Unusual attachment of the pectoralis minor muscle

The authors report a presumably unusual bony attachment of the pectoralis minor muscle in an adult cadaver. The specimen's left pectoralis minor had no attachment to the coracoid process of the scapula but attached directly to the fibrous capsule of the glenohumeral joint. Some have theorized that the coracohumeral ligament represents fibers of the pectoralis minor that attach to this bone in some animals but that has degenerated in man. This case report seems to support this possibility.     

胸大肌、胸小肌的肌梭形态、分布及其与梭外肌纤维型的关系

目的：探讨人胸大肌、胸小肌肌梭的形态、分布及其与梭外肌纤维型的关系。方法：用HE染色结合体视学方法并肌球蛋白ATPase染色,观察肌梭形态、分布及肌纤维型构成。结果：胸大肌锁骨部和胸小肌肌梭密度较高,存在较多的肌梭联合体,Ⅰ型肌纤维比例高于Ⅱ型。结论：肌梭在不同肌之间以及同一肌各亚部之间密度不等,肌梭密度较高部位,肌梭以联合体形式存在的比例较高,梭外肌纤维以Ⅰ型占优势。     

胸小肌移植重建拇对掌功能的临床解剖研究

目的:为吻合血管神经的选择性胸小肌移植重建拇对掌功能术式提供解剖学依据。方法:在20侧成人胸部及手部标本中,解剖观察胸小肌的血管神经分布及胸小肌和大鱼际肌的形态、大小并将二者进行比较;然后按照大鱼际肌纤维走行方向,参考血管神经位置,将胸小肌修剪合适后移植固定于同侧手部大鱼际,模拟正常手部拇对掌功能予以牵拉,观察标本手部拇对掌过程。结果:胸小肌位置恒定,具备独立的动、静脉和神经支配;有针对性地选择部分胸小肌进行移植模拟,获得了标本手部的拇对掌过程。结论:在标本上选取部分胸小肌移植于手部大鱼际重建拇对掌功能的术式是可行的。     

An unusual innervation of pectoralis minor and major muscles from a branch of the intercostobrachial nerve

Variations of the branching pattern of the intercostobrachial nerve have been known to complicate dissection during mastectomy and other procedures involving the axilla. We present a unilateral case of a 73-year-old Caucasian female, in which the intercostobrachial nerve gives rise to an additional medial pectoral branch, which partially innervates the pectoralis minor muscle, as well as the abdominal head of pectoralis major muscle. Clinical consequences of such a variation may include motor losses, in addition to the commonly reported sensory losses, resulting from accidental or intentional dissection of the intercostobranchial nerve.     

Localization of nerve entry points and the center of intramuscular nerve-dense regions in the adult pectoralis major and pectoralis minor and its significance in blocking muscle spasticity

The aims of this study were to localize the body surface position and depth of nerve entry points, and the center of the intramuscular nerve-dense regions of the pectoralis major and pectoralis minor in order to provide guidance for blocking muscle spasticity. Formalin-fixed adult cadavers (66.3 ± 5.2 years) were used. The curved line on the skin from the acromion to the most inferior point of the jugular notch was defined as the horizontal reference line (H). The line from the most inferior point of the jugular notch to the xiphisternal joint was defined as the longitudinal reference line (L). The nerve entry points was anatomically exposed. Sihler's staining, barium sulfate labeling, and computed tomography were employed to determine the projection points (P) on the body surface. The intersection of the longitudinal line through the P point and the H line and the horizontal line through the P point and the L line were recorded as P_H and P_L, respectively. The projection of the nerve entry points or the center of the intramuscular nerve-dense regions were in the opposite direction across the transverse plane and were recorded as P'. The percentage positions of P_H and P_L on the H and L lines, as well as the nerve entry points and the center of the intramuscular nerve-dense regions depths, were determined using the Syngo system. The pectoralis major had two nerve entry points, while the pectoralis minor had only one. In addition, two intramuscular nerve-dense regions were found in the pectoralis major, while only one region was found in the pectoralis minor. The P_H of the nerve entry points were located at 47.83%, 32.31%, and 34.31%, while the P_H of the center of the intramuscular nerve-dense regions were at 41.95%, 55.88%, and 32.58% of line H, respectively. The P_L of the nerve entry points were at −9.84%, 36.16%, and 2.44%, while the P_L for each of three center of the intramuscular nerve-dense regions was at −3.87%, 25.29%, and −7.13% of line L, respectively. The depth for each of the nerve entry points was at 17.76%, 17.53%, and 25.51% of line P-P′’, respectively, and the depth of the center of the intramuscular nerve-dense regions was at 5.23%, 6.75%, and 13.73% of line P-P′, respectively. These percentage values are all means. The definition of the surface position and depth of these nerve entry points and center of the intramuscular nerve-dense regions can improve the localization efficiency and efficacy of target blocking for pectoralis major and minor spasticity.     

Unusual pectoralis major muscle: The chondroepitrochlearis

Presented herein is a case of an extremely rare muscle in the pectoral region. It involved an accessory muscular slip originating from the pectoralis major and inserting onto the medial epicondyle of the humerus and the medial intermuscular septum. According to the literature this muscle is defined as chondroepitrochlearis. The arterial and nervous supply to the muscle came from the lateral thoracic artery and the medial pectoral nerve, respectively. Clinical considerations of such a variation include ulnar nerve entrapment and functionally limited abduction of the humerus.     

Bilateral variation of the pectoralis minor muscle discovered during practical dissection

We describe a case of an original insertion of the pectoralis minor on the coracohumeral ligament, supraspinatus tendon and the capsule of the glenohumeral joint. This variation has been described in anatomy textbooks since the nineteenth century. The peculiarity of this case is that the right shoulder presented type 2 and the left type 1 of the three varieties described by Le Double in 1897. Le Double (1843–1913) was a French anatomist who wrote a treaty on anatomical variations, in particular those of the muscle. Lately, only three publications have reported this variation in anatomic studies. Some authors have described the rotator cuff syndrome caused by this variation and an ultrasound study has demonstrated a frequency of 9.57% for the detection of this variation. It is possible to try and find this variation while investigating in order to diagnose impingement, through ultrasound, CT arthrography or MRI. We believe that this variation should be taken into consideration by surgeons during surgical procedures and arthroscopy.     

Unusual variation of a third head of the biceps brachii muscle

A human cadaver was studied which presented a biceps brachii with three heads of origin in the left arm. The third or humeral head presented an unique area of insertion into the bicipital aponeurosis (lacertus fibrosus).     

A reappraisal of the blood supply of the pectoralis minor muscle

Recently the pectoralis minor muscle has been introduced as a free muscle transplant for facial reanimation in peripheral facial paralysis. However, reports on the vascular supply of this muscle are incomplete or contradictory. Therefore the pectoral region was examined in 57 human cadavers. A complex pattern of variations in the arterial supply was found: it was, however, systematically arranged and limited to a small part of the arterial tree. A topographical classification was made, based on the dominant muscle artery, to provide a useful orientation during reconstructive surgery. Related to the origin of this dominant artery, three main patterns are distinguished. In the most frequent pattern a major role is played by an artery not mentioned in Nomina Anatomica (Edinburgh: Churchill Livingstone, 1989). This artery usually arises directly from the axillary artery, accompanies the medial pectoral nerve, and supplies the major lateral part of the muscle from its deep surface. For topographical reasons we propose the name “lateral pectoral artery.” The classification, presented in this study, may provide a better insight for the reconstructive surgeon working in this area. © 1994 Wiley-Liss, Inc.     

Bilateral asymmetric deficiency of the pectoralis major muscle

We observed a rare, bilateral congenital deficiency of the pectoralis major muscle in a 72-year-old female cadaver in our gross anatomy dissection laboratory. The outward appearance of the anterior thoracic wall, which included well-developed breasts, revealed no obvious abnormalities. Upon dissection, the following features were observed: 1) on the left side, the sternal portion of the sternocostal head of the pectoralis major muscle was absent, the costal portion of the sternocostal head and the clavicular head were both well developed, a normal pectoralis minor was present, and the deltoid and subclavius muscles were not hypertrophied as is often the case when the pectoralis major muscle is deficient; 2) on the right side, the entire pectoralis major muscle was absent and the pectoralis minor, deltoid, and coracobrachialis muscles were infiltrated with connective tissue and fat; and 3) on both sides, the lateral pectoral nerves were absent and the medial pectoral nerves were present. The absence of the lateral pectoral nerves suggests that the deficiencies in the pectoralis major muscles are congenital malformations resulting from a developmental failure of the embryonic muscles rather than a sequel to polio or Poland's syndrome.     

Avid 18F-FDG uptake of pectoralis major muscle: an equivocal sequela of strenuous physical exercise

Avid functional ¹⁸F-FDG uptake of skeletal muscle is a known false positive finding of PET-CT study especially after involuntary muscle exercise just prior to the study. We describe the case of a 50-year-old man in whom the finding of avid ¹⁸F-FDG uptake of pectoralis major muscle was encountered during investigation of metastatic melanoma.     

Anterior intercostobrachial nerve penetrating the pectoralis minor or major muscle

Two previously unknown anomalies of the anterior intercostobrachial nerve were described. In one case, the anterior intercostobrachial nerve penetrated the pectoralis minor muscle. In the other case, it penetrated the pectoralis major muscle. In both cases, the anomalous nerve supplied the skin of the upper arm.     

Coexistence of a pectoralis quartus muscle and an unusual axillary arch: case report and review

A pectoralis quartus muscle and an unusual axillary arch were found on the left side of a female cadaver. The axillary arch was a musculoaponeurotic complex continuous with the iliacal fibers of the latissimus dorsi. The muscular part, together with the tendon of pectoralis major, inserted into the lateral lip of the bicipital groove of the humerus, whereas the aponeurotic part was formed by a fibrous band that extended deep to the pectoralis major to insert into the coracoid process between the attachments of the coracobrachialis and pectoralis minor. The pectoralis quartus originated from the rectus sheath, and joined the inferior medial border of the fibrous band of the axillary arch, at the lateral edge of the pectoralis major. The axillary arch muscle crossed anteriorly the axillary vessels and the brachial plexus. The clinical importance of these muscles is reviewed.     

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. Clin. Anat. 28:520–526, 2015. © 2015 Wiley Periodicals, Inc.     

胸小肌蒂喙突骨瓣移位术的应用解剖

目的:为胸小肌喙突骨瓣移位术提供应用解剖资料.方法:观测65例肩胛骨的喙突形态及26具52侧防腐尸体胸小肌与喙突的解剖关系.结果:肩胛骨喙突大小为4.1×1.4×1.0cm,胸小肌止于喙突者80.8%,不止于喙突者11.5%,部分止于喙突者7.7%.结论:并非所有患者均有胸小肌喙突骨瓣移位术的解剖学良好条件.拟行此术前应考虑相应的替代手术方案.     

胸小肌移植重建拇对掌功能的神经解剖学研究

目的为临床应用胸小肌移植重建拇对掌功能手术过程中神经吻接提供解剖学依据。方法解剖观测胸内侧神经及尺神经深支分支特点,比较相关神经有髓神经纤维数目,确定手术过程中神经吻接。结果胸内侧神经为胸小肌的主要支配神经,其在第3肋间隙近锁骨中线处入胸小肌,有髓神经纤维计数为(868±130)根;尺神经深支穿出内侧肌间隔后在第3、4掌骨间隙分别发出两明显肌支,其有髓神经纤维计数分别为(394±49)根、(708±78)根;P3L4(尺神经深支在第4掌骨间隙的分支,其分布于第3骨间掌侧肌和第4蚓状肌)与胸内侧神经、正中神经返支有髓神经纤维数目都比较接近。结论胸小肌移植重建拇对掌功能手术中,在切取胸小肌时以胸内侧神经作为供体神经,以第3肋间隙与锁骨中线交点为标记寻找该神经;尺神经深支中P3L4肌支与胸内侧神经吻合最匹配。     

Left musculus sternalis

During routine dissection in the Morphological Sciences Department II of the Universidad Complutense de Madrid, the presence of a sternalis muscle was observed in the left hemithorax of a 70-year-old male cadaver. We report on its position, relationships, and innervation, as well as its clinical relevance, indicating some guidelines for its physical examination. We also present a brief overview of the existing literature regarding the nomenclature, historical reports, and incidence of this muscle.