H&N week 11- Ear and Eye Flashcards
Label this diagram of the ear
Label this diagram of the middle ear.
Label this diagram of the inner ear.
Discuss the 3 parts of the ear
External ear gathers soundwaves
It is made of the aurcicle and the external aucoustic meatus.
Middle ear- magnifies the sound vibrations
This contains air and 3 ossciles (malleus, incus and stapes)
Inner ear- For hearing and balance.
This contains the semi-circular canals and cochlea
Where is the chordae tympani found?
Inside the tympanic membrane.
Discuss the safety mechanisms of the external ear.
Hairs- to prevent bodies entering
Ceruminous glands- to produce wax.
What is otitis externa?
Inflammation of the skin lining.
Discuss the auricle
Function: gathers sound and sends it into the aucoustic meatus
Made of: A skeleton of elastic cartilage and lined with skin.
It is also known as the Pinna.
What is the external aucoustic meatus?
A bony canal running from the outer ear to the middle ear.
The outer part of the canal is made of cartilage and the inner part is made of bone.
What is the tympanic membrane
A thin membrane in the middle ear that is made of skin and collagen.
It sits under tension and vibrates when soundwaves come through.
What is the umbo?
The most concave part of the tympanic membrane.
How is the ear protected from loud sounds?
Tensor tympani muscle
- A tendon attached to the handle of the malleus
- it contracts to hold the malleus more steady, reducing vibrations
- Supplied by CN5
Stapedius muscle.
- It contracts and anchors the stapes to reduce movement
- Supplied by CN7
What is the tympanic cavity ?
Where you find the ossicles.
What is the Malleus?
A hammer shaped bone which attaches to the central part of the tympanic membrane.
What is the incus?
An anvil shaped bone which has a long process that articulates with the stapes
What is the stapes?
A bone that is shaped like a horse stirup (food rest) whcih fits into an inner window that seperates the middle and inner ear.
How does the stapes magnify sounds?
the tympanic membrane vibrates causing the food plate of the Stapes to move in and out.
This causes the movement of fluid.
How are sounds converted to electrical impulses?
the movement of fluid to the inner ear causes the movement of special receptor cells (hair cells with long cilia) and convert to electrical impulses.
What is chronic otitis?
A middle ear infection.
Sometimes the patient’s tympanic membrane can break down causing pus to go to the external ear.
What is glue ear?
When there is fluid in the middle ear (also known as chronic Otitis media with effusion.
Discuss the clinical relevance of a throat infection
The auditory tube allows infections to pass to the nose from the oral cavity.
This passage causes the lymphoid tissue around the aduitory tube to get bigger and block air getting into the middle ear.
This causes goblet cells to produce more mucous and prevents the ossicles from moving.
Therefore causing hearing problems.
What is the function of the cochlea?
this picks up electrical impulses.
Discuss the two windows of the middle ear:
Fenestra vestibuli-
An oval window that moves in and out, pushing on the fluid. This puts pressure on the water.
Fenestra Cochleae-
The round window which has a membrane in it.
As fluid moves into the inner ear, this membrane bulges to compensate.
Discuss the semi-circular canals
These are involved with movement of the head, balance and the position of the head within the space.
Label this diagram of the eye
Label this diagram of the disection of the orbit from above.
What is the cornea?
A transparent dome covering the iris.
Discuss the eyelashes
These arise from hair follicles along the outer edge of the eyelid.
The eye lashes are slightly curved to prevent them sticking together when you close your eye.
What is the clinical name for an infected eyelash follice?
A stye.
WHat is the sclera?
The white of the eye
What is the conjunctiva?
A mucous membrane which covers the white of the eye
What is an infection of the conjunctiva called?
Conjunctivitis.
What is the iris?
The coloured part of the eye that is partially covered by the upper eyelid.
Function- it is a diaphragm that controls the amount of light that enters the eye by regulating the pupil size.
Discuss the eye of a thryoid patient
They show opthalmopathy
- There is excessive fat deposition in the orbit which pushes the eye forward.
- The upper eyelid does not cross the upper iris
- You can see white all around the eye.
What is the pupil?
The opening into which the light enters the eye.
What is the lacrimal carnucle?
A fleshy papilla found in the medial corner of the eye.
What are the meibomian glands?
Glands found on the eyelid that produce oil secretions that keep the tears between the eyelid and the front of the eye (preventing tears spilling onto your face)
What is the lacrimal sac?
A mucosa lined sac which carries tears down from the orbit into the nasal cavity.
What is the lacrimal canaliculus?
The duct which takes the tears away.
This is lined by mucous membrane.
The tears are drawn into the duct by papillary action and fed into the lacrimal sac.
What is the lacrimal puncture?
The opening of the lacrimal duct which drains the tears away.
Discuss the lacrimal gland
This is found on the front part of the orbit (on the distal side)
This produces tears and has lot of little ducts that drain into the conjunctival sack
What is the conjunctival sack?
A recess between the front of the eye and the inside of the eyelid.
Discuss the lateral rectus muscle
This is supplied by the abducens muscle and moves the eye to the side.
What is the levator palpebral superiorous
This is a mixture of skeletal and smooth muscle that raises the upper eyelid.
Skeletal muscle is supplied by the oculomotor nerve
Smooth muscle is supplied by the sympathetic supply.
Discuss the superior oblique muscle
This comes from the roof of the orbit and is supplied by CN4 (trochlea nerve. )
It gives way to atendon which goes through the trochlea
Discuss the tendon of the superior oblique muscle
This changes direction after the trochlea, becomes thinner and stretches out to attach to the eyeball itself.
What is the trochlea?
This is a pully used to change the directon of the tendon of the superior oblique.
