The lumbar and sacral plexuses

The lumbar plexus is derived from the anterior primary rami of L1, L2, L3, and part of L4. It may also receive a contribution from T12. Its major derivatives are the femoral and the obturator nerves. The sacral plexus arises from the anterior primary rami of the five sacral nerves and the coccygeal nerve, together with the lumbosacral trunk, an important contribution which comprises the whole of L5 together with a contribution from L4. Its terminal branches are the sciatic and the pudendal nerve. In addition, both plexuses have numerous collateral muscular and cutaneous branches, and the sacral plexus gives rise to the pelvic parasympathetic outflow from S2 and S3.     

Brachial plexus variations in human fetuses

OBJECTIVE: We examined the anatomic variations of the brachial plexus (BP) in human fetuses. METHODS: This study was performed with 200 BPs from spontaneously aborted fetuses without detectable malformations. The plexuses were dissected, and the normal position and/or morphological variations of the BP were determined and photographed. RESULTS: There were no variations in 93 plexuses, and 107 plexuses were observed to have different variations. Morphological variations were observed more frequently among female fetuses and right sides. The BPs were composed mostly of the C5, C6, C7, and C8 nerves and the T1 nerve (71.5%). A prefixed plexus was observed in 25.5% of cases, and a postfixed plexus was observed in 2.5% of cases. In one case (0.5%), the C4 and T2 nerves joined the formation. The inferior trunk was not formed in 9% of cases. The superior trunk was not formed in 1% of cases. In one plexus, the superior trunk was formed by the ventral rami of the C4 and C5 nerves. In one case, the inferior trunk was formed by the ventral rami of the T1 and T2 nerves. Division variations were observed most frequently. There were also variations in the terminal branches, such as the roots of the median nerve joining in the distal part of the arm (8.5%), the axillary nerve being separate from the posterior division of the superior trunk (2.5%), and a connection existing between the median and musculocutaneous nerves (1%). CONCLUSION: Knowledge of BP variations is important for surgeons who perform surgical procedures in the cervical and axillary regions.     

The innervation of the spinal dura mater: Anatomy and clinical implications

Summary The nerves supplying the spinal dura mater were studied in four human foetuses (16–22 weeks) with the acetylcholinesterasein toto staining method.The ventral spinal dura contains a dense, longitudinally oriented, nerve plexus, which receives its contributions from: (I) the sinuvertebral nerves, (II) the nerve plexus of the posterior longitudinal ligament, (III) the nerve plexus of radicular branches of segmental arteries.Dorsal dural nerves are much smaller in number, do not form an evident plexus and do not reach the medial region of the dorsal dura. The dorsal nerves are derived from the ventral dural plexus at the level of the intersleeval parts of the dura mater.The ventral dural nerves may extend up to eight segments, with a great amount of overlap between adjacent nerves. This may provide an anatomical substrate for the understanding of extrasegmentally referred dural pain. The curled bundles of nerve fibres of pathways (I) and (II) provide an adequate adaptation to displacements of the spinal dura mater during flexion and extension. Pathway (III) has not been described before. The described nerve plexuses may be of importance in elucidating the mechanisms of epidural therapies in back pain and peripheral vascular disease.     

直肠癌根治术中保留骨盆自主神经的神经解剖学基础及临床意义

目的　探讨直肠癌根治术中保留神经的解剖学基础。　方法　解剖 6例完整尸体标本(男 4例 ,女 2例 )和 4例直肠及盆腔未受破坏的矢状半骨盆标本 ,观察骨盆神经组成及走行。　结果　显露下腹神经干 ,确定其在第 5腰椎处分为左、右下腹神经。其特点是较为粗大 ,位置固定 ,在腹主动脉分叉处易找到 ,呈网状联系 ,质地较实 ,为灰白色 ,与腹主动脉较近。分叉后左右下腹神经还有较粗大分支。骨盆内脏神经在大体标本上较难辨认 ,在矢状半骨盆标本中见到发自骶前孔 2～ 4的骨盆内脏神经 ,该神经较纤细 ,在侧韧带处呈丛状的细小纤维。　结论　保留下腹神经临床上较易完成。保留骨盆内脏神经则须细心操作 ,预保留神经的一侧在侧韧带水平的手术操作应尽量贴近直肠进行。     

Anatomical feasibility of anastomosing intercostal nerves (D10&D11) and subcostal nerve (D12) to S2 ventral root and lumbar plexus for management of bladder function after spinal cord injury

ObjectiveThe transfer of peripheral nerves originating above the level of injured spinal cord into the nerves/roots below the injury is a promising approach. It facilitates the functional recovery in lower extremity, bladder/bowel and sexual function in paraplegics. We assessed anatomical feasibility of transfer of lower intercostal nerves to S2 ventral root in human cadaver for management of neurogenic bladder dysfunction in patients with spinal cord injury.MethodsStudy was performed in five formalin fixed cadavers. Cadavers were placed in prone position. A transverse incision was made along 11th ribs on both sides and 10th, 11th Intercostal nerves (ICN) and subcostal nerve were harvested up to maximum possible length. In four cadavers the ventral root of S2 was exposed by endoscope and in one by the standard open laminectomy. Intercostal nerves were brought down to lumbo-sacral region, S2 ventral root was cut cranially and feasibility of intercostal to S2 anastomosis was assessed.ResultsThe mean length of intercostal nerves was 18.4 cm for the 10th 19.5 cm for the 11th and 22.15 cm for the subcostal nerve. The length of harvested nerve and the nerve length necessary to perform sacral roots neurotization were possible in all cases by only by subcostal nerve while T11 and T10 ICN fall short of the required length.ConclusionFor Spinal cord lesions located at the conus, subcostal nerve could be connected to ventral root of S2 in an attempt to restore bladder function while 10th and 11th ICN had enough length to neurotize lumbar plexus.     

A study of the myelinated fibres in the branches of the pelvic plexus

In a 20-year-old human female specimen the nerves to the pelvic organs were dissected and analysed. The gross anatomy of the branches of the pelvic plexus was described. The composition of these nerves was studied and the sizes and distribution of the diameter of a great part of the myelinated nerve fibres were measured and analysed. It was confirmed that the ventral roots S2 and S3 contain many nonmyelinated nerve fibres. There are direct connections between the sacral sympathetic chain and the pelvic plexus. They contain myelinated fibres with sizes as large as 11 μm. There are two different groups of fibres which supply the bladder, one on the dorsal side, mainly nonmyelinated (postganglic sympathetic?), and another group to the lateral side which contains many thin myelinated fibres (parasympathetic preganglionic?). The pelvic plexus and its branches are fixed to the vagina and the rectum. Surgical interventions in this area and perhaps also childbirth can damage the nerve supply to the bladder and the urethra. The functional disturbances of the bladder after such interventions can depend on what group of nerve fibres is most seriously damaged. The large number of thick myelinated fibres which reach the ventro lateral side of the urethra makes it highly probable that these fibres innervate the intrinsic striated urethral musculature. The large number of nonmyelinated nerve fibres in the nerves to the m. levator ani probably innervate smooth muscle tissue which is found in the fasciae of the pelvic floor.     

Anatomy of the spinal nerves and dermatomes

There are 31 pairs of spinal nerves: eight cervical, 12 thoracic, five lumbar, five sacral and one coccygeal. They form by fusion of a posterior sensory spinal root (bearing its posterior root ganglion) with an anterior motor root. These join at each intervertebral foramen. Typically, the nerve then divides into a posterior and an anterior primary ramus. The former supplies the vertebral muscles and dorsal skin. The anterior primary ramus in the thoracic region bears a white ramus communicans to the sympathetic ganglion. Each spinal nerve receives a grey ramus from the sympathetic chain. The nerves T2–T12 supply the skin and muscles of the trunk sequentially. The other nerves are arranged into the cervical, brachial, lumbar and sacral plexuses. The cervical plexus supplies the skin and anterior muscles of the neck and forms the phrenic nerve (C3–C5), while the brachial plexus supplies the skin and muscles of the upper limb, and the lumbar and sacral plexuses supply the skin of the lower limb and perineum and the muscles of the posterior abdominal wall, pelvis, perineum and lower limb. The segmental nerves are arranged to supply the skin (dermatomes), while the segmental supply to the limb muscles, the myotomes, is more complex.     

颈脊神经后内侧支卡压的解剖及其临床意义

目的为临床诊治颈神经后内侧支卡压提供解剖学基础。方法对10具（20侧）成人尸体头颈标本颈脊神经后内侧支易受卡压的部位进行解剖学观测。结果（1）C2颈脊神经后内侧浅支（枕大神经）易受卡压处分别位于该神经走行于头下斜肌与枢椎椎弓板之间段、穿过头半棘肌段和穿上项线骨纤维孔处。（2）C3-5脊神经后内侧浅支（第三枕神经）易受卡压处分别位于该神经穿行头半棘肌和穿头夹肌段。C3颈脊神经后内侧深支即头夹肌支,该神经穿过头半棘肌处。（3）C3-8后内侧支穿颈脊神经后支骨纤维管。结论颈神经后内侧支穿行的骨纤维管、项部肌肉、项部肌肉的腱性组织是造成颈脊神经后内侧支卡压的解剖学基础。     

Anatomy of the lumbar and sacral plexuses and lower limb peripheral neuropathies

The lumbosacral plexus originates from the anterior rami of the lumbar and sacral nerve roots forming a network of nerves which supply the lower half of the body. The lumbar plexus (L1–L4) is situated within the upper two-thirds of psoas major and gives rise to the iliohypogastric nerve, ilioinguinal nerve, genitofemoral nerve, lateral femoral cutaneous nerve, femoral nerve and obturator nerve. The sacral plexus (L4–S4) is located within the pelvis and gives rise to the superior gluteal nerve, inferior gluteal nerve, sciatic nerve, posterior cutaneous nerve, perforating cutaneous nerve and the pudendal nerve. Peripheral neuropathy of these nerves may occur from an autoimmune, inflammatory, endocrine, infective, congenital, traumatic, neoplastic, vascular, degenerative or metabolic cause. This article will give an overview of the relevant anatomy of the lumbosacral plexus and neuropathies which affect the peripheral nerves of the lower limb.     

脊神经前根选择性切断治疗痉挛性脑性瘫痪

目的了解脊神经前根选择性切断对肢体功能的影响,探讨在痉挛性脑瘫治疗中的应用。方法对健康家犬左侧Ｌ５、Ｌ６及Ｌ７脊神经前根分束选择性切断。对痉挛性脑瘫患者Ｌ２、Ｌ４、Ｌ５及Ｓ１按５０％、２５％、４０％及７５％行选择性切断。结果脊神经前根选择性切断与肌肉有较好对应性,术后共济运动、平衡功能尚好,对应肌张力下降。临床应用３例,近期疗效满意。结论脊神经前根可接受分束选择性切断,在痉挛性脑瘫的治疗中是一种值得探讨的新方法     

Cutaneous territory of the posterior branches of spinal nerves. A review of Dejerine's scheme

This report concerns not only anatomical study of posterior branches of the spinal nerves, but has also a clinical aim. The cutaneous territories and the sites of pain irradiation are precised. In the cervico-thoracic region emphasis is placed on the importance of the fourth cervical posterior branch and of the second dorsal posterior branch. At the lumbar and sacral levels the authors distinguish three pain pathways: from up to down and from outside to inside: the first corresponding to posterior branches of 11th and 12th dorsal nerves, the second to those of first, second and third lumbar nerves and the third to sacral nerves.     

Neuroanatomy of the brachial plexus: the missing link in the continuity between the central and peripheral nervous systems

The brachial plexus is a complex network of nerves which extends from the neck to the axilla and which supplies motor, sensory, and sympathetic fibers to the upper extremity. Generally it is formed by the union of the ventral primary rami of the spinal nerves, C5-C8 and T1, the so-called "roots" of the brachial plexus. The goal here is to examine the neural architecture of the brachial plexus. The most constant arrangement of nerve fibers will be delineated, and then the predominant variations in neural architecture will be defined, particularly the prefixed and postfixed plexus, as well as the microanatomy and anatomy of the major terminal branches of the plexus. Multiple tracts connect many parts of the nervous system, and multiple ascending and descending tracts connect the peripheral nervous system (PNS) and lower spinal centers with the brain. This reflects that the nervous system is able to extract different pieces of sensory information from its surroundings and encode them separately, and that it is able to control specific aspects of motor behavior using different sets of neurons. Examination of the major sensory or motor pathways reveals a highly and tightly organized nervous system. In particular, at each of many levels, we see fairly exact maps of the world within the brain. In an effort to understand the functional neuroanatomy of the brachial plexus, this paper will focus briefly on the nervous connections of the nerves of the upper extremity with the brain. The goal here is to better understand "what the brain sees" after nerve injury and repair.     

Urinary Bladder Response to Hypogastric Nerve Stimulation After Bilateral Resection of the Pelvic Nerve or Spinal Cord Injury in Rats

Background: We examined the mechanism of urinary bladder motility return after bladder areflexia induced by interruption of the sacral parasympathetic outflow to the urinary bladder following damage to the sacral cord or pelvic nerves in the rat.
Methods: The L6 and SI nerve bundles were resected near the vertebrae, and bilateral pelvic nerve resections (PNR) performed. Spinal cord injury (SCI) was performed by means of a legion generator at the T12 vertebra. Thirty days after PNR and SCI, cystometrograms were recorded under anesthesia.
Results: In all rats subjected to PNR or SCI, overflow incontinence continued, yet some rats subjected to SCI recovered within 2 weeks after the operation. Cystometrograms showed that repetitive bladder contractions appeared in rats subjected to SCI irrespective of hypogastric nerve (HCN) innervation, while bladder contractions did not appear in rats subjected to PNR. Electrical stimulation of the HGN induced higher bladder pressure elevation in rats who underwent PNR than in rats subjected to SCI.
Conclusions: These results suggest that the generation of repetitive bladder contractions induced by bladder distention after bladder areflexia requires the presence of intact pelvic nerves that transmit sacral cord-originating excitatory information to the bladder. However, the HGN system and functioning pelvic nerve ganglia are not involved in this process. Also, the connection from the preganglionic HGN to the postganglionic parasympathetic nerves in the pelvic plexus did not form after PNR.     

The anatomy of the pectoral nerves and their significance in brachial plexus reconstruction

Twenty-nine brachial plexuses from 13 embalmed and 5 fresh cadavers were examined under x3.5 loupe magnification to collect systematic and topographic anatomical data regarding the lateral and medial pectoral nerves. Additionally, nerve biopsy specimens were harvested in 5 fresh cadavers to obtain histomorphometric data. In all dissections the pectoral nerves exited at the trunk level as 3 distinct nerves. The superior pectoral nerve (from the anterior division of the superior trunk) commences just distal to the suprascapular nerve and courses laterally to innervate the lateral clavicular portion of the pectoralis major muscle (PM) with 2 to 4 branches. The middle pectoral nerve (from the anterior division of the middle trunk) courses distally and enters the infraclavicular fossa with 2 constant branches. The superficial branch terminates in the medial clavicular and upper sternal parts of the PM. The deep branch always forms a plexus with the medial pectoral or inferior pectoral nerve (from the anterior division of the inferior trunk), which courses at a right angle around the the lateral thoracic artery. From this plexus several branches terminate in the Pm. The branch to the lower aspect of the PM pierces the pectoralis minor muscle in two thirds of cases, whereas it passes its inferior border to reach the lower aspects of the PM with an average length of 15 cm in one third of cases. Knowledge of the detailed anatomy of the pectoral nerves, as outlined in this study, clarifies the obscure anatomic relationship of the lateral and medial pectoral nerves and allows easy intraoperative location of the medial pectoral nerve at the exit of the lateral thoracic artery. The length of the inferior pectoral nerve, the number of motor axons, and the anatomical proximity of this nerve make it an expendable but powerful source of reinnervation to the musculocutaneous nerve in upper brachial plexus injuries.     

Evidence for local neural modulation of sympathetic influences on the feline bladder

It is known that resting conditions of bladder volume and pressure influence the response of the cat bladder in situ to sympathetic nerve stimulation. We observed that this was also true when the bladder was decentralized by cutting the sacral spinal roots, the hypogastric nerves, and one sympathetic chain. Under these conditions, elevating intravesical pressure by means of a reservoir of large surface area connected to the bladder resulted in an enhancement of the beta-adrenoceptor-mediated dilatory component of the response to stimulation of either the sympathetic chain or the hypogastric nerves. In order to test whether this enhancement was the result of mechanical or end-organ effects, the change in response to ia isoprenaline was also evaluated. Although the response to isoprenaline was modestly (2-fold) increased at intravesical pressures of 20–30 cm H₂O, the increase in response to hypogastric nerve stimulation (8.5-fold) was significantly greater. The increase in response to sympathetic chain stimulation was intermediate, but only one chain was stimulated. Thus, end-organ or physical factors have some influence on the dilatory response. However, there must be another modulatory component that exerts an effect on the neurally mediated dilatation but not on that produced by isoprenaline. This modulation appears to be activated by bladder distension and to be directed at the nerves, either on their terminals or at the intramural or plexus ganglia. Candidate mechanisms are humoral compounds (e.g., eicosanoids) or a local neural network.     

Ability of each lumbar splanchnic nerve and disability of thoracic ones to generate seminal emission in the dog.

Control of seminal emission by canine thoracolumbar splanchnic nerves which constitute the caudal mesenteric plexus (inferior mesenteric and superior hypogastric plexuses in human) was investigated. Electrical stimulation of a splanchnic nerve group which branched from sympathetic trunks at thoracic and L1 ganglia and descended on the ventral wall of the aorta between bilateral spermatic arteries via the intermesenteric plexus did not cause seminal emission in all 13 dogs examined. In contrast, electrical stimulation of the other splanchnic nerve group which branched from lumbar sympathetic trunks at ganglia L1-L5 and descended behind bilateral spermatic arteries induced seminal emission regardless of branching levels or sides. The results indicate that efferent signals via the intermesenteric plexus do not generate seminal emission, while those via each lumbar splanchnic nerve have ability to generate seminal emission in the dog.     

Restoration of prehension with the double free muscle technique following complete avulsion of the brachial plexus. Indications and long-term results

BACKGROUND: Recent interest in reconstruction of the upper limb following brachial plexus injuries has focused on the restoration of prehension following complete avulsion of the brachial plexus. METHODS: Double free muscle transfer was performed in patients who had complete avulsion of the brachial plexus. After initial exploration of the brachial plexus and (if possible) repair of the fifth cervical nerve root, the first free muscle, used to restore elbow flexion and finger extension, is transferred and reinnervated by the spinal accessory nerve. The second free muscle, transferred to restore finger flexion, is reinnervated by the fifth and sixth intercostal nerves. The motor branch of the triceps brachii is reinnervated by the third and fourth intercostal nerves to restore elbow extension. Hand sensibility is restored by suturing of the sensory rami of the intercostal nerves to the median nerve or the ulnar nerve component of the medial cord. Secondary reconstructive procedures, such as arthrodesis of the carpometacarpal joint of the thumb, shoulder arthrodesis, and tenolysis of the transferred muscle and the distal tendons, may be required to improve the functional outcome. RESULTS: The early results were evaluated in thirty-two patients who had had reconstruction with use of the double free muscle procedure. Twenty-six of these patients were followed for at least twenty-four months (mean duration, thirty-nine months) after the second free muscle transfer, and they were assessed with regard to the long-term outcome as well. Satisfactory (excellent or good) elbow flexion was restored in twenty-five (96 percent) of the twenty-six patients and satisfactory prehension (more than 30 degrees of total active motion of the fingers), in seventeen (65 percent). Fourteen patients (54 percent) could position the hand in space, negating simultaneous flexion of the elbow, while moving the fingers at least 30 degrees and could use the reconstructed hand for activities requiring the use of two hands, such as holding a bottle while opening a cap and lifting a heavy object. The results were analyzed to identify factors affecting the outcome. CONCLUSIONS: The double free muscle procedure can provide reliable and useful prehensile function for patients with complete avulsion of the brachial plexus.     

Neurotization in brachial plexus injuries. Indication and results

In neurotization or nerve transfer, a healthy but less valuable nerve or its proximal stump is transferred in order to reinnervate a more important sensory or motor territory that has lost its innervation through irreparable damage to its nerve. In brachial plexus injuries, extraplexal nerves such as the spinal accessory nerve, rami of the cervical plexus, or intercostal nerves are transferred onto trunks, cords, or individual nerves or else segments of the brachial plexus that maintain continuity with the spinal cord may be coapted to trunks or cords the surgeon wishes to innervate. This method is particularly indicated in root avulsion injuries that occur frequently following traction trauma to the brachial plexus. The authors convey their experience with neurotization using the long thoracic nerve in seven cases, the accessory nerve in 30 cases, intercostal nerves in 66 cases, and various nerve transfers within the plexus in 31 cases. Results of other authors are also reported. With these methods, it is possible to obtain good elbow flexion in more than one-half of patients; however, only limited shoulder function and no useful finger function are obtained.     

腺病毒介导的LacZ基因靶向性导入脊髓及示踪周围神经的动态过程

目的由损伤的周围神经靶向性导入腺病毒介导的LacZ基因(AdLacZ)至脊髓，动态观察病毒裁体逆行输送到脊髓前角运动神经元、脊髓后根神经节(dorsal root ganglia，DRGs)感觉神经元及基因产物顺行标记周围神经的全过程和特点。方法分别将AdLacZ转染大鼠正中神经和胫神经近断端，然后以10-0无创线吻合神经。在转染后9周内的24个不同时间点取出正中神经组的C5～T1脊髓节段、DRGs连同臂丛，胫神经组的L2～L6脊髓节段、DRGs连同骶丛。将脊髓和DRGs的50μm横切片行X—gal染色和免疫组织化学染色，臂丛和骶丛的整个标本分别行X—gal染色。计数阳性脊髓前角运动神经元、DRGs神经元及周围神经轴突数，研究转基因表达在脊髓前角运动神经元、DRGs神经元及正中神经、胫神经的最早时间、高峰时间和持续时间。结果LacZ基因能特异性、高效表达在损伤周围神经的感觉和运动神经元。转基因在脊髓和周围神经的表达严格限于感染神经的同侧。正中神经组标本各部位的转基因表达均早于胫神经组。胫神经组被标记的运动神经元和感觉神经元数均高于正中神经组。表达持续的时间在运动神经元最短，然后是感觉神经元，在周围神经持续时间最长。在同一组内，转基因表达在DRGs神经元最早．然后是运动神经元，最后是周围神经干，而且被标记的感觉神经元数多于运动神经元数。结论由损伤的周围神经导入的AdLacZ不但在靶神经元高效特异性表达，而且能高效顺行标记神经元突起、周围神经直至吻合口远端的再生轴突。这对周围神经损伤的基因治疗和神经示踪研究有实用价值。     

Double muscle transfer for upper extremity reconstruction following complete avulsion of the brachial plexus

Recent interest in reconstruction of the upper limb following brachial plexus injuries has focused on the restoration of prehension following complete avulsion of the brachial plexus. The authors use free muscle transfers for reconstruction of the upper limb to resolve the difficult problems in complete avulsion of the brachial plexus. This article describes the authors' updated technique--the double free muscle procedure. Reconstruction of prehension to achieve independent voluntary finger and elbow flexion and extension by the use of double free muscle and multiple nerve transfers following complete avulsion of the brachial plexus (nerve roots C5 to T1) is presented. The procedure involves transferring the first free muscle, neurotized by the spinal accessory nerve for elbow flexion and finger extension, a second free muscle transfer reinnervated by the fifth and sixth intercostal nerves for finger flexion, and neurotization of the triceps brachii via its motor nerve by the third and fourth intercostal motor nerves to extend and stabilize the elbow. Restoration of hand sensibility is obtained via the suturing of sensory rami from the intercostal nerves to the median nerve. Secondary reconstruction, including arthrodesis of the carpometacarpal joint of the thumb and glenohumeral joint, and tenolysis of the transferred muscle and distal tendons, improve the functional outcome. Based on the long-term result, selection of the patient, donor muscle, and donor motor nerve were indicated. Most patients were able to achieve prehensile functions such as holding a can and lifting a heavy box. This double free muscle transfer has provided prehension for patients with complete avulsion of the brachial plexus and has given them new hope to be able to use their otherwise useless limbs.