title: Relationships between the arteries and veins and the connective tissue system in the human orbit.
abstract: The arteries and veins in the apical region of the orbit occupy different areas. Furthermore, there is a difference in their relationships to the connective tissue system. In this part of the orbit, where only a few connective tissue septa are present, the arteries are mainly concentrated in the inner-space. The veins, on the other hand, are predominantly found peripherally, outside the muscle cone. The arteries are surrounded by adipose tissue. They are only in contact with connective tissue fibres when perforating the septa on their way to the outer regions of the inner-space. A small number of vessels, the posterior ciliary arteries and the central artery of the retina, keep their central position, grouped around the optic nerve. The conduct of this group of arteries in respect to the connective tissue is somewhat different than that of the other arteries. The ciliary arteries and the central retinal artery have varying contacts with the optic sheath. In contrast to the arteries, which in general lack firm connections with fibrous connective tissue, the major veins are encased in the tight connective tissue of the orbital fissures, or enveloped in connective tissue septa. For the smaller veins, these fibrous relationships are usually less intimate and occasionally disrupted. More extensive discussion and conclusions will be given in the following article. This will deal with the rest of the retrobulbar part of the orbit.
mesh_terms: D000328:Adult; D000368:Aged; D001158:Arteries / Q000033:anatomy & histology; D003238:Connective Tissue / Q000033:anatomy & histology*; D006801:Humans; D008875:Middle Aged; D009880:Ophthalmic Artery / Q000033:anatomy & histology; D009915:Orbit / Q000033:anatomy & histology / Q000098:blood supply*; D014680:Veins / Q000033:anatomy & histology