及图片系统测得正中神经指浅屈肌第4肌支有髓神经纤维数目为(1378.9±107.9)条.结论 正中神经指浅屈肌第4肌支可修复尺神经运动支,以期恢复手内在肌的功能.     

Anatomic study of the ramus communicans between the ulnar and median nerves

The communicating branch between the fourth and third common digital nerves in the palm of the hand was studied. The incidence and branching pattern were studied in 53 dissected cadaveric hands. The "danger zone" in which the nerve is at risk during surgery was established using morphometric data. A communicating branch was found in 50 hands. It originated proximally from the fourth common digital nerve to join the third common digital nerve distally in 44 hands and traversed perpendicularly between the third and fourth common digital nerves in 4 hands. In the 2 remaining hands the branch left the third common digital nerve proximally to join the fourth digital common nerve distally. In 90% of the hands the ramus communicans crossed over in the middle third of the palm of the hand. As a cautious measure, hand surgeons should take into account that this structure could cross over anywhere in the middle three fifths of the palm.     

Anatomic study of variations of hypothenar muscles and arborization patterns of the ulnar nerve in the hand

PURPOSE: To show the variations in the hypothenar muscles and the arborization patterns of the ulnar nerve and to investigate the relationship between the hypothenar muscles and the ulnar nerve. METHODS: We performed an anatomic study of 35 hands from embalmed cadavers. After dissecting the ulnar side of the hand we recorded the number of hypothenar muscles and their variations, the site of the hiatus for the deep branch of the ulnar nerve, and the branching patterns of the ulnar nerve in each hand. We then investigated the relationship between the variations in the hypothenar muscles and the arborization patterns of the ulnar nerve. RESULTS: The abductor digiti minimi (ADM) had 1 belly in 6 hands, 2 bellies in 28 hands, and 3 bellies in 1 hand. The flexor digiti minimi brevis was absent in 8 hands, had 1 belly in 24 hands, and had 2 bellies in 3 hands. The opponens digiti minimi had 2 layers of origin and the deep branch of the ulnar nerve passed between these 2 layers in all hands. We classified the structural patterns of the hiatus into 3 types, the arborization patterns of the ulnar nerve into 5 types, and the branching patterns of the motor branch to the ADM into 4 types according to their morphologic characteristics. We found variations of the arborization pattern in which the deep branch originated from the ulnar trunk of the ulnar nerve distal to bifurcation in 3 hands, a communicating branch was present between the 2 sensory branches to the fingers in 3 hands, and the ulnar sensory branch pierced the ADM in 2 hands. CONCLUSIONS: We confirmed that the anatomic relationship between the ulnar nerve and the hypothenar muscle is complex and that the formation of the hiatus varies. This knowledge can assist the surgeon in the diagnosis and treatment of conditions associated with the ulnar aspect of the hand.     

Median nerve compression in the palm of the hand by an anomalously enlarged ulnar artery

Median nerve compression in the carpal tunnel by a thrombosed persistent median artery and a large aberrant artery substituting for the radial artery has been described but there have been no reports of median nerve compression in the palm of the hand by an anomalously enlarged ulnar artery. A 46 year old man is described who presented with clinical and electrophysiological features consistent with a median neuropathy at the wrist but surgical exploration revealed median nerve compression in the palm of the hand by an anomalously enlarged palmar branch of the ulnar artery. This case highlights another treatable cause of median nerve compression and illustrates that symptoms suggestive of carpal tunnel syndrome may be produced by median nerve compression in the palm of the hand.     

Digital innervation patterns following median or ulnar nerve laceration and their correlation to anatomic variations of the communicating branch between these nerves

The midline of the ring finger is classically considered as the neural watershed between the median and ulnar nerve sensory territories on the palmar surfaces of the fingers. Variations of this division exist and may be explained by a communicating branch between the third and fourth common digital nerves. The palmar sensibility patterns of fingers were assessed with Semmes Weinstein filaments after either a complete median or an ulnar nerve transection in 43 patients. Eight out of nine observed sensibility patterns could be explained by known anatomic types and subtypes of the communicating branch. The type of communicating branch, but not its subtype, could be established in the one remaining pattern.     

Use of pronator quadratus bone flap in bony reconstruction around the wrist

A bone graft can be raised from the distal end of the radius with intact blood supply derived from a vascular pedicle, i.e., the anterior interosseous artery proximally or the communicating branch from the dorsal carpal plexus distally. This graft has been used to produce proximal radiocarpal fusion, carpal bone replacement, and distal ulnar replacement. This viable graft with excellent blood supply gives very satisfactory clinical results.     

Aberrant course of a communicating branch of the ulnar nerve to the median nerve contributing to hypothenar Hammer syndrome

This presentation represents a unique anatomic predisposition to the development of hypothenar hammer syndrome (HHS). In this case, a communicating branch of the ulnar nerve to the median common digital nerve of the ring finger was identified crossing volar to the superficial palmar arch. This relationship caused thrombosis of the superficial palmar arch proximal to this crossing nerve branch. The aberrant course of this nerve created a structural anomaly contributing to HHS, which ultimately mandated surgical intervention.     

The importance of internal anatomy of the peripheral nerves to nerve repair in the forearm and hand

We have completed and analyzed recent studies on the internal topography of the median and ulnar nerves of the forearm and hand. These findings have been compared with the classic studies of Sir Sydney Sunderland and more recent work by other authors has been included. Our studies confirm that there is a complex interfascicular relationship between the various components of the median and ulnar nerves in the forearm and hand, but, with careful dissection, several anatomic relationships can be defined. Individual branches and bundles can be traced within the main nerve trunks for considerable distances without significant trauma to the conducting fibers. These include the recurrent branch of the median nerve, the branches to the lumbrical muscles, the motor and sensory components of the ulnar nerve, and the dorsal sensory branch of the ulnar nerve. These findings have a direct relationship to the clinical repair of fresh nerve injuries as well as those injuries that require nerve grafting for significant gaps in the neural tissue. Intraneural neurolysis can be safely performed if detailed knowledge of the internal topography of the peripheral nerves is understood. This knowledge may also be applied to the dissection and management of neuromas in continuity. The increased awareness of the interfascicular relationships of the peripheral nerves may well influence a more favorable outlook in the care of patients with nerve injuries.     

指固有神经背侧支的应用解剖学研究

目的 为指固有神经背侧支的临床应用提供解剖学基础。方法 观测12只新鲜成人手标本48个手指指固有神经背侧支出的出现率、直径、走向及分支。结果 示、中、环指及小指桡侧指固有神经发出的单一分支形成背侧支者占92．86％（78．84）,背侧支缺如者占7．14％（6．84侧）。各指背侧支均在近节手指近、中1／3平面发出,并从指侧面斜向指背远端走行。在近指间关节桡背（或尺背）侧向背面及中节指背发出2－5条分支。除小指外,2－4指指桡、尺侧背侧支的直径粗细均有显著性差异（P＜0．05）,桡侧＞尺侧。小指飞侧无指固有神经背侧支。结论 示、中、环及小指的桡侧指固有神经背侧支走向恒定,可包含在同指逆行岛状皮瓣内,适用于修复指腹软组织缺损。     

尺动脉腕上皮支及下行支筋膜皮瓣修复手部创面的临床应用

目的探讨带尺动脉腕上皮支及下行支的筋膜皮瓣修复手部创面的临床疗效。方法对24例手部皮肤软组织缺损患者采用带尺动脉腕上皮支及下行支的筋膜皮瓣逆行转移修复;其中手掌尺侧缺损创面6例,手背尺侧3例,环指掌侧5例,小指掌侧4例,环指背侧3例,小指背侧3例;急诊一期手术19例,手部瘢痕挛缩二期手术修复5例。结果24例皮瓣全部成活。患者均获得随访,时间3～36（12±3）个月,修复后的皮瓣质地、外形满意,无色素沉着,13例修复感觉神经者两点分辨觉为6～9mm;5例瘢痕挛缩者手部屈曲挛缩解除,手指主被动活动度得到明显改善。结论应用带尺动脉腕上皮支及下行支的筋膜蒂皮瓣修复手部缺损创面解剖较恒定,操作简便,成活率高,值得临床推广。     

尺神经深支卡压的解剖学及临床意义

目的：探讨尺神经深支卡压的病因及诊治方法：方法：显微镜下观测３０例成人手的尺神经深支。封闭及手术治疗９例患者。结果：尺神经深支分４段。封闭（４例）和手术（７例０各治愈同１例、５例。结论：腕尺管段尺神经深支最易受损,在其它部位也会被止准确无误。本病应尽早手术。     

Autogenous nerve pedicle graft in the forearm

We report our experience during a 15-year period with three patients who had severe segmental loss of more than 10 cm of both the median and ulnar nerves in the arm and forearm. The procedure was described by St. Clair Strange and by Silverstone in 1947. A modification of the procedure was used in our three patients. In two patients, the proximal stumps of the median and ulnar nerves were sutured together in the proximal forearm. The ulnar nerve was transected high in the axilla, leaving its blood supply intact. Several months later the ulnar nerve was transposed distally, and a juncture with the distal median nerve was created. The third patient had a significant segmental loss in the arm of both the median and ulnar nerves. The distal stumps of the median and ulnar nerves were sutured together, and at a later stage the ulnar nerve was transposed proximally and sutured to the median nerve in the axilla. In all three patients, an advancing Tinel sign was observed. Subjectively, all three patients believed there was a definite improvement in sensibility. Objective testing was, however, less convincing. This operation has limited applicability but definitely has a place in situations where direct sutures or nerve grafting are impossible.