Translational Research in Anatomy最新文献

Introduction

The third head of the biceps brachii is the predominant variation of the arm muscles. Awareness of muscular variations is essential for the management of upper limb pathologies. Variations in the shape of the muscles are rarely explored. This study aimed to describe the prevalence and anatomical presentation of the third head of the biceps brachii muscle (origin, insertion and innervation) with an emphasis on the shape and form variations.

Materials and methods

Biceps brachii of eighty-nine cadavers were examined. The presence of the third head, its origin, shape patterns, blood supply, and nerve innervation were determined and recorded.

Results

The third head of the biceps brachii was present in 20.2 %, with a prevalence of 22.2 % in males and 18.2 % in females. Half (50 %) of these were bilateral presentations. Most (92 %) of the third head of the biceps brachii variations were flat, thin and straight in shape. All the shape variation patterns were observed in males and on the left arm. The third head originated from the humerus on its anteromedial aspect in 92 % of cases. The musculocutaneous nerve innervated the third head of the biceps brachii in 96 % of the cases, and a nerve anomaly of musculocutaneous and median nerves innervated it in a single (4 %) case. The muscular branches of the brachial artery supplied the third head of the biceps brachii in all cases.

Conclusion

Studies on the variation of arm muscles may assist in identifying new patterns of morphological variations like the shape of the muscle and may aid in the accurate diagnosis and management of arm pathologies.

Purpose

This study sought to establish the prevalence and morphological characteristics of lumbosacral transitional vertebrae (LSTV) in the South African population and its correlation with South African's population affinities.

Methods

A retrospective review was performed of 3096 consecutive thoracic-abdominal-pelvic radiographs at two large public hospitals in South Africa. Categorisation of LSTV was classified according to Castellvi et al. (1984): Types II, III, and IV with unilateral (A) or bilateral (B) subtypes present. The three largest South African population groups (participant self-identified), namely Black African, Coloured and White population affinities were equally sampled, comprising 1032 radiographs for each population affinity.

Results

The overall prevalence of LSTV was 10 % (N = 308 of 3096). Prevalence by classification/type was 67.9 %, 27.6 % and 4.5 % for II, III, and IV, respectively. The most prevalent subtype was Type IIA (41.9 %), Type IIB (26 %), Type IIIB (21.8 %), and Type IV (5.8 %), respectively. Prevalence by frequency of side was bilateral (47.7 %), left (26.6 %), right (21.1 %), while 4.5 % could not be sided (Type IV morphology). The sex distribution was 53.9 % (166/308) female and 46.1 % (142/308) male. Prevalence by population affinity was 10.5 %, 9.3 % and 9.9 % for the Black African, Coloured and White population affinities, respectively. Analyses of all groups found that the Black African and Coloured populations demonstrated two statistically significant results: greater affinity for the prevalence of sacralisation (95 % CI: 0.396–4.33, p = 0.008), and sacralisation amongst males (95 %, CI: 0.42–3.36, p = 0.010).

Conclusion

This study was the first dedicated study of LSTV prevalence in a South African population. There was no significant difference in the prevalence of LSTV between the three largest population groups. Statistically, sacralisation was observed in greater proportions in the Black African and Coloured populations, particularly among males.

Introduction

Typically, the lateral femoral cutaneous nerve, also known as the lateral cutaneous nerve of the thigh (LCNT), runs under the inguinal ligament near the anterior superior iliac spine, runs anterior to the sartorius muscle and then divides into two terminal branches, i.e., anterior and posterior, which provide sensory innervation to the anterior and lateral thigh. This report describes an unusual anatomic variant in which terminal branches of the LCNT pierced the sartorius muscle.

Case description

Dissection involved formalin-fixed right isolated lower limb. The procedure revealed anatomical variation of the LCNT. The nerve's division level into anterior and posterior branches was at the level of the inguinal ligament under the sartorius muscle. The posterior branch of the LCNT was directly adjacent to the anterior superior iliac spine. After a short course, this branch emerged from under the sartorius muscle lateral border 39 mm distally (in a straight line) to the inguinal ligament. The nerve's anterior branch pierced the sartorius muscle. It exited on the anterior surface of the muscle, 72 mm (in a straight line) from the inguinal ligament. The innervation territory of both branches was typical. We found no other anatomical variations of lumbar plexus branches.

Conclusions

The LCNT terminal branches may show anatomic variations, which clinicians should consider during neurological assessments of nerve lesions. Deviations from the typical course of nerves should also be kept in mind when conducting surgical interventions.

Introduction

Variations in muscles of the pollex are common, and some can elicit significant clinical implications. The abductor pollicis longus (APL) frequently exhibits non-typical morphologies; however, descriptions of uncharacteristic distal fibers from APL (APL_udf) that form a reticular tunnel around the tendons of extensor carpi radialis longus (ECRL) and brevis (ECRB) are scarce in current literature. The objective of this study is to investigate the prevalence of APL_udf with concurrent report of in situ and cross-sectional gross imaging.

Methods

The distal aspect of 110 APL muscles was examined for APL_udf and reticular tunnel formation. Reticular tunnel length was measured over the long axis of the underlying ECRL tendon, and APL_udf pennation angle was recorded. Characteristic APL and APL_udf examples were photographed in situ, and one example of APL_udf was cross-sectioned to show the bony attachment of the atypical fibers in relation to contiguous anatomy. A unique finding of an APL_udf accessory tendon inserting onto an accessory abductor pollicis brevis muscle was removed, splayed, and photographed.

Results

APL_udf were present in 65 (59.1%) of upper limbs. The APL_udf originated from a free origin over the ECRL and ECRB tendons and a fixed origin from the lateral margin of the distal radius and inserted onto the main APL tendon or an accessory tendon, creating a distinct reticular tunnel around the ECRL and ECRL with a mean length of 20.25 ± 5.55 mm (range = 11.09 mm–36.09 mm) and 12.99° ± 1.44° pennation. All APL muscles displayed one main tendon and at least one accessory tendon which originated solely from APL_udf on 43 (39.1%) of the specimens.

Conclusions

The present study suggests the prevalence of APL_udf is 59.1% and often occurs bilaterally. The restriction of intersecting movements within the APL_udf reticular tunnel could cause ECRL and ECRB tendon inflammation (i.e., intersection syndrome), directly affect respective functions (e.g., radial extension of the wrist, abduction and extension of the thumb), and complicate surgical management in the region. This report may inform educators and healthcare providers when deliberating diagnosis, treatment, and healing of associated forearm, wrist, and pollex conditions.

Anatomical variations related to the sciatic nerve and its surrounding structures are well-documented, relevant for certain medical procedures, and identified as contributors to pathological conditions. Variations of the sciatic nerve are often classified by its relative position to the piriformis muscle. However, there are inconsistencies in the description and depiction of these variations, along with instances of atypical variations that do not fall within any specific classification. This case report describes an anatomic abnormality found during a routine cadaver dissection involving the bilateral presence of a double piriformis, absence of sciatic nerve formation (tibial and common fibular nerves never within a shared sheath) and an atypical course of the inferior gluteal vessels perforating the right tibial nerve.

Introduction

The infraspinatus and teres minor are scapulohumeral muscles that laterally rotate the arm. Multiple variations in these muscles have been reported; however, the impact of concurrent accessory infraspinatus (a-I) and teres minor (a-TM) muscles has yet to be described. The present study aims to employ gross cross-sectional and biomechanical analyses to investigate a case of coexistent a-I and a-TM muscles for structural effects, functional impacts, and clinical implications.

Methods

Bilateral a-I muscles and a left a-TM muscle were discovered during routine dissection of a human cadaver. The aberrations were carefully cleaned of extraneous tissue and photographed. The left glenohumeral joint was sectioned sagittally and photographed to confirm the relation of a-I and a-TM to contiguous structures. The infraspinatus, a-I, teres minor, and a-TM muscles were examined for gross and microscopic structural features that were used to calculate maximal isometric force (F_max) and bilateral comparability (δ).

Results

The 8.66 g (bilateral mean) a-I and 13.42 g (left) a-TM inserted on the greater tubercle just distal to their namesake muscle. At the left glenohumeral joint, a-I remained distinct from infraspinatus while a-TM and teres minor exhibited connected bellies. Bilateral a-I and teres minor muscles were structurally similar (δ < 0.30), while left and right infraspinatus muscles approached non-similarity (δ = 0.69). F_max of the left infraspinatus, a-I, teres minor, and a-TM were 117.12 N, 26.45 N, 59.93 N, and 29.88 N, respectively.

Conclusions

Coexistent a-I and a-TM muscles can increase the rotator cuff's lateral rotation force by 31.82%, but they may imbalance glenohumeral joint stability, complicate injury and surgical repairs to the region, and increase risk of quadrangular space syndrome. This study provides gross and functional analyses of concurrent a-I and a-TM muscles that may help guide diagnosis, treatment, research, and education for related cases.

Introduction

Anatomical variations of the nerves derived from the lumbar plexus are common and clinically valid. Therefore, this report aims to present the coexisting anatomical variations of the lateral femoral cutaneous and genitofemoral nerves.

Case description

During routine dissection of an isolated male left lower limb (fixed in 10 % formalin solution), atypical arrangements of the lateral femoral cutaneous and genitofemoral nerves were found. The lateral femoral cutaneous nerve division level into anterior and posterior branches was high, above the inguinal ligament. Both branches passed beneath the inguinal ligament at the midpoint of the distance between the anterior superior iliac spine and the femoral artery. The anterior branch of the lateral femoral cutaneous nerve was better developed and had a greater diameter than the posterior branch. The femoral branch of the genitofemoral nerve was absent and partially replaced by the most medial branch derived from the anterior division of the lateral femoral cutaneous nerve.

Conclusions

The lateral femoral cutaneous and genitofemoral nerves can show anatomic variability, which should be remembered during clinical assessments of nerve lesions and while performing surgical interventions.

Background

The anatomical variations at the suprascapular region have great impact on the suprascapular nerve and its entrapment syndrome.

Aim

This study aimed to describe the morphological types and morphometric parameters of the superior transverse scapular ligament (STSL) and its relation to suprascapular neurovascular triad.

Material & methods

The suprascapular region was dissected in 60 (40 male & 20 female) cadaveric shoulders. The morphological variants, length, widths, thickness of STSL, and its relation to suprascapular triad were evaluated.

Results

Five morphological types of STSL were identified. The common variant was the fan-shaped followed by the band-shaped and the triangular-shaped, while the ossified and bifid forms revealed lower incidence rates with no side or sex significant difference. Morphometrically, the length of STSL measured 16.4 ± 2.4 mm, medial width was 13.3 ± 3 mm and its lateral width measured 5.4 ± 1.3 mm with no side significant difference (p > 0.05). Moreover, its length measured 16.6 ± 2.6 mm in male and 15.8 ± 1.9 mm in female, its medial width was 13.7 ± 2.2 mm in male and 12.2 ± 2 in female, and its lateral width measured 5.6 ± 1.3 in male and 5.1 ± 1.1 mm in female specimens. The relation between the suprascapular triad and STSL showed three main variants: where the blood vessels pass above the STSL (56.7 %), followed by the passage of the artery above and the vein below STSL (23.3 %), and the blood vessels below STSL (11.7 %).

Conclusion

Knowledge the morphological variants and morphometric measurements of STSL and its relation to the suprascapular triad are important during surgical and arthroscopic procedures of the shoulder region.

Background

Variation of the different components of the brachial plexus is fairly common and well documented. Some of these variations may have clinical consequences in terms of clinical manifestations or altering the surgical intervention plan while others may be benign with no functional or clinical consequences. Therefore, thorough reporting and knowledge of different anatomical variations is of utmost clinical importance.

Method

During routine human anatomical dissection of the axilla and posterior triangle of the neck, an unusual C5 nerve branch caught our attention. After careful cleaning and thorough dissection of the brachial plexus, we realized the full details of this anomalous variant of C5 nerve branch.

Results

Here, we report bilateral anatomical variance of the C5 nerve root which supplied the levator scapulae muscle (LSM) and superior slip of the serratus anterior (SSSA). This innervation was completely independent of the dorsal scapular (DSN) and long thoracic nerves (LTN), both of which existed bilaterally. However, on the right side, the LTN did not receive any contribution from C5, whereas on the left side the LTN did receive a contribution from C5.

Conclusion

We believe this is one of the rare reports of a C5 nerve root having combined LSM and serratus anterior (SA) innervations bilaterally. As such, this finding may prove useful in clinical applications such as LTN injury, thoracic outlet syndrome, winged scapula, and surgical cases pertaining to the head and neck.

Introduction

A right-sided aortic arch is a rare congenital cardiovascular anomaly that arises from persistence of the right fourth aortic arch and regression of the left fourth aortic arch. This variation commonly gives rise to an aberrant left subclavian artery (ALSA). In this report, we present an unusual variation of a right-sided aortic arch with an isolated common subclavian trunk (CST).

Methods

During a routine dissection of a female cadaver, a right-sided aortic arch variation with an aberrant left subclavian artery was observed. The thorax was further dissected to reveal the right-sided aortic arch and anomalous origin of the ALSA from a CST.

Results

The ascending aorta arose from the heart to form a right-sided aortic arch which branched into 1) a CST, 2) a left common carotid artery, and 3) a right common carotid artery. The CST branched into a right subclavian artery and an ALSA which traversed posteriorly to the esophagus to its normal anatomical position. The descending thoracic aorta passed along the right lateral aspect of the vertebral column, traversed posteriorly to the esophagus, and continued descending in its anatomical position through the aortic hiatus.

Conclusion

Rare aortic arch congenital anomalies such as a common subclavian trunk predispose the body to numerous clinical complications. A common subclavian trunk can cause cardiovascular complications and gastrointestinal complications due to compression of the esophagus. A deep understanding of the variations in the aortic arch and its branches is necessary for all physicians when managing patients with cardiovascular and upper gastrointestinal symptoms.