The relationship of callosal anatomy to paw preference in dogs.

Previous studies have described the paw preference and asymmetry in dog brains, based on experimental studies. The purpose of the present study is to investigate a possible association between callosal anatomy and paw preference in dogs. The midsagittal area of the dog corpus callosum was measured in its entirety and in six subdivisions in a sample of 21 brains obtained from 9 male and 12 female mongrel dogs which had paw preference testing. The present study showed significant paw differences in dog corpus callosum. A posterior segment of the callosum, the isthmus, was significantly larger in the right pawedness than the left.

Sex differences in dog corpus callosum.

Human studies reported sex differences in size and shape of the corpus callosum. These observations have been contested. The purpose of the present study is to investigate possible sex differences in the corpus callosum of dogs. The entire brains including the medulla from 12 female and 9 male adult mongrel dogs were removed and weighed. Total and partial area measurements of the callosum were made from photographic tracings of its outline. The callosum was partitioned into 3 regions; anterior half, posterior half, posterior one-fifth. The total corpus callosum, anterior half, posterior half, and posterior fifth or splenium areas were measured. Sex differences were found. The anterior half, the posterior half, the posterior fifth, and the total callosum were significantly greater in absolute area in males than in females.

Heights of the lumbar intervertebral discs related to age in Turkish individuals.

The present study investigated the changes in the heights and anteroposterior diameters of human intervertebral discs by means of measurements from radiographs, to determine age changes of lumbar intervertebral discs in Turkish people. Measurements of anterior and posterior disc heights and disc depths were made for 200 clinic subjects of different age groups from lateral radiographs. The height of the intervertebral disc increases with aging only in males and the disc depth in both sexes. Our findings generally corroborate previous studies. It is suggested that the different findings from the present study might be peculiar to the society.

Variations of abductor pollicis longus and extensor pollicis brevis muscles: surgical significance.

To investigate variations of the abductor pollicis longus and the extensor pollicis brevis muscles, an anatomic study was performed on 15 cadaver forearms. Some variations were observed as reported in previous studies. An unusual insertion of the abductor pollicis longus muscle and the extensor pollicis brevis muscle also was encountered during the dissection. Both tendons of these muscles were found to have inserted into the inferior side of the base of the first metcarpal bone together, instead of dorsal side. Our study suggested that the extensor pollicis brevis muscle and the abductor pollicis longus muscle differentiate from a common muscle.

Facial asymmetry in right- and left-handed men and women.

A posteroanterior cephalometric radiographic study was performed on the right- and left-handed men and women with normal occlusion. A posteroanterior cephalometric radiography was conducted in these subjects. Method of triangulation was used to measure various face areas. The surface areas of these triangles were compared with their equivalents on the contralateral side. Sex and its interactions with handedness and side were significant factors influencing facial areas. Areas on the left were found to be significantly larger than those on the right in right-handers. Left-handers were inconsistent in facial asymmetry, but they tended to have larger facial areas on the right than the left. Sex was especially significant for left-handers. It was suggested that an asymmetric development in some brain regions may be responsible for the development of asymmetric facial regions.