Special Senses

Question 1

What are the three tunics of the eyeball? What is their function?

Answer 1

Fibrous
- Includes Sclera and Cornea
- Sclera is white and similar to dura mater. Provides anchoring for extrinsic muscles
- Cornea allows light to enter (transparent)

Vascular
- Includes Choroid, Ciliary body, Iris, and Pupil
- Choroid is 5/6 of vasc. tunic and prevents light scatter
- Ciliary body is a thick ring of tissue made of smooth muscle that focuses lens and makes aq. humor
- Iris is the colored part of the eye with smooth muscle that allows light to enter (contains sphincter and dilator)
- Pupil is the opening of the iris allowing light to pass

Retina
- Consists of pigmented layer and neural layer
- Pigmented layer absorbs light and prevents scatter
- Neural layer contains photoreceptors, bipolar ganglia, and ganglion cells

Question 2

What are the accessory structures of the eye? (6)

Answer 2

• Eyelids
• Palpebral fissure
• Canthi
• Levator palpebrae
• Conjungtiva
• Conjunctiva sac

Question 3

What is conjunctiva and conjunctival sac? What is congunctivitis? What is pink eye?

Answer 3

Conjunctiva - Transparent mucous membrane that covers eyelids and anterior of the eye

Conjunctival sac - Space between the eyelid and eye ball that is lined with conjunctiva to moisten and protect the eye

Conjunctivitis/Pink eye - When the conjunctiva of the eye becomes inflamed or infected causing redness, itching, and more

Question 4

Know the 6 extrinsic eye muscles and their actions? What is strabismus?

Answer 4

Superior Rectus - Moves the eye up, contributes to medial rotation
Inferior Rectus - Moves the eye down, contributes to lateral rotation
Medial Rectus - Moves the eye toward the nose (adduction)
Lateral Rectus - Moves the eye away from the nose (abduction)
Superior Oblique - Moves the eye down and outward, contributes to medial rotation
Inferior Oblique - Moves the eye up and outward, contributes to lateral rotation

Strabismus - Condition leading to an eyes being misaligned resulting in one pointing in/out/up/down

Question 5

What are the specialized areas of the retina?

Answer 5

Ora serrata - Neural layer meets ciliary body
Macula Lutea
Fovea centralis - Center of Macula
Optic Disc - Blind spot

Question 6

Identify this structure.

Answer 6

Sclera

Question 7

Identify this structure.

Answer 7

Cornea

Question 8

Identify this structure.

Answer 8

Ciliary body
- Ciliary muscle (1st from top)
- Ciliary process (2nd from top)

Question 9

Identify this structure.

Answer 9

Suspensory ligament
(ciliary zonule)

Question 10

Identify this structure.

Answer 10

Iris dilator (points in) and sphincter (circular)

Question 11

Identify this structure.

Answer 11

Cone and rod Photoreceptors

Question 12

Label the image. What is the function of the external ear?

Answer 12

• Helix, auricle, External acoustic canal, External auditory meatus, Lobule (descending order)
• The function is to funnel sound toward the eardrum and protect the inner ear of debris

Question 13

Label the image. What is the function of the middle ear?

Answer 13

• Auditory ossicles (Malleus, Incus, Stapes), Tympanic membrane, Round Window, pharyngotympanic tube
• The middle ear transmits sound from the external ear to the inner ear, amplifies sound, equalizes air pressure, and protects from loud noises

Question 14

Label the image? What are their membranous components and what is their function?

Answer 14

• Semicircular canals: Contains semicircular ducts responsible for equilibrium for angular rotation
• Vestibule: Contains utricle and saccule responsible for static and linear equilibrium
• Cochlea: Contains cochlear duct responsible for hearing