背阔肌腱下滑囊炎的应用解剖研究

目的    为临床诊治背阔肌腱下滑囊炎提供应用解剖学基础。  方法　20侧成人肩关节标本（右11侧、左9侧），对背阔肌腱下滑囊及与其邻近易误诊的解剖结构进行观测。  结果　背阔肌腱下滑囊位于肱骨结节嵴间沟底、肱骨小结节嵴、大圆肌附着部与背阔肌腱止点之间。肱骨结节间沟可分为肱骨大、小结节间沟和大、小结节嵴间沟，确定该滑囊的上下位置，即从肱骨小结节最高点至背阔肌腱下滑囊上端距离为（27.43±4.71）mm，可以确定该滑囊的上下位置，背阔肌腱下滑囊的内外位置关系，从肱二头肌长头腱内侧缘距背阔肌腱下滑囊中点为（8.12±1.23）mm，可以确定该滑囊的内外位置关系。背阔肌腱下滑囊的相关数据，在肱骨结节嵴间沟上、下高度为（36.5±4.79）mm，中点宽度为（8.62±1.83）mm。背阔肌腱下滑囊周围易发生炎症的有肱二头肌长头腱滑液鞘、大圆肌腱下滑囊、喙突下滑囊、胸大肌骨管等。  结论　本研究为背阔肌腱下滑囊的诊疗提供了形态学依据。     

The moment arms of the muscles spanning the glenohumeral joint: a systematic review

The moment arm of a muscle represents its leverage or torque‐producing capacity, and is indicative of the role of the muscle in joint actuation. The objective of this study was to undertake a systematic review of the moment arms of the major muscles spanning the glenohumeral joint during abduction, flexion and axial rotation. Moment arm data for the deltoid, pectoralis major, latissimus dorsi, teres major, supraspinatus, infraspinatus, subscapularis and teres minor were reported when measured using the geometric and tendon excursion methods. The anterior and middle sub‐regions of the deltoid had the largest humeral elevator moment arm values of all muscles during coronal‐ and scapular‐plane abduction, as well as during flexion. The pectoralis major, latissimus dorsi and teres major had the largest depressor moment arms, with each of these muscles exhibiting prominent leverage in shoulder adduction, and the latissimus dorsi and teres major also in extension. The rotator cuff muscles had the largest axial rotation moment arms regardless of the axial position of the humerus. The supraspinatus had the most prominent elevator moment arms during early abduction in both the coronal and scapular planes as well as in flexion. This systematic review shows that the rotator cuff muscles function as humeral rotators and weak humeral depressors or elevators, while the three sub‐regions of the deltoid behave as substantial humeral elevators throughout the range of humeral motion. The pectoralis major, latissimus dorsi and teres major are significant shoulder depressors, particularly during abduction. This study provides muscle moment arm data on functionally relevant shoulder movements that are involved in tasks of daily living, including lifting and pushing. The results may be useful in quantifying shoulder muscle function during specific planes of movement, in designing and validating computational models of the shoulder, and in planning surgical procedures such as tendon transfer surgery.     

Significance of the latissimus dorsi for shoulder instability. I. Variations in its anatomy around the humerus and scapula

In a cadaveric instability model that leaves all muscles intact initially, we studied anteroinferior glenohumeral dislocation behavior after section of the ligaments on the humeral side of the joint. In this study, the latissimus dorsi seemed to play a role when complete section did not result in a locked anteroinferior dislocation. We therefore initiated a study to test the hypothesis that the latissimus dorsi may, in certain circumstances, depending on variations in its anatomy, influence dislocation behavior. Here, in Part I, we present the results of the anatomic study of latissimus dorsi and its tendons. The anatomy of the latissimus dorsi pertaining to the scapula and humerus was studied in 100 cadaver specimens. The distance between the uppermost part of the tendon of both the latissimus dorsi and the teres major and the edge of the articular cartilage of the humeral head (tendon-cartilage distance, TCD) as well as the width and length of the tendons were measured. Furthermore, the relationship between latissimus dorsi and the inferior angle of the scapula was studied. The tendon of the latissimus dorsi inserted at a variable distance from the cartilage of the humeral head: the TCD ranged from 12.6 to 31.6 mm (mean 21.06 mm+/-5.11 mm). The latissimus dorsi can have muscular fibers arising from the inferior angle of the scapula (type 1 scapular connection, 43%). Alternatively, there may be only a few fibrous strands between the muscle and the scapula or there may be an intervening bursa (type 2 scapular connection, 57%). This variability in the morphology of the latissimus dorsi may be a factor explaining the differences observed in a study of humerus-based sequential cutting of the glenohumeral capsule. This possibility is explored in Part II of the study. The latissimus dorsi may also complete the tendinous protection of the humeral side of the capsule generally provided by the rotator cuff.     

Development and clinical significance of the musculus dorsoepitrochlearis in men

Musculus dorsoepitrochlearis is a typical muscle variation, which, if in full extent, is represented by the muscular or fibromuscular slip detached from the anteroinferior border of the musculus latissimus dorsi. It passes over the axilla under the axillary fascia crossing the medial side of the brachial plexus and continues as a septum intermusculare mediale brachii distally to the medial epicondyle of humerus. Its full extent is rarely developed—the connection into the intermuscular septum being mostly absent. Muscular slips from the musculus latissimus then insert on various structures in the axilla, often on the crest of greater tubercle of humerus or into the musculus pectoralis major (this variation is known as the axillary arch of Langer) or to other neighboring structures (coracoid process, fasciae of muscles). In our observations, 209 patients with traumatic lesions of the brachial plexus underwent surgical procedure. The presence of the musculus dorsoepitrochlearis has been observed. It was found in the form of various slips from the musculus latissimus dorsi in 4 patients. In 3 of those 4 patients, the innervation was derived from the nervus thoracodorsalis. We also presented 2 case reports of patients with clinical symptoms caused by compression of nerves in the axilla by the dorsoepitrochlear strip. Clin. Anat. 22:481–488, 2009. © 2009 Wiley‐Liss, Inc.     

Anomalous fascicle and high origin of latissimus dorsi compensating for absence of serratus anterior

The unilateral absence of the right serratus anterior muscle was found in a 78 year old white male subject. In addition, on the same side, a high origin (5th thoracic level) of latissimus dorsi with an accessory muscle fascicle which covered the inferior angle of the scapula and fused with teres major and with the deep fascia of infraspinatus was also found. The structural arrangement suggests that the absence of serratus anterior was compensated for by the anomalous latissimus dorsi.     

Musculotopic organization of the motor neurons supplying forelimb and shoulder girdle muscles in the mouse

We identified the motor neurons (MNs) supplying the shoulder girdle and forelimb muscles in the C57BL/6J mouse spinal cord using Fluoro-Gold retrograde tracer injections. In spinal cord transverse sections from C2 to T2, we observed two MN columns (medial and lateral) both with ventral and dorsal subdivisions. The dorsolateral column consisted of the biceps brachii, forearm extensors, forearm flexors, and hand MNs, and the ventrolateral column consisted of the latissimus dorsi, trapezius, teres major, deltoid, and triceps MNs. The supraspinatus muscle MNs were located in the dorsomedial column, and pectoralis major and serratus anterior MNs were located in the ventromedial columns. MNs of the dorsolateral column innervated the biceps brachii in mid-C4 to mid-C7, forearm extensors in caudal C4 to mid-T1, forearm flexors in rostral C5 to mid-T1, and hand muscles in mid-C8 to mid-T2 segments. The MNs innervating the trapezius were located in mid-C2 to mid-C4, triceps brachii in mid-C6 to rostral T1, deltoid in rostral C4 to mid-C6, teres major in rostral C5 to mid-C8, and latissimus dorsi in mid-C5 to caudal C8. In addition, MNs innervating the supraspinatus were located from rostral C4 to caudal C8, pectoralis major in mid-C6 to mid-T2, and serratus anterior in rostral C5 to caudal C7/rostral C8 segments. While the musculotopic pattern of MN groups was very similar to that documented for other species, we found differences in the position and cranio-caudal extent of some MN pools compared with previous reports. The identification of mouse forelimb MNs can serve as an anatomical reference for studying degenerative MN diseases, spinal cord injury, and developmental gene expression.     

Innervation of the scapular muscles and its morphological significance in man

The origin, course and distribution of the nerves supplying the supraspinatus, infraspinatus, subscapularis, teres minor, deltoid, teres major and latissimus dorsi were examined in 40 human body-halves. All the nerves supplying these 7 muscles derive from the brachial plexus between the upper trunk and the posterior cord. Within the plexus the nerves originate in the following order: the suprascapular nerve in the most cranial and ventral position followed caudally and dorsally the superior subscapular nerve, the axillary nerve, the inferior subscapular nerve and the thoracodorsal nerve. The superior subscapular nerve tends to innervate the upper and middle (thoracic) portions of the subscapularis. Both the axillary and inferior subscapular nerves tend to innervate the lower (axillary) portion of the subscapularis as well as the teres minor and deltoid, and the teres major, respectively. The subscapularis can be regarded as the compound muscle deriving from the components supplied by these nerves, 4 segmental nerves from C5 to C8 innervate the 7 muscles: C5, and (C6) innervate the supraspinatus; C5, and C6 the infraspinatus, the thoracic portion of the subscapularis, and the teres minor; C5, C6, and (C7) the deltoid; (C5), C6, and (C7) the axillary portion of the subscapularis; (C5), C6, and C7 the teres major; and (C6), C7, and C8 the latissimus dorsi. The relationships between the nerves and muscles suggest that these 7 muscles morphologically belong to the same group, the second group of the dorsal musculature attached to the shoulder girdle and limb. The probable process of formation of these muscles from the cervical myotoms is proposed.     

A rare muscular anomaly in the upper arm--the chondroepitrochlearis muscle with an aberrant type of the muscular arch of axilla.

A rare muscular anomaly was found in the right arm of a 92-year-old man at Nagoya University in 1995. The anomalous muscle had two heads, one ventral and one dorsal. The ventral head was a continuation of the abdominal part of the pectoralis major muscle, and the dorsal head arose from the lateral surface of the latissimus dorsi muscle. The two heads united at the medical surface of the upper third of the arm to form a common tendon, which descended on the medial surface of the upper arm parallel with a long tendon of the coracobrachialis muscle and attached to the medial epicondyle of the humerus. This anomalous muscle was supplied by the most caudal branch of the pectoral ansa (caudal pectoral nerve) and the intercostobrachial nerve (Th2). This pectoral nerve first innervated the ventral head, and next the greater part of the dorsal head. The intercostobrachial nerve (Th2) innervated a small part of the dorsal head. The present anomaly looked quite similar to the case reported by Yokoh as the coexistence of the chondroepitrochlearis and the dorsoepitrochlearis muscles. However, judging from the muscular origin, insertion and innervation, the ventral head was considered to be the chondroepitrochlearis muscle, whereas the dorsal head was not dorsoepitrochlearis muscle but an aberrant type of the muscular arch of axilla.     

Bilateral four-headed biceps brachii muscles: The median nerve and brachial artery passing through a tunnel formed by a muscle slip from the accessory head

Bilateral four-headed biceps brachii muscles were observed in the dissected cadaver of a 95-year-old Japanese woman. The third head on both sides originated from the humerus at the insertion of the coracobrachialis and inserted into the distal part of the biceps brachii and the proximal part of the common biceps tendon on the ipsilateral side. The fourth head on both sides arose from a thin fibrous origin from the intertubercular sulcus and the insertion of the pectoralis major, and inserted into the confluence of the biceps brachii and the third head. This anomaly is relatively rare. Moreover, the left third head gave off a muscle slip into the posterior fascia of the pronator teres, forming a tunnel. The median nerve and the brachial artery passed through the tunnel, where the nerve and artery seemed to be compressed. The possible production of clinical symptoms, given the anatomy, is discussed. Clin. Anat. 11:209–212, 1998. © 1998 Wiley-Liss, Inc.     

Nerve fiber analysis on the so-called accessory subscapularis muscle and its morphological significance

A rare muscular anomaly, so-called accessory subscapularis muscle, was found in the left axillary fossa of a 95-year-old male cadaver during a student dissection practise. The muscle arose near the lateral margin of the scapula from the surface of the subscapularis muscle and ran upward to fuse with the capsule of the shoulder joint via a tendon. It measured 1.0 cm in width, 7.0 cm in length and 1.5 mm in thickness, and was separated from the underlying subscapularis muscle by the axillary and inferior subscapular nerves. Macroscopically, the anomalous muscle received its nerve supply from a branch arising from the lower root of the radial nerve near the origin of the thoracodorsal nerve and entered the muscle from its ventral surface. Nerve fiber analysis showed that the supplying nerve originated from fibers of the dorsal element of C7 immediately cranial to the thoracodorsal nerve. These findings indicate that the present anomalous muscle might be close to the formation of the latissimus dorsi muscle in its derivation rather than the subscapularis muscle.     

Axillopectoral muscle (Langer's muscle)

In a routine dissection of the axillary fossa, a muscle originating from the coracoid process of the scapula and extending to the long head of triceps brachii muscle was observed. The mentioned muscle was adhering to both the triceps brachii muscle and the tendinous part of the latissimus dorsi muscle. This anatomical variation is referred to as axillary arch (Langer's muscle or axillopectoral muscle). The muscle mass was measured 9.6 cm in length and 1.4 cm in width. The accessory muscle can be a reason of an axillary mass and can exert pressure on the neighboring neurovascular bundle or lymph routes; thus, exposing a wide range of symptoms. Therefore, variations of this area should be kept in mind in surgical interventions.     

Low origin of the radial artery: a case study including a review of literature and proposal of an embryological explanation

A low origin of the radial artery is a rare anatomical variation, with the incidence estimated at 0.2 %. This report presents a previously unrecorded case of an unusual distal origin of the radial artery, co-occurring with a double recurrent radial artery. The radial artery arose under the pronator teres muscle, 76 mm below the intercondylar line of the humerus. After emerging from under the tendon of the pronator teres muscle, the radial artery took a typical course and terminated in the deep palmar arch. Additionally, the double radial recurrent artery branched directly off the brachial artery, near the level of the radial neck. A well-developed muscular branch of the first radial recurrent artery ran beneath the brachioradialis muscle and supplied the brachioradialis, extensor carpi radialis longus and brevis, as well as supinator muscles. The second (accessory) radial recurrent artery took origin from the posterior aspect of the brachial artery, ran deep to the distal tendon of the biceps brachii muscle and terminated by joining the articular network of elbow. According to recent theories, the plexiform appearance of the arteries at early stages of upper limb development allows for formation of alternative pathways of blood flow, which may give rise to variations in the definitive arterial pattern.     

Elevator muscle of the tendon of latissimus dorsi muscle

Muscular dispositions in the axilla acquire importance under certain surgical procedures that involve the axillary artery ligature. These supernumerary muscles make the approach to the axillary fossa and their content difficult. We dissected 108 formalized corpses from adult male individuals. The specimens belong to the topographic Anatomy Unit of the Faculty of Medicine, Universidad de La Frontera, Chile. In all dissections, a rare and infrequent muscular variation attributed to the presence of a elevator muscle at the dorsal part of the latissimus muscle on the right upper limb from an adult individual was found. This muscle was fusiform and originated at the coracoid process by a short tendon of cylindrical form inserted in the dorsal superior part of the tendon of the latissimus dorsi muscle. Muscular belly and tendons of origin and insertion were closely related to the brachial plexus and the axillar vessels that they crossed.     

Transverse humeral ligament: Does it exist?

The insertion of the tendon of subscapularis is accepted as being on the lesser tubercle of the humerus. The transverse humeral ligament (THL) is described as a distinct entity in most textbooks, overlying the long tendon of biceps as it emerges from the capsule of the shoulder joint. In this study, we dissected 85 embalmed shoulders to clarify the anatomy of the THL and variation in the insertion of the tendon of subscapularis. In all specimens no distinct THL could be identified, but in every shoulder a fibrous expansion arose from the posterior lamina of the tendon of pectoralis major overlying the long tendon of biceps. In 86% of shoulders, fibres from the tendon of subscapularis passed over the long tendon of biceps within this fibrous expansion and inserted on to the greater tubercle of the humerus where one would expect to find the THL. In 33% of dissections, fibres from the tendon of subscapularis lay deep to the long tendon of biceps, inserting either into the bicipital groove or on to the greater tubercle. In only 8% of cases did the tendon of subscapularis insert exclusively on to the lesser tubercle. We conclude that the THL does not exist as a separate entity. We suggest that in the majority of cases, the structure overlying the long tendon of biceps as it emerges from the capsule of the shoulder joint consists of tendinous fibres from subscapularis, contained within a fibrous expansion derived from the posterior lamina of the tendon of pectoralis major. In the minority of shoulders, where the tendon of subscapularis inserts exclusively on to the lesser tubercle, we hypothesise that this fibrous expansion acts as a retinaculum preventing the long tendon of biceps from "bowstringing."     

Moment arms of the muscles crossing the anatomical shoulder

The objective of the present study was to determine the instantaneous moment arms of 18 major muscle sub-regions crossing the glenohumeral joint during coronal-plane abduction and sagittal-plane flexion. Muscle moment-arm data for sub-regions of the shoulder musculature during humeral elevation are currently not available. The tendon-excursion method was used to measure instantaneous muscle moment arms in eight entire upper-extremity cadaver specimens. Significant differences in moment arms were reported across sub-regions of the deltoid, pectoralis major, latissimus dorsi, subscapularis, infraspinatus and supraspinatus (P < 0.01). The most effective abductors were the middle and anterior deltoid, whereas the most effective adductors were the teres major, middle and inferior latissimus dorsi (lumbar vertebrae and iliac crest fibers, respectively), and middle and inferior pectoralis major (sternal and lower-costal fibers, respectively). In flexion, the superior pectoralis major (clavicular fibers), anterior and posterior supraspinatus, and anterior deltoid were the most effective flexors, whereas the teres major and posterior deltoid had the largest extensor moment arms. Division of multi-pennate shoulder muscles of broad origins into sub-regions highlighted distinct functional differences across those sub-regions. Most significantly, we found that the superior sub-region of the pectoralis major had the capacity to exert substantial torque in flexion, whereas the middle and inferior sub-regions tended to behave as a stabilizer and extensor, respectively. Knowledge of moment arm differences between muscle sub-regions may assist in identifying the functional effects of muscle sub-region tears, assist surgeons in planning tendon reconstructive surgery, and aid in the development and validation of biomechanical computer models used in implant design.     

A rare human variation: the relationship of the axillary and inferior subscapular nerves to an accessory subscapularis muscle

A case of bilateral occurrence of a variant subscapularis muscle is reported. The superior lateral aspect of each subscapularis muscle presented a small accessory muscle with an accompanying tendon that inserted into the lesser tubercle of the humerus along with the primary tendon of the subscapularis muscle. Each accessory subscapularis muscle was separated from the primary subscapularis muscle by the axillary and inferior subscapular nerves. No branches of the axillary or inferior subscapular nerves supplied the primary subscapularis muscle or the accessory muscle while the nerves passed through the myotendinous tunnel. The relationship of the nerves with the variant subscapularis muscles has clinical significance with regard to entrapment neuropathy.     

A rare human variation: The relationship of the axillary and inferior subscapular nerves to an acessory subscapularis muscle

A case of bilateral occurrence of a variant subscapularis muscle is reported. The superior lateral aspect of each subscapularis muscle presented a small accessory muscle with an accompanying tendon that inserted into the lesser tubercle of the humerus along with the primary tendon of the subscapularis muscle. Each accessory subscapularis muscle was separated from the primary subscapularis muscle by the axillary and inferior subscapular nerves. No branches of the axillary or inferior subscapular nerves supplied the primary subscapularis muscle or the accessory muscle while the nerves passed through the myotendinous tunnel. The relationship of the nerves with the variant subscapularis muscles has clinical significance with regard to entrapment neuropathy.     

Two bellies of the coracobrachialis muscle associated with a third head of the biceps brachii muscle.

Reports that describe the abnormalities and complexities of the anatomy of the arm are important with regard to surgical approaches. This case study reports a combined abnormal form of the coracobrachialis and biceps brachii muscles of the left arm of an adult male cadaver that was detected during the educational gross anatomy dissections of embalmed cadavers. The coracobrachialis muscle demonstrated two bellies which formed shortly inferior to its origin from the coracoid process of the scapula. One belly inserted into the middle of the antero-medial surface of the humerus, whereas the other belly inserted into the medial head of the triceps brachii muscle. The musculocutaneous nerve passed between the two bellies, giving a separate branch to each. We suggest that the two bellies of the coracobrachialis muscle may represent the incompletely fused short heads of the ancestral muscle. The biceps brachii muscle showed a third head, which originated mainly from the antero-medial surface of the humerus and partially from an aponeurosis belonging to the medial head of the triceps brachii muscle. These observations were confined to the left upper limb and were not accompanied by any other abnormality.     

Lines of action and stabilizing potential of the shoulder musculature

The objective of the present study was to measure the lines of action of 18 major muscles and muscle sub‐regions crossing the glenohumeral joint of the human shoulder, and to compute the potential contribution of these muscles to joint shear and compression during scapular‐plane abduction and sagittal‐plane flexion. The stabilizing potential of a muscle was found by assessing its contribution to superior/inferior and anterior/posterior joint shear in the scapular and transverse planes, respectively. A muscle with stabilizing potential was oriented to apply more compression than shear at the glenohumeral joint, whereas a muscle with destabilizing potential was oriented to apply more shear. Significant differences in lines of action and stabilizing capacities were measured across sub‐regions of the deltoid and rotator cuff in both planes of elevation (P < 0.05), and substantial differences were observed in the pectoralis major and latissimus dorsi. The results showed that, during abduction and flexion, the rotator cuff muscle sub‐regions were more favourably aligned to stabilize the glenohumeral joint in the transverse plane than in the scapular plane and that, overall, the anterior supraspinatus was most favourably oriented to apply glenohumeral joint compression. The superior pectoralis major and inferior latissimus dorsi were the chief potential scapular‐plane destabilizers, demonstrating the most significant capacity to impart superior and inferior shear to the glenohumeral joint, respectively. The middle and anterior deltoid were also significant potential contributors to superior shear, opposing the combined destabilizing inferior shear potential of the latissimus dorsi and inferior subscapularis. As potential stabilizers, the posterior deltoid and subscapularis had posteriorly‐directed muscle lines of action, whereas the teres minor and infraspinatus had anteriorly‐directed lines of action. Knowledge of the lines of action and stabilizing potential of individual sub‐regions of the shoulder musculature may assist clinicians in identifying muscle‐related joint instabilities, assist surgeons in planning tendon reconstructive surgery, aid in the development of rehabilitation procedures designed to improve joint stability, and facilitate development and validation of biomechanical computer models of the shoulder complex.