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

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.

We studied the topographical distribution and morphological characteristics of NADPH-diaphorase-positive neurons and fibers in the human claustrum. These neurons were seen to be heterogeneously distributed throughout the claustrum. Taking into account the size and shape of stained perikarya as well as dendritic and axonal characteristics, Nicotinamide adenine dinucleotide phosphate-diaphorase (NADPHd)-positive neurons were categorized by diameter into three types: large, medium and small. Large neurons ranged from 25 to 35 μm in diameter and typically displayed elliptical or multipolar cell bodies. Medium neurons ranged from 20 to 25 μm in diameter and displayed multipolar, bipolar and irregular cell bodies. Small neurons ranged from 14 to 20 μm in diameter and most often displayed oval or elliptical cell bodies. Based on dendritic characteristics, these neurons were divided into spiny and aspiny subtypes. Our findings reveal two populations of NADPHd-positive neurons in the human claustrum—one comprised of large and medium cells consistent with a projection neuron phenotype, the other represented by small cells resembling the interneuron phenotype as defined by previous Golgi impregnation studies.

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Objectives: The present study aims to explain the interesting discrepancy between the occipital emissary foramina and the respective emissary veins in the literature. Majority of the studies report that the foramina have a low and variable frequency, but the emissary veins are reported to be disproportionately present in quite large number of patients in some diagnostic imaging studies. Methods: Seventy-five adult skulls were examined for the presence of occipital foramina. Results: A complete occipital emissary foramen was found only in one skull (1.33%), but a number of other skulls also showed some foramina on the external and internal surfaces of squamous part of the occipital bone. Conclusion: It can be concluded that foramina of another vein which is related to the squamous part of occipital bone, the occipital diploic vein, might be the main reason for the discrepancies present in the literature. The suggested classification scheme of venous anastomoses in the posterior cranial fossa can explain the variable bony foramina observed in skull series.

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The claustrum is a complex telencephalic structure owing to its reciprocal connectivity with most--if not all--cortical areas. However, there is a paucity of data in the literature concerning its histochemical components, including opioid peptide neurotransmitters. The aim of the present study was to examine the morphology, distribution and ultrastructure of leucine-enkephalin-immunoreactive (Leu-enk-ir) neurons and fibers in the dorsal claustrum (DC) of the cat. Seven healthy, adult male and female cats were used in our study. All animals received humane care. They were irreversibly anesthetized and transcardially perfused with fixative. Brains were removed, postfixed, blocked and sectioned. Sections were incubated with polyclonal anti-Leu-enk antibodies using the Avidin-Biotin-Peroxidase Complex method. Leu-enk-ir neurons and fibers were distributed throughout the DC. Some of the neurons were lightly-stained, while others were darkly-stained. Light-microscopically, they varied in shape: oval, fusiform, multipolar and irregular. With regard to size, they were categorized as small (15 μm or less in diameter), medium (16-20 μm in diameter) and large (21 μm or more in diameter). No specific pattern of regional distribution was found. On the electron microscope level, immunoproduct was observed in neurons, dendrites and terminal boutons. Different types of Leu-enk-ir neurons differ in their ultrastructural features, including two types of synaptic boutons. No gender-specific features were observed. In conclusion, it is our hope that our study will serve to contribute to a better understanding of the functional neuroanatomy of the DC in the cat, and that it can be extrapolated and applied to other mammals, including humans.