Descriptive Analysis of Cerebral Arterial Vascular Architecture in Dromedary Camel (Camelus dromedarius)

Abstract

The artiodactyl brain has multiple levels of vascular pooling and the rostral epidural rete mirabile (RERM) at its base. The current study is the first of its kind to precisely demonstrate the arterial vasculature of the dromedary brain, utilizing a new casting method with colored latex and epoxy paint. In total, 35 freshly slaughtered dromedary heads were injected with colored latex or colored epoxy paint prior to dissection in order to reveal cerebral vasculature; Ten processed heads were chemically digested with 5% potassium hydroxide to obtain hard casts of cerebral arteries and anastomosing structures. The outcomes of this study ascertain the distinct vascular features of dromedaries that set them apart from other artiodactyls. In addition to the RERM, the dromedary possesses a well-developed ophthalmic and chiasmatic rete. The dromedary is similar to giraffe, goat, cat and pig in the contribution of middle meningeal artery to the rete mirabile; however, dromedaries have several arteries emerging directly from the cerebral arterial circle that supply the choroid plexus and pineal gland. Additionally, dromedaries exhibit a dominant basilar system that dominates the blood supply to the medulla oblongata, pons, and cerebellum. In our study, we were able to graphically prove the lack of connection between the areas supplied by vertebrobasilar system and carotid system in the dromedary. Furthermore, the vertebral artery does not branch into the basilar artery; instead, it acts as a contributing vessel to the ventral spinal artery that later fuse to form the basilar artery. This study employed the new casting method to illustrate a new arterial source to RERM and the various anastomoses among arterial sources supplying the brain in the dromedary. These anastomoses play an important role in maintaining an uninterrupted cerebral blood supply, decreasing the vulnerability of the fragile brain against ischemia and stroke, as well as, play an important role in maintaining blood pressure and flow in long-necked dromedaries when they raise or lower their heads.

Keywords: Circle of Willis; brain; camel; corrosion cast; dromedary; rostral epidural rete mirabile.

Figure 1

A photograph showing the arterial supply to the dromedary brain (left lateral view). 1, maxillary artery; 2, external ophthalmic artery; 3, rostral branches to the rostral epidural rete mirabile (RERM); 4, internal carotid artery; 5, vertebral artery; 6, lateral branch of the vertebral artery; and 7, basilar artery. Note: middle meningeal artery was not a dominant supplier to RERM in this sample.

Figure 2

Arterial supply to the brain in the dromedary (left lateral view). Note: middle meningeal artery was not a dominant supplier to RERM in this sample. The middle cerebral artery in the contralateral hemisphere has been removed for better image clarity.

Figure 3

Dorsal view of the RERM of the dromedary. 1, RERM; 2, internal carotid artery; 3, middle meningeal artery; 4, rostral root of the rete; 5, caudal connection of the rete; 6, caudal communicating artery; 7, rostral cerebral artery; 8, crista galli; 9, ethmoid fossa; 10, tentorium cerebelli; 11, caudal cranial fossa; 12, dorsum sellae; 13, chiasmatic sulcus; 14, hypophyseal fossa; 15, internal opening of the foramen ovale; and 16, intracranial entrance of internal carotid artery. Note: middle meningeal artery was a dominant supplier to RERM on the right.

Figure 4

Afferent arteries to the RERM in the dromedary. (A) Right medial view, (B) right lateral view and (C) rostral view; 1, maxillary artery; 2, internal carotid artery; 3, middle meningeal artery; 4, rostral branches to the RERM; 5, external ophthalmic artery; 6, RERM; and 7, ophthalmic rete. Note: this specimen contains a dominant middle meningeal artery contribution to RERM.

Figure 5

Ventral view of the RERM in the isolated encephalon of the dromedary. 1, Olfactory bulb; 2, optic nerve; 3, optic chiasm; 4, pituitary gland; 5, abducent nerve; 6, trigeminal nerve; 7, left cerebral hemisphere; 8, pons; 9, medulla oblongata; 10, cerebellum; 11, RERM; 12, caudal connection of the rete; 13, maxillary artery; 14, internal carotid artery; 15, basilar artery; and 16, lateral anastomosing branch of the vertebral artery.

Figure 6

Ventral view of the dromedary brain. 1, Vertebral artery; 2, medial branch of the vertebral artery; 3, lateral branch of the vertebral artery; 4, ventral spinal artery; 5, basilar artery; 6, medullary branches of the basilar artery; 7, caudal cerebellar artery; 8, labyrinthine artery accompanied by the vestibulo-cochlear nerve; 9, pontine branches of the basilar artery; 10, rostral cerebellar artery; 11, caudal choroidal artery; 12, caudal cerebral artery; 13, caudal communicating artery; 14, rostral cerebral artery; 15, middle cerebral artery; and 16 internal ethmoidal artery.

Figure 7

Ventral view of the RERM. 1, Maxillary artery; 2, internal carotid artery; 3, middle meningeal artery; 4, rostral branch to the RERM; 5, external ophthalmic artery; 6, RERM; 7, ophthalmic rete; 8, chiasmatic rete; 9, rostral cerebral artery; 10, internal ophthalmic artery; 11, caudal communicating artery; and 12, basilar artery leading to the cerebral arterial circle. Note: middle meningeal artery was a dominant supplier to RERM in this sample.