Part 50

Action.—Rotates the eyeball.

=Obliquus Inferior= (Fig. 26, No. B, 6). (Synonym.—Obliquus ventralis.)

Location.—Inferior to the eyeball.

Origin.—From the interorbital septum near the inner canthus of the eye.

Insertion.—By a broad expansion to the inferior portion of the eyeball.

Shape.—Tendinous at its insertions; fan-shaped as it passes downward and outward.

Relations.—Internally, with the eyeball; and externally, with the bony orbital wall, with the inferior rectus muscle, inferiorly.

Action.—Aids in rotating the eye; opposes the obliquus superior.

=Rectus Superior= (Fig. 26, No. B, 1). (Synonym.—Rectus dorsalis.)

Location.—Superior to the eyeball.

Origin.—Along the supero-posterior border of the optic foramen.

Insertion.—To the sclera just within the margin of the bony circle of the eye.

Shape.—Flat, thin.

Relations.—Internally, with the obliquus superior; superiorly, with the bony wall of the orbit.

Action.—To pull the eyeball upward.

=Rectus Inferior= (Fig. 26, No. B, 3). (Synonym.—Rectus ventralis.)

Location.—Inferior to the eyeball.

Origin.—From the inferior border of the optic foramen.

Insertion.—To the lower portion of the eyeball within the margin of the bony circle of the eye.

Shape.—Thin, fan-shaped.

Relations.—Superiorly, with the eyeball; inferiorly, with the bony wall of the orbit.

Action.—Pulls the eyeball downward.

=Rectus Externus= (Fig. 26, No. B, 4). (Synonym.—Rectus lateralis.)

Location.—External to the eyeball.

Origin.—By two heads infero-laterally to the optic foramen.

Insertion.—To the postero-external side of the eyeball.

Shape.—Short, fan-shaped.

Relations.—Internally, with the eyeball; externally, with the bony wall of the orbit.