Anatomy Bones and Muscles · MU Pleven

202. Orbit – middle and lower floor

Covers the orbit as a four-sided pyramidal bony socket, noting its uneven wall thickness and the orbital septum, then sets out its cranial, medial, lateral, caudal, ventral and dorsal boundaries. It lists the passages through the fissures, canals and foramina with the nerves and vessels in each, then works through the upper, middle and lower levels of the orbital contents. Clinical notes on blow-out fractures, orbital fat prolapse and the connection of the eye's veins with the face close the note.

Inside: 2 sections · 10 labelled pictures · 14 flashcards · 5 min

Topic 201 of 236 in the MU Pleven syllabus for Anatomy Bones and Muscles (Medicine, Year 2). The free AceMed note covers it in 2 sections, about 724 words (5 min of reading), with 14 flashcards.

In this note

  1. ORBITAL REGION
  2. Clinical notes

ORBITAL REGION

The orbit (eye socket) is a bony case that provides support and mechanical protection for the eye and its accessory structures. It is a four-sided pyramid, with the base projecting forwards. The walls of the orbit have different thicknesses. The lateral wall and roof are thicker and the medial wall and floor are thinner. The orbital septum extends from the periosteum of the orbit to the fibrous layer of the eyeball. It separates the orbit proper from the palpebral region.

Boundaries

Cranially:

  1. 1 Frontal bone – the orbital part
  2. 2 Sphenoid bone – the lesser wing

Medially:

  1. 3 Maxilla – the frontal process
  2. 4 Lacrimal bone
  3. 5 Ethmoidal bone – the orbital plate
  4. 6 Sphenoid bode – the lesser wing

Laterally:

  1. 7 Zygomatic bone – the orbital surface
  2. 8 Sphenoid bone (greater wing) – the orbital surface

Caudally:

  1. 9 Maxilla (body) – the orbital surface
  2. 10 Zygomatic bone – the orbital surface
  3. 11 Palatine bone – the orbital process

Ventrally:

Orbital opening (aditus orbitalis)

Dorsally:

Orbital apex (apex orbitalis)

Passages

  1. 1 Superior orbital fissure
  2. 1.1 Oculomotor nerve
  3. 1.2 Nasociliary nerve (branch of n. V1)
  4. 1.3 Abducent nerve
  5. 1.4 Trochlear nerve
  6. 1.5 Frontal nerve (branch of n. V1)
  7. 1.6 Lacrimal nerve (branch of n. V1)
  8. 1.7 Superior ophthalmic vein
  9. 2 Inferior orbital fissure
  10. 2.1 Zygomatic nerve (branch of n. V2)
  11. 2.2 Nervus infraorbitalis (branch of n. V2)
  12. 2.3 Infraorbital artery (branch of the maxillary artery)
  13. 2.4 Inferior ophthalmic vein
  14. 3 Optic canal
  15. 3.1 Optic nerve
  16. 3.2 Ophthalmic artery
  17. 3.3 Ophthalmic plexus
  18. 4 Frontal and supraorbital foramina
  19. 4.1 Supraorbital nerve (branch of n. V1)
  20. 4.2 Supraorbital artery and vein (branch of the ophthalmic artery)
  21. 5 Anterior and posterior ethmoidal foramina
  22. 5.1 Anterior and posterior ethmoidal artery and vein (branch of the ophthalmic artery and tributary of ophthalmic veins)
  23. 5.2 Anterior and posterior ethmoidal nerve (branch of n. V1)
  24. 6 Zygomaticoorbital foramen
  25. 6.1 Zygomatic nerve (branch of n. V2)
  26. 7 Infraorbital groove and canal
  27. 7.1 Infraorbital nerve (branch of n. V2)
  28. 7.2 Infraorbital artery (branch of the maxillary artery)
  29. 7.3 Infraorbital vein (tributary of the inferior ophthalmic vein)
  30. 8 Nasolacrimal canal
  31. 8.1 Nasolacrimal duct

Levels

  1. 1 Upper level – between the ceiling of the orbit and the levator palpebrae superioris
  2. 2 Middle level – between the rectus superior and a virtual plane at the level of the optic nerve

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