A&P II Lab: Quiz 1 - Visual Senses & Hearing and Equilibrium

Rectus

Straight Muscles

Oblique

Slanting Muscles

Superior Oblique

Depresses, turns laterally

Inferior Oblique

Elevates, turns laterally

Superior Rectus

Elevates, turns medially

Inferior Rectus

Depresses, turns medially

Medial/Lateral Rectus

Turns eye medially/laterally

Trochlea

Pulley system

Eye Muscles Diagram

 External/ Fibrous Layer

1. Sclera - White connective tissue of the eye

2. Cornea - Continuous with sclera; Transparent anterior bulge with no blood vessels

Middle/ Vascular Layer 

1. Choroid - Blood vessel-rich dark membrane, produces nutrients and melanin

2. Ciliary Body - Choroid modification that encircles the lens

   1. Ciliary Muscle - Smooth muscle in ciliary body

   2. Ciliary Process - Radiating folds of ciliary muscle with capillaries

3. Ciliary Zonule - Suspensory Ligament; Halo of fine fibers extending from ciliary process around lens

4. Iris & Pupil - Eye pigment; 2 layers of smooth muscle: sphincter pupillae and dilator pupillae

   1. Sphincter pupillae: Contracts to constrict pupil

   2. Dilator pupillae: Contracts to dilate pupil

Inner Layer/ Retina

1. Pigmented Layer - Outer layer composed of a single layer of melanocytes (pigmented cells)

2. Neural Layer - Thicker layer composed of 3 neurons: 1. Photoreceptors (rods and cones), 2. Bipolar cells, 3. Ganglion cells

3. Macula Lutea - Part of retina responsible for sharp, detailed, central vision

   1. Fovea Centralis - Center of macula lutea, responsible for Fovea vision (sharp, central vision)

4. Optic Disc - Location where ganglion cell axons exit the eye to form optic nerve

• No light sensitive rods/cones to respond to light stimulus – blind spot

Internal Eye Anatomy

Internal Eye Anatomy 2

a. Sclera
b. Choroid
c. Retina
d. Ciliary processes
e. Lens
f. Vitreous humor
g. Aqueous humor
h. Iris
i. Cornea
j. Anterior chamber
k. Pupil
l. Suspensory ligaments (zonular fibers)
m. Ciliary muscle
n. Conjunctiva

Cones and Rods

Cones = Colors
Rods = Low Light Levels

Ear Anatomy

External Ear

1. Auricle (pinna) - Outer part of the ear; Elastic cartilage covered with skin

• Collects and directs sound waves into the external acoustic meatus

2. Lobule (“earlobe”) - Part of auricle inferior to external acoustic meatus; Where ears are pierce

3. Helix - Between lobule and auricle

4. External acoustic meatus (“ear canal”) - Short, narrow canal carved into temporal bone lined with ceruminous glands

• Transports sound waves from the auricle to the tympanic membrane

3. Tympanic Membrane (“ear drum”) - Thin membrane that separates the external ear from the middle ear

External Ear Simplified

Collect then transport sound waves:
Auricle → Lobule → External Acoustic Meatus → Tympanic Membrane

Middle Ear/Tympanic Cavity

1. Auditory Ossicles

   1. Malleus (hammer) - Tiny “hammer”-like bone with its “handle” attached to the eardrum

   2. Incus (anvil) - Tiny “anvil”-like bone that articulates with malleus and stapes

   3. Stapes (stirrup) - Tiny “stirrup”-like bone with its “base” fitted inside the oval window

2. Oval Window - Oval-shaped membrane located deep to the stapes

2. Pharyngotympanic / Auditory Tube - Tube that connects the middle ear to the superior portion of the pharynx (throat)

Middle Ear Simplified

Transmit and amplify vibrations:
Ear Drum → Malleus → Incus → Stapes → Oval Window → Perilymph

Internal Ear

1. Cochlea

• Membranous Labyrinth: Cochlea duct

• Structure containing receptors: Spiral organ

• Function of receptors: Hearing

2. Vestibule

• Membranous Labyrinth: Utricle and saccule

• Structure containing receptors: Maculae

• Function of receptors: Equilibrium - Static equilibrium and linear acceleration of the head

3. Semicircular Canals

• Membranous Labyrinth: Semicircular ducts

• Structure containing receptors: Ampullae

• Function of receptors: Equilibrium - Rotational acceleration of the head

Hair Cell Detection

Otoliths (ear stones) - Calcium / Ear crystals that serve as weights on top of the hair cells that detect the movement

• If the crystal is knocked off the hair cell, the person will feel a sense of motion/spinning, dizziness – vertigo

Ear Anatomy 2

a. Auricle (pinna)
b. External auditory meatus
c. Malleus (hammer)
d. Semicircular canals
e. Vestibulocochlear nerve
f. Cochlea
g. Middle ear cavity (tympanic cavity)
h. Auditory tube
i. Tympanic membrane (eardrum)
j. External ear
k. Lobule

Internal Ear Anatomy

a. Cochlear nerve
b. Vestibular nerve
c. Semicircular canals
d. Semicircular canal
e. Incus (anvil)
f. Malleus (hammer)
g. Stapes (stirrup)
h. Tympanic membrane (eardrum)
i. Cochlea