CASE PRESENTATIONR outine dissection of the left upper extremity of an 82-year-old Caucasian female cadaver, performed in the Department of Anatomy at the University of Saskatchewan (Saskatoon, Saskatchewan), revealed a rare variation in the anatomy of the palmaris longus (PL) muscle.On dissection and examination, it was discovered that the PL of the left upper extremity of this cadaver was 'reversed' -with the proximal portion being tendinous and the distal portion being muscular.Examination of the upper extremity showed no signs of atrophy or hypertrophy, nor median or ulnar nerve entrapment in the left upper extremity. The cadaver's medical history, occupation and handedness were unknown. No anatomical variations were noted in the right upper extremity of this cadaver.In the present case, the PL originated at the common flexor origin from the medial epicondyle. However, the origin was tendinous -a long thin tendon, instead of the normally observed PL muscle fibres. Two-thirds down the forearm, the PL structure became more muscular in nature, with a muscle belly that spanned the distal one-third of the forearm. At the distal insertion of the PL, at the level of the wrist, the muscle fibres became tendinomembranous and continued into the palmar aponeurosis where they ultimately terminated (Figure 1). DISCUSSIONThe standard anatomical origin of the PL is the common flexor at the medial epicondyle, shared by other superficial flexors such as the flexor digitorum superficialis -located beneath the PL -and the flexor carpi radialis and flexor carpi ulnaris -between which the PL is located. The standard anatomical insertion is the palmar aponeurosis, volar to the flexor retinaculum. Although the palmar aponeurosis joins the PL tendon, the two are distinct entities, as shown by their different origin and development (1). The vascularity is most commonly supplied by branches of the ulnar artery, followed by branches of the brachial artery. Branches of the median nerve supply innervation (2). The palmaris longus, a slender fusiform muscle, is especially prone to exhibiting anatomical variance relative to other muscles in the upper extremity. The most frequent anatomical variation is the completely absent palmaris longus, followed by the reversed, duplicated, bifid or hypertrophied palmaris longus muscles. The reversed palmaris longus muscle represents a structure that is tendinous proximally and muscular distally (opposite of the normal palmaris longus). The present report describes a case of reversed palmaris longus muscle, followed by a literature review to illustrate the wide spectrum of anatomical variations in the palmaris longus muscle and their clinical and surgical relevance. CASE REPORT ©2013 Canadian Society of Plastic Surgeons. All rights reserved Key Words: Anatomical variations; Palmaris longusL'inversion du grand palmaire, une variante anatomique : rapport de cas et analyse bibliographique Le grand palmaire, un muscle fusiforme mince, est particulièrement enclin aux variations anatomiques par rapport aux ...

This cadaveric study showed that the ultrasound-guided percutaneous tenotomy of the LHBT is a feasible procedure. The deep to superficial approach using an arthroscopic hook blade resulted in complete transection. Further cadaveric studies with larger numbers are warranted to confirm this novel technique's applicability in clinical practice.

PurposeWe measured dynamic biomechanics of loss-of-resistance (LOR) epidural placement in prone cadavers, focussing on the period immediately following LOR, to estimate forces acting on the tissue of the epidural space.MethodsAn epidural syringe with 17G Hustead needle was instrumented to track force on the plunger, pressure in the chamber, and movement of barrel and plunger. Insertions were attempted in five formalin-preserved cadavers from T2–3 to L4–5, using LOR with saline or air, and confirmed with X-ray.ResultsSixteen insertions were successful. Soft tissues in formalin-preserved cadavers are much harder than in living humans. With continuous pressure on the plunger, fluid thrust through the needle at the point of LOR was significantly greater (P = 0.005) with saline (mean ± standard deviation [95% confidence intervals]: 19.3 ± 14.9 [8.3 to 30.3] N); than with air (0.17 ± 0.25 [0 to 0.39] N). Stress exerted on epidural tissue was similar (air = 7792 ± 920 [6986 to 8598] Pa; saline = 7378 ± 3019 [5141 to 9614] Pa); and in both cases was greater than the stress exerted by cerebrospinal fluid pushing outwardly on the dura (4800 Pa).ConclusionFormalin-preserved cadavers are too stiff to make them an experimental model from which we can generalize to live humans, although we were successful in entering the epidural space and testing the instrumentation for further studies on live animals or humans. Continuous pressure on the plunger while advancing the epidural needle may “blow” the dura away from the needle tip and help prevent dural puncture. Better results are seen with saline rather than air.

Congenital partial absence of the trapezius muscle is a relatively common variation. Several cases of partial absence of the trapezius muscle have been reported. However, complete unilateral agenesis of this muscle has not been previously reported. In our case, a complete cadaver dissection of an 87-year-caucasian male was performed at the Department of Anatomy, College of Medicine in Saskatoon, Canada. The entire body dissection revealed a complete agenesis of the left trapezius muscle fibers. No other significant congenital anomalies were found.

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Distributed under a Creative Commons Attribution-NonCommercial-NoDerivatives| 4.0 International License