Ear Flashcards
(25 cards)
Three layers of the tympanic membrane:
- Outer
- Middle
- Innermost
Outer: stratified squamous epithelium skin)
Middle: connective tissue
Innermost: continuous with mucosa of middle ear (ciliated columnar)
Structure and make-up of auditory tube:
- Ant/post make up?
- Length
- Relationship b/t cartilage and bony portions
- Location of membranous portion
-Anterior 2/3: cartilaginous & Posterior 1/3: bony (osseous)
– ~36 mm long
– Cartilaginous & bony portions meet at narrow isthmus
• Bony portion of tube opens at base of skull • Only superior & Medial walls cartilaginous •
-Inferior & Lateral walls membranous
Tegman Tympani:
- relationship to tegman tympani
- serves as a “cover” for what?
- Formed by what bone (be specific)
superior border of middle ear cavity
Covers the epitympanic recess
Formed by thin plate of temporal bone
What is the Tympanic Sulcus?
bony ring that secures the lower 5/6 of tympanic membrane
Describe the Notch of Rivinus
Upper 1/6 of the tympanic membrane that is secured by ant/post malleolar folds
Relationship b/t oval window and ossicles
Receives the base of the stapes (acts as a kind of piston)
Another name for the oval window?
Fenstra Vestibuli
Describe the round window
membrane covered structure inferior to oval window on medial wall
Another name for the round window
Fenestra Chochlea
Name the 6 structures on the medial wall of the tympanic cavity
Promontory Fenstra vestibuli = oval window Fenestra Cochlea = round window Facial canal prominence – Lateral semicircular canal prominence Tendon of the tensor tympani m.
Name for the anterior wall of the tympanic cavity is ______?
Carotid Wall
What is/are the major landmarks (structures) in the carotid wall?
- Auditory Tube
2. Semicanal for tensor tympani
What is/are the major landmarks (structures) on the posterior wall of the middle ear?
- Pyramidal Eminence= hollow projection of bone
– Serves as origin of stapedius m. - Aditus ad antrum= entrance to tympanic antrum
– Leads to post./infr. into mastoid air cells
Describe the structure, location, action and innervation of the Tensor Tympani m.
Contained in bony semicanal – Superior to auditory tube
• Runs posterior thru canal& then bends laterally
• Inserts on to handle of malleus
• Tenses tympanic membrane by drawing it medially
• Innervated by CN V3
What makes the stapedius m unique in the body?
Smallest striated skeletal muscle in the body (~1mm)
Describe the origin, insertion, action, and innervation of the stapedius m.
Arises from cavity inside pyramidal eminence
• Inserts into neck of stapes
• Pulls head of stapes posteriorly
• Innervated by CN VII
What is the pathway of the Chorda Tympani
Branches in facial canal
Enters ear cavity through posterior iter chordae- crosses m. tympanic membrane
Passes between handle of malleus & incus
Exits thru anterior iter chordae –> tongue
Describe the Autonomic innervation of the ear
Tympanic plexus- covers promontory
Tympanic nerve (branch of CN IX (p-symp))
Cartoticotympanic nn (symp from carotid plexus)
Supplies mucosal lining of promontory, mastoid air cells and auditory tube
What ate the branches of CN VII that can be found in the ear?
- Chorda Tympani
2. Greater petrosal n.
What is the pathway of the lesser petrosal n.?
IX –> tympanic nerve –> tympanic plexus –> lesser petrosal –> carries p-symp fibers –> exits via hiatus of l. petrosal (now in middle cranial) –> out thru ovale –> otic ganglion (synapse) –> postganglionic fibers to parotid gland
What is the parasympathetic and sensory innervation to the middle ear?
Tympanic nerve (Jacobson) of CN IX
What is the function of the auricle?
Directs sound to the external acoustic meatus
What is the function f the External Acoustic Meatus?
Directs sound to the tympanic membrane
What part of the external acoustic meatus is cartilaginous?
Distal 1/3
