Analysis of the positional relationship of the long thoracic nerve considering clinical treatment.

INTRODUCTION: The long thoracic nerve (LTN) has a risk of being damaged during chest surgery and should be considered when performing anesthesia such as a serratus anterior plane block (SAPB). We analyzed the relationship between landmarks-the fourth to ninth intercostal space (ICS) at the midaxillary line (MAL), through which the distal part of the LTN passes-and the LTN. MATERIALS AND METHODS: We used 25 specimens from 17 embalmed Korean cadavers. The MAL, level of rib and ICS, and regions 5 cm anteroposterior to the MAL (aMAL/pMAL) were established to measure the position of the LTN crossing the MAL, pathway of the LTN, and entering points of the LTN to the SA. RESULTS: The LTN crossed the MAL in 76% of the specimens. The LTN crossed the MAL within the fifth to sixth rib level in 70.8%. Seventy-six percent of the branches entered the SA within the fourth to sixth ICS. The fifth rib and ICS were the most frequent regions aMAL; however, several branches were found pMAL. The LTN entered the SA in 92.6% of the specimens within 3 cm anterior and 1 cm posterior to the MAL. CONCLUSIONS: We set the danger zone as 4 cm near the MAL at the fourth to sixth ICS for thoracotomy. In addition, we proposed the fifth ICS in aMAL at the superficial plane as the alternative injection point for SAPB when blocking the LTN, and the fifth ICS in pMAL at the deep plane to prevent blocking the LTN.

Anatomical Evaluation of a Conventional Pectoralis II Versus a Subserratus Plane Block for Breast Surgery.

BACKGROUND: Pectoralis I and II (Pecs I/Pecs II) blocks are modern regional anesthetic techniques performed in combination to anesthetize the nerves involved in breast surgery and axillary node dissection. Pecs II spread and clinical efficacy is thought to be independent of whether injection occurs between pectoralis minor and serratus anterior or deep to serratus anterior. Injecting deep to serratus anterior onto the rib may be technically easier; however, our clinical experience suggests that this approach may be less effective for axillary dissection. We undertook a cadaveric study to evaluate a subserratus plane approach for use in breast and axillary surgery. METHODS: Ultrasound-guided blocks using methylene blue dye were performed on 4 Genelyn-embalmed cadavers to assess and compare dye spread after a conventional Pecs II and a subserratus plane block at the third rib. RESULTS: Conventional Pecs II injection demonstrated staining of the intercostobrachial nerve, third intercostal nerve, thoracodorsal nerve, long thoracic nerve, medial pectoral, and lateral pectoral nerve. The subserratus plane produced significantly less axillary spread, incomplete staining of the medial pectoral, and very minimal staining of the lateral pectoral nerve. Dye spread was limited to the lateral cutaneous branches of the intercostal nerves in both injections. CONCLUSIONS: In our cadaveric study, injecting deep to serratus plane produced significantly less axillary spread. For breast surgery excluding the axilla, both techniques may be effective; however, for axillary dissection, the conventional Pecs II is likely to produce superior analgesia and additionally may help achieve complete coverage of the deeper pectoral nerve branches.

Origin and distribution of the brachial plexus of the Van cats.

Knowing the structure and variations of the plexus brachialis is important in neck and shoulder surgery. The knowledge of the brachial plexus reduces the injury rate of the nerves in surgical interventions to the axillary region. The major nerve trunks of the thoracic limb were the suprascapular, subscapular, axillary, radial, musculocutaneous, median and ulnar nerves. In Van cats, the brachial plexus was formed by the ventral branches of the spinal nerves, C6-C7-C8 and T1. The 7th cervical nerve was quite thick compared to the others. The subscapular nerve was the thinnest (on the right side, the average length was 6.55 ± 0.60 mm and on the left side was 6.50 ± 0.60 mm), and the radial nerve was the thickest (the average length on the right side was 28.48 ± 0.44 mm and on the left side was 29.11 ± 0.55 mm). The suprascapular nerve was formed by the ventral branch of the 6th cervical nerve. The subscapular nerves were formed by a branch originating from the 6th cervical nerve and the two medial and caudal branches originating from the 7th cervical nerve. No communicating branch between the ulnar nerve and the median nerve was observed in the palmar region. The axillary nerve was formed by the ventral branches of the 7th nerve, the musculocutaneous nerve was formed by ventral branches of the 6th and 7th cervical nerves, and the ulnar nerve was formed by ventral branches of the 8th cervical and the 1st thoracic nerves. The radial nerve was the thickest branch in the brachial plexus. In Van cats, the origin and distribution of nerves were similar to those reported in the literature for other species of cats, with the exception of the suprascapular, subscapular and axillary nerves.

The pecs anesthetic blockade: A correlation between magnetic resonance imaging, ultrasound imaging, reconstructed cross-sectional anatomy and cross-sectional histology.

The interfascial thoracic wall blockades Pecs I and Pecs II are increasingly applied in breast and axillary surgery. Despite the clear anatomical demarcations depicted at their introduction, the clinical outcome is more variable than would be expected based upon the described anatomy. In order to elucidate factors that explain this variability, we evaluated the spread of each injection-medial Pecs I, lateral Pecs I, the deep injection of the Pecs II-separately. A correlation of in vivo landmarks and ultrasound images with ex vivo ultrasound, reconstructed anatomical planes, histology and magnetic resonance imaging. The medial Pecs I, similar to the sagittal infraclavicular block positioning with needle position medial to the pectoral branch of the thoracoacromial artery, reaches the medial and lateral pectoral nerves. The lateral Pecs I, below the lateral third of the clavicle at the level of the third rib with needle position lateral to the pectoral branch of the thoracoacromial artery, additionally spreads to the axilla and reaches the intercostobrachial nerve. The deep Pecs II injection spreads to the lateral cutaneous part of the III-VI intercostal nerves and reaches the long thoracic nerve. The variability of the Pecs anesthetic blockades is driven by the selected Pecs I approach as only the lateral approach stains the intercostobrachial nerve. The pectoral branch of the thoracoacromial artery can serve as the landmark to differentiate the needle position of the medial and lateral Pecs I block. Clin. Anat. 32:421-429, 2019. © 2019 Wiley Periodicals, Inc.

Predictable Location of Breast Sensory Nerves for Breast Reinnervation.

The sensory innervation to the breast originates from the medial and lateral cutaneous branches of the third to fifth intercostal nerves, which are at risk for injury or loss during mastectomy. Providing reinnervation after mastectomy was introduced almost 20 years ago, but it is not widely performed, perhaps because of the difficulty of locating a recipient nerve. The authors have performed cadaveric dissections to allow for precise anatomical localization of the lateral intercostal branch providing breast sensation. Bilateral chest dissections were performed on 10 female cadavers. The lateral intercostal nerve providing sensation to breast tissue was identified. The distances from the sternum, the midclavicular line, and the lateral pectoralis minor-in addition to nerve diameter-were measured. The nerve was successfully identified bilaterally in all cadavers. The majority of nerves (16 of 20) exited from under the fourth rib. The average distance from the sternum was 13.1 ± 1.3 cm (range, 10 to 15 cm) and the average distance from the midclavicular line was 11.8 ± 2.2 cm (range, 8 to 16 cm). The nerve exited at the lateral border of the pectoralis minor or within 2 cm from the lateral border for all cadavers. The diameter of the nerve was consistently 2 mm. The nerve traveled under the thoracodorsal vessels, aiding in identification. The authors identified the predictable location of the lateral intercostal nerve providing sensation to the breast. The authors hope that by enabling surgeons to locate this nerve, more well-conducted studies will be performed investigating techniques and outcomes for breast reinnervation.

Pectoral Block Failure May Be Due to Incomplete Coverage of Anatomical Targets: A Dissection Study.

BACKGROUND AND OBJECTIVES: The popularization of ultrasound-guided nerve blocks in cosmetic and reconstructive breast surgery calls for better anatomical understanding of chest wall innervation. When inserting subpectoral implants, pain from pocket dissection, stretching of muscle, and release of costal attachments may be relieved by blocking the pectoral nerves in the interpectoral (IP) space.We describe the variable anatomy of the pectoral nerves in the IP space in order to define the area to be covered for sufficient blockade, based on cadaver dissections. METHODS: Twenty-six fresh cadavers were dissected bilaterally. The number, location, and course of the pectoral nerves were recorded. Distances to surface landmarks (sternum, clavicle, and costae) and ultrasound landmarks (thoracoacromial artery [TAA] and pectoralis minor muscle [Pm]) were recorded. RESULTS: The lateral pectoral nerve and the TAA entered together into the IP space 8.9 cm (range, 8.0-12.0 cm) lateral to the midsternal line. The medial pectoral nerve (MPN) had between 1 and 4 branches that pierced the Pm, and 69% had additional branches lateral to the Pm. The muscle-piercing MPN branches were located 3.8 cm (range, 0.4-8.1 cm) and the lateral MPN branches 5.4 cm (range, 3.0-8.4 cm) from the lateral pectoral nerve. The IP course was 2.6 cm (range, 0.7-6.5 cm). All specimens were asymmetrical in location or number of MPN branches. CONCLUSIONS: The MPN branches that innervate the lower part of the pectoralis major muscle are asymmetrical and variable in location and length; all located in a triangular area easily defined by sonographic landmarks, lateral to the TAA.

Variations of Cords of Brachial Plexus and Branching Pattern of Nerves Emanating From Them.

Brachial plexus is complex network of nerves, formed by joining and splitting of ventral rami of spinal nerves C5, C6, C7, C8, and T1 forming trunks, divisions, and cords. The nerves emerging from trunks and cords innervate the upper limb and to some extent pectoral region. Scanty literature describes the variations in the formation of cords and nerves emanating from them. Moreover, the variations of cords of brachial plexus and nerves emanating from them have iatrogenic implications in the upper limb and pectoral region. Hence study has been carried out. Twenty-eight upper limbs and posterior triangles from 14 cadavers fixed in formalin were dissected and rare and new variations of cords were observed. Most common variation consisted of formation of posterior cord by fusion of posterior division of upper and middle trunk and lower trunk continued as medial cord followed by originating of 2 pectoral nerves from anterior divisions of upper and middle trunk. Other variations include anterior division of upper trunk continued as lateral cord and pierced the coracobrachialis, upper and middle trunk fused to form common cord which divided into lateral and posterior cords, upper trunk gave suprascapular nerve and abnormal lateral pectoral nerve and formation of median nerve by 3 roots. These variations were analyzed for diagnostic and clinical significance making the study relevant for surgeons, radiologists in arresting failure patients and anatomists academically in medical education.

Anatomical study of prefixed versus postfixed brachial plexuses in adult human cadaver.

BACKGROUND: The brachial plexus is usually formed by the fusion of anterior primary rami of the fifth to eighth cervical and the first thoracic spinal nerves. Variations in the formation of the brachial plexus may occur. Variations in brachial plexus anatomy are important to radiologists, surgeons and anaesthesiologists performing surgical procedures in the neck, axilla and upper limb regions. These variations may lead to deviation from the expected dermatome distribution as well as differences in the motor innervation of muscles of the upper limb. This study is aimed to describe the anatomical variations of brachial plexus in its formation among 20 Ethiopian cadavers. METHODS: Observational based study was conducted by using 20 cadavers obtained from the Department of Human Anatomy at University of Gondar, Bahir Dar, Addis Ababa, Hawasa, Hayat Medical College and St Paul Hospital Millennium Medical College. Data analysis was conducted using thematic approaches. RESULTS: A total of 20 cadavers examined bilaterally for the formation of brachial plexus. Of the 40 sides, 30 sides (75%) were found normal, seven sides (17.5%) prefixed, three sides (7.5%) postfixed and one side of the cadaver lacks cord formation. CONCLUSION: The brachial plexus formation in most subjects is found to be normal. Among the variants, the numbers of the prefixed brachial plexuses are greater than the postfixed brachial plexuses.

Neurovascular distribution within the abdominal head of the pectoralis major muscle: Application to breast and flap surgery.

The abdominal head of the pectoralis major (AHPM) is important in cosmetic and flap surgeries. Few studies have reported on its neurovascular entry points and distribution patterns. We aimed to determine the entry points and distribution patterns of the neurovascular structures within the AHPM. Thirty-two hemithoraxes were dissected, and the distribution patterns of the neurovascular structures were classified into several categories. The neurovascular entry points were measured at the horizontal line passing through the jugular notch (x-axis) and the midclavicular line (y-axis). The AHPM was innervated by the communication branches of the medial pectoral nerve (MPN) and the lateral pectoral nerve (LPN) in 78.1% of the specimens and of the MPN without the communication branches in 21.9%. All the LPNs had communication branches, which could be classified as independent in 46.9% of the samples, with the MPN in 21.9%, and with the LPN in 9.3%. The blood supply of the AHPM was composed of branches from the lateral thoracic artery (LTA) in 62.5% of the specimens, the thoracoacromial artery (TA) in 15.6%, and the LTA with the TA in 21.9%. The mean distance of the entry point was 6.3 cm ± 1.3 cm lateral to the y-axis, 8.1 cm ± 3.3 cm below the x-axis in the nerves, 6.5 cm ± 1.2 cm lateral to the y-axis, and 8.6 cm ± 3.0 cm below the x-axis in the arteries. This study defined the average neurovascular entry point and distribution pattern in detail using standard lines to enable the AHPM to be better understood.

Lesiones del nervio torácico largo de Bell. Revisión de conceptos terapéuticos / Long thoracic nerve of Bell. Review of therapeutic management

Las lesiones del nervio torácico producen parálisis del serrato anterior y originan una deformidad característica (escápula alata), que genera debilidad y alteraciones importantes en la movilidad del hombro. En esta revisión, se analizan conceptos sobre anatomía, etiología, presentación clínica y alternativas terapéuticas.

The long thoracic nerve injuries are manifested by a characteristic deformity called scapula alata, causing weakness, and impaired shoulder mobility. In this review current concepts of the anatomy, etiology, clinical presentation and therapeutic management are analyzed.

Anatomic sites of origin of the suprascapular and lateral pectoral nerves within the brachial plexus.

BACKGROUND: The goal of this study was to clarify the anatomical origins of the suprascapular and lateral pectoral nerves from the brachial plexus as an aid to surgical exploration. METHODS: Both nerves were studied in 100 adult cadaver specimens. Topographic points of origin were described as distance from the bifurcation of the upper trunk or distance from the formation point of the lateral cord, using visual anatomical models. RESULTS: The suprascapular nerve originated from (1) the posterior division of the upper trunk distal to the bifurcation of the upper trunk (61 specimens); (2) the point of upper trunk bifurcation (29 cases); (3) the upper trunk proximal to the bifurcation point (six cases); and (4) directly from the C5 root (four cases). The lateral pectoral nerve originated from (1) the anterior division of the upper trunk proximal to the point of lateral cord formation (88 cases); (2) the point of lateral cord formation (five cases); (3) the lateral cord distal to the lateral cord formation point (four cases); and (4) the anterior division of the middle trunk (three cases). Eighty-two cases had origins from both the anterior upper trunk and the anterior middle trunk. CONCLUSIONS: The suprascapular nerve most frequently originates from the posterior division of the upper trunk, and the lateral pectoral nerve from the anterior divisions of the upper and middle trunks. This information can be used to guide the surgeon in identifying the key landmarks of the supraclavicular brachial plexus at surgical exploration.

The anatomy of the pectoral nerves and its significance in breast augmentation, axillary dissection and pectoral muscle flaps.

BACKGROUND: In many plastic surgeries, a detailed understanding of the pectoral nerve anatomy is often required. However, the information available on the anatomy of pectoral nerves is sparse and unclear. The purpose of this study is to provide detailed anatomical information on the pectoral nerves to allow for their easy intra-operative localisation and to improve the understanding of the pectoral muscle innervation. METHODS: We dissected 26 brachial plexuses from 15 fresh cadavers. The origins, locations, courses and branches of the pectoral nerves were recorded. RESULTS: We found three constant branches of the pectoral nerve. The superior branch travelled in a straight course to the pectoralis major to innervate the clavicular aspect. The middle branch coursed on the under-surface of the pectoralis major near the pectoral branch of the thoraco-acromial artery to innervate the muscle's sternal aspect. The inferior branch passed beneath the pectoralis minor muscle to innervate the pectoralis minor muscle and the costal aspect of the pectoralis major muscle. CONCLUSIONS: Knowing the pectoral nerves' origins, courses and connections, in addition to understanding the functional consequences of iatrogenically severing these nerves, leads to a better understanding of the pectoral muscle's innervation. Precise anatomical data on the pectoral nerve allow for its easy localisation during axillary breast augmentation, axillary dissection, removal of the pectoralis minor muscle and harvesting the pectoralis major muscle island flap.

The existence of axillary arch in human fetus and applied importance and clinical implications in the axillary brachial plexus blocks / La existencia de arco axilar en el feto humano y la importancia aplicadae implicancias clínicas en los bloques de plexo braquial

Axillary arch is the most common muscle variation of axillary fossa that gains importance for regional interventional procedures, screening methods and physical examination. In order to avoid malpractice the variations must be borne in mind. This study has been planned to research the frequency and the features of the axillary arch in human fetus, to mention the potential clinical and functional significance of axillary arch while applying axillary brachial plexus block and reflect on possible complications. Axillary fossa was examined with a stereomicroscope in 20 upper extremities of ten human fetuses. The gestation ages ranged from 16 to 36 weeks. Axillary arch was determined in 2/20 specimen unilaterally. In both specimen, muscular slip detached from latissimus dorsi, passed anterior neurovascular bundle and ended posterior pectoralis major tendon and lateral border of intertubercular groove. In one specimen axillary arch was innervated with medial pectoral nerve whereas the other one did not have a particular innervating nerve branch. The possible effects of axillary arch in the axillary brachial plexus block applications are discussed. Arcus axillaris may have a potential clinical and functional significance with regard the axillary brachial plexus block applications and may have possible effects on failure rate and acute complications. Also, we think that this fetus study which the pure structure of the muscles without any usage effect can be observed will be beneficial regarding this topic.

El arco axilar es la variación muscular más común de la fosa axilar, siendo de importancia para la región en los procedimientos de intervención, los métodos de selección y el examen físico. Con el fin de evitar las negligencias se debe tener en cuenta las variaciones. El objetivo de este estudio fue determinar la frecuencia y las características del arco axilar en el feto humano. Es necesario mencionar la importancia del potencial clínico y funcional del arco axilar en la aplicación de bloqueo axilar del plexo braquial y sus posibles complicaciones. La fosa axilar fue examinada bajo microscopio estereoscópico en 20 miembros superiores de diez fetos humanos. La edad de gestación varió de 16 a 36 semanas. El arco axilar se observó unilateralmente en 2/20 especímenes. En ambos especímenes el músculo cruzó anteriormente el paquete neurovascular y terminó en el tendón del músculo pectoral mayor y en el margen lateral del surco intertubercular. En un especimen el arco axilar se encontraba inervado por el nervio pectoral medial, mientras que en el otro no existía una determinado ramo del nervio. Se discuten los posibles efectos del arco axilar en las aplicaciones de bloqueo axilar del plexo braquial. Puede tener un significado potencial clínico y funcional, en lo que se refiere a la aplicación de bloqueo axilar del plexo braquial y aademás producir efectos de complicaciones agudas.

Back to the debate: sternalis muscle / Volver al debate: músculo esternal

The sternalis muscle (SM) is an anatomical variant found in the anterior thoracic wall. While the attachment sites of SM are generally agreed upon, the innervation and function of this muscle are not well established. Cadaveric and surgical explorations to date report that SM is innervated by either the pectoral nerves or the anterior branches of the intercostal nerves, or a combination of both. Knowledge of SM is relevant to health care providers specialising in imaging and/or surgery of the anterior thoracic wall. This paper aims to raise awareness in the medical community of the clinical relevance of SM through two case reports and a brief literature review.

El músculo esternal (ME) es una variante anatómica en la pared torácica anterior. Mientras que los sitios de fijación del ME estan acordados, la inervación y la función de este músculo no están bien establecida. Exploraciones cadavéricas y quirúrgicas han informado que el ME está inervado por los nervios pectorales o ramos anteriores de los nervios intercostales, o una combinación de ambos. El conocimiento del SE es relevante para los proveedores de atención de salud especializada de imágenes y/o cirugía de la pared torácica anterior. Este documento tiene como objetivo crear conciencia en la comunidad médica de la relevancia clínica de ME a través de dos reportes de caso y una breve revisión bibliográfica.

Innervation of the pectoralis major muscle: anatomical study.

BACKGROUND: Owing to the diverse application of the pectoralis major muscle (Pmaj) in reconstructive surgery, with special reference to its safe and functional transfer, a precise knowledge of its nerve supply becomes mandatory. The aim of the present study was to investigate its innervations. METHODS: A total of 30 specimens of pectoral regions pertaining to 15 embalmed adult human cadavers, aged between 30 and 67 years (10 males, 5 females), were dissected in pursuit of this aim. RESULTS: The proximal and the upper third of the distal segments of the muscle were constantly supplied by the ventral division, through medial and lateral branches, and the dorsal division of the lateral pectoral nerve, respectively. The ventral branches of either the pectoral loop (in 26/30 specimens) or the medial pectoral nerve (MPN) (4/30) penetrated the upper third of the pectoralis minor to supply the lower two-thirds of the distal segment of the Pmaj through 1 or 2 branches. Concomitantly, the dorsal branch of either the MPN (26/30) or the pectoral loop (4/30) supplied the posterior limb of its tendon. The fourth intercostal nerve participated in the inferolateral muscle supply (4/30). CONCLUSIONS: The muscle is mainly innervated by the lateral pectoral nerve supplemented by the branches of the MPN. The proximal segment, having a separate nerve, allows its functional transfer. Care should be practiced whenever the distal segment is to be harvested, because of having multiple nerves.

Surgical anatomy of the pectoral nerves and the pectoral musculature.

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.

Transfer of pectoral nerves to suprascapular and axillary nerves: an anatomic feasibility study.

PURPOSE: We conducted an anatomic study to provide detailed information on the pectoral nerves and anatomic data on the transfer of the pectoral nerves to the axillary nerve. Moreover, we experimentally determined the feasibility of transferring the pectoral nerves to the suprascapular nerve in upper brachial plexus injury. METHODS: We dissected 26 brachial plexus from 15 fresh cadavers. The origin, location, course, and branching of the pectoral nerves were recorded. The length and the diameter of the pectoral nerves were measured. The diameter of the suprascapular and axillary nerves was recorded. In all dissections, we assessed the feasibility of directly transferring the pectoral nerves to the suprascapular and axillary nerves. RESULTS: We found 3 constant branches of pectoral nerves arising from 3 distinct origins in 20 cases, and 3 constant branches arising from 2 distinct origins in 6 cases. The C7 sent nerve fibers to all 3 branches. The average length and diameter of the superior, middle, and inferior branches of the pectoral nerves were 65 mm, 110 mm, and 105 mm, and 2.0 mm, 2.3 mm, ad 2.4 mm, respectively. The average diameter of the suprascapular and axillary were 2.8 mm and 3.6 mm, respectively. The superior branch reached the suprascapular and axillary nerves in 17 and 8 cases. The middle and inferior branches reached the suprascapular and axillary nerve in all dissections. CONCLUSIONS: With an adequate length, diameter, and nerve composition, the middle and inferior branches of the pectoral nerves are suitable donor nerves to the axillary nerve and a potential source of reinnervation of the suprascapular nerve in upper brachial plexus injury.

The sternalis muscle in cadavers: anatomical facts and clinical significance.

The sternalis is an anomalous muscle located in the anterior wall of thorax and several past reports have described its presence with clinical implications. The sternalis muscle may be incidentally detected during routine cadaveric dissections and autopsies. We observed the presence of anomalous sternalis muscle on both sides of the anterior chest wall in 25 cadavers (n = 50), over a span of three years. Out of a 50 cases, we observed a single case of sternalis on the right side of the 55-year-old male cadaver (2%). The sternalis was found to be absent in the rest 49 cases (98%). The sternalis muscle displayed an oblique course in the anterior wall of the thorax. The muscle originated near the seventh costal cartilage extending obliquely upwards to insert into the second costal cartilage close to the sternum. The originating portion of the muscle was located at a distance of 3.5 cm lateral to the mid-sternal plane. The vertical length and the maximum width of the anomalous sternalis muscle measured 9 cm and 1.9 cm, respectively. The fibers of the muscle vertically ascended upwards. No other associated anomalies were observed in the same cadaver. The presence of sternalis muscle is considered to be a rare variation with no earlier studies being performed in the Malaysian population. The anomalous sternalis muscle may be important for reconstructive surgeons performing mastectomy and radiologists interpreting mammograms. Thus, the sternalis muscle may be academically, anthropologically and surgically important.

A cadaveric study of the serratus anterior muscle and the long thoracic nerve.

The anatomy and function of the serratus anterior muscle and the long thoracic nerve have not been fully elucidated. The purposes of this investigation were (1) to clarify which nerve roots of the cervical spine supply each part of the muscle and contribute to the long thoracic nerve and (2) to investigate the anatomy of the 3 parts of the muscle to understand the function of each part. We collected specimens from 70 dissections of 35 cadavers (11 men and 24 women). The serratus anterior muscle consisted of the upper, middle, and lower parts. The upper part was supplied mainly by the C5 nerve root, and the C4, C6, or C7 nerve roots also had multiple branches in 64 of 70 dissections. The long thoracic nerve, consisting of the C6 and C7 nerve roots, innervated the middle and lower parts. The upper part traversed in a posterior direction compared with the middle or lower part. The upper part of the muscle, which is supplied from multiple nerve roots and runs in a posterior direction, may stabilize the rotational motion of the scapula on the thorax in shoulder elevation. The middle part provides the scapular abduction, and the lower part contributes to upward rotation, abduction, and posterior tilting.