ABSTRACT
Extraocular muscles are highly specialized striated muscles exhibiting generous innervation and more variation in fiber size and type than other skeletal muscles. The arterial supply of the extraocular recti muscles [EORMs] is liable to be severely damaged during medial and lateral approaches to the orbit to treat various disorders. Was to study the arterial blood supply of the EORMs to help the surgeons to adopt procedures in which these arteries can be saved. Also to study the difference in the vascularity between the global and orbital layers of the muscles. Twenty human orbits were dissected after arterial injection of the internal carotid artery with red latex. The different arterial pedicles for each muscle were studied regarding their number, origin and points of entry. Morphometric study was done to count the number of the blood vessels in the orbital and global layers. The luminal cross sectional area of these blood vessels were studied, measured and statistically analyzed. The arterial supply to the extra ocular recti muscles came from the ophthalmic artery, the lacrimal artery and the inferior muscular artery. The superior rectus muscle was supplied by 1-2 arterial pedicles from the ophthalmic artery, while the medial rectus muscle was supplied by 2-6 pedicles from the ophthalmic and inferior muscular arteries. The inferior rectus muscle was principally supplied by 2-5 branches from the inferior muscular artery but the lateral rectus muscle was supplied by 2- 5 pedicles coming from the lacrimal artery and muscular branches from the ophthalmic artery. Through morphometric study, there were abundant blood vessels in the orbital layer and larger luminal cross sectional area of the blood vessels at midorbital portion in the global layer. The arterial blood supply to the EORMs was variable but always substantial and the pedicles were numerous, their number was 1-5 arterial pedicles for each muscle. Since 70-80% of the blood supply of the anterior segment of the eye ball arise from the forward extension of the muscular arteries[5]. So, in cases of transposition procedures during strabismus or retinal reattachment surgery, surgeons must take care of these muscular arteries in order to keep the blood flow within the corresponding anterior ciliary arteries.Also It could be concluded that the orbital layer of the EORMs has increased vascularity and increased content of mitochodria and oxidative enzymes than the global layer