Cranial arterial patterns of the alpaca (Camelidae:Vicugna pacos)

Abstract

Artiodactyl cranial arterial patterns deviate significantly from the standard mammalian pattern, most notably in the possession of a structure called the carotid rete (CR)—a subdural arterial meshwork that is housed within the cavernous venous sinus, replacing the internal carotid artery (ICA). This relationship between the CR and the cavernous sinus facilitates a suite of unique physiologies, including selective brain cooling. The CR has been studied in a number of artiodactyls; however, to my knowledge, only a single study to date documents a subset of the cranial arteries of New World camelids (llamas, alpacas, vicugñas and guanacoes). This study is the first complete description of the cranial arteries of a New World camelid species, the alpaca (Vicugna pacos), and the first description of near-parturition cranial arterial morphology within New World camelids. This study finds that the carotid arterial system is conserved between developmental stages in the alpaca, and differs significantly from the pattern emphasized in other long-necked ruminant artiodactyls in that a patent, homologous ICA persists through the animal's life.

Arterial Patterns of the Face in Camelidamorpha

“…The buccal artery in representatives of Camelidae was a bifurcation of the maxillary artery, similarly as it is in the described ruminants (Frąckowiak, 2003) as well as equines and rhinos (Kowalczyk and Frąckowiak, 2017) and it vascularized the buccal region. Our description of the exit and course of this artery in Camelidae was consistent with the description given by O'Brien (2017) in alpacas.…”

“…In ruminants this artery reaches the lateral surface of the mandible extending over the notch for the facial vessels (Nickel and Schwarz, 1963;Godynicki, 1972;Frąckowiak, 2003). In the Camelidae analyzed in this study we stated that the facial artery is transformed into the inferior labial artery, while O'Brien (2017) reported that in the alpaca it terminates splitting into the superior and inferior labial arteries. Comparing the caliber of the inferior labial contribution from the facial artery observed in our specimens with this vessel described by O'Brian (2017) we have noticed that this labial contribution in alpaca was much smaller and created anastomoses with the infraorbital artery.…”

“…In the two other suborders of Artiodactyla (Nickel and Schwarz, ; Godynicki ; Frąckowiak, ) and in all the described species from the order of Odd‐toed ungulates (Kowalczyk and Frąckowiak, ) the inferior alveolar artery branched off independently from the maxillary artery. In turn, O'Brien () showed that in Vicugna pacos the caudal deep temporal artery shares a common origin with the inferior alveolar and masseteric arteries. The transverse facial artery in Suiformes and Ruminantia exits from the superficial temporal artery (Nickel and Schwarz, ; Godynicki, ; Frąckowiak, ).…”

Cranial Morphology and Phylogenetic Relationships of Trigonostylops wortmani, an Eocene South American Native Ungulate

“…To make progress on this issue it will be important to look for new indicia that could point to the involvement of other vessels in cerebral arterial circulation. For example, in extant artiodactylans, almost all clades of which lack intact internal carotid arteries in the adult stage, major anastomoses between the external and cerebral carotids significantly supplement the relatively small blood supply brought to the circulus arteriosus by the vertebral arteries (Daniel et al, 1953;O'Brien et al, 2016;O'Brien, 2017). Whether a similar solution existed in some SANUs, perhaps via an anastomotic link (arteria anastomotica) passing through the foramen ovale, has not been previously considered but should not be ruled out without a thorough search for potential indicia.…”

The Natural Historian's Guide to the CT Galaxy: Step-by-Step Instructions for Preparing and Analyzing Computed Tomographic (CT) Data Using Cross-Platform, Open Access Software

“…The embrace of this new data type has, in turn, catalyzed many recent biological discoveries, such as revealing brain and muscle activity during bird flight (positron emission tomography scanning; Gold et al. 2016 ), determining how blood circulates through vasculature (magnetic resonance imaging; O'Brien and Williams 2014 ; O'Brien 2017 ), revealing the function of the appendicular skeleton during locomotion and feeding in live sharks (X-ray Reconstruction of Moving Morphology, 3D fluoroscopy coupled with computed tomographic [CT] animation; Camp et al. 2017 ; Scott et al.…”