The clinical significance of the petroclinoid ligament

This report describes the topography and structure of the petroclinoid ligament with reference to its clinical significance. Observations of this ligament were performed on 24 sections of human heads. Remnants of the ossified form of this ligament were sought in 73 dry human skulls. It was found that the petroclinoid ligament existed as an anterior and posterior fold of the dura mater and stretched from the petrous apex and the anterior and posterior clinoid process respectively. We assessed the close proximity of this ligament to the oculomotor nerve. In one case we found a partially ossified posterior petroclinoid ligament, which appeared as a bony spike that arose posteriorly and inferiorly from the posterior clinoid process

A case of occipitalization in the human skull

Occipitalization of the atlas is an osseous anomaly of the craniovertebral junction. The aim of this paper is to present an anatomical variant of the fused atlas with the occipital bone and discuss similar cases described in literature. The skull of an adult male analysed in this study belonged to the cranial collection of the Department of Anatomy of the Jagiellonian University, Medical Collage. A tight bony fusion between the anterior arch of the atlas, the left portion of the posterior arch, the lateral masses of the atlas, and the occipital bone was observed. Hence, the left and right superior articular facets of the atlas were fused with the corresponding occipital condyles. The anteroposterior dimension of both inferior articular facets was the same (20 mm), while the transverse diameter of the right one was considerably smaller (12 mm). The transverse diameter of the left inferior articular facets was 17 mm. The right and the left transverse process of the atlas were normally developed, each of them contained transverse foramen, and they were not fused with the occipital bone. The circumference of the foramen magnum was minimally diminished by the osseous structures of the atlas fused to the occipital bone. The sagittal and transverse diameters of the foramen magnum (38 mm x 34 mm) were within the normal range of variation. However, the asymmetrical anatomy of the inferior articular facets of the atlas give rise to speculation that movement in the atlantoaxial joint was disturbed by assimilation with the occipital bone. (Folia Morphol 2010; 69, 3: 134-137

Bilateral ossification of the stylohyoid ligament

This paper presents the case of an adult male skull with bilateral ossification of the stylohyoid complex. The total length of the stylohyoid complex amounts to 62 mm on the left side and 65 mm on the right side. Visual inspection of the stylohyoid revealed the presence of callosities that are located on both stylohyoid complexes at nearly the same level. These sites are regarded as the ossified attachments of the stylohyoid ligaments to the corresponding styloid processes. The skull studied is an example of extreme development of the stylohyoid complex, which could cause severe pain and a restriction of head and neck movement

From Thomson formula to resonant equivalent diagrams

Until the 1970s, only three basic elements: R, C, and L have been used to construct RLC circuits. These elements are two-ports of zero order (resistances) and of first order (capacitances and inductances). Their presence in electronic circuits causes a certain phase shift between voltage and current. In 1969, Bruton published an inductorless filter. There are two two-ports of second order (supercapacitances) in this circuit. Supercapacitance causes a phase shift of 180 degrees. In the next years, many two-ports of higher orders (e.g. of second and third order) were developed and, in theory, their number may be infinite. The use of such two-ports in resonant circuits makes it possible to obtain other phase shifts. In this paper, we show how to transform basic circuits into their resonant equivalent diagram. The analysis of these diagrams allows us to describe precisely resonant phenomena occurring in the circuit and to identify all resonant circuits, even when the basic diagram does not indicate resonance properties