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Variation of brachial plexus characterized by the absence of musculocutaneous nerve in right arm was found during routine dissection of a 54 year old male cadaver. After giving lateral pectoral nerve, rest of the lateral cord continued as lateral root of median nerve. An unusual branch was arising from lateral cord which crossed the axillary artery anteriorly and then divided into two branches. One of these branches joined ulnar nerve and other medial root of median nerve. All the muscles of front of arm were supplied by branches of median nerve. These variations are important for the anesthetists, surgeons, neurologists during surgery and for anatomists during dissection in the region of axilla. DOI: http://dx.doi.org/10.3126/ajms.v3i2.6626 Asian Journal of Medical Sciences 3(2012) 21-24

Spinal accessory nerve (SAN) injury results in loss of motor function of the trapezius muscle and leads to severe shoulder problems. Primary end-to-end or graft repair is usually the standard treatment. The authors present 2 patients who presented late (8 and 10 months) after their SAN injuries, in whom a lateral pectoral nerve transfer to the SAN was performed successfully using a supraclavicular approach.

Thank you very much to the editors for the invitation to comment on the cadaveric study, “An Anatomic Appraisal of Biplanar Muscle-Splitting Breast Augmentation.”1 I commend the authors for going back to the anatomy lab to further elucidate the nuances associated with this relatively new approach to breast augmentation. This laboratory study aims to identify a safe zone for performing the biplanar muscle-splitting (BMS) augmentation mammaplasty. I would like to offer my compliments and complements. First let me compliment the authors on a well-structured study and an honest presentation of the weaknesses of the study and areas for future research. Let me also say that I have no personal experience with the BMS technique. Before delving into the merits of the article, it is instructive to revisit the pectoral nerve anatomy to avoid confusion interpreting the literature and this study. The anatomy of the pectoral nerves is a bit confusing. The classic description has the pectoralis major innervated by two nerves; the lateral pectoral nerve and the medial pectoral nerve.2-7 Some authors describe three separate nerves.8-11 One author describes four different nerves.12 The nomenclature can cause confusion as well, anatomists name the nerves according to their origin from the brachial plexus. Unfortunately the course of the medial pectoral nerve is lateral to the lateral pectoral nerve. A very detailed and wonderfully illustrated study of the pectoral nerves by David et al deserves special attention by any aspiring surgeon of the pectoral region.9 In it, they describe a superior, middle, and inferior branch consistently found during 26 brachial plexus dissections. Most importantly the upper two branches (classically referred to as the …

The pectoral nerves (PNs) may be selectively injured through various traumatic mechanisms such as direct trauma, hypertrophic muscle compression, and iatrogenic injuries (breast surgery and axillary node dissection, pectoralis major muscle transfers). The PN may be surgically recovered through nerve transfers. They may also be used as donors to the musculocutaneous, axillary, long thoracic, and spinal accessory nerves and for reinnervation of myocutaneous free flaps. Thus, in this article, we reviewed the surgical anatomy of PN. A meta-analysis of the available literature showed that the lateral pectoral nerve (LPN) arises most frequently with two branches from the anterior divisions of the upper and middle trunks (33.8%) or as a single root from the lateral cord (23.4%). The medial pectoral nerve (MPN) usually arises from the medial cord (49.3%), anterior division of the lower trunk (43.8%), or lower trunk (4.7%). The two PN are usually connected immediately distal to the thoracoacromial artery by the so-called ansa pectoralis. The MPN may also show communications with the intercostobrachial nerve. In 50%-100% of cases, it may pass, at least with some branches, through the pectoralis minor muscle. The LPN supplies the upper portions of the pectoralis major muscle; the MPN innervates the lower parts of the pectoralis major and the pectoralis minor muscle. Among the accessory muscles of the pectoral girdle, the LPN may also innervate the tensor semivaginae articulationis humero-scapularis, pectoralis minimus, sternoclavicularis, axillary arch, sternalis, and infraclavicularis muscles; the MPN may innervate the pectoralis quartus, chondrofascialis, axillary arch, chondroepitrochlearis, and sternalis muscles.

Introduction/Background Little is known about shoulder hypertonia in patients with brain injury. The principal aim of our study was to assess the results of spastic shoulder surgery in our team experience. Material and method Sixteen patients (18 shoulders) were retrospectively reviewed. The following were studied: etiology of hypertonia, shoulder deformation schemes, initial aims of surgery, shoulder pre- and postoperative mobility, impact of surgery on limb function when possible. None limb was functional preoperatively. Spontaneously, shoulders were all in a medial rotation, in adduction in 15 cases, in abduction in 3 cases. One had spontaneous retroposition. Therapeutic aim was hygienic in all and pain-relief in 6. Ten neurotomies of the lateral pectoral nerve (LPN), 8 intramuscular lengthening of the latissimus dorsi (LD), 9 percutaneous tenotomies of the pectoralis major (PM), one neurotomy of the motor nerve for the long head of triceps brachii (LHTB) and one intramuscular lengthening of the teres major (TM) were performed. Results Mean age at surgery was 52.1 (24–73). Etiology was vascular in 11, anoxic in 2, one had traumatic brain injury, one multiple sclerosis, one cervicarthrosic myelopathy. Preoperatively, the mean results for passive abduction of the shoulder was 50.6° (10–90) and for the passive lateral rotation was −5° (−70; 20). Postoperatively, there were respectively improved at 87.7° (60–160) and 6.7° (−20; 20). Only 3 muscles presented with residual tightness (two PM and 1TM) in patients where an isolated neurotomy of the lateral pectoral nerve (LPN) had been achieved. All of the initial objectives of the surgery were satisfied. One patient recovered a partial functionnal limb thanks to a recovered active shoulder flexion. Conclusion In classical medial rotation-adduction deformation schemes, surgery performed on the 3 main involved muscles (PM, LD, TM) offers good results in term of passive mobility of the shoulder and pain-relief.

Anomalous disposition of pectoral muscles was encountered in an adult female cadaver on the left side. A prominent cleft separating the sternocostal and clavicular portions of the pectoralis major was noticed. The fibers of pectoralis major were partially fused with the deltoid, resulting in obliteration of the deltopectoral groove. Interestingly, cephalic vein was seen traversing superficial to the clavicular portion of the pectoralis major and pierced it to drain into the axillary vein. The pectoralis minor was inserted mainly on the coracoid process and few fibers were found blending with the coracobrachialis and short head of biceps brachii. Further, pectoralis minimus, a rare anatomic variant, was also observed lying superior to pectoralis minor. It was innervated by a twig from the lateral pectoral nerve at its superficial surface. Awareness of possibility of such anomalous muscles is important for surgeons operating on the chest wall.

Lateral and medial pectoral nerves are distributed to the pectoralis major and minor muscles. The purpose of this study was to identify the spinal origins of lateral and medial pectoral nerves and to evaluate the participating amounts of each spinal nerve composing both pectoral nerves. Two types of spinal origins appeared in lateral pectoral nerves. The first type was composed of nerve fibers from C5, C6, and C7 with a frequency of 50.0% and the second type was composed of nerve fibers from C6 and C7 at a frequency of 50.0%. Regarding the average participating diameter to the lateral pectoral nerve, C7 was the thickest with a value of 1.60 +/- 0.35 mm (mean +/- SD), next was C6 at 0.83 +/- 0.18 mm, and C5 was the third at 0.42 +/- 0.24 mm. Three types of spinal origin appeared in the medial pectoral nerve. The first type was comprised of nerve fibers from C8 and T1 in 73.3% of cases. The second type was comprised of C8 only in 23.4% of cases, and the third type was comprised of T1 only in 3.3% of cases. The average participating diameter was 0.71 +/- 0.22 mm from C8 and 0.52 +/- 0.17 mm from T1. These results show that the spinal origins of the both pectoral nerves were various. Participating amounts of the lateral pectoral nerve appeared sequentially in the order of C7, C6, and C5. In the medial pectoral nerve, C8 participated more amounts than T1.

Pectoralis major injuries are relatively uncommon and can pose a diagnostic challenge. Deformity and weakness of this muscle in weight lifters is typically due to traumatic tendon rupture and often requires surgical repair. However, there are other less common etiologies that can mimic the clinical presentation of pectoralis major wasting and weakness that require different treatment approaches. This article describes a case of a 48-year-old recreational weight lifter who presented with severe pectoralis major wasting and weakness secondary to isolated mononeuropathy of the lateral pectoral nerve possibly due to Parsonage Turner syndrome. The patient was treated nonoperatively and achieved full recovery 18 months after onset. Parsonage Turner syndrome should be included in the differential diagnosis of patients with atraumatic weakness and wasting of the pectoralis major muscle and dysfunction. [ Orthopedics. 2016; 39(4):e756–e759.]

Introduction: Adequate knowledge on variant morphology of brachial plexus and its branches are important in clinical applications pertaining to trauma and surgical procedures of the upper extremity. Aim: Current study was aimed to report variations of the branches of the lateral cord of brachial plexus in the axilla and their possible clinical complications. Materials and Methods: Total number of 82 upper limbs from 41 formalin embalmed cadavers was dissected. Careful observation was made to note the formation and branching pattern of lateral cord. Meticulous inspection for absence of branches, presence of additional or variant branches and presence of abnormal communications between its branches or with branches of other cords was carried out. Results: In the present study, we noted varied branching pattern of lateral cord in 6 out of 82 limbs (7%). In one of the limb, the median nerve was formed by three roots; two from lateral cord and one from medial cord. Two limbs had absence of lateral pectoral nerve supplemented by medial pectoral nerves. One of which had an atypical ansa pectoralis. In 2 upper limbs, musculocutaneous nerve was absent and in both cases it was supplemented by median nerve. In one of the limb, coracobrachialis had dual nerve supply by musculocutaneous nerve and by an additional branch from the lateral cord. Conclusion: Variations of brachial plexus and its branches could pose both intraoperative and postoperative complications which eventually affect the normal sensory and motor functions of the upper limb.

This chapter examines the main cutaneous and/or motor nerves of the upper limb. First, the chapter will provide an overview about the general layout of the upper limb. Further, it will discuss the general skeletal arrangement of the upper limb, and the regions of the upper limb. This will enable the reader to gain a greater understanding of the main anatomical regions of the upper limb. It will also discuss briefly the embryological development of the upper limb. Following this, a detailed account will be given of the main sensory and/or motor nerves. Further, details about the brachial plexus, as well as other nerves contributing to the innervation of the upper limb will also be given. Then each nerve will be discussed in turn in terms of what musculature and/or cutaneous innervation it supplies. Later, the following nerves will be discussed in greater detail: the dorsal scapular nerve, long thoracic nerve, suprascapular nerve, nerve to subclavius, lateral pectoral nerve, medial pectoral nerve, musculocutaneous nerve, median nerve, medial cutaneous nerve of arm, medial cutaneous nerve of forearm, ulnar nerve, upper subscapular nerve, lower subscapular nerve, thoracodorsal nerve, axillary nerve and radial nerves. At the relevant points, this chapter will then discuss clinical examination of each of these nerves, providing hints and tips on how to effectively examine each territory. Clinical examination of these nerves will be described in relation to approaching the patient, and hints and tips on how to effectively examine each of these nerves to elicit relevant signs and symptoms. Pathologies of the nerves will be discussed not only relating it to current research in the field but also highlighting historical perspectives, where relevant. In addition, to place it into clinical context, related pathologies and findings on clinical examination would be given, as relevant.

The lateral cord of the brachial plexus represents the confluence of the anterior divisions of the upper and middle trunks. The lateral pectoral nerve is the first branch of the lateral cord and provides motor innervation to the pectoralis major muscle. The lateral cord then branches to form the lateral contribution to the median nerve and the musculocutaneous nerve. The musculocutaneous nerve innervates the biceps brachii, coracobrachialis, and brachialis muscles, and is therefore primarily responsible for flexion of the forearm. The musculocutaneous nerve terminates as the lateral cutaneous nerve of the forearm. Each of these nerve structures is associated with a number of relatively common variations.

Detailed anatomical knowledge of the pectoral nerves is of clinical importance in surgeries as diverse as limb neurotization, mastectomy, orthopedic procedures and operations related to trauma. The brachial plexus of 200 cadavers were examined in an attempt to clarify the normal origins, courses and variations of the nerves with special emphasis on the ansa pectoralis (AP). In 75% the MPN arose from the anterior division of the inferior trunk of the brachial plexus and in 25% it arose from the medial cord. In 40% of specimens, the LPN arose from a single contributing nerve (anterior division of the superior trunk, 11%; anterior division of the middle trunk 18%; lateral cord, 11%). In the remaining 60% of specimens, the LPN arose from the fusion of two rootlets derived variably from the anterior divisions of the superior and middle trunks and the lateral cord. A single AP was found to be present bilaterally in 200 (100%) of the specimens. Classification of the AP was based upon its origin from the upper or lower rootlet of the LPN, the LPN itself, or from the deep branch of the LPN. AP-1 (42%) arose from the deep branch of the LPN; AP-2 (28%) arose directly from the LPN; AP-3 (25%), arose from the lower rootlets of the LPN and rarely, the AP arose from the upper rootlet of the LPN and crossed posterior to the lower rootlet to communicate with the MPN (AP-4, 5%). Irrespective of the aforementioned types, the AP was found to be present, crossing the second segment of the axillary artery in 90% of the specimens. These results could prove useful during the preoperative planning of neurotization and other surgical procedures involving the axilla.

We report on two cases of isolated damage to a muscle branch of the lateral pectoral nerve. Diagnosis was established by the clinical presentation and electromyographic examination. In the few reported cases of such injuries, the cause was trauma to this region. However, in both of our patients, focal muscle atrophy gradually developed after initiation of training schedules to increase the cross-section of the major pectoral muscle; we therefore assume that compression injury to the nerve by repetitive muscle contractions may be of pathogenic relevance. Anatomical studies of this region showed that the nerve branches of the lateral pectoral nerve, having to pierce through a connective tissue septum that is thicker here by a few millimeters, may be subjected to additional risk of compression. Early recognition and treatment are vital to prevent associated morbidity of these rare but serious injuries.

During dissection practice, a cutaneous branch to the deltoid region, which originated from the lateral pectoral nerve, was found bilaterally in one Japanese male (two of 125 sides, 1.6%). The branch originated from the superior surface of the lateral pectoral nerve, ran on the superior surfaces of the coracoid process and the coraco-acromial ligament, and pierced the deltoid muscle close to the tip of the acromion. The distribution area of this cutaneous branch was similar to the cutaneous branch of the suprascapular nerve. Although the branch from the suprascapular nerve has been reported in man and primates, a minute description of such a branch from the lateral pectoral nerve is not currently available in the literature. According to the detailed analyses of the roots of the lateral pectoral nerve and the suprascapular nerve, the roots of both nerves are close to each other in the upper part of the superior trunk of the brachial plexus. Therefore, these cutaneous branches have different courses, but are considered to be a single nerve to complement the supraclavicular nerves.

The purpose of this study was to document the distribution of the articular branch of the lateral pectoral nerve (LPN) to the shoulder and to identify a suitable point for its blockade. This study involved the dissection of 43 shoulders of 22 unembalmed cadavers (6 male and 16 female) to identify the LPN and its articular branch to the shoulder. To identify the suitable anatomical point for blocking the articular branch of the LPN, several anatomical landmarks around the shoulder were measured. The articular branch of the LPN to the shoulder was present in 29 of 43 cases (67.4 %). The appropriate point to block the articular branch of the LPN was identified at a mean distance of 1.5 cm below the clavicle, on the line connecting the closest points between the clavicle and the coracoid process, and at a mean depth of 1.0 cm from the skin. The articular branch of the LPN to the shoulder, as well as the muscular and cutaneous branches of the LPN, covers a portion of the shoulder joint with suprascapular and axillary nerves. Surgeons might consider a peripheral block of the suprascapular, axillary, and LPNs to provide maximum block coverage after shoulder joint surgery.

The lateral pectoral nerve (LPN) is commonly injured along with the brachial plexus, but its isolated lesions are rare. Here, we present a case of an isolated LPN lesion confused with cervical radiculopathy. A 41-year-old man was admitted to our clinic because of weakness in his right arm. Previous magnetic resonance imaging (MRI) examination revealed right posterolateral protrusion at the C6-7 level. At the initial assessment, atrophy of the right pectoralis major muscle was evident, and mild weakness of the right shoulder adductor, internal rotator, and flexor muscles was observed. Therefore, electrodiagnostic evaluation was performed, and a diagnosis of isolated LPN injury was made. Nerve injury was thought to have been caused by weightlifting exercises and traction injury. Lateral pectoral nerve injury can mimic cervical radiculopathy, and MRI examination alone may lead to misdiagnosis. Repeated physical examinations during the evaluation and treatment phase will identify the muscle atrophy that occurs 1 or more months after the injury.

Introduction: This anatomical study of the pectoral nerves and their innervation is to provide detail informations on the pectoral nerves and their variations in their course, to guide the cosmetic and plastic surgeons for their easy intra operative localization and to improve the understanding of the pectoral muscle innervation, which is very much required during breast reconstruction after modified radical mastectomy (MRM) in breast cancer; axillary dissection; removal of the pectoralis minor muscle, and in harvesting the pectoralis major for myocutaneous head and neck island flap surgeries. Materials and Methods: A total of 50 pectoral region specimens (both right and left sided) from 25 embalmed adult human cadavers (20 female & 05 male) were studied by dissection method. Statistical Analysis: The data were tabulated in Microsoft excel and analysed by using Statistical Package for Social Science (SPSS 17th version). Mean, Proportion, Standard deviation and Unpaired t-test were applied for analysing the data obtained. Result and Conclusion: In all the specimens, the medial pectoral nerve pierces the pectoralis minor muscle; but as a single trunk in 76%, and as dividing branches in 34% specimens. The extent of costal attachment of the pectoralis minor muscle found to be less than 6.0 cm in cases of the medial pectoral nerve piercing the pectoralis minor muscle as a single trunk. The medial pectoral nerve after piercing the pectoralis minor, ramify within the muscle supplying it, finally runs along the lateral aspect (lower border) of the pectoralis minor muscle to supply the lower portion or distal segment of the pectoralis major muscle. Similarly, the lateral pectoral nerve runs along the upper border (medial aspect) of the pectoralis minor muscle (98%) and then runs under surface of the pectoralis major muscle along with the pectoral branch of thoracoacromial artery, supplying the upper portion or most of the proximal 2/3rd of the pectoralis major muscle. Therefore, when the pectoralis minor muscle is removed in a modified radical mastectomy or during dissection between the two muscles, there is partial denervation of the pectoralis major muscle with partial atrophy and decrease in muscle mass. If the lateral pectoral nerve also injured along with the medial pectoral nerve, it can result in total denervation of the pectoralis major muscle with severe atrophy and fibrosis. In breast augmentation implants placing behind the pectoralis major muscle, it is found to be more advantageous if the pectoralis major muscle is partially denervated for the better projection and contour. The distance of the branches of the medial pectoral nerve and the lateral pectoral nerve in the pectoral muscles from the lateral margin of the sternum being 8.8-10.8 cm and 5.8-10.2 cm respectively. The proximal segment or upper portion of the pectoralis major muscle has got separate independent vascular and nerve supply; therefore, it can be safely used as a myocutaneous flap in surgeries of head and neck or anterior chest wall.

Knowledge of normal and anomalous formation of brachial plexus and its branches is of utmost importance to anatomists, clinicians, anesthesiologists and surgeons. Possibility of variations in the origin, course and distribution of branches of brachial plexus must be kept in mind during anesthetizing the brachial plexus, mastectomy and plastic surgery procedures. In the current case, the medial pectoral nerve arose directly from the middle trunk of the brachial plexus and the lateral pectoral nerve arose from the anterior division of the upper trunk of the brachial plexus. The lateral pectoral nerve supplied the pectoralis major and the medial pectoral nerve supplied pectoralis major and pectoralis minor muscles through two separate branches.

Background: The deltoid muscle is innervated by the axillary nerve. There is no collateral nerve supply described for this muscle. Palsy of the axillary nerve is common in shoulder trauma due to its close relationship to the surgical neck of humerus. Methods: A dissection of the pectoral and axillary regions of two female cadavers was performed bilaterally for a detailed analysis of the innerva- tion of the deltoid muscle. Results: A branch of the lateral pectoral nerve provided supplemental innervation to the anterior portion of the deltoid muscle bilaterally in both cadavers. Conclusion: A branch of the lateral pectoral nerve could provide collat- eral nerve supply to the deltoid muscle. The frequency of this anatomical variation requires further exploration. Anat. Rec. 249:506-509, 1997.

Microvascular free tissue transfer has revolutionized head and neck reconstruction and currently is considered the most successful and reliable method of primary oromandibular reconstruction. This study was designed to assess the feasibility of full thickness free vascularized transfer of the clavicle based on the clavicular branch of the thoracoacromial artery and the soft tissue component associated with the thoracoacromial axis. Forty dissections of the pectoral region were performed on 26 cadavers. The anatomic relations of the region and the thoracoacromial arterial and venous systems were documented in detail. Selective ink injections of the thoracoacromial arterial branches were also performed on fresh cadavers. The clavicle was supplied mainly by the clavicular artery (medial three quarters), with minor contribution from the deltoid artery (lateral quarter). An average of 16.1 cm (range of 12 to 20 cm) was obtained with total clavicular harvest and the clavicle had sufficient width and height to support dental implants. Two soft tissue donor sites were associated with the thoracoacromial artery: the sternocostal head of the pectoralis major muscle, with the overlying skin supplied by the pectoral artery, and the clavicular head of the pectoralis major muscle, with the overlying skin supplied by the deltoid and clavicular arteries. Sensory innervation of the upper chest was supplied through the supraclavicular nerves, whereas the lateral pectoral nerve supplied motor innervation to both heads of the pectoralis major muscle. The anatomy of the clavipectoral donor site and the first case of full thickness free clavicular transfer for mandibular reconstruction in the English literature are presented. The donor site is an excellent source of well vascularized, thin, pliable, hairless, potentially innervated (motor and sensory) soft tissue, along with up to 20 cm of clavicular bone. The surgical anatomy is familiar to the head and neck surgeon. The harvesting does not require repositioning of the patient and is amenable to a two-team, simultaneous approach. The functional and cosmetic donor site morbidity is minimal even with clavicular harvest. The major disadvantage of this flap is the relatively short pedicle. The authors conclude that the thoracoacromial system provides a free flap with osseous and soft tissue components that are well suited for oromandibular reconstruction.

Summary: Breast surgery is one of the most frequently performed surgeries in hospitals and can be associated with significant postoperative pain. We report a novel technique of intraoperative lateral pectoral nerve block under direct vision for analgesia post subpectoral implant placement for breast reconstruction.

Ansa pectoralis neurotomy is a surgical approach in the treatment of the pectoralis major muscle spasticity causing an attitude in adduction and internal rotation of the shoulder.To establish the anatomical landmarks allowing an easier localisation of the ansa pectoralis during neurotomy.Fifteen adult human cadavers (10 embalmed and 5 fresh) were dissected in order to determine anatomical landmarks allowing an easier localization of the ansa pectoralis during neurotomy.In all the cadavers, the lateral pectoral nerve arose from the lateral cord of the brachial plexus, 0.2 cm above to 1.5 cm below the inferior border of the clavicle with a mean distance of 0.76 cm for left and right side, whereas the medial pectoral nerve arose from the medial cord of the brachial plexus, 0.7-2.3 cm below the inferior border of the clavicle with a mean distance of 0.61 cm for the left side and 0.68 cm for the right side. We systematically found both the origin of pectoral nerves and the ansa pectoralis at the level of the middle third of the distance between the sternoclavicular and the acromioclavicular joints. Moreover, ansa pectoralis was constantly localized lateral to the thoracoacromial artery. In four cases, the division of the lateral pectoral nerve was not found. In one case, medial pectoral nerve did not exist.Ansa pectoralis can be found by a curved incision made at the mid-third of the distance between the sternoclavicular and the acromioclavicular joints, the medial point being located just below the lower edge of the clavicle and the lateral point 2 cm below the inferior edge of the clavicle.

Weight lifting has occasionally been associated with focal neuropathies of unknown cause. We describe a case of progressive bilateral medial pectoral neuropathy in a body builder. Whereas the medial pectoral nerve passes through pectoralis minor to reach the pectoralis major, the lateral pectoral nerve has no such intramuscular course. We postulate that weight lifting and concomitant pectoralis minor hypertrophy in our patient produced intramuscular entrapment of the medial pectoral nerves.

During modified radical mastectomy or cosmetic surgery, denervation of the lower part of the pectoralis major frequently occurs and may reduce muscle spasm, with consequent better reconstruction of the breast. The aim of this study was to determine the relationship between the pectoral nerves and the pectoral muscles. Eight unembalmed female cadavers were dissected and vascular and radiologic studies performed. The lateral pectoral nerves showed a constant course, parallel to the thoraco-acromial vessels. They coursed for 55 +/- 7 mm inferomedially on the deep surface of pectoralis major, under its fascia. The medial pectoral nerves showed two main patterns of branching, which correlated with the extent of the costal attachments of the pectoralis minor muscles. In pattern A (56%), associated with costal attachments narrower than 6.0 cm, the nerve pierced the deep aspect of the pectoralis minor as a single trunk, ramified in the muscle, and gave some branches that appeared on the superficial aspect to enter the pectoralis major. In pattern B (44%), associated with costal attachments wider than 6.6 cm, the nerve divided before entering pectoralis minor and its branches passed through the muscle or round its lower border to reach pectoralis major. The most medial branch of the medial pectoral nerve directed to the pectoralis major muscle emerged from pectoralis minor at the third intercostal space in the midclavicular line, a mean of 10.3 cm lateral to the margin of the sternum. Knowledge of the relationship between the extent of the costal attachment of pectoralis minor and the two patterns of branching of the medial pectoral nerve may be useful when performing elective denervation of the major pectoralis muscle.

The aim of this study was to measure the motor conduction time (MCT) and velocity of the lateral pectoral nerve (LPN) in normal subjects and patients with neuropathy. For the LPN, we determined that the average AICT was 3.9 m/s using Erb stimulation with needle recording, and the average motor conduction velocity was 70.6 m/s using Erb stimulation and axilla stimulation with needle recordings in normal subjects. In patients, prolonged MCT in LPN was found in 3 of 6 Patients with unilateral plexopathy and 3 of 4 patients with polyneuropathy. If was determined that MCT and motor conduction velocity in LPN was as sensitive as biceps brachii MCT in patients with unilateral plexopathy. Furthermore, the motor conduction velocity in the LPN may be beneficial to elucidate the localization of involvement in polyneuropathies, such as distal or proximo-distal.

In head and neck reconstructive surgery, the pectoralis major musculocutaneous flap is a major reconstructive tool, both in primary as well as secondary reconstructions. In a few cases the authors have been able to demonstrate that when the pectoralis major musculocutaneous flap is translocated to the mouth through a noncompromised neck tunnel, as is done for head and neck reconstructions, the taut lateral pectoral nerve is seen to compress the vascular pedicle of the flap, adversely affecting its vascularity, which can lead to partial or total necrosis of the flap. The authors explain this feature, very specific to this flap, with the help of a prospective series of patients.

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.

It has previously been shown that in 62% of patients the medial pectoral nerve courses through the pectoralis minor muscle to innervate the lower half or two thirds of the pectoralis major muscle. In the other 38% of patients, the medial pectoral nerve exits around the lateral aspect of the pectoralis minor muscle. The lateral pectoral nerve courses on the undersurface of the pectoralis major muscle, innervating the proximal one third or more of the muscle. Consequently, when the pectoralis minor muscle is removed in a modified radical mastectomy, or dissection between the two muscles is performed, there is partial deinnervation of the pectoralis major muscle with partial atrophy and a decrease in size. Further, if the lateral pectoral nerve also is injured or removed, it can result in total deinnervation of the pectoralis major muscle with more severe atrophy and fibrosis of the muscle. In cosmetic augmentations, when the breast implant is placed behind the pectoralis major muscle, that muscle is partially deinnervated. In this clinical situation, this is believed to be advantageous because it allows the breast to project better. This paper details the anatomy of the pectoral nerves and discusses the clinical implications of surgery in this region as it relates to the size and function of the pectoral muscles.

The upper part of the pectoralis major muscle is innervated by the medial pectoral nerve, whereas the lateral pectoral nerve supplies approximately the lower third of the muscle. The lateral pectoral nerve is closely associated with the pectoralis minor muscle, with its branches passing through or around the lateral margin of the muscle, or both. As a result, the nerve may be compromised during division, retraction or removal of the pectoralis minor muscle and during resection of the central and anterior lymph nodes. The medial pectoral nerve distributes with the thoracoacromial vessel branches, and both should be avoided during removal of the lymph nodes at the apex of the axillary space. Injury to the lateral pectoral nerve by accidental division or by evulsion produces variable postoperative atrophy, fibrosis and shortening of the lower third of the pectoralis major muscle, with limitation of shoulder motion and change in the cosmetic contour of the pectoral region of the chest. Routine removal of the pectoralis minor muscle and the lateral pectoral nerve as described by Patey and Handley during their modified mastectomy is not recommended because of the loss of innervation of the lower part of the pectoralis major muscle. The medial and lateral pectoral nerves described herein were named according to their anatomic position in the pectoral area. Furthermore, it is suggested that the use of the terms medial and lateral as applied to these pectoral nerves should denote their actual course, location and distribution and not perpetuate the confusing traditional practice of reversing the names of these nerves on the basis of their origin.

The "island" pectoralis major myocutaneous flap has been used in nine patients for immediate hypopharyngeal and cervicoesophageal reconstruction following laryngopharyngectomy. Two patients underwent total hypopharyngeal and cervicoesophageal reconstruction. Postoperative evaluation revealed adequate lumens with no evidence of stricture. There was retained innervation of the flaps through the lateral pectoral nerve, but no additional innervation from the cricopharyngeal musculature could be demonstrated. Normal esophageal motility was maintained, but cervicoesophageal pressures were diminished. Donor site morbidity was minimal, and the complication rate was low. We present the pectoralis major myocutaneous flap as an alternate method for hypopharyngeal and cervicoesophageal reconstruction.