12 Functional Anatomy of the Ear Flashcards
What are the parts of the external ear lined with?
Skin
What is the middle ear filled with?
Air (fluid in middle ear= pathological)
What is the middle ear lined with?
Respiratory epithelium
What structure allows for equilibration of pressure in middle ear (air filled cavity) and drainage of mucus from middle ear?
Pharyngotympanic tube ( Eustachian tube) connects middle ear to oropharynx
Fill in the missing labels:
Which nerves carry general sensation from the ear ( touch, temperature, pain)? (implications for referred pain)
Branches of:
- V- Trigeminal
- Auriculotemporal
- VII- Facial (small contribution)
- IX- Glossopharyngeal
- Tympanic
- X- Vagus
- Cervical spinal nerves
Explain why nerves carrying general sensory information has implications for referred pain.
Pain/sensation felt in ear even if no pathology in ear
Eg in pharyngitis- ear pain even through no pathology of ear
Otalgia with normal ear examination- think alternative site of pathology
Give some examples of non-otological origins of otalgia. (general)
What makes up the external ear and what is its function?
Pinna, external auditory meatus and lateral surface of tympanic membrane
Function: collects, transmits and focuses sound waves onto tympanic membrane
What is Ramsey Hunt syndrome?
Viral- varicella zoster
Patient with facial nerve palsey and evidence of rash on external ear (may need to look in canal)
Shingles of facial nerve
What pathology is shown in this image:
Perichondritis
=inflammation of cartilage in pinna
(can be due to infection from ear piercing)
Why is it so important to recognise a pinna haematoma and treat it apporopriately?
Pericondrium- supplies blood to cartilage underneath
Haematoma- cuts off blood supply and may cause pressure necrosis
Ear will scar and alter shape of cartilage (califlower ear)
Where does the blood accumulate in a pinna haematoma?
Between cartilage and overlying pericondrium
Pericondrium- supplies blood to cartilage underneath
How is a pinna haematoma treated?
Drainage
Prevent re-accumulation of blood
Describe the structure of the external acoustic meatus (lining, composition, shape)
Composition:
Cartilaginous (outer 1/3)
Bony (inner 2/3)
Shape:
Sigmoid
Lining:
Keratinising, stratified squamous epithelium
Cartilaginous part: hair, sebaceous and ceruminous glands (produce ear wax)
Explain the self-cleaning function of the external acoustic meatus: