Background: The palmaris longus muscle is one of the most variable muscles in the human body and there have been numerous variations reported. The diff erent palmaris longus variations are interesting not only from an anatomical point of view, but they could also have defi nite clinical signifi cance. Aim: The aim of this study was to examine the diff erent types of variations of palmaris longus muscle in the Bulgarian population. Materials and methods: Over a period of 15 years, 56 formol-carbol fixed human cadavers were studied to investigate the diff erent variations of palmaris longus muscle (PLM). Results: Various anatomical variations of PLM have been reported: absence (2.68%); reversed palmaris longus coexisting with an additional abductor digiti minimi muscle (0.89%); digastric (0.89%); palmaris longus with intermediate muscle belly (1.79%) and duplication (1.79%). Conclusions: To reveal the wide variety of the types of palmaris longus muscle and their importance for clinical practice, we make a brief literature review concerning the diff erent types of variations, their role in the median and ulnar neuropathy in the wrist or as structures simulating a soft tissue tumour and the application of palmaris longus tendon in plastic and reconstructive surgery as grafting material. We also present new systematic anatomical and clinical classifi cations of palmaris longus variations by dividing them into two simple groups. BACKGROUND

AIMTo examine the normal morphology of the epiligament tissue of the knee medial collateral ligament (MCL) in humans.METHODSSeveral samples of the mid-substance of the MCL of the knee joint from 7 fresh human cadavers (3 females and 4 males) were taken. Examination of the epiligament tissue was conducted by light microscopy and photomicrography on semi-thin sections of formalin fixed paraffin-embedded blocks that were routinely stained with haematoxylin and eosin, Mallory stain and Van Gieson’s stain. Electron microscopy of the epiligament tissue was performed on ultra-thin sections incubated in 1% osmium tetroxide and contrasted with 2.5% uranyl acetate, lead nitrate, and sodium citrate.RESULTSThe current light microscopic study demonstrated that the epiligament of the MCL consisted of fibroblasts, fibrocytes, adipocytes, neuro-vascular bundles and numerous multidirectional collagen fibers. In contrast, the ligament body was poorly vascularised, composed of hypo-cellular fascicles which were formed of longitudinal groups of collagen fibers. Moreover, most of the vessels of the epiligament-ligament complex were situated in the epiligament tissue. The electron microscopic study revealed fibroblasts with various shapes in the epiligament substance. All of them had the ultrastructural characteristics of active cells with large nuclei, well developed rough endoplasmic reticulum, multiple ribosomes, poorly developed Golgi apparatus, elliptical mitochondria and oval lysosomes. The electron microscopy also confirmed the presence of adipocytes, mast cells, myelinated and unmyelinated nerve fibers and chaotically oriented collagen fibers.CONCLUSIONSignificant differences exist between the normal structure of the ligament and the epiligament whose morphology and function is to be studied further.

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The morphology and distribution of parvalbumin-immunoreactive neurons (PV-ir) were studied in the human claustrum. PV-ir neurons were observed throughout the claustrum, with the highest numbers noted in the central (broadest) portion as compared with the dorsal and ventral aspects. Reaction product was evident in the neuronal perikarya, dendritic processes, and spines. In the majority of these labeled neurons, the cytoplasm was devoid of lipofuscin pigment. Cell bodies varied widely in both shape and size, ranging from oval and small, to multipolar and large. PV-ir neurons were classified into two groups, primarily based on dendritic morphology: spiny neurons with long and straight dendrites, and aspiny neurons with thin and curving dendritic processes. PV-ir fibers were seen throughout the neuropil, with many immuno-positive puncta noted.

During a routine anatomical dissection in the right brachium of a 75-year-old male cadaver, a novel variation of the coracobrachialis muscle (CB) was discovered. It consisted of three parts: proximal, starting from the upper border of the scapula; medial, presenting the well-accessed CB; and distal, formed by a proximal tendinous part that arose from the coracoid process and then transitioned into a well-defined muscle body and a distal tendinous part attached to the medial epicondyle. We also present a new systematic classification of CB variations, dividing them into two simple groups.