Anatomy (Bones and Muscles) · MU Sofia

14. Orbit

Covers the bony orbit as a four-sided pyramidal space, describing its apex, base and four walls, then its three openings: the superior orbital fissure, the inferior orbital fissure and the optic canal, with the structures passing through each. It goes on to the walls and openings of the bony orbit, and finishes with the orbital fascia, including the periorbital and bulbar fascia and the suspensory and medial and lateral check ligaments. A mnemonic for the nerves passing through the superior orbital fissure is included.

Inside: 5 sections · 6 labelled pictures · 14 flashcards · 5 min

Topic 14 of 49 in the MU Sofia syllabus for Anatomy (Bones and Muscles) (Medicine, Years 1 and 2). The free AceMed note covers it in 5 sections, about 682 words (5 min of reading), with 14 flashcards.

In this note

  1. ORBIT
  2. OPenings in the orbit
  3. The bony Orbit :
  4. The orbital fascia:
  5. Ligaments of the bulbar fascia

ORBIT

  • The orbits are 4-sided pyramidal spaces on either side of the root of the nose.
  • Each orbit has :
  • Apex: is directed backwards.
  • Base: it is the orbital opening on face.
  • Four walls: roof, floor. Medial wall, and lateral wall. The medial walls of both orbits are parallel to each other, while the lateral walls are set at right angle to each others.

OPenings in the orbit

1. Superior orbital fissure :

  • it lies at the junction between the roof and the lateral wall of the bony orbit. It allows passage of structures between the middle cranial fossa and the orbit. The common tendinous ring of the extra-ocular muscles divides it into 3 parts.

✓Structures passing through it: lacrimal, frontal, trochlear, superior division of oculomotor, naso-ciliary, inferior division of oculomotor, and abducent nerves. In addition to the superior ophthalmic vein.

“ Live Free To See Absolutely No Insult ”

N.B:

  • Divisions of oculomotor nerve, naso-ciliary nerve, and abducent nerve pass through the superior orbital fissure (within the common tendinous ring).

2. Inferior orbital fissure :

  • It lies between the floor and the lateral wall of the bony orbit. It allows communication between the orbit and temporal fossa (anteriorly), infratemporal fossa (in the middle), and pterygopalatine fossa (posteriorly).

✓Structures passing through it: the continuation of maxillary nerve, zygomatic nerve, infraorbital vessels, and communication between inferior ophthalmic vein and pterygoid venous plexus.

3. Optic canal :

  • It represents the apex of the bony orbit, connecting the orbit to the middle cranial fossa.

✓Structures passing through it: optic nerve and ophthalmic artery.

← (III , IV , VI & V₁) Superior orbital fissure

  • lacrimal
  • frontal
  • naso-ciliary

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