ABO Ocular Anatomy & Physiology 4 — Questions and Answers
Question 1: The lens derives its nutrition primarily from:
- The hyaloid artery (in adults)
- The aqueous humor bathing its surfaces (Correct answer)
- The zonular fibers carrying nutrients
- Direct blood supply from ciliary arteries
Correct answer: The aqueous humor bathing its surfaces
The adult lens is avascular and depends entirely on the aqueous humor for nutrients such as glucose and oxygen, and for waste removal.
Question 2: Which layer of the retina contains the cell bodies of bipolar cells?
- Outer nuclear layer
- Inner nuclear layer (Correct answer)
- Ganglion cell layer
- Inner plexiform layer
Correct answer: Inner nuclear layer
The inner nuclear layer contains the cell bodies of bipolar, horizontal, amacrine, and Müller cells.
Question 3: The cornea receives its sensory innervation from which nerve?
- Facial nerve (CN VII)
- Nasociliary branch of CN V1 (Correct answer)
- Maxillary branch of CN V2
- Oculomotor nerve (CN III)
Correct answer: Nasociliary branch of CN V1
The cornea is innervated by the nasociliary branch of the ophthalmic division (V1) of the trigeminal nerve via the long ciliary nerves.
Question 4: In the visual pathway, fibers from the inferior nasal retina (representing the superior temporal visual field) decussate at the chiasm and travel in which portion of the optic tract?
- Dorsal optic tract
- Ventral optic tract (Correct answer)
- They do not decussate at the chiasm
- Lateral optic tract only
Correct answer: Ventral optic tract
Inferior nasal retinal fibers decussate at the chiasm and travel in the ventral portion of the contralateral optic tract.
Question 5: Which structure connects the ciliary body to the lens and is responsible for maintaining lens shape during accommodation?
- Hyaloid membrane
- Zonules of Zinn (zonular fibers) (Correct answer)
- Anterior hyaloid face
- Vitreous cortex
Correct answer: Zonules of Zinn (zonular fibers)
The zonules of Zinn (zonular fibers) connect the ciliary body to the lens capsule and transmit ciliary muscle forces to change lens shape during accommodation.
Question 6: The ora serrata is clinically significant because it marks the:
- Junction of the optic nerve and retina
- Boundary between the pigmented and non-pigmented ciliary epithelium
- Anterior termination of the neurosensory retina (Correct answer)
- Posterior limit of the vitreous base
Correct answer: Anterior termination of the neurosensory retina
The ora serrata is the anterior boundary of the neurosensory (photoreceptor-containing) retina, where it transitions to the non-photoreceptive pars plana.
Question 7: Which cells in the corneal epithelium are considered the stem cells that replenish the epithelial layer?
- Superficial squamous cells
- Wing cells
- Limbal basal cells at the palisades of Vogt (Correct answer)
- Central corneal basal cells
Correct answer: Limbal basal cells at the palisades of Vogt
Limbal basal cells at the palisades of Vogt are the stem cells that continuously proliferate and migrate centrally to replenish the corneal epithelium.
ABO Ocular Anatomy & Physiology 4
The lens derives its nutrition primarily from: