Ophthalmology · MU Sofia

3. Applied anatomy of the orbit

Walks through the four walls of the orbit (roof, floor, lateral and medial walls), naming the bones that form each and the foramina and fissures they enclose. It then covers the nerves passing through the orbit and their branches, with a mnemonic for the cranial nerves supplying the eye muscles, and closes with a short section on the extraocular muscles, their actions and innervation.

Inside: 3 sections · 5 labelled pictures · 13 flashcards · 5 min

Topic 3 of 91 in the MU Sofia syllabus for Ophthalmology (Medicine, Year 4). The free AceMed note covers it in 3 sections, about 665 words (5 min of reading), with 13 flashcards.

In this note

  1. Anatomy of the orbit Topic 1
  2. Extraocular muscles
  3. Topic 4

Anatomy of the orbit Topic 1

Consists of 4 parts : 1. Roof 2. Lateral wall 3. Medial wall 4. Floor

1. Roof

  • Superior margin= mainly frontal bone +posteriorly lesser wing of sphenoid
  • Sphenoid forms Optical foramen + orbital fissure
  • Medially at the roof the supraorbital not is located
  • At Anteromedial angle → small trochlear fossa where the trochlea attaches ( a loop interacting with superior oblique

2. Floor

  • Mainly maxilla +a little bit zygomaticus +palatine bone

3. Lateral wall

  • Zygomatic bone + greater wing of sphenoid

4. Medial wall

  • Maxilla (main) Ethmoid bone (forming anterior &posterior ethmoidal formina)+ lacrimal bone (together with maxilla form Lacrimal groove)

Foramina and openings

1. Optical canal→ transmits optic nerve + ophthalmic artery

2. Superior orbital fissure→ between lesser &greater wing

Live Freely To See Absolutely No Insult

Lacrimal frontal Trochlear superior division abducens nasocilliary inferior division

Superior and inferior from Oculomotor (III) → most eye movements , constriction of pupil +eyelid opening

Lacrimal frontal and nasocilliary branch of ophthalmic (branch of trigeminal)

Lacrimal → sensory from lateral part of upper eyelid + conjunctiva +innervates lacrimal gland

Frontal → innervates skin of forehead – mucosa of frontal sinus –skin of upper eyelid

Via its branches supratrochlea and supraorbital

Nasocilliary = (Main) is divided into A)nasocilliary nerve B) posterior C)anterior Ethmoid

A) the following division arise

Long ciliary → pierces posterior sclera runs between it and the choroid thus provides sensory innervation of the eyeball + sympathetic fibres to dilator pupillae muscle

Infratrochlear→ skin of upper eyelid & bridge of nose , conjunctiva, lacrimal sac & caruncle

Branches to the ciliary ganglion→ then short ciliary nerves go to the eyeball

B) Posterior Ethmoid → supplies linings of Ethmoid + sphenoid sinuses

C) anterior Ethmoid → gives rise to anterior meningeal nerves + supplies anterior superior nasal mucosa

T rochlear nerve (IV)→ innervates superior oblique

A bducens (VI) →innervates lateral rectus

Superiors orbital fissure also contains superior &inferior ophthalmic nerve

Inferior Orbital fissure

a) Zygomatic nerve (branch of maxillary which is branch of trigeminal)

→ supplies skin of Zygomatic and temporal bones

b) pterygoid palatine ganglion → supplies lacrimal gland and paranasal sinuses

C) infra orbital fissure → passes through it then exits through infraorbital foramen

Infraorbital foramen

Passage for infraorbital nerve (sensory lower eyelid), artery and veins

Supraorbital formina (notch) supraorbital nerve+artery

Zygomatico –orbital foramina

Zygotmatcofacial nerve → inferior lateral angle of the orbit → area of skin over cheek

Continue reading free

The whole note, all 3 sections, is free with an AceMed account, with its 13 flashcards. Premium adds flashcard recall, highlights and Ask AI.

Start freeAlready a member? Open the note