The orbitThe orbit

Orbital Contents

The contents of the orbit are :-• the eyeball the eyeball • optic nerve optic nerve • ocular musclesocular muscles• fascia fascia • nervesnerves• vessels vessels • fat fat • lacrimal gland lacrimal gland • and conjunctival sacand conjunctival sac.

Levator Palpebrae Superioris

• This thin, flat elevator muscle of the superior eyelid broadens into a wide aponeurosis as it approaches its distal attachment to the tarsal plate. This muscle is the opponent of the orbicularis oculi, the sphincter of the palpebral fissure.

Levator Palpebrae Superioris

•Tarsal gland•Palpebral surface•Posterior margin

•Anterior margin

Recti and Oblique Muscles

• The four recti arise from a fibrous cuff, the common tendinous ring, that surrounds the optic canal and part of the superior orbital fissure.

• The lateral and medial recti lie in the same horizontal plane, and the superior and inferior recti lie in the same vertical plane. All four recti mus cles attach to the sclera on the anterior half of the eyebal

• All four recti muscles attach to the sclera on the anterior half of the eyeball.

• • Medial and lateral recti rotate the pupil medially and laterally, respectively

• • Superior rectus rotates the pupil superiorly (elevation)

• • Inferior rectus rotates the pupil inferiorly (depression).

• The inferior oblique directs the pupil laterally and superiorly; therefore, when it works synergistically with the superior rectus, superior movement of the eyeball occurs. Similarly, the superior oblique directs the pupil inferiorly and laterally; therefore, when it works synergistically with the inferior rectus, an inferior movement results.

Tendinous ring

Lacrimal Apparatus

• The lacrimal apparatus consists of:• • Lacrimal glands, which secrete

lacrimal fluid• • Lacrimal ducts, which convey

lacrimal fluid from the lacrimal glands to the conjunctiva! sac

• • Lacrimal canaliculi (L. small canals), each commencing at a lacrimal punctum (opening) on the lacrimal papilla near the medial angle of the eye, which conveys the lacrimal fluid from the lacrimal lake—a triangular space at the me dial angle of the eye where the tears collect—in the lacrimal sac, the dilated superior part of the nasolacrimal duct

Temporal Region

• The temporal region includes the temporal and infratemporal fossae—superior and inferior to the zygomatic arch, respectively

Temporal Fossa

• The temporal fossa, in which the temporal muscle is located, is bounded:

• Posteriorly and superiorly by the temporal lines.

• Anteriorly by the frontal and zygomatic bones

• Laterally by the zygomatic arch

• Inferiorly by the infratemporal crest

The floor of the temporal fossa

• formed by parts of the four bones that form the pterion: frontal, parietal, temporal, and greater wing of the sphenoid.

• The fan-shaped temporal mus cle arises from the floor (i.e., the temporal fossa extending to the inferior temporal line) and the overlying temporal fascia.

• which comprises the roof of the temporal fossa