Extra-ocular Muscles of Eye: their attachment, actions and nerve supply


Describe the attachment of extra-ocular muscles.
Describe the action and nerve supply of extra-ocular muscles.

Extra-ocular muscles of eye
The muscle acting on the eye ball to produce various movements of eye are called extr-aocular muscles which consists of

Four recti
Two oblique muscles
Superior rectus
Superior oblique
Inferior rectus
Inferior oblique
Medial rectus

Lateral rectus

Recti muscles
Origin – from posterior part of the orbit from a common tendinous ring
Insertion – the muscles proceed forwards in a cone of muscles and spread out at the sites of insertion into the sclera of the eyeball.

Oblique Muscles
Superior oblique: arises from the lesser wing of sphenoid bone and inserts into the sclera behind the equator of eyeball.
Inferior Oblique: arises from orbital surface of maxilla in the floor of the orbit and inserts into the sclera behind the equator of the eyeball.

Innervations or Nerve supply of extra-ocular muscles
All these muscles are supplied by oculomotor nerve (Cranial Nerve III) except lateral rectus (by abducent nerve – CN VI) and superior rectus (by trochlear nerve – CN IV).

Actions of extra-ocular muscles
Superior rectus –elevates, adducts and medially rotates the eyeball
Inferior rectus –depresses, adducts and medially rotates the eyeball
Medial rectus – adducts the eyeball
Lateral rectus – abducts the eyeball

Superior oblique – depresses, abducts and medially rotate the eye ball
Inferior oblique – elevates, abducts and laterally rotate the eyeball.

Following resources are used while preparing this post (readers are strongly recommended to go             through them for more details):

K. L. Moore's Clinically Oriented Anatomy
R. Snell's Clinical Anatomy