Relationship between the ulnar nerve and the branches of the radial nerve to the medial head of the triceps brachii muscle

One branch of the radial nerve to the medial head of the triceps brachii muscle (MHN) has been described as accompanying or joining the ulnar nerve. Mostly two MHN branches have been reported, with some reports of one; however, the topographical anatomy is not well documented. We dissected 52 upper limbs from adult cadavers and found one, two, and three MHN branches in 9.6%, 80.8%, and 9.6% of cases, respectively. The MHN accompanying the ulnar nerve was always the superior MHN. The relationship between the ulnar nerve and the MHN was classified into four types according to whether the MHN was enveloped along with the ulnar nerve in the connective tissue sheath and whether it was in contact with the ulnar nerve. It contacted the ulnar nerve in 75.0% of cases and accompanied it over a mean distance of 73.6 mm (range 36–116 mm). In all cases in which the connective tissue sheath enveloped the branch of the MHN and the ulnar nerve, removing the sheath confirmed that the MHN branch originated from the radial nerve. The detailed findings and anatomical measurements of the MHN in this study will help in identifying its branches during surgical procedures. Clin. Anat. 00:1–16, 2018. © 2018 Wiley Periodicals, Inc.     

Surgical anatomy of the radial nerve branches to triceps muscle

The objectives of the study are to demonstrate the innervation patterns of the triceps muscles and the most suitable branch of the radial nerve for nerve transfer to restore the motor function of the deltoid muscle in patients with complete C5–C6 root injury. Seventy‐nine arms (40 left arms and 39 right arms) from 46 embalmed cadavers (24 male and 22 female) were included in the study. The nerves to the triceps were dissected from the triceps muscles (long head, lateral head, and medial head). The lengths of the branches were measured from the main trunk. The distance from the inferior margin of the teres major muscle to the origin of the nerve to the long head, lateral head, and medial head of the triceps were recorded as well. The first branch was the nerve to the long head of the triceps in 79 arms (100%). The second branch was the nerve to the upper medial head in 30 arms (38%), nerve to the medial head in 8 arms (10.1%), nerve to the upper lateral head in 35 arms (44.3%) and nerve to the lateral head in 6 arms (7.6%). The patterns of branches to the triceps were classified according to our dissections. The nerve to the long head of the triceps was constant as the first branch of the nerve to the triceps branch of the radial nerve in the vicinity of the inferior margin of the teres major muscle. Clin. Anat. 2013. © 2012 Wiley Periodicals, Inc.     

Topographical anatomy of the radial nerve and its muscular branches related to surface landmarks

Understanding of the anatomy of the radial nerve and its branches is vital to the treatment of humeral fracture or the restoration of upper extremity function. In this study, we dissected 40 upper extremities from adult cadavers to locate the course of the radial nerve and the origins and insertions of the branches of the radial nerve using surface landmarks. The radial nerve reached and left the radial groove and pierced the lateral intermuscular septum, at the levels of 46.7, 60.5, and 66.8% from the acromion to the transepicondylar line, respectively. Branches to the long head of the triceps brachii originated in the axilla, and branches to the medial and lateral heads originated in the axilla or in the arm. The muscular attachments to the long, medial, and lateral heads were on average 34.0 mm proximal, 16.4 mm distal, and 19.3 mm proximal to the level of inferior end of the deltoid muscle, respectively. The radial nerve innervated 65.0% of the brachialis muscles. Branches to the brachioradialis and those to the extensor carpi radialis longus arose from the radial nerve above the transepicondylar line. Branches to the extensor carpi radialis brevis usually arose from the deep branch of radial nerve (67.5%); however, in some cases, branches to the extensor carpi radialis brevis arose from either the radial nerve (20.0%) or the superficial branch of the radial nerve (12.5%). Using these data, the course of the radial nerve can be estimated by observing the surface of the arm. Clin. Anat. 26:862–869, 2013. © 2012 Wiley Periodicals, Inc.     

肱三头肌长头重建肩外展功能的应用解剖

目的研究肱三头肌长头血管神经蒂特点为以其重建肩外展功能提供解剖学基础。方法对44侧固定尸体的肱三头肌长头肌肉起点及血管神经蒂进行解剖与测量。结果肱三头肌长头起点背侧为肌性,腹侧为腱性,腱性起点长度(9.9±1.5)cm,宽度(2.4±0.4)cm。神经支配来自桡神经的分支,可分离长度(6.8±2.7)cm,直径(2.0±0.4)mm。血供来自①肱动脉肱三头肌支,长度(3.4±1.4)cm,外径(2.0±0.3)mm;②肱深动脉的分支,长度(2.5±0.9)cm,外径为(1.6±0.5)mm,分离至肱动脉长度为(3.9±1.3)cm。血管神经蒂以多级分支为主。结论依据肱三头肌长头及其血管神经蒂的特点,可作为肩外展功能重建术中的动力肌。     

Evolutionary adaptations in the flexor digitorum profundus muscle in Tamandua mexicana (Xenarthra,Myrmecophagidae)

The northern tamandua (Tamandua mexicana) is a neotropical mammal of the order Pilosa, suborder Vermilingua, and family Myrmecophagidae. This species has anatomical and functional adaptations in its forelimb for semiarboreal quadrupedal locomotion. Several studies have reported that the medial head of the triceps brachii and flexor digitorum profundus muscles are fused in species belonging to the family Myrmecophagidae. However, there is no reference to the innervation in these. The triceps brachii muscle is commonly innervated by the radial nerve and the flexor digitorum profundus muscle by the ulnar and median nerves. This study aims to describe the gross anatomy of the flexor digitorum profundus muscle in Tamandua mexicana with respect to the shape, origin, insertion, innervation, and arterial supply. Both forelimbs of nine specimens were used, which were dissected from superficial to deep layers. The formalin-fixed caudomedial forearm muscles were weighed, and the weight percentages of individual forearm muscle specimens were calculated. The flexor digitorum profundus had the highest weight among the forearm muscles and consisted of five heads (three humerals, one radial, and one ulnar). These heads were innervated by median and ulnar nerves; therefore, based on the innervation pattern, we concluded that the medial head of the triceps brachii muscle is not fused with the flexor digitorum profundus. Therefore, the flexor digitorum profundus muscle is highly developed in Tamandua and occupies the caudal part of the arm and forearm, which is an evolutionary adaptation that could have occurred during evolution from the common ancestor of Tamandua and Myrmecophaga.     

Lateromedial and dorsoplantar borders among supplying areas of the nerves innervating the intrinsic muscles of the foot

The branching patterns of nerves supplying the intrinsic muscles of the foot were analyzed as a basis to confirm the muscle layer structure. Thirty‐eight feet of 20 Japanese cadavers were examined in detail in this study. The first dorsal interosseus was innervated by a branch from the deep peroneal nerve as well as a branch of the lateral plantar nerve in 92.1%, the second dorsal interosseus in 10.5% and the third dorsal interosseus in 2.6%. In three specimens, branches from the deep peroneal nerve innervated the oblique head of the adductor hallucis or the lateral head the flexor hallucis brevis. In addition, branches from the medial and lateral plantar nerves and the deep peroneal nerve formed communication loops in three specimens. The first dorsal interosseus, the oblique head of the adductor hallucis and the lateral head of the flexor hallucis and their innervating nerve branches are closely related within the first intermetatarsal space. Since the tibial part of the first interosseus muscle primordium is occupied in the space during development, the variations of innervation patterns and formation of the communicating nerve loops may be explained by various combinations of the part and the other muscle primordia. Anat Rec 255:465–470, 1999. © 1999 Wiley‐Liss, Inc.     

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.     

肱三头肌的解剖特点及其在臂后中部桡神经显露中的意义

目的观察肱三头肌与桡神经的位置关系,改进臂中后部桡神经的显露方法。方法尸体标本31具(62侧),在臂中部将肱三头肌外侧头自臂外侧肌间隔上钝性剥离达肱骨,继续向内侧钝性分离肱三头肌外侧头,显露桡神经,观察肱三头肌外侧头和内侧头融合的位置、融合前二者分界是否清晰,观察肱三头肌内侧头起点和外侧头起点与桡神经的位置关系。结果肱三头肌内、外侧头融合近端与桡神经穿过臂外侧肌间隔处距离(6.7±2.6)cm,约在鹰嘴窝上缘水平,融合前肱三头肌内、外侧头分界清晰。肱三头肌外侧头全部起自桡神经沟近端肱骨骨面的为79%(49侧),部分起自桡神经沟以远肱骨骨面的为21%(13侧),其中腱性的9例,肌性的4例。结论利用臂中部肱三头肌内、外侧头的解剖特点,可使臂后中部桡神经的显露更安全、合理。     

Lateromedial and dorsoplantar borders among supplying areas of the nerves innervating the intrinsic muscles of the foot.

The branching patterns of nerves supplying the intrinsic muscles of the foot were analyzed as a basis to confirm the muscle layer structure. Thirty-eight feet of 20 Japanese cadavers were examined in detail in this study. The first dorsal interosseus was innervated by a branch from the deep peroneal nerve as well as a branch of the lateral plantar nerve in 92.1%, the second dorsal interosseus in 10. 5% and the third dorsal interosseus in 2.6%. In three specimens, branches from the deep peroneal nerve innervated the oblique head of the adductor hallucis or the lateral head the flexor hallucis brevis. In addition, branches from the medial and lateral plantar nerves and the deep peroneal nerve formed communication loops in three specimens. The first dorsal interosseus, the oblique head of the adductor hallucis and the lateral head of the flexor hallucis and their innervating nerve branches are closely related within the first intermetatarsal space. Since the tibial part of the first interosseus muscle primordium is occupied in the space during development, the variations of innervation patterns and formation of the communicating nerve loops may be explained by various combinations of the part and the other muscle primordia.     

Accessory muscles in the lower part of the anterior compartment of the arm that may entrap neurovascular elements

The aim of this study was to evaluate the incidence of abnormal muscular bands of the anterior compartment of the arm that may compress the median, the ulnar, and the medial antebrachial cutaneous nerve as well as the brachial artery and vein, thus causing entrapment at and above the elbow. A total of 56 adult cadavers were studied during routine dissections that occurred in our laboratory. In the 112 upper limbs studied, we found three variant muscles of the flexor compartment of the arm (2.68%) entrapping nerves and vessels. The first muscle was emerging from the tendon of long head of biceps brachii and coracobrachialis muscle insertion. The second muscle inserted partially into the belly of biceps brachii and should be considered as a supernumenary head of biceps brachii. The third muscle, in fact, represents an accessory fascicle of the brachialis muscle that is an embryonic remnant of that muscle. A number of structures cross anterior to the median, ulnar, and medial antebrachial cutaneous nerve as well as the brachial artery and vein. Compression of nerves and vessels may be caused by additional muscular bundles that pass anterior to these structures. These additional muscular bundles arise either from the brachialis, coracobrachialis, or biceps brachii muscle. Such variations have clinical implications and should be considered in patients, with a high median or ulnar or medial antebrachial cutaneous nerve paralysis with symptoms of lower brachial artery or brachial vein compression.     

Rare case of high origin of the ulnar artery from the brachial artery

Arterial variations in the arm are numerous and occur at the level of the axillary, brachial, radial, and ulnar arteries as well as in the palmar arches. We report on a high branching site of the ulnar artery. A high branching brachial artery was found in a 72-year-old white female during a dissection course. The brachial region was then dissected carefully and the preparation steps were documented. The axillary artery, after entering the arm, was located posterior to the junction of the two roots of the median nerve, just 2 cm distal to the latter, and divided into the ulnar and the radial arteries. The radial artery was located medial to the median nerve in the arm and approached the lateral side of the arm to reach the cubital fossa. Just distal to its origin, the ulnar artery ran laterally crossing ventral to the median nerve, thereafter supplying the biceps brachii muscle with three branches from a common stem. The ulnar artery then approached the medial side of the arm, crossed ventral to the median nerve again and took its course toward the cubital fossa as usual. This high bifurcation of the brachial artery and the abnormal course of the ulnar artery is of interest to clinicians; in particular vascular and plastic surgeons and radiologists. Clin. Anat. 10:253–258, 1997. © 1997 Wiley-Liss Inc.     

Triceps brachii muscle demonstrating a fourth head

Variations of the triceps brachii muscle are apparently rare. We report an additional attachment site of the medial head of the triceps brachii found on the left side of a male cadaver. This head originated from the posterior aspect of the surgical neck of the humerus. Clinicians diagnosing or treating patients with weakness or pain of the posterior arm should consider anomalous muscles in this region that may result in neurovascular compression.     

Morphological characteristics of the posterior brachial cutaneous nerve--a consideration of the development of cutaneous nerves in man

The posterior brachial cutaneous nerve (Cbp) has certain characteristic features, being different from adjacent cutaneous nerves such as the medial brachial cutaneous nerve (Cbm) and the intercostobrachial nerve (Icb). These features are summarized as follows. 1) At the dorsal surface of the arm, the Cbp passes deeply beneath the fascia of the arm covering the dorsal surface of the long head of the triceps brachii, whereas the Cbm and the Icb pass superficial to it. In this area, the Cbp is accompanied in its course by a small artery. 2) The Cbp has no communication with the Cbm and the Icb on its way to the arm. 3) A precise and more detailed examination using a stereoscopic microscope reveals that the Cbp supplies the branches to the fascia of the dorsal surface of the arm, before passing through it. 4) The Cbp arises from the stem of the radial nerve forming a common trunk with the muscular branch to the long head of the triceps brachii. 5) In the brachial plexus, the Cbp is derived from segments C7 and C8, mainly the latter, and is composed of the most caudal elements of the radial nerve. According to the dermatome map, it would be unreasonable to consider that the Cbp (C8) is distributed in the skin, being intercalated between the Cbm (T1) and the Icb (T2). 6) Comparative anatomically, the Cbp cannot be observed in the monkey, dog, cat, rabbit or rat. Instead, in these animals, the muscular branch to the dorsoepitrochlearis arises from the radial nerve and takes the same course as that of the Cbp in man. According to Eisler (1901, 1912), when a muscle degenerates during the process of phylogeny or ontogeny, the supplying nerve sometimes remains in loco, as if representing the site where the muscle previously existed. As examples of these cases, Eisler described the following findings. 1) A fine branch arises from the loop of the cervical nerve and supplies the fascia, which extends between the clavicle and the omohyoid muscle. Eisler considered the fascia to be a remnant of the cleidohyoid muscle, which normally exists in lower mammals. 2) A branch sometimes arises from the lateral cutaneous branch of the upper intercostal nerve and passes along the ventral thoracic wall. Eisler considered this branch to be derived from the nerve supplying the external oblique abdominal muscle. 3) The interosseous nerve of the legs shows a remnant of the nerve supplying the pre-existing posterior interosseous muscle.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nerve dysfunction leads to muscle morphological abnormalities in chronic inflammatory demyelinating polyneuropathy assessed by MRI

Neuropathic features of chronic inflammatory demyelinating polyneuropathy (CIDP) have been well documented, however very little is known about the implication of this neuropathy on skeletal muscle, and whether nerve lesions in CIDP lead to uniform disruptions in skeletal muscles. In this study, we assessed the triceps surae complex, using magnetic resonance imaging (MRI) in a group (n = 10) of CIDP patients compared with a healthy age-matched control group (n = 9). MRI (T1 and T2) of the leg musculature as well as plantar flexion strength measurements were obtained from both groups. CIDP patients compared with controls had ∼28% lower plantar flexion strength and ∼19% less total muscle volume (T1) of the triceps surae. When strength was normalized to fat corrected triceps surae volume CIDP patients were ∼30% weaker than controls. Relaxation times from the T2 scans were significantly longer in CIDP with the soleus, medial head of gastrocnemius and lateral head of gastrocnemius showing ∼37%, ∼38% and ∼26% longer relaxation times, respectively. CIDP patients were significantly weaker compared to controls and despite normalizing strength to total triceps surae contractile tissue volume this difference remained. CIDP patients had significantly longer T2 times, reflecting increased noncontractile tissue infiltration. These results indicate reduced muscle quantity and quality as a result of alterations in axonal function. Furthermore, when present study results are considered together with a prior report on the anterior compartment (Gilmore et al. 2016, Muscle Nerve 3:413–420), it is clear that both anterior and posterior leg compartments are affected similarly in CIDP despite different terminal nerve innervation and functional properties. Clin. Anat. 32:77–84, 2019. © 2019 Wiley Periodicals, Inc.     

Histochemical and morphometric investigations of the musculature of forelimb mass of sheep with reference to its function. 1. Bending and extension of elbow joints]

Muscle tissue was removed from the extensors and flexors of the elbow joint of six male sheep (180 days old) and stained for NADH tetrazolium oxidoreductase and myofibrillar ATPase after preincubation at pH 4.3 in order to identify three fiber types: slow twitch oxidative (STO), fast twitch oxidative (FTO) and fast twitch glycolytic fibers (FTG). The medial head of the M. triceps brachii and the anconaeus muscle had the largest fibers (> 50 and 60 microns). The smallest muscle fibers (35-43 microns) were found in the dorsal part of the long head of the triceps muscle. The medial head of the triceps muscle and the anconaeus muscle possessed a very high percentage of STO-fibers (90 and 100%) and FTG-fibers were absent in these muscles. In the other extensors and flexors of the elbow joint the STO-percentage amounted to less than 30%. The dorsal part of the long head of the triceps muscle contained only 13% STO-fibers, but had the highest percentage of FTG-fibers (49%), which is representative of fast-muscles. The muscles of the elbow joint perform both static and dynamic functions. The medial head of the triceps brachii muscle and the anconaeus muscle possess the complement of enzymes which permits them to fulfil the work of extensors in the standing position. Therefore, they are typical of antigravity muscles. The histochemical structure of the other extensors and flexors reflect their function in motion. The lateral and long head of triceps muscle oppose the flexors and extend the elbow joint of the raised limb in the swing phase, during the landing phase they also function to support the other extensors of the elbow.     

Anatomical variations of the pronator teres muscle in a Central European population and its clinical significance

The pronator teres (PT) muscle is a forearm flexor with radial and ulnar heads. It is innervated by the median nerve (MN), which passes between these heads. Nerve entrapment, known as “PT syndrome”, may occur in this passage. Anatomical variations in this region may be potential risk factors of this pathology. Therefore, the aim of the study was to determine the relationship between morphologic variations of the PT and the MN. In 50 isolated, formalin-fixed upper limbs, the cubital region and the forearm were dissected. The following measurements were taken: origin of the PT muscle heads, the length of these heads, the length of the forearm, diameter of the MN and the number of its muscular branches to the pronator teres muscle. The forearms with the humeral head originating from the medial humeral epicondyle and medial intermuscular septum (72%) were significantly shorter (p = 0.0088) than those where the humeral head originated only from the medial humeral epicondyle. Moreover, in these specimens, the MN was significantly thinner (p = 0.003). The ulnar head was present in 43 limbs (86%). The MN passed between the heads of the PT muscle (74%) or under the muscle (26%). In the majority of cases, it provided two motor branches (66%). There is an association between the morphologic variation of the PT muscle heads and the course and branching pattern of the MN. Both are related to differences in forearm length. This may have an impact on the risk of PT syndrome and the performance of MN electrostimulation.     

The medial head of the triceps brachii. Anatomy and blood supply of a new muscular free flap: the medial triceps free flap

Purpose

The anatomical features of the posterior compartment of the arm seem to provide the basis to raise one of the smallest free muscular flaps, with minimal donor site morbidity: the medial triceps free flap.

Methods

The anatomic study was carried out on 27 fresh cadaver arms: 7 prepared for corrosion cast, 15 for simple dissection and 5 for dissection after latex injection. Morphological data of the muscle, as well as pedicle constancy and size, were recorded.

Results

The mean size of the medial head was 10.7?×?2.5?×?3.3?cm; the mean weight was 30.1?g. We found a constant and unique pedicle supplying the whole medial head of triceps muscle, composed by the middle collateral artery (MCA), two veins and a nerve. The mean length of MCA was 2.9?cm and the ??extended?? pedicle, including the deep brachial artery (DBA), was 8?C12?cm long. At their origin, the mean caliber of MCA was 1.5?mm and the mean caliber of DBA 2.4?mm.

Conclusions

Our findings confirmed the reliability of the MC vessels and their anatomical relationships with the medial head of triceps brachii muscle, which could be harvested as a free flap or as a pedicled flap based on anterograde or retrograde flow. This technique should be safe, yielding mild donor site morbidity, and suitable in regional reconstruction or distant reanimations.     

Surgical anatomy of the radial nerve at the elbow

An anatomical study of the brachial portion of the radial nerve with surgical implications is proposed. Thirty specimens of arm from 20 fresh cadavers (11 male, 9 female) were used to examine the topographical relations of the radial nerve with reference to the following anatomical landmarks: acromion angle, medial and lateral epicondyles, point of division between the lateral and long heads of the triceps brachii, lateral intermuscular septum, site of division of the radial nerve into its superficial and posterior interosseous branches and entry and exit point of the posterior interosseous branch into the supinator muscle. The mean distances between the acromion angle and the medial and lateral levels of crossing the posterior aspect of the humerus were 109 (±11) and 157 (±11) mm, respectively. The mean length and calibre of the nerve in the groove were 59 (±4) and 6 (±1) mm, respectively. The division of the lateral and long heads of the triceps was found at a mean distance of 126 (±13) mm from the acromion angle. The mean distances between the lateral point of crossing the posterior aspect of the humerus and the medial and lateral epicondyles were 125 (±13) and 121 (±13) mm, respectively. The mean distance between the lateral point of crossing the posterior aspect of the humerus and the entry point in the lateral intermuscular septum (LIS) was 29 (±6) mm. The mean distances between the entry point of the nerve in the LIS and the medial and lateral epicondyles were 133 (±14) and 110 (±23) mm, respectively. Our study provides reliable and objective data of surgical anatomy of the radial nerve which should be always kept in mind by surgeons approaching to the surgery of the arm, in order to avoid iatrogenic injuries.     

Differences between motor unit firing rate,twitch characteristics and fibre type composition in an agonistic muscle group in man

Summary A comparison was carried out between the motor unit (MU) firing rate and the characteristics of the twitch and the fibre type composition of anconeus and triceps brachii. Fibre type composition (type I, type II) was determined in whole cross-sections of cadaver specimens. The proportion of type I fibre was 60%–67% in anconeus and 32–40% in the lateral head of triceps brachii. Reflecting these histochemical differences, the contraction time of anconeus and triceps was 92±9 ms and 68±9 ms respectively. It follows that anconeus can be classified as a slow muscle, as opposed to the lateral head of triceps. The relationship between MU firing rate and isometric force, tested at 90° elbow flexion, differed between the two muscles for force values below 30% of maximal voluntary contraction. No significant increase in MU firing rate was found in anconeus at forces above 5% of maximal voluntary contraction. It is concluded that even within a single agonistic muscle group acting at a single joint there is an adaptation of MU firing rate to the contractile characteristics of each muscle.