A Cadaveric Case of an Accessory Cleido-Occipital Muscle Over the Common Trunk of the Supraclavicular Nerves.

The current study describes a case of an aberrant cleido-occipital muscle. In particular, this muscle was arising from the middle part of the clavicle, inserted into the medial part of the upper trapezius muscle, and crossed over the supraclavicular nerves with possible compression of them, especially during shoulder abduction. Knowledge of the muscular variability of the posterior cervical triangle is crucial for supraclavicular nerve entrapment syndrome diagnosis and treatment. The appearance of aberrant muscular fascicles may lead to misinterpretation of neck imaging, as well as difficulties during surgical procedures undertaken in the region.

Two Functional Epithelial Sodium Channel Isoforms Are Present in Rodents despite Pronounced Evolutionary Pseudogenization and Exon Fusion.

The epithelial sodium channel (ENaC) plays a key role in salt and water homeostasis in tetrapod vertebrates. There are four ENaC subunits (α, ß, γ, δ), forming heterotrimeric αßγ- or δßγ-ENaCs. Although the physiology of αßγ-ENaC is well understood, for decades the field has stalled with respect to δßγ-ENaC due to the lack of mammalian model organisms. The SCNN1D gene coding for δ-ENaC was previously believed to be absent in rodents, hindering studies using standard laboratory animals. We analyzed all currently available rodent genomes and discovered that SCNN1D is present in rodents but was independently lost in five rodent lineages, including the Muridae (mice and rats). The independent loss of SCNN1D in rodent lineages may be constrained by phylogeny and taxon-specific adaptation to dry habitats, however habitat aridity does not provide a selection pressure for maintenance of SCNN1D across Rodentia. A fusion of two exons coding for a structurally flexible region in the extracellular domain of δ-ENaC appeared in the Hystricognathi (a group that includes guinea pigs). This conserved pattern evolved at least 41 Ma and represents a new autapomorphic feature for this clade. Exon fusion does not impair functionality of guinea pig (Cavia porcellus) δßγ-ENaC expressed in Xenopus oocytes. Electrophysiological characterization at the whole-cell and single-channel level revealed conserved biophysical features and mechanisms controlling guinea pig αßγ- and δßγ-ENaC function as compared with human orthologs. Guinea pigs therefore represent commercially available mammalian model animals that will help shed light on the physiological function of δ-ENaC.

Basivertebral foramina of true vertebrae: morphometry, topography and clinical considerations.

PURPOSE: Basivertebral foramina (BVF) are openings of the posterior wall of vertebral body (VB) that lead to basivertebral canals (BVC), where homonymous neurovascular bundle courses. BVF and BVC are implicated with spinal fractures, vertebral augmentation and basivertebral nerve radiofrequency ablation. Despite their essential clinical impact, knowledge of BVF precise anatomy is scarce. The current study describes in detail the BVF typical morphological and topographical anatomy, morphometry and variants. METHODS: In total, 1561 dried true vertebrae of 70 Greek spines of known gender and age were examined. BVF number, location, shape and size (in foramina > 1 mm), BVF distance from VB rims and pedicles, as well as VB morphometry (diameters, heights and distance between pedicles) were studied. Ten spines were re-examined by computed tomography and BVC depth and shape were recorded. Correlations and differences were statistically analyzed. RESULTS: C1 lack BVF (3.4%). One BVF was found in 45.1%, two in 36.9%, three in 3.8% and four BVF in 0.6%. Multiple small (< 1 mm) foramina were observed in 10.1%. Asymmetry was detected in 12.3%. C2 and T10-L1 presented typical pattern, whereas C3 and T2 had the greatest variability. BVF were significantly closer to the upper rim in C2 and T10-L4 and to the lower rim in C7-T4, T6-T8 and L5. The mean BVC depth was 12-21.8% of the VB anteroposterior diameter. CONCLUSION: BVF number, shape, size and topography are described, in detail, per vertebral level. The provided morphological classification and the created cumulative BVF topographic graphs should assist in clinical practice and surgery.

Sciatic Nerve Variants and the Piriformis Muscle: A Systematic Review and Meta-Analysis.

The present systematic review and meta-analysis provides a comprehensive assessment of the sciatic nerve (SN) variants relative to the piriformis muscle (PM) and compares those variants' prevalence among different geographical populations with respect to gender and laterality. A database search was conducted to identify cadaveric studies pertinent to SN variants relative to the PM. A total of 44 articles were included. The typical morphological pattern (type A, with the SN passing undivided below the PM) was found to be the most common variant, with 90% pooled prevalence. SN variants were more common among East Asians, with a 31% pooled prevalence of total variants. No significant differences were established with respect to gender and laterality. In greater than 10% of the population, the SN coursed through or above piriformis. Patients' epidemiological characteristics may predispose them to certain variants. The common peroneal nerve (CPN) is more susceptible to injury during a total hip arthroplasty or a hip arthroscopy where anomalies are encountered. As anatomical variants are commonly associated with piriformis syndrome, they should always be considered during diagnosis and treatment.

Double Muscular Thenar Branch and Anatomical Variation of Thenar Muscle Innervation Observed in a Cadaver.

The muscular thenar branch typically arises from the median nerve distal to the transverse carpal ligament and supplies the thenar musculature. In the present cadaveric case, the existence of double muscular thenar branches is described. The two nerves originated from the first common palmar digital nerve and gave off five terminal muscular branches. The proximal nerve supplied the abductor pollicis brevis (two branches) and the opponens pollicis (two branches) muscles, whereas the distal muscular thenar branch presented a loop and innervated the superficial head of flexor pollicis brevis muscle. Variations of the muscular thenar branch in the anatomical and surgical literature are discussed, along with the potential implications during surgical treatment of carpal tunnel syndrome (CTS).

Five Roots Pattern of Median Nerve Formation.

An unusual combination of median nerve's variations has been encountered in a male cadaver during routine educational dissection. In particular, the median nerve was formed by five roots; three roots originated from the lateral cord of the brachial plexus joined individually the median nerve's medial root. The latter (fourth) root was united with the lateral (fifth) root of the median nerve forming the median nerve distally in the upper arm and not the axilla as usually. In addition, the median nerve was situated medial to the brachial artery. We review comprehensively the relevant variants, their embryologic development and their potential clinical applications.

Double sternal foramina in a dried sternum: a rare normal variant and its radiologic assessment.

Sternal foramina (SF) constitute developmental defects of the sternum and are usually radiologic or postmortem accidental findings. A rare case is presented, concerning the dried sternum of Greek origin and unknown age. The manubrium, sternal body and xiphoid process were fused and ossified, while two SF of undocumented size were present. The proximal SF was located at the sternal body extending between the fourth and fifth intercostal spaces, whereas the distal SF was located at the xiphoid process being surrounded by a thin "ring-like" osseous rim. Computed tomography was utilized for further investigation. Awareness of this variation is essential for the radiologist to avoid misdiagnosis and interpret with accuracy the current combination of normal anatomic variants. Moreover, SF existence is associated with clinical and forensic implications that are shortly discussed.

Variant distribution of the calf cutaneous nerves - case report and clinical impact

We report a cadaveric case of unusual innervation pattern of the right calf and ankle. During dissection of an 82 years-old, formalin-fixed, male cadaver, the posterior femoral cutaneous nerve was found providing sensory supply to the lateral knee region, while it terminated at the level of the ankle. Moreover, the medial sural cutaneous nerve did not anastomose with a peroneal communicating branch and it continued as the lateral dorsal cutaneous nerve of the foot. In cases that the peroneal communicating branch is absent, the medial sural cutaneous nerve is called sural nerve. Additionally, the lateral sural cutaneous nerve travelled over the calf crossing the sural nerve at its middle and thus, providing sensory supply to the upper lateral calf and the lower medial aspect of the calf and ankle. This peculiar sensory supply may cause diagnostic hazard in cases of nerve injury with neurological symptomatology, whereas due to the presented variability, nerves are prone to iatrogenic injury during procedures in the area

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Entrapment of the superficial peroneal nerve: an anatomical insight.

Entrapment of the superficial peroneal nerve is an uncommon neuropathy that may occur because of mechanical compression of the nerve, usually at its exit from the crural fascia. The symptoms include sensory alterations over the distribution area of the superficial peroneal nerve. Clinical examination, electrophysiologic findings, and imaging techniques can establish the diagnosis. Variations in the superficial peroneal sensory innervation over the dorsum of the foot may lead to variable results during neurologic examination and variable symptomatology in patients with nerve entrapment or lesions. Knowledge of the nerve's anatomy at the lower leg, foot, and ankle is of essential significance for the neurologist and surgeon intervening in the area.

Sternal foramina: incidence in Greek population, anatomy and clinical considerations.

PURPOSE: Sternal foramina represent developmental defects in the sternum, which occur due to incomplete fusion of the sternal ossification centers. Sternal foramina have been correlated with several clinical implications and constitute a subject of interest for the forensic practice. The aim of this study is to define their incidence in Greek population. METHODS: The presence of midline foramen was studied in 60 dried, adult sterna derived from the Anatomy Department of Medical School of Aristotle University of Thessaloniki. Measurements were made with a 0.01-mm accuracy caliber and photographic documentation was obtained. Additionally, computed tomography scanning of the sterna was performed. RESULTS: Sternal foramina were found in 11 subjects, resulting in an incidence of 18.3% over the total population. In 27.3% of the subjects with sternal foramen, a single sternal foramen was observed in the body of the sternum, while in 45.5% of the sterna presenting sternal foramina, multiple xiphoidal foramina were noticed. In two specimens, association of xiphoidal foramina with sternal cleft was documented. CONCLUSION: Sternal foramina are variant quite common in the population, with distinct imaging pattern and awareness of their existence is important for the physician.

Entrapment of the superficial peroneal nerve: an anatomical insight.

Entrapment of the superficial peroneal nerve is an uncommon neuropathy that may occur because of mechanical compression of the nerve, usually at its exit from the crural fascia. The 2 symptoms include sensory alterations over the distribution area of the superficial peroneal nerve. Clinical examination, electrophysiologic findings, and imaging techniques can establish the diagnosis. Variations in the superficial peroneal sensory innervation over the dorsum of the foot may lead to variable results during neurologic examination and variable symptomatology in patients with nerve entrapment or lesions. Knowledge of the nerve's anatomy at the lower leg, foot, and ankle is of essential significance for the neurologist and surgeon intervening in the area.

Fascial entrapment of the sural nerve and its clinical relevance.

Sural nerve presents great topographic variability and it is responsible for sensory innervation of the posterolateral side of the distal third of the leg and lateral aspect of the foot. Entrapment of the nerve could be caused by compression due to fascial thickening, while the symptomatology includes sensory alterations and deficits at the nerve distribution area. We report a cadaveric case of a variant sural nerve that presented a distinct entrapment site. A supernumerary sensory branch was encountered originating from the common peroneal nerve, while the peroneal component of the sural nerve was observed to take a course within a fibrous fascial tunnel 3.1 cm in length that caused nerve fixation and flattening. The tension applied to the aforementioned branch was shown to worsen during passive forcible foot plantaflexion and inversion. The etiology, diagnosis and the treatment options are discussed comprehensively.

Potential entrapment of an accessory superficial peroneal sensory nerve at the lateral malleolus: a cadaveric case report and review of the literature.

The superficial peroneal nerve presents great anatomic variability regarding its emergence from the crural fascia, course, branching pattern, and distribution area. Entrapment neuropathy of the superficial peroneal nerve has been documented in the published data, resulting in pain and paresthesia over the dorsum of the foot. We report a case of a female cadaver in which an accessory superficial peroneal sensory nerve was encountered. The nerve originated from the main superficial peroneal nerve trunk, proximal to the superficial peroneal nerve emergence from the crural fascia, and followed a subfascial course. After fascial penetration, the supernumerary nerve was distributed to the skin of the proximal dorsum of the foot and lateral malleolar area. A potential entrapment site of the nerve was observed at the lateral malleolar area, because the accessory nerve traveled through a fascial tunnel while perforating the crural fascia, and presented with distinct post-stenotic enlargement at its exit point. The likely presence of such a very rare variant and its potential entrapment is essential for the physician and surgeon to establish a correct diagnosis and avoid complications during procedures to the foot and ankle region.

Variable origin and ramification pattern of the lateral femoral cutaneous nerve: a case report and neurosurgical considerations.

Variations in the anatomy of the lateral femoral cutaneous nerve (LFCN) have been reported in the literature. LFCN is vulnerable to injury during several surgical operations, therefore any surgeon intervening in the area should be familiar to its topographic variability. Lesion of the nerve leads to a condition known as "meralgia paresthetica". We present a cadaveric case of a variant LFCN where two LFCN branches were encountered arising from the lumbar plexus. In specific the anterior LFCN branch originated from the femoral nerve, whereas at the level of the inguinal ligament, four nerve branches were present. The existence of multiple LFCN branches could lead to diagnostic confusion in case of "meralgia paresthetica", while if the neurosurgeon is not aware of the potential variability during surgical decompression of the nerve, postoperative complications may occur. The supernumerary LFCN branches could be identified by ultrasound imaging and be used as optimum vascularized grafts for sensory nerve repair.

Abnormal origin of internal thoracic artery from the thyrocervical trunk: surgical considerations.

An unusual case of left internal thoracic artery (ITA) origin from the thyrocervical trunk (TCT) was detected during routine cadaver dissection. The variability of origin and course of ITA has less or more frequently been documented in the literature. However, the ITA origin from the TCT on the left side has been detected less commonly, making its dissection and preparation during coronary artery bypass grafting surgery more difficult. We discuss the ITA origin and course variability as well as clinical significance of the present variant, reviewing the relative literature. The objective of our study is to exhibit a rare ITA origin in order to provide a more accurate knowledge of such variations.

Human body exhibitions: public opinion of young individuals and contemporary bioethics.

PURPOSE: The exhibitions of plastinated cadavers and organs have attracted millions of visitors globally, while raising serious controversy about their content and purpose of implementation. METHODS: We performed a survey based study on 500 randomly chosen individuals, aged 18- to 35-year old, in order to access their opinion regarding the conduction of such shows as well as body donation for scientific purposes. RESULTS: We found that 46.3% of the participants had moral concerns, and 46.1% did not. Religious and philosophical beliefs concerned 21.8% of the sample, while 28% believed that the exhibits may affect visitors' mental health. Human dignity violation was stressed by 21.6%, whereas 26.6% disagreed with body donation to science. CONCLUSIONS: The desire for qualitative-guided anatomy education is evident from the highly popular plastinated body and specimen exhibitions. Hence, additional focused effort could be provided to educate the public about normal and pathological anatomy in order to amend their life-style. This could be effected by certified anatomy demonstrators in graduated steps according to the cohort's age, education, occupation, and health status.

Sternalis muscle: an underestimated anterior chest wall anatomical variant.

Over the recent years, an increased alertness for thorough knowledge of anatomical variants with clinical significance has been recorded in order to minimize the risks of surgical complications. We report a rare case of bilateral strap-like sternalis muscle of the anterior chest wall in a female cadaver. Its presence may evoke alterations in the electrocardiogram or confuse a routine mammography. The incidental finding of a sternalis muscle in mammography, CT, and MRI studies must be documented in a patient's medical records as it can be used as a pedicle flap or flap microvascular anastomosis during reconstructive surgery of the anterior chest wall, head and neck, and breast. Moreover, its presence may be misdiagnosed as a wide range of benign and malignant anterior chest wall lesions and tumors.