Continuous three-in-one block for postoperative pain after lower limb orthopedic surgery: where do the catheters go?

Continuous three-in-one block is widely used for postoperative analgesia after proximal lower limb surgery, but location of the catheter has not been well addressed in the literature. We prospectively studied, in 100 patients, the characteristics of catheter threading under the iliac fascia and the correlations between catheter tip location and effective sensory and motor blockade of the three principal nerves of the lumbar plexus. Postoperatively, in conscious patients, 16 to 20 cm of a catheter was placed in the fascial sheath after femoral nerve location with a nerve stimulator. Contrast media (3 mL Iopamidol 390) was injected, and the catheter tip was located by means of an anteroposterior pelvic radiograph. An equal-volume mixture of 0.5% bupivacaine/2% lidocaine with epinephrine (30 mL) was injected through the catheter. Patient and catheter-insertion characteristics were noted. Thirty minutes after injection, sensory blockade was evaluated in the cutaneous territories of the lateral femoral cutaneous, femoral, and obturator nerves, along with motor blockade of the last two nerves. Pain scores at 30 min were also recorded. Seven block failures were noted. The tip of the catheter reached the lumbar plexus (Group 1) in 23% of the patients and lay deep to the medial (Group 2) or lateral (Group 3) part of the fascia iliaca in 33% and 37% of the patients, respectively. Demographic data and catheter threading characteristics were comparable among the groups. A three-in-one block was noted in 91% of Group 1 patients, but in only 52% and 27% of Group 2 and 3 patients, respectively (P < 0.05). Comparing Group 2 and 3 patients, sensory block was achieved in respectively 100% and 94% for the femoral nerve, 52% and 94% for the lateral femoral cutaneous nerve (P < 0.05), and 82% and 27% for the obturator nerve (P < 0.05). Visual analog scale pain scores on movement were significantly lower in Group 1 patients (P < 0.05). We conclude that during a continuous three-in-one block, the threaded catheter rarely reached the lumbar plexus. The quality of sensory and motor blockade and initial pain relief depend on the location of the catheter tip under the fascia iliaca. IMPLICATIONS: The course of a continuous three-in-one block catheter is unpredictable. Only 23% of the catheters lie near the lumbar plexus. The success of sensory and motor blocks, as well as postoperative analgesia, depend on the position of the catheter under the fascia iliaca.     

A description of the spread of injectate after psoas compartment block using magnetic resonance imaging

BACKGROUND AND OBJECTIVES: Magnetic resonance imaging (MRI) provides for excellent visualization of spread of solution after peripheral nerve block. The aim of this observational study was to utilize MRI to describe the distribution of injectate (gadopentetate dimeglumine) administered for continuous psoas compartment block (PCB) performed by use of two approaches (Capdevila and modified Winnie) and to describe the spread of injectate to the lumbar plexus. METHODS: Four volunteers were enrolled in a prospective crossover study. Each volunteer underwent PCB with catheter placement performed by use of Capdevila's approach followed 1 week later by PCB, with catheter placement performed by use of a modified Winnie approach. MRI of injectate distribution was performed after each PCB. RESULTS: The catheter was unable to be inserted in 1 volunteer undergoing Winnie's approach; therefore, 7 sets of MR images were analyzed. In 6 of 7 cases (4 Capdevila and 2 Winnie) spread was primarily within the psoas muscle. Contrast surrounded the L2-3 lumbar branch of the femoral nerve at L4 and cleaved the fascial plane within the psoas muscle and spread cephalad to reach the lumbar nerve roots. In 1 case (Winnie approach) contrast spread between the psoas and quadratus lumborum muscles. Contrast surrounded the femoral and obturator nerves where they lie outside the psoas muscle at L5. CONCLUSION: The most common pattern of injectate spread seen on MRI with both approaches to PCB was spread within the body of the psoas muscle around the lumbar branches (L2-4), with cephalad spread to the lumbar nerve roots. One catheter resulted in injectate between the psoas and quadratus lumborum muscles.     

Comparison of the fascia iliaca compartment block with the 3-in-1 block in children

A new single injection procedure, the fascia iliaca compartment block, is described for blocking the femoral, lateral cutaneous, and obturator nerves. The technique consists of injecting a local anesthetic immediately behind the fascia iliaca at the union of the lateral with the two medial thirds of the inguinal ligament, and forcing it upward by finger compression. This block was prospectively evaluated in 60 pediatric patients aged 0.7 to 17 years undergoing surgery of the lower limb, and then compared with a similar group of 60 children given a 3-in-1 block. Adequate analgesia was only obtained in 20% of the patients given 3-in-1 blocks (group 1), whereas the fascia iliaca compartment block proved to be easy, free of complications, and effective in more than 90% of patients (group 2). Such a high failure rate in group 1 was not due to misplacement of the needle since a femoral nerve block developed in all patients. Therefore it is unlikely that the local anesthetic can spread rostrally towards the lumbar plexus then return peripherally along the issuing nerves, and this was, indeed, not confirmed by radiological findings. In the authors' opinion, a multieffective block can only develop when the local anesthetic is introduced behind the fascia iliaca, which circumscribes a potential space where the femoral, lateral cutaneous, and obturator nerves run for a considerable part of their course. This report shows that deliberately injecting this space almost always results in an easy and effective block of these three nerves. The fascia iliaca compartment block can be recommended for use in children.     

Extent of blockade with various approaches to the lumbar plexus

The extent of blockade when four different techniques were used for blocking the lumbar plexus was prospectively evaluated in 80 adult patients. The extent of blockade was measured by testing motor function of all nerves except the lateral and posterior femoral cutaneous nerves, which were evaluated by pinprick response. The posterior approaches of Dekrey at L3 (n = 20) and Chayen at L4-5 (n = 20) proved similarly effective in producing blockade of the femoral, obturator, and lateral femoral cutaneous nerves, as well as the nerves to the psoas muscle. The anterior approach of Winnie (femoral sheath or 3-in-1 block) using paresthesia (n = 20) or peripheral nerve stimulation (n = 20) proved effective in producing blockade of the femoral and lateral femoral cutaneous nerves, but ineffective for obturator nerve blockade. None of the four techniques produced blockade of the sacral plexus. Perhaps our means of assessing blockade (motor) is what produced the difference between our findings and those of others.     

An evaluation of the cutaneous distribution after obturator nerve block.

In 1973, Winnie et al. introduced the inguinal paravascular three-in-one block, which allegedly provides anesthesia of three nerves--the femoral, lateral cutaneous femoral, and obturator nerves--with a single injection. This concept was undisputed until the success of the obturator nerve block was reassessed by using evidence of adductor weakness rather than cutaneous sensory blockade, the latter being variable in its distribution and often absent. We performed this study, therefore, to evaluate the area of sensory loss produced by direct injection of local anesthetic around the obturator nerve. A selective obturator nerve block with 7 mL of 0.75% ropivacaine was performed in 30 patients scheduled for knee surgery. Sensory deficit and adductor strength were evaluated for 30 min by using sensory tests (cold and light-touch perception) and the pressure generated by the patient's squeezing a blood pressure cuff placed between the knees. Subsequently, a three-in-one block was performed, and the sensory deficit was reassessed. The obturator nerve block was successful in 100% of cases. The strength of adductors decreased by 77% +/- 17% (mean +/- SD). In 17 patients (57%), there was no cutaneous contribution of the obturator nerve. The remaining 7 patients (23%) had an area of hypoesthesia (cold sensation was blunt but still present) on the superior part of the popliteal fossa, and the other 6 (20%) had sensory deficit located at the medial aspect of the thigh. The three-in-one block resulted in blockade of the lateral aspect of the thigh in 87% of cases, whereas the anteromedial aspect was always anesthetized. By use of magnetic resonance imaging in eight volunteers, we demonstrated that the obturator nerve has already divided into its two branches at the site of local anesthetic injection. However, the injection of blue dye after having simulated the technique in five cadavers showed that the fluid regularly spread to both branches. We conclude that after three-in-one block, a femoral nerve block may have been assessed as an obturator nerve block in 100% of cases when testing the cutaneous distribution of the obturator nerve on the medial aspect of the thigh. IMPLICATIONS: Previous studies reporting an incidence of obturator nerve block after three-in-one block may have mistaken a femoral nerve block for an obturator nerve block in 100% of cases when the cutaneous distribution of the obturator nerve was assessed on the medial aspect of the thigh. The only way to effectively evaluate obturator nerve function is to assess adductor strength.     

Paravascular lumbar plexus block: block extension after femoral nerve stimulation and injection of 20 vs. 40 ml mepivacaine 10 mg/ml

The goal of this prospective randomized study was to assess the extension of the "three-in-one" paravascular lumbar plexus block after femoral nerve stimulation and injection of 20 vs. 40 ml mepivacaine 10 mg/ml. Three-in-one blocks were achieved in 12 of 39 (31%) patients given 20 ml of 1% mepivacine (group 1), and 17 of 41 (41%) patients given 40 ml (Group 2) of the same solution (n.s). The level of successful blockade at each nerve did not differ between groups: The femoral nerve was blocked in 92% vs. 93% of patients in groups 1 and 2, respectively; the obturator nerve in 62% vs. 78%; and the lateral cutaneous femoral nerve in 41% vs. 44%. We conclude that femoral nerve stimulation is effective in faciliating blockade in the femoral nerve but not the obturator or lateral cutanous femoral nerve with the tested solution and volumes, and therefore not particularly effective for achieving complete 3-in-l blockade. Whithin the clinically relevant range of 20–40 ml, the volume of mepivacaine 10 mg/ml does not appear to influence the extent of blockade.     

Bloc ≪ 3 en 1 ≫ ou bloc femoral. Que faut-il faire et comment le faire ?

The “3 in 1” block and the femoral nerve block are widely used for lower limb surgery and postoperative analgesia. Whether these blocks are in fact a same regional block with two different names or represent definitively two different blocks remains controversial. A large number of anatomical as well as functional variations of the lumbar plexus have been described and complicate a rational analysis of the spread of local anaesthetics following these blocks. Anatomical, radiological and especially clinical data seem to confirm that these blocks are to be distinguished from one another. Femoral nerve block requires the use of a nerve stimulator and has a high success rate in the territory of the femoral nerve; a spread towards other lumbar nerves, especially the lateral femoral cutaneous nerve, is sometimes observed. The “3 in 1” block is supported by the idea of diffusion within a space that is located after going through two fascial layers. Even in experienced hands, the success predictive value is not high. However, once the “3 in 1” block is well performed, a complete anaesthesia covering the territories of the femoral nerve, the lateral femoral cutaneous nerve, and the obturator nerve occurs. Specific indications of each technique are different: major knee surgery and postoperative analgesia for the “3-in-1” block and leg surgery for femoral nerve block. The best approach for knee arthroscopy remains open for discussion.     

Effects of using the posterior or anterior approaches to the lumbar plexus on the minimum effective anesthetic concentration (MEAC) of mepivacaine required to block the femoral nerve: a prospective, randomized, up-and-down study

BACKGROUND AND OBJECTIVES: To evaluate if psoas compartment block requires a larger concentration of mepivacaine to block the femoral nerve than does an anterior 3-in-1 femoral nerve block. METHODS: Forty eight patients undergoing anterior cruciate ligament repair were randomly allocated to receive an anterior 3-in-1 femoral block (femoral group, n = 24) or a posterior psoas compartment block (psoas group, n = 24) with 30 mL of mepivacaine. The concentration of the injected solution was varied for consecutive patients using an up-and-down staircase method (initial concentration: 1%; up-and-down steps: 0.1%). RESULTS: The minimum effective anesthetic concentration of mepivacaine blocking the femoral nerve in 50% of cases (ED(50)) was 1.06% +/- 0.31% (95% confidence interval [CI], 0.45%-1.68%) in the femoral group and 1.03% +/- 0.21% (95% CI, 0.6%-1.45%) in the psoas group (P = .83). The lateral femoral cutaneous and obturator nerves were blocked in 4 (16%) and 5 (20%) femoral group patients as compared with 20 (83%) and 19 (80%) psoas group patients (P = .005 and P = .0005, respectively). Intraoperative analgesic supplementation was required by 15 (60%) and 5 (20%) patients in the femoral and psoas groups, respectively (P = .01). CONCLUSIONS: Using a posterior psoas compartment approach to the lumbar plexus does not increase the minimum effective anesthetic concentration of mepivacaine required to block the femoral nerve as compared with the anterior 3-in-1 approach, and provides better quality of intraoperative anesthesia due to the more reliable block of the lateral femoral cutaneous and obturator nerves.     

In with the new, out with the old? Comparison of two approaches for psoas compartment block

We compared the approaches of Winnie and Capdevila for psoas compartment block (PCB) performed by a single operator in terms of contralateral spread, lumbar plexus blockade, and postoperative analgesic efficacy. Sixty patients underwent PCB (0.4 mL/kg levobupivacaine 0.5%) and subsequent spinal anesthesia for primary joint arthroplasty (hip or knee) in a prospective, double-blind study. Patients were randomly allocated to undergo PCB by using the Capdevila (group C; n = 30) or a modified Winnie (group W; n = 30) approach. Contralateral spread and lumbar plexus blockade were assessed 15, 30, and 45 min after PCB. Contralateral spread (bilateral from T4 to S5) and femoral and lateral cutaneous nerve block were evaluated by sensory testing, and obturator motor block was assessed. Bilateral anesthesia occurred in 10 patients in group C and 12 patients in group W (P = 0.8). Blockade of the femoral, lateral cutaneous, and obturator nerves was 90%, 93%, and 80%, respectively, for group C and 93%, 97%, and 90%, respectively, for group W (P > 0.05). No differences were found in PCB procedure time, pain scores, 24-h morphine consumption, or time to first morphine analgesia.     

A review of approaches and techniques for lower extremity nerve blocks

PURPOSE: The purpose of this narrative review is to summarize the evidence derived from randomized controlled trials (RCTs) regarding approaches and techniques for lower extremity nerve blocks. SOURCE: Using the MEDLINE (January 1966 to April 2007) and EMBASE (January 1980 to April 2007) databases, medical subject heading (MeSH) terms "lumbosacral plexus", "femoral nerve", "obturator nerve", "saphenous nerve", "sciatic nerve", "peroneal nerve" and "tibial nerve" were searched and combined with the MESH term "nerve block" using the operator "and". Keywords "lumbar plexus", "psoas compartment", "psoas sheath", "sacral plexus", "fascia iliaca", "three-in-one", "3-in-1", "lateral femoral cutaneous", "posterior femoral cutaneous", "ankle" and "ankle block" were also queried and combined with the MESH term "nerve block". The search was limited to RCTs involving human subjects and published in the English language. Forty-six RCTs were identified. PRINCIPAL FINDINGS: Compared to its anterior counterpart (3-in-1 block), the posterior approach to the lumbar plexus is more reliable when anesthesia of the obturator nerve is required. The fascia iliaca compartment block may also represent a better alternative than the 3-in-1 block because of improved efficacy and efficiency (quicker performance time, lower cost). For blockade of the sciatic nerve, the classic transgluteal approach constitutes a reliable method. Due to a potentially shorter time for sciatic nerve electrolocation and catheter placement than for the transgluteal approach, the subgluteal approach should also be considered. Compared to electrolocation of the peroneal nerve, electrostimulation of the tibial nerve may offer a higher success rate especially with the transgluteal and lateral popliteal approaches. Furthermore, when performing sciatic and femoral blocks with low volumes of local anesthetics, a multiple-injection technique should be used. CONCLUSIONS: Published reports of RCTs provide evidence to formulate limited recommendations regarding optimal approaches and techniques for lower limb anesthesia. Further well-designed and meticulously executed RCTs are warranted, particularly in light of new techniques involving ultrasonographic guidance.     

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.     

Anatomy and anaesthesia of the lumbar somatic plexus

Cadaveric dissection demonstrated the lumbar plexus to lie within the substance of psoas major, with the major branches of the lumbar plexus emerging into the psoas compartment adjacent to the L5 vertebra. Within psoas major, the lateral femoral cutaneous and femoral nerves were separated from the obturator nerve by a muscular fold in 36 of 60 plexuses. Anatomical variations were common, with the accessory obturator nerve being identified in 12 per cent of plexuses. All previously described lumbar plexus block approaches positioned the needle within close proximity to the lumbar plexus. Modifications to these approaches may increase efficacy and reduce complication rates.     

Use of test dose allows early detection of subdural local anesthetic injection with lumbar plexus block

A 56 year-old woman underwent a lumbar plexus block for a revision of a left total hip arthroplasty. During the block procedure, the needle was advanced over the transverse process and isolated quadriceps twitches were elicited. After administering a test dose of 3 ml of 1.5% lidocaine, the patient developed loss of sensation in the L3–4 dermatomal distribution that progressed caudally to involve both legs followed by inability to move the left leg. The patient shortly thereafter became hypotensive and sensory block spread cephalad and peaked at C7 bilaterally suggesting possible subdural spread of local anesthetic. The patient was resuscitated with normalization of blood pressure and eventually had full resolution of motor and sensory block. Subdural spread of local anesthetic is a potential complication of lumbar plexus block related perhaps to injection of local anesthetic near dural sleeves of nerve roots. The use of a test dose allows early recognition of subdural injection and may limit consequences of inadvertent subdural spread of local anesthetic.     

Effective radiofrequency lesioning for obturator nerve neuropathy

A 73-year-old female complained of pain in the right lower-abdomen and medial aspect of the distal thigh after a gynecological operation. Computer tomography and MRI findings excluded obturator canal herniation or lumbar plexopathy. Both lumbar epidural block and obturator nerve block with local anesthetics were effective, except their limited duration of pain relief and muscle weakness for several hours after the blockade. Treatment with radio-frequency lesion of 50 degrees C for 60 seconds of the right obturator nerve relieved her pain for 9 months without muscle weakness. This case shows usefulness of radiofrequency lesion for obturator nerve pain.     

Cutaneous Branch of the Obturator Nerve Extending to the Medial Ankle and Foot: A Report of Two Cadaveric Cases

The area of skin supplied by the cutaneous branch of the obturator nerve (CBO) is highly variable. Although most introductory anatomy texts describe the CBO as innervating only a portion of the medial thigh, there are numerous reports in the literature of CBOs passing the knee to innervate the proximal, middle, or even distal leg. There are no previous reports of CBOs extending to the ankle and foot. Herein we describe 2 cases of CBOs extending at least to the medial foot. Both cases were discovered incidentally, during routine cadaver dissections by osteopathic and podiatric medical students in the anatomy laboratory of Western University of Health Sciences in California. In both instances, the anomalously long CBOs shared several characteristics: (1) they arose as direct branches of the anterior division of the obturator nerve, not from the subsartorial plexus; (2) they coursed immediately posterior to the great saphenous vein from the distal thigh to the distal leg, only deviating away from the saphenous vein just above the medial malleolus; and (3) they terminated in radiating fibers to the posterior half of the medial ankle and foot. In both cases, the saphenous branch of the femoral nerve was present but restricted to the area anterior to the great saphenous vein. It is likely that the variant CBOs carried fibers of the L4 spinal nerve and thus provided cutaneous innervation to the medial foot and ankle, a function most commonly reserved for the saphenous branch of the femoral nerve distal to the knee. Saphenous neuropathy is a common postoperative complication of saphenous cutdowns for coronary artery bypass grafts, so the potential involvement of a long CBO can add additional complexity to regional anesthetic blocks for foot and ankle surgery and procedures such as vein harvesting for coronary artery bypass grafts.     

Regional anesthesia in knee arthroscopy: A new technique involving femoral and sciatic nerve blocks in knee arthroscopy

We describe a new anesthetic technique of femoral and sciatic nerve blocks in knee arthroscopy. The sciatic nerve block is administered through a posterior approach, and the block of the femoral and lateral femoral cutaneous nerves in a single anterior approach. This type of regional anesthesia is safe and effective, providing excellent intraoperative and postoperative analgesia as well as minimizing postoperative complications.     

Anatomy of the posterior approach to the lumbar plexus block

The purpose of this study was to describe the relation of the lumbar plexus with the psoas major and with the superficial and deep landmarks close to it. Four cadavers were dissected and 22 computed tomography files of the lumbosacral region studied. Cadaver dissections demonstrated that the lumbar plexus, at the level of L₅, is within the substance of the psoas major muscle rather than between this muscle and the quadratus lumborum. The femoral nerve lies between the lateral femoral cutaneous and obturator nerves. However, while the lateral femoral cutaneous nerve is in the same fascial plane as the femoral nerve, the obturator nerve can be found in the same plane as the two other nerves or in its own muscular fold. Radiological data provided the following measurements: the femoral nerve is at a depth of 9.01 ± 2.43 cm; the psoas major medial border is at 2.73 ± 0.64 cm from the median sagital plane; and its lateral border is at 6.41 ± 1.61 cm from the same plane. It is concluded that the lumbar plexus is within the psoas major, that the obturator nerve localization within the psoas major varies and that computed tomography data define precisely the relationship of the lumbar plexus with superficial and deep landmarks.     

Comparison of the Different Approaches to Saphenous Nerve Block

Background: The authors compared the efficacy of the different approaches to saphenous nerve block.

Methods: The following approaches to saphenous nerve block were compared in 10 volunteers: perifemoral, transsartorial, block at the medial femoral condyle, below-the-knee field block, and blockade at the level of the medial malleolus. Each volunteer underwent all five blocks, and the interval between blocks was 3-7 days. The sequence of injection was randomized by Latin square design. Sensory blockade at the medial aspects of the leg and foot and the strength of the anterior thigh muscles were noted.

Results: The transsartorial, perifemoral, and below-the-knee field block approaches were more effective than block at the medial femoral condyle in providing sensory anesthesia to the medial aspect of the leg. The transsartorial approach was more effective than block at the medial femoral condyle and below-the-knee field block in providing sensory anesthesia to the medial aspect of the foot. Compared with the perifemoral approach, the transsartorial approach did not cause weakness of the hip flexors and the knee extensors. In volunteers with partial numbness in the medial aspect of the foot, supplemental block of the medial dorsal cutaneous branch of the superficial peroneal nerve resulted in complete sensory blockade.     

股神经联合坐骨神经阻滞应用在踝关节镜手术中的效果评价

目的 比较两种不同的麻醉方式在踝关节镜手术中的应用效果。方法 选择2018年1月至2019年12月在中山大学孙逸仙纪念医院行踝关节镜手术的患者60例,随机分为股神经组和腰丛组,每组各30例,股神经组实施股神经联合坐骨神经阻滞,腰丛组实施腰丛联合坐骨神经阻滞。比较两组患者术中和术后的麻醉和镇痛效果、麻醉操作时间、不同时间的心率及平均血压和麻醉并发症及不良反应。结果 两组患者术中额外使用局麻药和麻醉性镇痛药人数、术后24小时内静息或运动的VAS评分及额外使用镇痛药的人数和使用时间差异均无统计学意义;股神经组麻醉操作时间显著少于腰丛组;股神经组在麻醉操作过程中的心率和平均血压显著低于腰丛组;两组患者术后不良反应比较差异无统计学意义。结论 股神经联合坐骨神经阻滞与腰丛联合坐骨神经阻滞在踝关节镜手术中的麻醉和术后镇痛效果无显著差别,但前者麻醉操作时间更短,围术期生命体征更平稳。     

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.