Anatomy & Histology of Ear Flashcards
This portion of the ear is from the Auricle to the Tympanic Membrane.
External ear
This portion of the ear is from the Tympanic Membrane to the Oval Window.
Middle ear
This portion of the ear is from the Oval Window to the Internal Acoustic Meatus.
Inner ear
This part of the external ear is made of non-cartilaginous CT.
Lobule (Ear lobe)
What provides blood supply to the external ear?
External Carotid A. via the Posterior Auricular A. and Superficial Temporal A.
What innervates the posterior external ear?
Lesser Occipital N. (from Cervical Plexus)
Greater Auricular N. (from Cervical Plexus)
What innervates the anterior external ear?
Auriculotemporal N. (from CN V)
***Runs with Superficial Temporal A. (from ECA)
What innervates the central area of the external ear?
Vagus N. (CN X)
Glossopharyngeal N. (CN IX)
This nerve provides sporadic innervation to the external ear. Some in the central area, some in the back near the mastoid.
Facial N. (CN VII)
This is the canal leading to the Tympanic Membrane (2-3 cm). The lateral third is S-shaped and it contains ceruminous glands (make wax) and sebaceous glands. Cartilage is beneath fibrous CT.
External auditory canal (meatus)
The area in the external ear (central, inferior) that is innervated by the Vagus N. (also called the _______ N.). This causes the cough reflex to occur.
Arnold
What is the outer 2/3 of the External Acoustic Meatus made of?
CT and Elastic cartilage
What is the inner 1/3 of the External Acoustic Meatus made of?
Skin and bone
This is the only place in the entire body where skin, periosteum, and bone exist directly on top of each other. There is no CT, therefore it bleeds easily.
Inner 1/3 of External Acoustic Meatus
What type of epithelium is the External Acoustic Meatus made of?
Keratinized Stratified Squamous Epithelium
***Also has hair follicles, ceruminous glands, and sebaceous glands
This is a semi-transparent membrane that is approximately 1 cm in diameter. It is connected to the handle of the Malleus, which gives it concavity making it cone-shaped. The cone is oriented toward the External Auditory Meatus.
Tympanic Membrane
The Tympanic Membrane has an outside layer and inside layer. What type of epithelium are each of these made of?
Outer layer – Stratified squamous epithelium
Inner layer – Simple cuboidal epithelium
What is the time of the cone of the Tympanic Membrane called?
Umbo
The Tympanic Membrane has a flaccid part and a tense part. It moves with sound and transmits to the _________.
Ossicles
What is important to see in the 2nd quadrant of the Tympanic Membrane?
Cone of light
The Tympanic Cavity (middle ear) is located in the petrous portion of the Temporal bone. It contains two parts, which are…
Tympanic Cavity Proper (called Mesotympanum)
Epitympanic Recess
What make up the “walls” of the Tympanic Cavity?
Tegmental Wall (roof) Jugular Wall (floor) Membranous Wall (lateral) Labyrinthine Wall (medial) Mastoid Wall (posterior)
This nerve pierces through the Jugular Wall, the “floor” of the Tympanic Cavity.
Tympanic N.
The Tympanic N. meets with the Lesser Petrosal N. within the…
Tympanic Plexus
This muscle is attached to the Malleus.
Tensor Tympani M.
This nerve passes over the Tensor Tympani M.
Chorda Tympani (from Facial N.)
The Malleus connects to the ________, and this attaches to the _________, which attaches to the Oval Window.
Incus
Stapes
This muscle attaches to the Stapes and the Mastoid.
Stapedius M.
What are the three prominences within the middle ear?
Lateral Semicircular Canal
Facial N.
Labyrinth Wall (promontory)
This connects the Tympanic Cavity (middle ear) with the Nasopharynx (back of the throat).
Pharyngotympanic Tube (Eustachian Tube)
The proximal part of the Pharyngotympanic Tube is (BONE/CARTILAGE) but the distal remainder is (BONE/CARTILAGE).
Bone
Cartilage
- **Opposite pattern as External Acoustic Meatus
- **EAM – distal 2/3 cartilage, proximal 1/3 bony
- **PT – distal 2/3 bony, proximal 1/3 cartilage
What is the function of the Pharyngotympanic Tube?
Equalize pressure (gives ear popping sensation)
This muscle expands the Pharyngotympanic Tube. It contracts longitudinally which PUSHES against one wall.
Levator Veli Palatini
This muscle expands the Pharyngotympanic Tube. It PULLS on one wall (the other wall is being pushed by the other muscle).
Tensor Veli Palatini
The Pharyngotympanic Tube is _______ cartilage covered by integument.
Elastic
What type of epithelium is the Pharyngotympanic Tube composed of?
Pseudostratified Epithelium
***Different from External Acoustic Meatus, which is Keratinized Stratified Squamous Epithelium
What are the auditory ossicles?
Malleus
Incus
Stapes
The auditory ossicles bridge the Tympanic Membrane with the Round Window of the Cochlea.
False. The auditory ossicles bridge the Tympanic Membrane with the Oval Window of the Cochlea.
What are the parts of the Malleus?
Head
Neck
Handle
What are the parts of the Incus?
Body
Short Process
Long Process
The short process of the Incus is connected to what?
Mastoid (Posterior) wall
The handle of the Malleus is connected to what?
Tympanic Membrane
What are the parts of the Stapes?
Head
Limbs
Base (Footplate)
This component of the Stapes is what vibrates the Oval Window.
Base (Footplate)
The auditory ossicles amplify the force on the Tympanic Membrane by how much?
10x