Short Head Research Articles

Evaluating malformations of the lacrimal drainage system in brachycephalic dog breeds: A comparative computed tomography analysis.

ObjectivesThis study aimed to investigate and compare the anatomical features of the nasolacrimal drainage system (NDS) in three brachycephalic dog breeds with those of normocephalic dogs, taking into account how the NDS was related to the malformed brachycephalic head.AnimalsFifty-one brachycephalic dogs were examined, comprising 23 Pugs, 18 French Bulldogs, and 10 English Bulldogs. Six normocephalic dogs of different breeds served as a comparison.MethodsComputed tomographic dacryocystography was performed. Parameters such as length, angulation, and gradient were determined. Crossing of the nasolacrimal duct (NLD) beneath the maxillary canine root, as well as the incidence of an accessory opening, were also analyzed.Results and conclusionsIn all three brachycephalic breeds, the NDS was grossly malformed. We regard this as a further consequence of exaggerated breeding for a short head conformation. While the length of the NLD was substantially reduced by 41 to 57 percent in brachycephalic dogs, their lacrimal canaliculi were two to three times as long as those of normocephalic dogs. Varying parts of the nasolacrimal drainage system followed an inverse direction in short-headed dogs, giving the entire nasolacrimal apparatus an anomalous U- or V-shaped appearance. The NLD exhibited a three to five times steeper alignment in brachycephalic dogs than in normocephalic ones. Obviously, this strong slope did not cause clinical symptoms only because there was an aberrant outflow pathway. The brachycephalic dogs consistently exhibited an accessory opening, through which most of fluid escaped into the posterior nasal cavity instead of through the common route into the nasal vestibule via the nasolacrimal ostia.

Protective and Risk Factors for Humerus Head Necrosis After Proximal Humerus Fracture Treated with Internal Locking Plate.

Proximal humerus fractures (PHF) are common and lead to post-traumatic humerus head necrosis (HHN) in 3-35% after ORIF with an internal locking plate. Few studies focus on this condition and risk factors remain a discussion topic. Hertel's criteria for initial head ischemia right after fracture (fracture complexity, medial hinge displacement and short metaphyseal head extension) have recently been correlated to HHN, but there is still a clear lack of evidence on the topic. Due to its anatomical similarities to the proximal femur, some authors argue that PHF may as well benefit from early surgery to avoid head necrosis. In this 10-year retrospective study, we assessed 305 patients from a single center. All cases were treated with a PHILOS plate through a deltopectoral approach. The mean follow-up time was 467days. The primary endpoint was HHN. HHN was diagnosed in 12 patients (4%), 10 of which were diagnosed within the first year and one case 4years after surgery. A positive correlation (p < 0.04) was found between HHN and fracture type (both in AO and Neer's classification), initial neck-shaft-angle (NSA) and metaphyseal head extension (MHE). Medial hinge displacement (MHD) occurred in all HHN cases. Achieving perfect reduction (< 2mm dislocation) was relevant to avoiding HHN (p = 0.035). Although HHN developed in 32% of the high risk cases (four-part fractures with a short MHE), it was completely avoided (0%) when perfect reduction was achieved. Time until surgery after admission was neither a protective nor a risk factor for HHN. We conclude that fracture complexity (four-part and C-fractures) as well as disruption of the medial hinge with a metaphyseal head extension smaller than 8mm are relevant risk factors for humerus head necrosis. A combination of these criteria generated an high risk pattern with a 32% rate of HHN. Though often difficult to achieve, perfect reduction was a clear protective factor and reduced HHN to 0%. Perfect reduction may be key to inosculation and, therefore, salvage of the humerus head, especially in high risk cases. Surgery timing did not correlate with HHN. Level 3, retrospective cohort study.

Analysis on muscle force and injured femoral reduction force based on new muscle tendon model

Robot-assisted fracture reduction usually involves fixing the proximal end of the fracture and driving the distal end of the fracture to the proximal end in a planned reduction path. In order to improve the accuracy and safety of reduction surgery, it is necessary to know the changing rule of muscle force and reduction force during reduction. Fracture reduction force was analyzed based on the muscle force of femoral. In this paper, a femoral skeletal muscle model named as PA-MTM was presented based on the four elements of skeletal muscle model. With this, pinnate angle of the skeletal muscle was considered, which had an effect on muscle force properties. Here, the muscle force of skeletal muscles in different muscle models was compared and analyzed. The muscle force and the change of the reduction force under different reduction paths were compared and simulated. The results showed that the greater the pinnate angle was, the greater the influence of muscle strength was. The biceps femoris short head played a major role in the femoral fracture reduction; the force in the z direction contributed the majority to the resulting force with maximums of 472.18 N and 497.28 N for z and resultant, respectively, and the rationality of the new musculoskeletal model was verified.

Influence of osteoporosis and mechanical loading on bone around osseointegrated dental implants: A rodent study

This study aimed to evaluate the influence of estrogen deficiency and mechanical loading on bone around osseointegrated dental implants in a rat jaw model. The maxillary right first molars of 36 rats were extracted. One week later, the rats were divided into an unloaded group and a loaded group; short head implants and long head implants were inserted respectively. Nine weeks after implantation, the rats were further subjected to ovariectomy (OVX) or sham surgery. All animals were euthanized 21 weeks after OVX. Micro-computed tomography, histological and histomorphometrical evaluation were undertaken. Systemic bone mineral density and bone volume fraction decreased in OVX groups compared with the sham controls. Histomorphometrical observation indicated that unloaded OVX group showed significantly damaged osseointegration and bone loss versus the loaded OVX group. Both the bone density (BD) inside the peri-implant grooves and the percentage of bone-to-implant contact (BIC) were lower in the OVX groups than in the sham-surgery groups, although mechanical loading increased the BIC and BD in the loaded OVX group compared with the unloaded OVX group. An increased number of positive cells for tartrate-resistant acid phosphatase was observed in the OVX groups versus the sham controls. The percentage of sclerostin-positive osteocytes was lower under loaded compared with unloaded conditions in both the OVX groups and the sham controls. In conclusion, estrogen deficiency could be a risk factor for the long-term stability of osseointegrated implants, while mechanical loading could attenuate the negative influence of estrogen deficiency on bone formation and osseointegration.

Statin-associated anti-3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR) myopathy: Imaging findings on thigh-muscle magnetic resonance imaging (MRI) in six patients.

Anti-3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR) myopathy is a rare but serious complication of statin use. The aim of this study was to describe the imaging features of statin-associated anti-HMGCR myopathy on thigh muscle magnetic resonance imaging (MRI). Thigh muscle MRI images of six patients with statin-associated anti-HMGCR myopathy were reviewed for muscle edema, fatty replacement, and fascial edema in four compartments of each thigh: gluteal, anterior, medial, and posterior. Signal intensity ratio (SIR) was calculated in 17 muscles in both thighs on T2-weighted fat-suppressed images. Intracompartmental comparison of T2 SIRs of different muscles were performed. All patients demonstrated bilateral symmetrical pan-compartmental muscle edema. Three patients had fatty infiltration, involving gluteal and/or posterior compartments. In the anterior compartment, rectus femoris and vastus lateralis most frequently demonstrated the highest T2 SIR. In the posterior compartment, semimembranosus most frequently demonstrated the highest T2 SIR. The long head of the biceps femoris always had a higher T2 SIR than the short head. Statin-associated anti-HMGCR myopathy commonly demonstrates bilateral symmetrical pan-compartmental edema on thigh muscle MRI, with anterolateral predilection in the anterior compartment, and greater involvement of the semimembranosus with relative sparing of the short head of the biceps femoris in the posterior compartment. These observations can contribute to the diagnosis of statin-associated anti-HMGCR myopathy.

Generalized EMG-based isometric contact force estimation using a deep learning approach

EMG-based force estimation is generally done in a subject specific manner. In this paper, we explore force estimation in a manner generalizable across individuals, where the EMG signals are recorded from the long head and the short head of biceps brachii, and the brachioradialis, under isometric elbow flexion, while the contact force is measured at the wrist. Deep convolutional neural networks (CNN), which utilize feature-level fusion of representations learned from high-density (HD) EMG in the time and frequency domains, are developed. The performance of the proposed solution (CNN-FLF) is compared to a number of baselines including CNNs with input-level fusion of HD-EMG data in the time and frequency domains, CNNs which estimate force from time or frequency domain EMG data separately, and a number of classical machine learning methods, which use hand-crafted features extracted from the EMG signals. Results show that the CNN-FLF, with optimized hyper-parameters, outperformed all other methods, giving a normalized mean squared error for estimated force of 1.6±3.69% (mean±SD). In visualization of the extracted features for the different CNN models, it is apparent that the final features of the CNN-FLF enable finding an accurate regressive relationship with output force levels.

Reliability of Distal Hamstring Tendon Length and Cross-sectional Area Using 3-D Freehand Ultrasound

The objective of this study was to investigate the reliability of distal hamstring tendon morphology using freehand 3-D ultrasound (US). Freehand 3-D US scans were acquired for 16 young males and females, in two sessions, spaced a week apart. The length, volume, cross-sectional area (CSA) and echo intensity (EI) of the semitendinosus (ST), biceps femoris long and short head and semimembranosus (SM) tendons were acquired. Measurements of the CSA and EI were obtained from three sites along each tendon. The intra-class correlation coefficients ranged from 0.88–0.99 of the examined variables, indicating high test–retest reliability. In addition, the minimal detectable change (MDC) ranged from 0.255–3.766 mm (MDC% of the mean: 0.406%–12.558%) for hamstring tendon length, from 0.036–0.077 mL (MDC%: 1.548%–3.178%) for tendon volume, from 0.512–1.948 mm2 (MDC%: 0.702%–3.586%) for CSA and from 0.898–2.586 au (MDC%: 1.145%–3.325%) for EI. Of the four hamstring tendons, ST had the greatest length (141.587 ± 10.701 mm) and EI (94.637 ± 5.536 au), while SM had the greatest volume (3.056 ± 0.421 mL) and CSA (115.277 ± 16.442 mm2) relative to other tendons. Freehand 3-D US appears to be a reliable tool for the evaluation of hamstring distal tendon morphology; hence, its use for in vivo evaluation of tendon properties is promising.

English

BACKGROUND Supernumerary heads of the biceps brachii are a common anatomical variation, with an incidence of 3.7 % to 20.5 % in various studies carried out around the world. They can occur in various forms, and produce a range of clinical symptoms, such as impingement syndromes at the shoulder joint, and nerve-compression syndromes in the arm. An awareness of these variations is helpful when assessing patients with pain symptoms in the region of the shoulder and arm. The purpose of this study was to examine the morphology, nerve supply, and variations in morphology, of the biceps brachii in a population in Eastern India. METHODS This observational study was carried out on 20 (17 males, 3 females) formalinembalmed cadavers during routine gross anatomy dissection of the upper limb, using standard dissection methods. We examined the morphology, nerve supply, and variations in morphology, of the biceps brachii in a population in Eastern India. RESULTS Three upper limbs (7.5 % out of 40 limbs) showed supernumerary heads. In one male, a third humeral head of origin, from the anteromedial surface of the shaft of the humerus was observed in the left upper limb. In another male cadaver, we found a unique case with bilateral third heads with an aponeurotic origin from the capsule of the shoulder joint, with the third head comparable in size and bulk to the long and short heads. The remaining upper limbs showed the usual morphology, with the long head originating intracapsularly from the supraglenoid tubercle of the humerus and the glenoid labrum, and the short head from the tip of the coracoid process of the scapula. Insertions were usual. CONCLUSIONS Our study found an incidence of 7.5 % in a population sample from Eastern India, North Bengal. Supernumerary heads can occur in various forms, and can result in varied clinical symptoms. KEYWORDS Biceps Brachii, Biceps Brachii Variations, Supernumerary Head, Third Head, Humeral Head, Long Head of Biceps

Is it the coracobrachialis superior muscle, or is it an unidentified rare variant of coracobrachialis muscle?

The coracobrachialis muscle (CBM) originates from the apex of the coracoid process, in common with the short head of the biceps brachii muscle, and from the intermuscular septum. The CBM demonstrates variability in both the proximal and distal attachment, with some extremely rare varieties, such as the coracobrachialis superior, coracobrachialis longus and coracocapsularis muscle. This case report describes an extremely rare variant of the coracobrachialis superior muscle, or a very rare variant of the CBM. Our findings highlight the importance of muscle variants in the shoulder region, especially the coracoid region, and are significant for radiologists, anatomists, physiotherapists and surgeons specializing in the shoulder joint.

Oxynoemacheilus isauricus, a new nemacheilid loach from Central Anatolia (Teleostei: Nemacheilidae).

Oxynoemacheilus isauricus, new species, from the Lakes Beyşehir and Suğla basins in Central Anatolia is distinguished from all other species of the O. angorae group by having a very slender caudal peduncle (its depth 2.22.6 times in its length). The new species is further distinguished by having a short head (head length 2124% SL), and a midlateral series of irregularly shaped blotches on the flank. Oxynoemacheilus isauricus is also distinguished by a minimum K2P sequence divergence of 7.5% and 8.0% in the mtDNA-COI barcode region from O. eregliensis and O. atili, its closest relatives.

Hamstring and gluteal activation during high-speed overground running: Impact of prior strain injury

ABSTRACT This study examined the spatial patterns of hamstring and gluteal muscle activation during high-speed overground running in limbs with and without aprior hamstring strain injury. Ten active males with arecent (<18 month) unilateral biceps femoris long head (BFLH) strain injury underwent functional magnetic resonance imaging before and immediately after arepeat-sprint running protocol. Transverse relaxation (T2) time, an index of muscle activation, of the BFLH and short head (BFSH), semitendinosus (ST), semimembranosus (SM), gluteus maximus (GMAX) and medius (GMED) was assessed pre-post exercise. No significant between-limb differences in running-induced mean T2 changes were observed (p = 0.949), however, decision tree induction revealed that previously injured limbs were characterised by highly variable intramuscular activation of the ST (SD5.3). T2 times increased more for GMAX than all other muscles (all p< 0.001, d= 0.5–2.5). Further, T2 changes were greater for ST than BFSH, SM, GMED, and BFLH (all p≤ 0.001, d= 0.5–2.9); and were greater for BFLH than BFSH, SM, and GMED (all p< 0.001, d= 1.2–1.6). Athletes display heterogenous patterns of posterior thigh activation when sprinting (GMAX>ST>BFLH>GMED>SM>BFSH) and may exhibit altered intramuscular hamstring activation after returning to sport from BFLH strain injury.

A new approach of inducing proprioceptive illusion by transcutaneous electrical stimulation

BackgroundNeurotraumas or neurodegenerative diseases often result in proprioceptive deficits, which makes it challenging for the nervous system to adapt to the compromised sensorimotor conditions. Also, in human machine interactions, such as prosthesis control and teleoperation, proprioceptive mismatch limits accuracy and intuitiveness of controlling active joints in robotic agents. To address these proprioceptive deficits, several invasive and non-invasive approaches like vibration, electrical nerve stimulation, and skin stretch have been introduced. However, proprioceptive modulation is still challenging as the current solutions have limitations in terms of effectiveness, usability, and consistency. In this paper, we propose a new way of modulating proprioception using transcutaneous electrical stimulation. We hypothesized that transcutaneous electrical stimulation on elbow flexor muscles will induce illusion of elbow joint extension.MethodEight healthy human subjects participated in the study to test the hypothesis. Transcutaneous electrodes were placed on different locations targeting elbow flexor muscles on human subjects and experiments were conducted to identify the best locations for electrode placement, and best electrical stimulation parameters, to maximize induced proprioceptive effect. Arm matching experiments and Pinocchio illusion test were performed for quantitative and qualitative analysis of the observed effects. One-way repeated ANOVA test was performed on the data collected in arm matching experiment for statistical analysis.ResultsWe identified the best location for transcutaneous electrodes to induce the proprioceptive illusion, as one electrode on the muscle belly of biceps brachii short head and the other on the distal myotendinous junction of brachioradialis. The results for arm-matching and Pinocchio illusion tests showed that transcutaneous electrical stimulation using identified electrode location and electrical stimulation parameters evoked the illusion of elbow joint extension for all eight subjects, which supports our hypothesis. On average, subjects reported 6.81° angular illusion of elbow joint extension in arm-matching tests and nose elongated to 1.78 × height in Pinocchio illusion test.ConclusionsTranscutaneous electrical stimulation, applied between the the synergistic elbow flexor muscles, consistently modulated elbow joint proprioception with the illusion of elbow joint extension, which has immense potential to be translated into various real-world applications, including neuroprosthesis, rehabilitation, teleoperation, mixed reality, and etc.

Association of the British Athletic Muscle Injury Classification and anatomic location with return to full training and reinjury following hamstring injury in elite football

BackgroundThe relationship between hamstring muscle injuries (HMIs) that involve the intramuscular tendon and prolonged recovery time and increased reinjury rate remains unclear in elite footballers.ObjectiveTo determine the association of time...

Risk Factors for Revision After Early and Delayed Total Hip Arthroplasty Dislocation. An Analysis of Lithuanian Arthroplasty Register.

Introduction: Despite relatively low incidence, dislocation remains one of the main reasons for total hip arthroplasty (THA) revision. It is a devastating complication for a patient and a surgeon, and has high burden on the healthcare system. The aim of the present study was to assess and compare the risk factors for revision after early and delayed THA dislocations.Methods: Some 3403 THA through posterior approach for primary osteoarthritis were retrospectively studied in the Lithuanian Arthroplasty Register from 2011 to 2018. Three months after THA was the splitting time between the first event of early and delayed dislocations. Revision was set as outcome measure. Gender, affected side, number of dislocations, femoral head and neck size, and prosthesis fixation type were tested as risk factors for revision after early and delayed THA dislocations.Results: Dislocation occurred in 108 patients (3.2%), and 26 cases (0.8%) required revision. Men had statistically significant higher risk for revision due to early dislocation [hazard ratio (HR) 4.7; 1.3-17.7 confidence interval (CI)] and considerably lower risk for revision due to delayed dislocation (HR 0.5; 0.1-1.7 CI). The left side THA had twice the risk as compared to the right in the early settings (HR 2.1; 0.6-6.9 CI) which equalized after three months (HR 1.1; 0.4-3.1 CI). Some 32 mm femoral head had significantly lower risk in the early group as compared to 28 mm head (HR 0.3; 0.1-0.5 CI). Short head was associated with increased risk for revision after early dislocation, although, not statistically significant. Prosthesis fixation type was not a risk factor for revision surgery neither after early nor after delayed dislocation.Conclusion: The unique finding of gender separation was found -- men tend for revision after early dislocation and women after delayed dislocation. In early stage, additional precautions should be considered when 28 mm short metal heads are used.

Third head of biceps femoris muscle-a case report

Sometimes variations in biceps femoris may be noticed like an accessory head of biceps femoris. Here during routine cadaveric dissection in the department of anatomy. All India institute of medical sciences, Jodhpur we found a case with an accessory head of biceps femoris in both the lower limbs. The muscle belly is originating from the fibers of long head of biceps femoris and going downward medially to get inserted to the medial condyle of tibia on its medial superior aspect. On the right-side insertion site is like a sheath and on half a way it is merging with medial intermuscular septum of thigh. On the left side insertion is first like a thin sheath and then a thin muscle belly. The muscle belly is thin as compared to the long and short head of the main muscle bellies. On the left side thickness is around 3.7 mm in the upper end and thinner in the lower end while on right side also it is around 3.75 mm. On right side length of muscle belly is around 5 cm and on left side it is around 5.5 cm muscle belly, then becomes a sheath with length around 0.5 mm and then again becomes a muscle belly of around 3.5 cm length. Short head is arising high up on the left side while on right side it is as normal.

Notoraja hesperindica sp. nov., a new colorful deep-sea softnose skate (Elasmobranchii, Rajiformes, Arhynchobatidae) and first generic record from the western Indian Ocean

A new deep-sea softnose skate, Notoraja hesperindica, is described based on six specimens caught in 1230–1600 m depths off southern Mozambique and northwestern Madagascar in the western Indian Ocean. The new species is a medium-sized species of Notoraja Ishiyama, 1958 reaching a total length of at least 539 mm. It is the only Notoraja species known from the western Indian Ocean and differs from most congeners in the intense dark blue-grayish coloration. The only congeners with similarly vibrant coloration are Notoraja azurea McEachran & Last, 2008 from off southern Australia and Notoraja sapphira Seret & Last, 2009 from the Norfolk Ridge (Coral Sea and Tasman Sea), which differ from the new species in a shorter and more obtusely angled snout, a shorter head, a shorter disc, and smaller dorsolateral tail thorns, as well as more predorsal tail and total predorsal vertebrae and more pectoral-fin radials. The large dorsolateral tail thorns also distinguish the new species from most congeners except for the eastern Pacific Notoraja martinezi Concha, Ebert & Long, 2016, which has even larger, randomly patterned dorsolateral tail thorns that give the tail a barbedwire-like appearance. This congener further differs from N. hesperindica sp. nov. in the absence (vs. presence) of malar thornlets, fewer median tail thorns, a shorter snout, more tooth rows in upper and lower jaws, and more pectoral radials. A key to the species of Notoraja in the Indian Ocean is provided.

The smoke sign: a secondary sign of unsuspected acute pectoralis major tendon injury on routine shoulder MRI.

To study the diagnostic utility of the "smoke sign" to detect unsuspected acute pectoralis major tendon injury on routine shoulder MRI. Retrospective study of 52 shoulder MRI in patients with (38) and without (14) acute pectoralis major injury confirmed on imaging. Two readers independently reviewed shoulder MRI for the presence of the "smoke sign"-feathery soft tissue edema lateral or anterior to short head biceps/coracobrachialis on fluid-sensitive coronal-oblique and sagittal-oblique images, respectively. The smoke sign was present on shoulder MRI in 24/24 (100%) humeral avulsions, 4/4 (100%) tendon tears, 4/8 (50%) of myotendinous junction injuries, and 0/2 (0%) intramuscular injuries. The smoke sign was present in 0/14 examinations without acute pectoralis major injury. While dedicated pectoralis MRI remains the preferred method for imaging pectoralis injury, the "smoke sign" can serve as an easy to recognize finding on routine shoulder MRI that can raise the suspicion of an acute pectoralis major tendon injury. Its detection should prompt evaluation of the pectoralis major tendon and recommendation for dedicated imaging to confirm and evaluate the full extent of injury.

Capoeta baliki Turan, Kottelat, Ekmekçi & Imamoglu, 2006 a junior synonym of Capoeta tinca (Heckel, 1843) (Teleostei: Cyprinidae)

Capoeta baliki was described from Sakarya basin, Turkey. It was distinguished from its nearest congener i.e. C. tinca based on a combination of characters, including fewer serrae along posterior margin of last simple dorsal-fin ray, modally fewer scale rows between lateral line and dorsal-fin origin, fewer vertebrae, deeper and shorter head and slenderer caudal peduncle. We examined the synonymy hypothesis of C.­ baliki and C. tinca by comparing their morphometric, meristic and molecular characters. Based on the results, their morphometric and meristic characters largely overlapped and no character was found to distinguish them. In addition, a low K2P mean genetic divergence of 0.37% C. baliki and C. tinca based on cyt b gene and clustering in same clad showed that they are identical in molecular characters. As no character could be found to clearly distinguish these species, we treat C. baliki as a junior synonym of C. tinca .

A proposal for a new classification of coracobrachialis muscle morphology

IntroductionThe coracobrachialis muscle (CRM) originates from the apex of the coracoid process, in common with the short head of the biceps brachii muscle, and from the intermuscular septum. It inserts to the medial part of the humerus between the attachment of the medial head of the triceps brachii and the brachial muscle. Both the proximal and distal attachments of the CRM, as well as its relationship with the musculocutaneus nerve, demonstrate morphological variability.Material and methodsOne hundred and one upper limbs (52 left, and 49 right) fixed in 10% formalin solution were examined.ResultsThree main types, with subtypes, were identified. The most common was Type I (49.5), characterized by a single muscle belly with a classical origin from the coracoid process, medially and posteriorly to the tendon of the biceps brachii. Type II (42.6%), characterized by two heads, was divided into two subtypes (A-B) depending on its origin: Type IIA, where one head originated from the coracoid process posteriorly to the tendon of the biceps brachii and the second head from the short head of the biceps brachii, and Type IIB, in which both heads originated from the coracoid process; however, the superficial head fused with the insertion of a short head of the biceps brachii, while the deep head was directly originating. Finally, Type III (7.9%) was characterized by three heads: two originated from the coracoid process (superficial and deep), and the third from a short head of the biceps brachii. Two types of insertion and two types of musculocutaneous nerve (MCN) relative to CRM could be distinguished.ConclusionAn adapted classification is needed for all clinicians working in this area, as well as for anatomists. The CRM demonstrates morphological variability in both its proximal and distal attachments, as well as the variable course of the MCN relative to the CRM.What is known about this subject "and" What this study adds to existing knowledgeNot much is known about the variability of coracobrachialis muscle. The present paper introduces a completely new classification, both clinical and anatomical.

Which Approach Is Most Optimal for Needle Electromyographic Examination of the Biceps Femoris Short Head: Medial or Lateral?

ObjectiveTo investigate the anatomical characteristics of the biceps femoris short head (BS) and determine the optimal needle placement for BS examination.MethodsTwenty-one lower limbs were dissected. The distances from the medial and lateral margins of the biceps femoris long head (BL) tendon to the common fibular nerve (CFN) (M_CFN_VD and L_CFN_VD, respectively) and the distance from the lateral margin of the BL tendon to the lateral margin of the BS (L_BS_HD) were measured 5 cm proximal to the tip of the fibular head (P1), four fingerbreadths proximal to the tip of the fibular head (P2), and at the upper apex of the popliteal fossa (P3).ResultsThe BS was located lateral to the BL tendon. The CFN was located along the medial margin of the BL tendon. The median values were 2.0 (P1), 3.0 (P2), and 0 mm (P3) for M_CFN_VD; and 17.4 (P1), 20.2 (P2), and 21.8 mm (P3) for L_CFN_VD; and 8.1 (P1), 8.8 (P2), and 13.0 mm (P3) for L_BS_VD.ConclusionThe lateral approach to the BL tendon was safer than the medial approach for examining the BS. Amore proximal insertion site around the upper apex of the popliteal fossa was more accurate than the distal insertion site. In this study, we propose a safer and more accurate approach for electromyography of the BS.