Orbit

See also Structural anatomy of the eye

Bony orbit - a cone pointing to the brain

  • Constituent bones of the orbital margin
  • Knowledge of the detailed anatomy of the orbital walls is not required

Eyelids

  • Composition: orbital septum blending into tarsal plates
  • Location of the Meibomian glands
  • Innervation

Conjunctiva

  • Appreciation of its composition as being primarily one of fibrous tissue and stratified squamous epithelium
  • Innervation

Lacrimal apparatus

  • Appreciation that this comprises glands, canaliculi, duct and sac
  • Location of the lacrimal glands (lateral orbital roof)
  • Location & function of the lacrimal sacs
  • Location & function of the nasolacrimal ducts

Orbital muscles

  • Overview of the anatomical arrangement of the muscles: the cone of orbital muscle

The functions and innervation of each of the following named muscles:

  • Superior rectus
  • Medial rectus
  • Inferior rectus
  • Lateral rectus
  • Superior oblique
  • Inferior oblique

Orbital stability:

  • Anatomical factors exerting anteroposterior eye stability (eg bony attachment of the recti)

Orbital nerves: (See also Face above)

Optic nerve

  • its emergence through the sphenoidal optic canal with the ophthalmic artery → Structures entering orbit

  • Appreciation of its composition as an outdrawing of white matter with a subarchnoid space

  • Understanding of this fact as the reason for the appearance of papilloedema in raised intracranial pressure

  • Blood supply of the nerve as being a combination of anterior cerebral, ophthalmic & central retinal arteries

  • A detailed knowledge of the anatomical course of the many other nerves with a presence in the orbit (eg lacrimal, nasociliary) is NOT required.

  • Visual pathways

Orbital blood supply

  • Ophthalmic artery as the prime artery of local supply
  • Appreciation (detail not required) that it supplies all the orbital muscles, the lacrimal gland & the eye

Orbital venous drainage

  • Appreciation of the superior ophthalmic vein having communication with the cavernous sinus
  • The additional role of the inferior ophthalmic vein

Orbital lymph drainage

  • Overview of the drainage pathway as being to deep cervical nodes via the pre-auricular & parotid groups

Functional anatomy of eye movement

  • Control of conjugate gaze, causes of nystagmus & the vestibulo-ocular reflexes are not within the scope of the anatomy curriculum -
  • However, knowledge of the following aspects of eye function is required

Clinical effects of palsies of the III, IV and VI nerves

  • Clinical effects of paralysis of a given extraocular muscle (eg superior rectus => diplopia on looking up)

#anatomy-eye #curriculum