VARIATIONS IN THE CAROTID ARTERIES OF THE 



RABBIT 



FRANCIS MARSH BALDWIN 



That the blood vessels of any group of mammals in general are 

 subject to great variations is well known. Such minor variations 

 as have been observed within any group have usually been ignored 

 or at most, resolved to conform to the type. Using the rabbit as a 

 basis of study in mammalian anatomy during the past two years 

 the writer has had an opportunity to make some interesting obser- 

 vations on the variations of the carotid arteries. Of one hundred 

 and fourteen specimens dissected in the laboratory, twenty-three, 

 or about twenty per cent were found to differ from the usual con- 

 dition described in the texts. Of these, eleven individuals possessed 

 marked differences, as shown in the illustrations in figure 9, which 

 are numbered 1 to 12. 



In the majority of cases, the common carotid artery (figure 1, C. 

 C.) passes forward from the superior thoracic aperture along the 

 side of the trachea. Its branches include the superior thyroid 

 artery supplying the thyroid gland, and the superior laryngeal 

 artery. The latter arises at the level of the thyroid plate (larynx) 

 and passes to the sternohyoid and sternothyroid muscles. A short 

 distance cephalad the common carotid artery gives off a very small 

 internal carotid artery which passes dorsad, and disappears beneath 

 the auditory bulla. From this point forward the vessel is the ex- 

 ternal carotid artery, which gives off successively the occipital, the 

 lingual, the external maxillary, the superficial temporal (one of the 

 terminal branches), and the internal maxillary (the other terminal 

 branch) arteries, in the order named. 



The occipital artery passes to the posterior portion of the head 

 from the dorsal wall of the external carotid artery at a point just 

 cephalad to the internal carotid. 



The lingual artery arises from the ventral wall of the external 

 carotid artery at a point about at the level of the occipital, and passes 

 forward into the tongue. 



The external maxillary artery is given off just cephalad of the 

 lingual branch, and passes to the medial surface of the ventral bor- 

 der of the mandible. It gives branches to the submaxillary gland 

 and the muscles of mastication. 



