The posterior inferior cerebellar artery and its branches in relation to the cerebellomedullary fissure.

The conventional approach to the fourth ventricle is by splitting the vermis on the suboccipital surface of the cerebellum. By a unilateral transcerebellomedullary fissure approach, it is possible to provide sufficient operative space from cerebral aqueduct to obex without splitting the vermis. This approach needs meticulous dissection of the cerebellomedullary fissure and preservation of the posterior inferior cerebellar artery (PICA) and its branches. The tonsillomedullary and telovelotonsillar segments of the PICA are the most important vessels encountered in the transcerebellomedullary fissure approach. The PICA was examined under a surgical microscope in a total of 40 specimens by perfusing with a mixture of 10% Indian ink and gelatin. The passing of the tonsillomedullary segment of the PICA through the cerebellomedullary fissure was observed superior to the tonsil in 5%, at the level of the upper pole of the tonsil in 17.5%, at the middle of the tonsil in 37.5% and at the level of the lower pole of the tonsil in 37.5% specimens. When the PICA arose from the lateral medullary (LM) segment of the vertebral artery (VA), a caudal loop was present in 90%, when the PICA originated from the premedullary segment of the VA, the loop was present in 87.5% specimens. When the PICA arose from the basilar artery (BA), the loop was absent, and the tonsillomedullary segment of the PICA showed a straight course (100%). A thorough understanding of the relationship of the branches of the PICA to the cerebellar tonsils are prerequisites for surgery in and around the fourth ventricle.

The relationship of the posterior inferior cerebellar artery to cranial nerves VII-XII.

The posterior inferior cerebellar artery (PICA) is the largest branch of the vertebral artery. It usually arises at the anterolateral margin of the medulla oblongata close to the lower cranial nerves. The PICA had the most complex relationship to the cranial nerves of any artery and it is frequently exposed in approaches directed to the fourth ventricle. The aim of this article is to describe the anatomical relationship of the PICA to the lower cranial nerves. In this study, 12.5% of PICAs passed between the glossopharyngeal and vagus nerves, 20% between the vagus and accessory nerves, and 65% through the rootlets of the accessory nerve. The lateral medullary segment of the PICA showed a lateral loop which in 20% specimens pressed against the inferior surfaces of the facial and vestibulocochlear nerves. The lateral medullary segment of the PICA in 20% specimens passed superior to the hypoglossal nerve, in 47.5% through the rootlets of the hypoglossal nerve, and in 30% inferior to the hypoglossal nerve. The findings on the relationship of the PICA to the lower cranial nerves could be helpful in microsurgery of this region.

Clinical importance of the muscular arch of the axilla (axillopectoral muscle, Langer's axillary arch).

The muscular arch of the axilla is described in a male cadaver on the left side. The condition may be the result of a factor affecting the intrauterin development. Because this muscular arch causes difficulties in staging lymph nodes, axillary surgery, thoracic outlet syndrome, shoulder instability or cosmetic problems, it should be kept in mind for axillary pathologies.

Anatomic characteristics and clinical importance of the superficial branch of the radial nerve.

The aim of this study was to demonstrate anatomic variations of the superficial branch of the radial nerve (SBRN) and to discuss the importance of this branch for surgical approaches. Upper extremities of 24 cadavers without any known history of disease or trauma were examined, the SBRN became subcutaneous at a mean of 9.20 cm and bifurcated at a mean of 4.90 cm proximal to the styloid process of the radius in 48 specimens. At the level of the extensor retinaculum, the mean distance of the closest branch to the first dorsal compartment was 0.54 cm, while its mean distance to the dorsal tubercle (Lister's tubercle) was 1.58 cm. The relations of the three branches of the SBRN (SR1, SR2, SR3) to the anatomic snuffbox and lateral antebrachial cutaneous nerve (LABCN) were also examined. It was demonstrated that on eight wrists, SR2 went through the snuffbox (16.67%). On ten specimens, SR3 had connections with LABCN (20.83%). In four specimens, the SBRN did not have any bifurcation and was directly divided into SR1, SR2, and SR3. It should be very helpful to know the anatomic characteristics of the SBRN, especially for hand surgeons, to minimize the risk of injury of the SBRN during surgical approaches.