Japanese Journal of Veterinary Research;Volume 12, Number 3

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MORPHOLOGICAL STUDIES OF THE TRIFURCATE PORTIONS OF THE COMMON CAROTID ARTERIES AND THE SO-CALLED INTERCAROTID BONE IN THE HORSE

FURUHATA, Kitao

Permalink : http://hdl.handle.net/2115/1796
JaLCDOI : 10.14943/jjvr.12.3.47

Abstract

For the purpose of filling in some gaps in the literature, the trifurcate portions of the common carotid artery were investigated. The author's primary purpose was X-ray and macroscopic investigations of this part and of the intercarotid bones. Histological investigations were also used. Results obtained may be summarized as follows. 1. Even in specimens treated with fixative there was a dilated carotid sinus in the initial portion of the internal carotid artery. Some dilation was also observed in the upper end of the common carotid artery. 2. There was a sinus-like dilation at the root of the occipital artery which was thought to be similar to the carotid sinus. 3. The mechanism of the dilation of the carotid and occipital sinuses seem to be similar. The author feels that these dilations are produced by the effect of the blood pressure on the structural differences in the medial and lateral walls of the corresponding arteries. 4. An abnormal branching in which the internal carotid and occipital arteries arise from a common stem was observed in 4 specimens. The genesis of this abnormal type was discussed. It was felt that these abnormal branchings have essentially embryonic origins in the third branchial artery. 5. The so-called intercarotid bones were observed and it was ascertained that while their individual form and sizes differ, they are generally flat with sharp serrated margins. 6. In horses less than 2 years old, cartilage tissue instead of the bone tissue was observed. This cartilage was also observed in some horses more than 3 years old, though bones were observed in the majority of horses older than 3 years. 7. The existence of the intercarotid bone or cartilage is thought to be essential and it is believed to have some physiological significance such as supporting the carotid body, or as a pressure-resisting structure in that portion of the artery constantly subjected to the pressure of the blood stream. 8. The author feels that the development of this bone or cartilage originates in the embryonic mesenchyma in the early embryonic period, and that it is directly related to the fibrous tissue and the carotid body.

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