Multiple muscular variations including tenuissimus and tensor fasciae suralis muscles in the posterior thigh of a human case

The posterior thigh muscles on the right side of an 81-year-old male cadaver had multiple variations, denoted muscles I–IV. Muscle I originated from the posteromedial surface of the greater trochanter and divided into two muscle bellies. These muscle bellies fused with the long head of the biceps femoris and were innervated by two branches from muscular branches of the semitendinosus and the long head of the biceps. Muscle II separated from the medial surface of the long head of the biceps in the proximal third and fused with the semitendinosus in the distal fourth. Muscle III was a biventer muscle. Its superior belly separated from the medial surface of the long head of the biceps in the distal third. The inferior belly of this muscle fused with the posterior surface of the crural fascia and was innervated by the tibial nerve. Muscle IV separated from the adductor magnus muscle, passed between the long and short heads of the biceps, fused with the inferior belly of muscle III, and was innervated by the muscular branch of the common fibular nerve to the short head of the biceps. Peeling off the epineurium of the muscular branches to the inferior belly of muscle III showed that this nerve fascicle divided from the common trunk with branches to the gastrocnemius and soleus muscles. The inferior bellies of muscle III and muscle IV were thought to be equivalent to the tensor fasciae suralis and tenuissimus muscles, respectively.     

Gross anatomic evidence of partitioning in the human fibularis longus and brevis muscles

Evidence from a variety of studies suggests that many mammalian muscles are partitioned with respect to their architecture and innervation. Each of these specific muscle subvolumes is innervated by an individual muscle nerve branch, contains motor unit territories with a unique array of physiological attributes and has been known as a neuromuscular compartment or segment. This gross anatomic study investigated for evidence of neuromuscular segmentation in human fibularis (peroneus) longus and brevis muscles. Forty-three legs (24 left, 19 right) from embalmed adult cadavers were dissected. Any architectural segments within these muscles were identified. The specific innervation patterns of these muscles were also described. The fibularis longus muscle was consistently found to have connective tissue partitions that separated it into four parts: anterior superficial, anterior deep, posterior superficial, and posterior deep. The innervation pattern of this muscle was consistent with the segments defined by the connective tissue partitions. There were consistently four primary motor branches, each supplying a specific portion of the fibularis longus muscle. While a typical branching pattern was recognized, there was some variability as to the order of these branches as they originated. The fibularis brevis muscle was consistently found to have a central connective tissue partition that separated it into two portions: anterior and posterior. In 91% of the fibularis brevis muscles, there were two primary motor branches, one for each of the two segments of the muscle. In the other 9%, only one primary motor branch supplying the muscle could be identified. © 1996 Wiley-Liss, Inc.     

Functional morphology of the maxillo-mandibular apparatus of the mini-Lewe minipig. 7. Intramuscular nerve ramification model of the masseter muscle of juvenile animals

The ramification patterns are basically the same at all ages. The existing patterns of intramuscular innervation change gradually only by increasing ramification. The masseter and zygomaticomandibularis muscles are innervated jointly by branches of the massetericus nerve. The medial pterygoid muscle is supplied by 2 branches. In 3 d old animals the lateral pterygoid muscle is supplied by a single branch, but 2 branches are already present in animals aged 2 months. The temporal muscle is innervated by 5 branches.     

Intramuscular nerve distribution of the hamstring muscles: Application to treating spasticity

The aim of this article is to elucidate the ideal sites for botulinum toxin injection by examining the intramuscular nerve distributions in the hamstring muscles. The hamstring muscles, biceps femoris, semitendinosus, and semimembranosus (10 specimens each) were stained by the modified Sihler method. The locations of the muscle origins, nerve entry points, and intramuscular arborized areas were recorded as percentages of the total distance from the line crossing the medial and lateral tibial condyles (0%) to the ischial tuberosity (100%). Intramuscular arborization patterns were observed at 15–30% and 50–60% for the biceps femoris, 25–40% and 60–80% for the semitendinosus, and 20–40% for the semimembranosus. This study suggests that botulinum toxin injection for spasticity of the hamstring muscles should be targeted to specific areas. These areas, where the arborization of intramuscular nerve branches is maximal, are recommended as the most effective and safest points for injection. Clin. Anat. 29:746–751, 2016. © 2016 Wiley Periodicals, Inc.     

Innervation of human soft palate muscles

Our objective was to determine the branching and distribution of the motor nerves supplying the human soft palate muscles. Six adult specimens of the soft palate in continuity with the pharynx, larynx, and tongue were processed with Sihler's stain, a technique that can render large specimens transparent while counterstaining their nerves. The cranial nerves were identified and dissection followed their branches as they divided into smaller divisions toward their terminations in individual muscles. The results showed that both the glossopharyngeal (IX) and vagus (X) nerves have three distinct branches, superior, middle, and inferior. Only the middle branches of each nerve contributed to the pharyngeal plexus to which the facial nerve also contributed. The pharyngeal plexus was divided into two parts, a superior innervating the palatal and neighboring muscles and an inferior innervating pharyngeal constrictors. The superior branches of the IX and X nerves contributed innervation to the palatoglossus, whereas their middle branches innervated the palatopharyngeus. The palatoglossus and palatopharyngeus muscles appeared to be composed of at least two neuromuscular compartments. The lesser palatine nerve not only supplied the palatal mucosa and palatine glandular tissue but also innervated the musculus uvulae, palatopharyngeus, and levator veli palatine. The latter muscle also received its innervation from the superior branch of X nerve. The findings would be useful for better understanding the neural control of the soft palate and for developing novel neuromodulation therapies to treat certain upper airway disorders such as obstructive sleep apnea.     

应用Sihler氏染色研究人喉神经分支分布类型

采用Sihler氏染色,经过染色后,在立体显微解剖镜下、可清晰地观察到喉内肌肌肉神经支配类型及神经间的联系,结果:(1)喉返神经支配除环甲肌以外的所有喉内肌,环甲肌由喉上神经外支支配.(2)喉上神经内支不仅支配声门上粘膜,也支配杓间肌(包括的横肌和杓斜肌)和声门下粘膜.(3)在每侧杓间肌肉.喉返神经和喉上神经内支之间百多个吻合支.(4)喉返神经的杓间肌神经和环杓后肌神经之间常有交通支.     

A variation of the brachial plexus characterized by the absence of the musculocutaneous nerve a case report

A variation of the brachial plexus characterized by the absence of the musculocutaneous nerve on both sides was observed during the dissection of a 72 year-old female cadaver. The long thoracic nerve included only the fibers from C5 and C6 on the left side. The musculocutaneous nerve was absent and two branches from the lateral cord innervated the coracobrachialis muscle. The median nerve innervated the biceps brachii and brachialis muscles in the arm and also gave off the lateral antebrachial cutaneous nerve. Additionally, a communicating branch was found from the median nerve to the ulnar nerve in the forearm. The knowledge of the anatomical variations of the peripheral nerve system can help give explanation when encountering an incomprehensible clinical sign.     

Basic anatomical investigation of semitendinosus and the long head of biceps femoris muscle for their possible use in electrically stimulated neosphincter formation

Summary Anal neosphincter formation with electrically stimulated gracilis muscle is used increasingly for the surgical treatment of fecal incontinence. An alternative to gracilis might be of interest if this muscle is not available. 30 semitendinosus muscles and 15 long heads of biceps femoris were investigated on human cadavers. In particular, the nerve and vascular supply of these muscles was studied, both representing basic factors for muscle transposition. The long head of biceps femoris m. was found to receive its dominant vascular supply from the first and second perforating artery and its nerve supply from one motor branch out of the sciatic nerve, both as described in literature. The examination of semitendinosus m., however, revealed new anatomical aspects in its vascular supply. In all cases semitendinosus m. was found to receive dominant vascular pedicles from the medial circumflex femoral artery close to the ischial tuberosity and the second perforating artery. The nerve supply consisted of two motor branches out of the sciatic nerve. Both muscles fulfilled several basic criterias for transposition to the anus. However, regarding these requirements, semitendinosus offered distinct advantages in comparison with the long head of biceps femoris. Due to its vascular and nerve topography, semitendinosus seems suitable to serve as an alternative to gracilis.

---

Bases anatomiques de l'utilisation du muscle semitendineux et du chef long du biceps fémoral comme néosphincter anal électro-stimulé

Résumé La graciloplastie électro-stimulée est utilisée de plus en plus fréquemment dans le traitement chirurgical de l'incontinence anale. L'utilisation d'un autre muscle peut être intéressante si le muscle gracile n'est pas utilisable. 30 muscles semitendineux et 15 longs chefs du biceps fémoral ont été étudiés sur des cadavres humains. Ce travail a porté particulièrement sur l'innervation et la vascularisation de ces muscles, dont dépendent les possibilités de transposition. Le long chef du m. biceps fémoral recevait sa vascularisation principale de la première et de la deuxième artère perforante et son innervation d'une branche motrice venant du nerf sciatique, tel que cela est décrit dans la littérature. L'étude du m. semitendineux a montré de nouveaux aspects anatomiques dans sa vascularisation. Dans tous les cas ce muscle recevait sa vascularisation principale de l'artère circonflexe médiale près de la tubérosité ischiatique et de la deuxième a. perforante. Son innervation venait de deux branches motrices du nerf sciatique. Ces deux muscles répondaient aux critères nécessaires pour leur transposition comme néo sphincter. Cependant, compte-tenu de sa vascularisation et de son innervation, le m. semitendineux répond mieux aux impératifs anatomiques que le long chef du biceps et représente une alternative au muscle gracile pour la création d'un néo sphincter anal.

     

Fast and slow muscles of the chick after nerve cross-union

1. The multiply innervated anterior latissimus dorsi (ALD) and the focally innervated posterior latissimus dorsi (PLD) muscles of the chick were investigated 2-18 months after nerve cross-union.2. The fast PLD muscle re-innervated by the slow muscle nerve became supplied with ;en grappe' end-plates and responded to a single nerve volley with local potentials only. Control PLD muscles re-innervated by the original nerve, had ;en plaque' end-plates and responded to a single nerve volley by synchronous action potentials in the same way as normal muscles.3. In the slow ALD muscle re-innervated with the ;mixed' PLD nerve, the type of innervation and of electromyographic response remained practically unchanged, with the exception of transplanted ALD muscles supplied with PLD nerves where, in addition to local responses, propagated action potentials were registered electromyographically in response to single nerve volleys.4. ALD muscles of young chickens re-innervated both with an implanted purely fast muscle nerve and with the regenerated original nerve, had two types of innervation: ;en plaque' end-plates around the nerve implant, and multiple ;en grappe' end-plates in areas supplied with the ALD nerve. Accordingly, propagated action potentials were registered in response to single nerve volleys in regions near the implant, whereas local potentials were recorded in areas with original innervation.5. Contraction velocity was not substantially altered in PLD and ALD muscles after nerve cross-union.6. No changes were observed in the fine structure of muscle fibres in extrajunctional regions.     

Intralaryngeal neuroanatomy of the recurrent laryngeal nerve of the rabbit

We undertook this study to determine the detailed neuroanatomy of the terminal branches of the recurrent laryngeal nerve (RLN) in the rabbit to facilitate future neurophysiological recordings from identified branches of this nerve. The whole larynx was isolated post mortem in 17 adult New Zealand White rabbits and prepared using a modified Sihler's technique, which stains axons and renders other tissues transparent so that nerve branches can be seen in whole mount preparations. Of the 34 hemi-laryngeal preparations processed, 28 stained well and these were dissected and used to characterize the neuroanatomy of the RLN. In most cases (23/28) the posterior cricoarytenoid muscle (PCA) was supplied by a single branch arising from the RLN, though in five PCA specimens there were two or three separate branches to the PCA. The interarytenoid muscle (IA) was supplied by two parallel filaments arising from the main trunk of the RLN rostral to the branch(es) to the PCA. The lateral cricoarytenoid muscle (LCA) commonly received innervation from two fine twigs branching from the RLN main trunk and travelling laterally towards the LCA. The remaining fibres of the RLN innervated the thyroarytenoid muscle (TA) and comprised two distinct branches, one supplying the pars vocalis and the other branching extensively to supply the remainder of the TA. No communicating anastomosis between the RLN and superior laryngeal nerve within the larynx was found. Our results suggest it is feasible to make electrophysiological recordings from identified terminal branches of the RLN supplying laryngeal adductor muscles separate from the branch or branches to the PCA. However, the very small size of the motor nerves to the IA and LCA suggests that it would be very difficult to record selectively from the nerve supply to individual laryngeal adductor muscles.     

Basic anatomical investigation of semitendinosus and the long head of biceps femoris muscle for their possible use in electrically stimulated neosphincter formation

Anal neosphincter formation with electrically stimulated gracilis muscle is used increasingly for the surgical treatment of fecal incontinence. An alternative to gracilis might be of interest if this muscle is not available. 30 semitendinosus muscles and 15 long heads of biceps femoris were investigated on human cadavers. In particular, the nerve and vascular supply of these muscles was studied, both representing basic factors for muscle transposition. The long head of biceps femoris m. was found to receive its dominant vascular supply from the first and second perforating artery and its nerve supply from one motor branch out of the sciatic nerve, both as described in literature. The examination of semitendinosus m., however, revealed new anatomical aspects in its vascular supply. In all cases semitendinosus m. was found to receive dominant vascular pedicles from the medial circumflex femoral artery close to the ischial tuberosity and the second perforating artery. The nerve supply consisted of two motor branches out of the sciatic nerve. Both muscles fulfilled several basic criterias for transposition to the anus. However, regarding these requirements, semitendinosus offered distinct advantages in comparison with the long head of biceps femoris. Due to its vascular and nerve topography, semitendinosus seems suitable to serve as an alternative to gracilis.     

Anatomical and physiological study of respiratory motor innervation in lampreys

The innervation of gill muscles of lampreys was investigated in a semi-intact preparation in which the respiratory rhythm was maintained for more than 2 days. Lesion experiments showed that the muscles of gill 1 are innervated by nerves VII (facial) and IX (glossopharyngeal), and those of gill 2 by nerve IX and the first branchial branch of nerve X (vagal). The other gills are supplied by the other branchial branches of nerve X. Retrograde tracers, injected in peripheral respiratory nerves, showed that branchial muscles are innervated by VII, IX and X motoneurons. Within the X nucleus, the motoneuron pools were branchiotopically organized, but with considerable rostro-caudal overlap. Electrophysiological recordings were used to show that the onset of activation of the branchial muscles was increasingly delayed with the distance from the brainstem, but that motoneuronal activity recorded with surface electrodes began at approximately the same time in all pools. The conduction velocity of VII and caudal X motor axons was found to be the same. Differences in the length of motoneuron axons appear to account for the rostro-caudal delay in gill contraction. The data presented here provide a much needed anatomical and physiological basis for further studies on the neural network controlling respiration in lampreys.     

Dual innervation of the brachialis muscle

A study of the innervation of the brachialis muscle was carried out on 45 male and 31 female Thai cadavers between the ages of 15 and 92 years (mean = 59 years). The dissections revealed that all brachialis muscles received innervation from the musculocutaneous nerve and that 81.6% were also innervated by a branch from the radial nerve. Among the brachialis muscles with a dual nerve supply, two patterns of branching from the radial nerve were observed: in one pattern the branch to the brachialis had a descending course (58%) and in the other pattern the nerve ascended or recurred (42%) to innervate the muscle. The radial nerve branch penetrated the inferolateral part of the brachialis muscle in 83% of cases (103/124) and its middle third in 17% of specimens (21/124). The basis for the dual innervation may result from fusion of two different embryonic muscular primordia: the ventral (flexor) and the dorsal (extensor) muscle masses. In contrast to a brachialis muscle innervated by the musculocutaneous nerve only, a muscle with dual innervation may be spared significant denervation by an anterior approach to the humerus through a longitudinally bisected muscle. In a dually innervated muscle, however, separation of the brachialis and brachioradialis muscles during surgery may put the radial nerve branch to the brachialis at risk.     

Cells of origin of the branches of the facial nerve: A retrograde HRP study in the rabbit

The origin of different branches of the facial nerve in the rabbit was determined by using retrograde transport of HRP. Either the proximal stump of specific nerves was exposed to HRP after transection, or an injection of the tracer was made into particular muscles innervated by a branch of the facial nerve. A clear somatotopic pattern was observed. Those branches which innervate the rostral facial musculature arise from cells located in the lateral and intermediate portions of the nuclear complex. Orbital musculature is supplied by neurons in the dorsal portion of the complex, with the more rostral orbital muscles receiving input from more laterally located cells while the caudal orbital region receives innervation from more medial regions of the dorsal facial nucleus. The rostral portion of the ear also receives innervation from cells located in the dorsomedial part of the nucleus, but the caudal aspect of the ear is supplied exclusively by cells located in medial regions. The cervical platysma, the platysma of the lower jaw, and the deep muscles (i.e., digastric and stylohyoid) receive input from cells topographically arranged in the middle and ventral portions of the nuclear complex. It is proposed that the topographic relationship between the facial nucleus and branches of the facial nerve reflects the embryological derivation of the facial muscles. Those muscles that develop from the embryonic sphincter colli profundus layer are innervated by lateral and dorsomedial portions of the nuclear complex. The muscles derived from the embryonic platysma layer, including the deep musculature, receive their input from mid to ventral regions of the nuclear complex.     

A functional and clinical reinterpretation of human perineal neuromuscular anatomy: Application to sexual function and continence

Modern anatomical and surgical references illustrate perineal muscles all innervated by branches of the pudendal nerve but still organized into anatomically distinct urogenital and anal triangles with muscles inserting onto a central perineal body. However, these conflict with the anatomy commonly encountered during dissection. We used dissections of 43 human cadavers to characterize the anatomical organization of the human perineum and compare our findings to standard references. We found bulbospongiosus and the superficial portion of the external anal sphincter (EAS) were continuous anatomically with a common innervation in 92.3% of specimens. The superficial transverse perineal muscle inserted anterior and lateral to the midline, interdigitating with bulbospongiosus. The three EAS subdivisions were anatomically discontinuous. Additionally, in 89.2% of our sample the inferior rectal nerve emerged as a branch of S3 and S4 distinct from the pudendal nerve and innervated only the subcutaneous EAS. Branches of the perineal nerve innervated bulbospongiosus and the superficial EAS and nerve to levator ani innervated the deep EAS. In conclusion, we empirically demonstrate important and clinically relevant differences with perineal anatomy commonly described in standard texts. First, independent innervation to the three portions of EAS suggests the potential for functional independence. Second, neuromuscular continuity between bulbospongiosus and superficial EAS suggests the possibility of shared or overlapping function of the urogenital and anal triangles. Clin. Anat. 29:1053–1058, 2016. © 2016 Wiley Periodicals, Inc.     

Scalenus muscles in macaque monkeys

The attachment and innervation of the scalenus muscles in both sides of two Japanese monkeys and a rhesus monkey were observed to discuss their morphological significance while comparing their findings in humans. The scalenus ventralis muscle in macaques had almost the same attachments as the scalenus anterior muscle in humans and was innervated by the cervical nerve branches, which were lower in spinal segment than in humans and had a close relationship with the branches to the intertransversus ventralis muscles. Furthermore, the scalenus ventralis muscle was penetrated by the phrenic nerve in all cases observed. The posterior part of the scalenus muscle in macaques (the scalenus dorsalis muscle) was divided into short (the scalenus dorsalis brevis) and long (the scalenus dorsalis longus) parts according to their attachments. The former was attached to the transverse processes of the lowest two cervical vertebrae and the first rib, whereas the latter was attached to the 3rd-5th ribs. It is notable that the scalenus dorsalis muscles in macaques were innervated by branches from the long thoracic nerve in addition to direct branches from the cervical nerve roots. In addition, the scalenus dorsalis longus was supplied by twigs from the lateral cutaneous branches of the 2nd and 3rd intercostal nerves. This indicates that the scalenus dorsalis muscles contain a muscular component derived from the upper limb girdle musculature, unlike the human scalenus muscles, which have been considered to belong to the cervical trunk muscles.     

Anatomical study of the obturator internus, gemelli and quadratus femoris muscles with special reference to their innervation

The manner of innervation of the obturator internus, superior and inferior gemelli, and the quadratus femoris in humans (101 pelvic halves) and in rhesus monkeys (Macaca mulatta: 8 pelvic halves) were investigated. In most specimens, the inferior gemellus originated from the lateral surface of the ischial tuberosity and also from the medial surface (intrapelvic origin) just beneath the obturator internus and was covered by the falciform process of the sacrotuberous ligament. The superior gemellus was frequently innervated by the nerve to the obturator internus and the nerve to the quadratus femoris (60.4%), and the inferior gemellus was innervated by the obturator internus nerve in two specimens. The quadratus femoris nerve originated from more cranial segments than the obturator internus nerve, however these nerves had various communication patterns inside and outside the muscles. According to the intramuscular nerve distribution, in some specimens the branches to the superior gemellus from the quadratus femoris nerve extended to the inferior gemellus, and the branches to the inferior gemellus were distributed to the obturator internus. The present findings revealed that the positional relationships among the branches to the obturator internus and gemelli muscles are relatively constant, although the branching patterns and innervation patterns were varied. The various patterns and routes are considered to reflect the variability of the differentiation patterns of the anlage of the muscles. A possible schematic model of the positional relationships between the muscles and the nerves is proposed.     

人大腿肌构筑学研究

对12侧人大腿肌的构筑研究表明，股四头肌的生理横切面积是臀大肌或腓肠肌的3倍，伸膝肌远较屈膝肌强大是人类骨骼肌的特征之一，Guo绳肌中，股二头肌长头和半膜肌提供主要肌力，股二头肌短头和半腱肌都是速度型肌，分别对前的力度和方向进行调节，内收肌群各肌的肌纤维长度，羽状角自上而下逐渐增大，适应于下肢以髋关节为中心的收，展运动，也表现为强化髋和膝的稳定性，本测定了大腿各肌在解剖方位下的肌节长。