Olfactory and vomeronasal organs drain via (i) the nasal veins (dorsal and medial walls of the principal chamber, and (ii) the anterior orbital veins (lateral and latero-ventral walls of the principal chamber; walls of the middle chamber) which join to form the orbito-nasal veins (Figs.
aov anterior orbital vein, hg Haderian gland, mc middle chamber, na nasal artery, nv nasal vein, ob olfactory bulb, on olfactory nerve, pc principal chamber.
The relationship between the orbital veins
and the paranasal veins facilitates this complication (2, 3).
Anteriorly draining fistula drain into orbital veins
leading to arterialisation of veins and shows neuro-ophthalmological features.
The periosteum is loosely attached to the orbital bones, especially the orbital roof, which is the most common site for NTSOH development (6) The orbital veins
are valveless, allowing increased jugular venous pressure to be transmitted to the veins in the subperiosteal orbital space, possibly causing rupture (2) Therefore, factors that increase venous pressures, such as vomiting, coughing and the Valsalva manoeuvre may play a major role in NTSOH (1).
Two vascular features of orbital venous malformations play a role in the lesion's characteristic appearance: (1) an absence of valves in the orbital veins
and (2) a low degree of intrinsic blood flow.
lack valves, allowing for free communication between facial vein and the cavernous sinus.
INTRODUCTION: Orbital venography,has been established as a research tool in the study of the anatomy of the orbital veins
and cavernous sinuses and was introduced by Defeen and Bondet in year 1951 by injecting contrast media into the frontal and supraorbital vein (1).