Ocular Anatomy and Physiology Flashcards

The crystalline lens is held in position by which structure?

Answer: Zonular fibers (suspensory ligaments)

Zonular fibers connect the lens equator to the ciliary body, suspending the lens in the optical axis.

Accommodation refers to which physiologic process?

Answer: Changing lens curvature to focus at different distances

Accommodation changes the curvature of the crystalline lens by ciliary muscle contraction to focus objects at near.

The vitreous humor consists primarily of:

Answer: Water with collagen fibrils and hyaluronic acid

The vitreous is approximately 99% water supported by a framework of collagen fibrils and hyaluronic acid.

Which photoreceptor cells are responsible for night (scotopic) vision?

Answer: Rods

Rod photoreceptors are extremely sensitive to light and mediate vision under low-light (scotopic) conditions.

Visual information travels from the retina via the optic nerve to which structure first?

Answer: Lateral geniculate nucleus of the thalamus

Retinal ganglion cell axons project through the optic nerve to synapse in the lateral geniculate nucleus of the thalamus.

Pupil constriction (miosis) and dilation (mydriasis) are controlled by which iris muscles?

Answer: Sphincter muscle for miosis and dilator muscle for mydriasis

The iris sphincter muscle (parasympathetic) constricts the pupil and the dilator muscle (sympathetic) dilates it.