[Anatomical studies of the plexus ophthalmicus and plexus orbitalis medialis in sheep]

Studied were the structure and the blood supply of plexus ophthalmicus and plexus orbitalis medialis in twenty newborn lambs and in ewes and rams aged up to eight years, employing the methods of preparation and corosion. It was found that sheep had well developed intraorbital venous plexuses. Plexus ophthalmicus was found to be formed by branches of the supraorbital and the external dorsal eye vein as well as by veins coming from the eye orbit and the accessory organs of the eye. It was said to have a cone-shaped form, 3 to 4 cm long, and with a dia at the base of about 2 cm. The veins that formed the plexus were found to be located radially and in a circular way, having a varying length and forming loops of different shape. Rete mirabile venosum ophthalmicum initiated from the dorsal wall of the plexus, embracing the arterial network--rete mirabile ophthalmicum. There was in the medial eye angle a well developed plexus orbitalis medialis connected with plexus ophthalmicus. The latter was found to be connected with plexus venosus cavernosus, the winglike plexus, and the maxillary vein. In newborn lambs plexus ophthalmicus and plexus orbitalis medialis were completely developed. It is believed that the venous plexuses have a collecting, distributing, and hemodynamic function with regard to the blood in the eye region, and particularly with regard to both rete mirabile ophthalmicum and rete mirabile epidurale rostrale.