Human Ear Model

Ear model - anterior view:

External ear - made up of 5 parts:

1. auricle (aka "pinna"):

The auricle or pinna refers tot he entire visible structure of the External ear (i.e. does not include the External acoustic meatus).

2. helix:

3. lobule:

4. external acoustic meatus (aka "auditory canal"):

Anterior view of External acoustic meatus.

Lateral view of External acoustic meatus.

5. tympanic membrane:

Middle ear - made up of 4 parts:

A. Oval window:

Oval window is the hollow circle formed by the "footplate" or base of the Stapes, which is broken on this model.

 

B. Round window:

C. Auditory tube (aka "Pharyngotympanic tube"):

D. Auditory ossicles (3 "little bones"):

i. malleus:

ii. incus:

iii. stapes: no picture available (stapes broken on model). Link to clear picture of stapes on a different ear model.

Internal ear (aka "Inner ear" or "Labyrinth") - made up of 2 separate labyrinths:

1. Osseous labyrinth (aka "Bony labyrinth"):

Bony labyrinth contains the fluid called "perilymph".

2. Membranous labyrinth:

Membranous labyrinth contains the fluid called "endolymph".

3 parts that make up the Bony (Osseous) Labyrinth: (1) vestibule, (2) semicircular canals, and (3) cochlea.

1. vestibule (of Bony Labyrinth) - contains 2 internal structures of interest.

The Vestibule of the inner ear connects the Cochlea with the Semicircular canals.

i. utricle (of vestibule, of Membranous labyrinth): one of two small cavities inside the vestibule; not visible on the model because it is an internal structure. Internet diagram of the utricle can be found here.


ii. saccule (of vestibule, of Membranous labyrinth): one of two small cavities inside the vestibule. See "utricle" entry above for a diagram of the saccule.


2. Semicircular Canals (of Bony Labyrinth, 3 total) - contains 1 internal structure of interest.

i. ampullae (of Semicircular canals):

Ampullae are dilated (enlarged) areas of the base of each Semicircular canal.

3. Cochlea - (of Bony labyrinth, made up of 3 internal tubes):

Cochlea is a "snail-like" structure dedicated to the sense of hearing (whereas the Vestibule and Semicircular canals are dedicated to balance/spatial orientation).

i. scala vestibuli (of Cochlea, of Bony labyrinth):

Scala vestibuli are Orange on this model. Scala vestibuli is filled with "perilymph".

 ii. scala tympani (of Cochlea, of Bony labyrinth):

Scala tympani are Blue on this model. Scala tympani is filled with "perilymph".

iii. scala media (of Cochlea, of Membranous labyrinth, aka "Cochlear Duct"):

Scala media (aka "Cochlear Duct") is filled with "endolymph".

Vestibulocochlear Nerve (aka "Cranial Nerve 8"):

Cow Eye

Cow Eye - anterior view:

Cow Eye - internal view:

Fibrous Tunic - made up of 2 parts/tissues:

1. cornea:

The probe indicates a "layer" (of tissue): Cornea of the eye.

2. sclera:

Vascular Tunic - made up of 4 parts:

A. choroid:

Choroid is the blue-black layer of tissue surrounding the lens (not pictured here) of the eye.

B. ciliary body:

C. iris:

 D. pupil:

The probe indicates the "hole": Pupil of the eye.

Retina (a tunic) - made up of 2 parts:

a. macula lutea: area on the retina with the largest concentration of cone photoreceptors (for color & bright light); usually not visible in cow eye specimens.


b. central fovea ("fovea centralis"): contains ONLY cone photoreceptors (no rods); it is the area of sharpest central vision (high visual acuity) due to an extreme "crowd of cones" in the center of the macula lutea, but is not visible in cow eye specimen.




Optic disc:

Probe is pointing to the Optic disc, which looks like a "dimple in the wrinkle" of the Retina (tunic), but is not technically a part of the Retina.

Optic nerve (Cranial Nerve 2):

Lens:

The probe indicates the lens, which has become opaque due to embalming fluid. In vivo, the lens is completely clear/translucent.

Anterior cavity - the cavity "from the Lens forward"; is made up of 3 parts:

1. Anterior chamber: no picture; chamber between Iris and the innermost surface of the Cornea.


2. Aqueous humor: no picture; fluid that fills the Anterior cavity; Aqueous humor is bounded by the gelatinous Vitreous humor of the Vitreous chamber.


3. Posterior chamber: no picture; chamber between the Iris and the Lens.









Vitreous chamber - area located behind the Lens; made up of 1 part.


A. Vitreous humor (aka "Vitreous Body"):

Vitreous Humor/Body is the gelatinous ball on the Right.

Extra structures (not on Lab Exam list):

zonular fibers (aka "suspensory ligaments"):

Suspensory ligaments connect the ciliary body to the lens; they are the "transparent strings" shown in the photo above.

tapetum lucidum (not in human eyes):

Tapetum lucidum is the super shiny part of the cow's eye: the "eyeshine" that causes superior night vision for many animals, especially carnivorous and nocturnal animals.