الفهرس 
Blood supply of the Extraocular Muscles (EOMs)Only 14 pages are availabe for public view
 |  | from | 148 |  |  |
| | | from | 148 | | |
Abstract
Every eye is provided with six extraocular muscles (EOMs). These muscles include superior, inferior, medial, and lateral recti muscles which arise from a common tendinous origin that surrounds the optic canal, and then run forwards in the orbit till they reach their insertion in the corresponding sites in the globe around the limbus. In addition to those four recti, there are two obliques, superior and inferior. The superior oblique originates from the sphenoid bone at a point above the tendinous ring, and then runs forward till it pass through the trochlea, and then backwards to be inserted in the globe superiorly. While the inferior oblique originates from the orbital floor lateral to the lacrimal fossa, and then runs postero-laterally be inserted in the globe inferiorly. (1) All these EOMs are responsible for coordinated eye movements in different directions. These movements include elevation, depression, abduction, adduction, intortion and extortion, in addition to conjugate eye movements towards right, left, up, down and during convergence. These muscles obey Sherrington’s law of reciprocal innervation so that when one muscle contracts, its antagonistic muscle relaxes simultaneously in the same degree e.g., contraction of the right lateral rectus muscle is associated with relaxation of the right medial rectus muscle. Also, these muscles obey Hering’s law of equal innervation so that when one muscle contracts, its yolk muscle contracts simultaneously in the same degree e.g., contraction of the right lateral rectus muscle is associated with contraction of the left medial rectus muscle. (1) Extraocular muscles enlargement (EOMsE) is usually seen in the cases presented with thyroid eye diseases (TEDs), but it is found that it’s not exclusive for them. Because of this, EOMsE is now classified into thyroid related extraocular muscles enlargement (TR-EOMsE) and non - thyroid related extraocular muscles enlargement (NTR-EOMsE).