The basic form of the mammalian eye contains six extrinsic
eye muscles and a retractor bulbi (absent in man, higher apes, and birds).
The retractor bulbi is cone shaped and is thought to support the eye in
animals who hang their head for a long period of time, which prevents congestion
that would occur otherwise. The dorsal and ventral oblique muscle form
a almost complete girdle around the eye. These muscles have a posterior
origin in mammals and work in a pulley system to move the eye.
Mammalian Muscles and Their Actions
|Dorsal Rectus||move eye up or rotates it medially, helps levator to lift upper lid|
|Ventral Rectus||move eye down or rotates it laterally, depresses lower lid.|
|Medial Rectus||move eye medially (inward)|
|Lateral Rectus||moves eye laterally (outward)|
|Dorsal Oblique||moves eye down or laterally|
|Ventral Oblique||moves eye up or laterally|
|Retractor Bulbi||retracts the eyeball|