Vascular Anatomy of the Cavernous Sinus and Involved Cranial Nerves

Analysis of the embryology of the vessels provides the basis for understanding the variations of collaterals between the external and internal carotid artery systems in the orbit and the cavernous sinus area. 1. The internal maxillary artery (IMA) anastomoses to the inferior and lateral branches (ILT- inferior lateral trunk of the cavernous carotid artery. These collaterals are found anteriorly, through the artery of the foramen rotundum, inferiorly, via the middle meningeal artery (MMA), and anterolaterally, through the accessory middle meningeal artery (AMA). 2. The ascending pharyngeal artery, which originates from the external carotid artery (less commonly from the occipital artery or ICA), gives a superior pharyngeal artery which provides a branch artery that anastamoses to the CS segment of the siphon on the ICA. Both ascending pharyngeal arteries provide a branch from the hypoglossal artery which passes medially to anastamose with the medial clival arterial arcade that connects the right and let C5 segments of both cavernous carotid arteries (Lasuaunias and Berenstien. Surgical Neuro-anglogrphy I, pp,129-143). 3. Another potential collateral between the two ICA's is the capsular artery which courses along the floor of the sella turcica (MacConnel EM. The arterial blood supply of the human hypophysis cerebral. Anatomy Rec 115:175- 203,1953).