An electrophysiological and morphological study of normal and denervated chicken latissimus dorsi muscles.

1. Some electrophysiological and morphological properties of 'fast' (singly innervated) and 'slow' (multiply innervated) muscle fibres were studied in normal and denervated posterior and anterior latissimus dorsi muscles of the young chickens. 2. Normal singly and multiply innervated muscle fibres are capable of generating action potentials which in all qualitative respects are similar. 3. The action potentials of multiply innervated muscle fibres are of lower amplitude and slower maximum rate of rise than action potentials in singly innervated muscle fibres. 4. Denervation causes the resting membrane potential and the maximum rate of rise of the action potential to fall. The changes are greater in singly innervated than in multiply innervated fibres, but in neither case are as great as in mammalian skeletal muscle fibres after surgical denervation. 5. In neither singly nor multiply innervated muscle fibres do the action potentials generate any 'resistance' to tetrodotoxin as a result of denervation. 6. The diameter of multiply innervated fibres is increased after denervation, but it is reduced in singly innervated fibres. The number of myofilaments increases in multiply innervated fibres, but decreases in single innervated fibres. In both types of muscle fibre the volume fraction of myofibrils is decreased. 7. In the singly innervated muscle fibres there is an increase in the volume fraction of mitochondria. 8. In the singly innervated muscle fibres, there is some rearrangement of the membrane systems in that some of the transversely orientated triads are replaced by longitudinally orientated dyads.     

Familial absence of the pectoralis major, serratus anterior, and latissimus dorsi muscles.

Congenital absence of shoulder girdle muscles is described in three generations of a family. The proband, a 3 year old boy, had absence of the sternocostal head of the right pectoralis major. His father had absence of the left serratus anterior and part of the left latissimus dorsi and his paternal grandfather had absence of the lower two-thirds of the left pectoralis major, with absence of the left serratus anterior and latissimus dorsi muscles. The condition is probably the result of a dominant gene. These observations show that absence of the pectoralis major is part of a wider spectrum of shoulder girdle defects. Where genetic advice is sought by persons with apparently sporadic absence of the pectoralis major, examination of the relatives is necessary.     

Anomalous arterial supply to the muscles in a combined latissimus dorsi and serratus anterior flap

The combined latissimus dorsi and serratus anterior flap has been employed for large defect reconstruction and has been shown to be reliable. These flaps are based on the subscapular-thoracodorsal vascular pedicle that usually supplies both muscles. In the case reported, serratus anterior possessed an anomalous arterial supply totally independent of the subscapular pedicle. The latissimus dorsi and serratus anterior muscles were used as a combined flap to reconstruct a massive thigh defect. The combined flap required two arterial anastomoses.     

Inactivity induces muscle hypertrophy and redistribution of myosin isozymes in chicken anterior latissimus dorsi muscle

Denervation of the anterior latissimus dorsi (ALD) muscle causes transient muscle fibre hypertrophy and leads to an increase of the SM1 myosin isoform. We tested whether the changes that take place after denervation can be attributed to loss of muscle activity which follows denervation. Neuromuscular activity was prevented by blocking the acetylcholine receptors with -bungarotoxin and thereby paralysing the muscle. Following this treatment, we found increased muscle weight and pronounced hypertrophy of muscle fibres. Also, the proportion of SM1 isomyosin was decreased. Due to the multiple innervation of ALD muscle fibres it is possible to paralyse only part of the muscle. When only a region of the muscle was paralysed a local hypertrophy of fibres was detected, and the change from SM1 to SM2 was most pronounced in the area where activity was blocked. Removal of muscle activity resulted in changes similar to those that occurred after denervation.     

Innervation of the avian tonus latissimus dorsi anterior muscle

The motor and cutaneous nerves associated with the pigeon's anterior latissimus dorsi tonus muscle are described. The motor nerve is traced from its origin within the brachialis longus superior nerve of the brachial plexus to within the epimysium of the muscle by means of serial cross sections. The nerve fibers differ in mean diameter at various sites along the nerve. They originate as small fibers within the plexus, become larger as they emerge and then gradually decrease in diameter as they approach the muscle. The number of nerve fibers remains relatively constant until the nerve divides into more than two branches, at which time the number increases. The cutaneous nerve passing through the anterior latissimus dorsi is described and is assumed not to play any role in the innervation, either sensory or motor, of the fibers in this muscle.     

Complexity of myosin species in the avian posterior latissimus dorsi muscle

Summary The myosin content of the avian posterior latissimus dorsi muscle, a small fast-twitch muscle similar in fibre type to the much-studied pectoralis major muscle (type IIB), has been explored using high resolution chromatography of the proteolytic fragment known as subfragment-1 and of the products of its limited tryptic digestion, followed by N-terminal sequencing of selected peptides. The complexity of species found greatly exceeds that anticipated from the fibre-type homogeneity of the muscle and from previous studies (Bandmanet al., Cell 29 (1982) 645–50; Loweyet al., J. Musc. Res. Cell Motility 4 (1983) 695–716; Crow & StockdaleDev. Biol. 118 (1986) 333–42). A minimum of four heavy chain species were identified. One form, approximately 40% of the heavy chain complement, appears to be identical to the well-characterized type IIB isoform of the pectoralis major muscle. The remaining species differ from the pectoralis major form in primary sequence. None is identical to the post-hatch isoform of the pectoralis major muscle.     

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。     

Spinal cord location of the motoneurons innervating the abdominal,cutaneous maximus,latissimus dorsi and longissimus dorsi muscles in the cat

Summary Horseradish peroxidase (HRP) injections were made in the rectus abdominis, obliquus externus, obliquus internus, transversus abdominis, cutaneous maximus, latissimus dorsi and the longissimus dorsi muscles in the cat. The results showed that motoneurons innervating the obliquus externus, obliquus internus and transversus abdominis muscles were located in greatly overlapping areas of midthoracic, caudal thoracic and upper lumbar spinal segments. These motoneuronal cell groups were present laterally in the ventral horn and at caudal thoracic and upper lumbar levels they bordered on the white matter. The location of the rectus motoneurons differed somewhat from the location of the other motoneuronal cell groups because they were also present at low cervical and upper thoracic levels and in the segments T12 to L3 they were found in the ventral horn medial to the other abdominal muscle motoneuronal cell group. At mid-thoracic levels rectus motoneurons were located in the same area as the other abdominal muscle motoneurons. Latissimus dorsi motoneurons were observed in a large cell group in the ventrolateral part of the ventral horn at the levels caudal C6 to rostral C8. Furthermore they were found in the segments T9 to L3 laterally in the ventral horn which is the same area in which the other abdominal muscle motoneurons except the rectus ones are located. Longissimus dorsi motoneurons were located in the most ventral portion of the ventral horn in all thoracic and upper 4 lumbar segments. The cutaneous maximus motoneurons were found in a cell group, located ventrolaterally in the ventral horn at the edge of the gray and white matter at the level caudal C8-rostral T1. This cell group corresponds to the caudal part of the ventral motor nucleus (VMN) of Matsushita and Ueyama (1973). Interestingly, labeled motoneurons were also present in the VMN after injecting HRP in the abdominal muscles as well as in the caudal (but not in the rostral) parts of the latissimus dorsi muscle but not in the longissimus dorsi injected cases. The possibility whether these motoneurons are labeled because of leakage of HRP to abdominal and caudal latissimus dorsi muscles is discussed. If leakage would not be the case, motoneurons in the VMN may be involved in specific functions of the abdominal muscles, such as the so-called steady state contractions.     

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.     

Morphological and histochemical differentiation of intrafusal fibres in the posterior latissimus dorsi muscle of the developing chick

Summary Morphological and histochemical differentiation of neuromuscular spindles was studied in the posterior latissimus dorsi (PLD) of the chick during embryonic and post-hatching development. A rapid increase in the number of spindles takes place between the 13th and 15th of embryonic life. By the 15th day in ovo, the spindle capsule appears filled with numerous contiguous cells. Large sensory endings and small primitive motor endings are observed on intrafusal fibres. Ultrastructural observations of the nerve supply of the spindles confirm that each developing spindle receives one thick Ia axon with one to three thin axons. The intracapsular space differentiates by the 17th day of embryonic development. All intrafusal fibres are morphologically of the nuclear-chain type, while two fibre types are distinguished as early as the 14th day of embryonic life, when myofibrillar ATPase activity is demonstrated after acid preincubation. These two histochemical types of intrafusal fibres are also described in the adult. The relation between these two histochemical types and different functional activity of intrafusal fibres is suggested.     

Unilateral absence of latissimus dorsi muscle

Latissimus dorsi (LD) is the broadest muscle of the back responsible for extension and adduction of shoulder. The authors report a case of isolated unilateral absence of the latissimus dorsi muscle observed during an ablative surgical procedure and flap reconstruction. The left LD muscle was completely absent in our patient and no tendon fibers belonging to this muscle could be observable on further dissection. The surrounding muscle anatomy was normal and in place suggesting a developmental etiology for its absence. Awareness of this possible variation is of importance in considering reconstructive options. Clin. Anat. 25:966–968, 2012. © 2012 Wiley Periodicals, Inc.     

EMG study of the pectoralis major (sternal portion), teres major, latissimus dorsi and deltoid medial muscles in volleyball players

The pectoralis major (sternal portion), teres major, latissimus dorsi and deltoid medial muscles has been studied through in the electromyography in 8 male individuals, who practice volleyball, youth category, (age between 15 and 17 (average 16.25), right-handed, involved in volleyball for about one year. The objective was to analyze the potential of action of these muscles engaged in the volleyball movements: service, spike, pass, set and blocking with and without ball. The work was developed in the laboratory of Electromyography and Biomechanics of Posture (Physical Education Faculty - State University of Campinas - UNICAMP). To caption the muscles action potential, surface electrodes were set with conductive gel and fixed on the skin, in the center of the muscles. It was used an electromyography Lynx with 6 channels. The apparatus calibration was 3000 microV; 1199.760 Hz. The sequential experiments without ball were performed for 10 seconds, and the sequential experiments with ball in 12 seconds. RESULTS: None of the muscles presented significative difference (p > 0,05) when compared to the sequential movements executed with and without ball. When compared to the sequential movements executed without ball, the only muscles that presented significative differences (p < 0,05) were: pectoralis major / deltoid and latissimus dorsi / deltoid, for another hand when in the comparative of the movements with ball, all muscles when compared to the latissimus dorsi, presented a significance difference (p < 0,05). It is interesting to observe, that the general average and the standard deviation of the deltoid muscle (medial portion), teres major, and latis-simus dorsi were higher in the sequential movements executed without ball.     

Transient appearance of a fast myosin heavy chain epitope in slow-type muscle fibres during stretch hypertrophy of the anterior latissimus dorsi muscle in the adult chicken

Summary Myosin expression during hypertrophy of the chicken anterior latissimus dorsi (ALD) muscle was investigated by immunocytochemical procedures using monoclonal antibodies to the fast and slow isoforms of the myosin heavy chain (myosin HC). Antifast antibody 1F9 bound to the adult fast HC of pectoralis muscle and cross-reacted with the HC found in early developing muscle. Antislow antibody 3D1 bound exclusively to the HC of slow myosin 2 (SM2). Stretch hypertrophy of the ALD was produced by attaching a weight to the wing; there was no evidence for a change in fibre number in the muscle. Between 4 and 6 days of stretch there appeared a dramatic increase in the number of fibres staining with the antifast antibody which reached a peak between 12 and 19 days. By this time between 28 and 52% of the fibres in the stretched ALD stained to varying degrees with the antifast antibody compared with 1% in the unstretched control ALD. Most antifast-stained fibres in the stretched muscle also stained with the antislow antibody; the contralateral control muscle showed mostly antislow staining except for the very small number of strongly antifast-stained fibres. By 50 days in some birds and by 80 days in all birds antifast staining had returned to normal. Analysis of the isomyosin composition of the ALD by native gel electrophoresis did not reveal a significant increase in fast myosin content of the hypertrophied muscle even though immunocytochemical staining may have suggested otherwise.     

Quantitative and histochemical aspects of the differentiation of muscle spindles in the anterior latissimus dorsi of the developing chick

Summary The differentiation of muscle spindles has been investigated both quantitatively and histochemically in the slow anterior latissimus dorsi (ALD) muscle during embryonic and post-hatching development of the chick. The first spindles are detected by the 13th day in ovo, and a rapid increase in number takes place until the 15th of embryonic life. Two histochemical fibre types of intrafusal fibres are distinguished as early as the 13th day of embryonic development when myofibrillar ATPase activity is demonstrated after acid preincubation. In ALD muscle from post-hatched animals, two intrafusal fibre types are also distinguished by histochemistry: one fibre type is characterized by an acid and alkali-stable myofibrillar ATPase activity while this activity is acid-labile and alkali-stable in the other type. As far as the properties of myofibrillar ATPase are concerned, such types of intrafusal fibres resemble the extrafusal and fibre types defined recently in ALD muscle.The development of spindles in the slow-tonic ALD muscle is compared to the differentiation of spindles in the fast-twitch posterior latissimus dorsi (PLD) muscle of the chick which has been previously described (Toutant et al. 1981).     

An aberrant muscular nerve to the latissimus dorsi muscle from the posterior cutaneous nerve of the arm]

In the 1987 student course on gross anatomy dissection of cadavers at Iwate Medical University School of Medicine, an aberrant muscular nerve to the latissimus dorsi muscle arising from the posterior cutaneous nerve of the arm was found bilaterally in a 65-year-old female who had died of acute pneumonia. The case was investigated anatomically. The posterior cutaneous nerve of the arm arose from the radial nerve approximately at the lateral axial border as the first branch independently on the right, and by forming a trunk with the nerve to the long head of the triceps brachii muscle on the left. The aberrant muscular nerve originated from the posterior cutaneous nerve of the arm about 3 cm distally to the point of the branching of the cutaneous nerve from the radial nerve. This aberrant nerve entered the latissimus dorsi muscle near the transitional area from the muscular part to the tendinous part while dividing into three on the right, and without dividing on the left. The side into which the aberrant nerve entered was just the reverse of the side into which the thoracodorsal nerve and artery supplied. The muscular part innervated by the aberrant nerve was bounded by a tendinous intersection for the most part of the latissimus dorsi muscle innervated by the thoracodorsal nerve. The intramuscular nerve distribution of the aberrant nerve was investigated under a binocular dissecting microscope. It was revealed that there was no communication between the ramification of the aberrant nerve and that of the thoracodorsal nerve.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

背阔肌多止端1例

在解剖一具成年女尸时，发现其左侧背阔肌有3处止端，分别位于肱骨小结节嵴、胸大肌止端腱和肩胛骨喙突。此种变异少见，现报道如下：