Facial Carotid Artery Research Articles

The Facial Carotid Artery in Snakes (Reptilia, Serpentes): Variations and Possible Cladistic Significance

It is reported that in henophidian snakes examined, except Acrochordus, the facial carotid artery passes forward ventral to the mandibular branch of the trigeminal nerve, and is typically of lesser diameter than the cerebral carotid. In contrast, in caenophidian snakes except Viperinae (not including Causus) and in Acrochordus, the facial carotid passes dorsal to the mandibular branch of the trigeminal, and is not of lesser diameter than the cerebral carotid. Viperinae except Causus show the ventral course. Because it also occurs in Scolecophidia, and is correlated with primitive states of many other characters, the ventral course seen in Henophidia except Acrochordus is interpreted as the primitive condition in snakes. The dorsal course seen in Caenophidia and Acrochordus is interpreted as a derived condition indicating that these two taxa form a monophyletic group. This is corroborated by presence of several other shared derived features in the group. The ventral course in Viperinae except Causus is interpreted as a derived reversal indicating the monophyly of 'true' Viperinae (ie. excluding Causus).

A Comparative Study of the Arterial Systems of Some New World Crotalinae (Reptilia: Ophidia)

The arterial systems of seven or eight latex-injected specimens, plus two uninjected specimens, of the following species were studied: Agkistrodon contortrix, A. piscivorus, Sistrurus catenatus, S. miliarius, Crotalus horridus, C. viridis and C. atrox. Six uninjected specimens of Lachesis muta, three of S. ravus, and one or two of each of 13 additional species of Crotalus were also used for studying pulmonary artery patterns. In general, the pulmonary artery patterns show a change from the dominant right pulmonary artery pattern in primitive Agkistrodon, to a modified version of this pattern in intermediate Sistrurus, to the right- left pulmonary artery pattern in advanced Crotalus, where the left pul- monary artery is dominant. However, S. ravus differs from S. catenatus and S. miliarius in its lung patterns, resembling the triseriatus group of the genus Crotalus. Laichesis has a large right and a small left pul- monary artery. This probably represents the earliest appearance of the right-left pulmonary artery pattern in the phylogeny of the North American Crotalinae. Primitive Agkistrodon usually feeds both the pterygoid and tem- poralis muscle complexes via the venom gland artery; Sistrurus does so partly via the venom gland vessel and partly by the facial carotid artery; Crotalus usually has both complexes fed by the facial carotid. The right side of the head of Agkistrodon differs from the left in its arterial ar- rangement. The number of branches from the left carotid artery to the esopha-