Dorsalis rectus muscle (Drm) \RL
The dorsalis rectus muscle is a sheet-like muscle composed of parallel
fibers that run dorsal to the dorsalis oblique muscle and ventral to the
medialis rectus muscle. It originates from the orbitosphenoid bone with
fleshy fibers, spreading out to form two aponeurotic branches that
insert on the scleral cartilage and the superior extension of the upper
eyelid. This aponeurosis passes over the dorsal surface of the
aponeurosis of the dorsalis oblique muscle. The origin of the dorsalis
rectus muscle lies dorsal to the optic nerve, posterodorsal to the
origin of the ventralis rectus muscle, and anterodorsal to the origin of
the lateralis rectus muscle. The insertion site of the dorsalis rectus
muscle is dorsal to the insertion site of the dorsalis oblique
muscle\RL.
Origin: Fleshy, from the orbitosphenoid bone\RL.
Insertion: Aponeurotic, on the scleral cartilage and superior
extension of the upper eyelid\RL.
Function: Elevation of the eyeball, upper eyelid elevation to
help open the palpebral fissure, and extorsion.