Ear Flashcards
(132 cards)
What is the sensory supply to the pinna?
Upper lateral surface - CN V3 auriculotemporal
Lower lateral/medial - C3 - greater auricular
Superior medial - C2/C3 lesser occipital nerve
External auditory meatus - auricular branch of vagus
So can perform regional nerve blocks
What is the anatomy of the external ear?
Auricle/pinna and external acoustic meatus
Lateral third of external acoustic meatus is cartilage, medial two thirds are bony from temporal bone
Contains keratinised squamous epithelium
What is the vascular supply to the auricle?
External carotid artery, superficial temporal, occipital
What is the innervation of the external acoustic meatus?
Auriculotemporal nerve branch of trigeminal
Auricular nerve - branch of vagus CN X
What is the tympanic membrane?
Middle layer of connective tissue
Oblique angle to maximise sound localisation
At centre - umbo attaches to handle of malleus
Transmits sound waves from external ear to ossicles of the middle ear
What is the innervation of the middle ear?
Vagus nerve and glossopharyngeal nerve
What is the anatomy of the middle ear?
Auditory ossicles - malleus, incus, stapes form oval window and transmit and amplify sound vibrations
Tensor tympani, stapedius muscles
What is the function of the Eustachian tube?
Aerates the middle ear to equalise pressure
For optimum movement of the tympanic membrane
What is the anatomy of the inner ear?
Vestibulocochlear organs, receives sound waves to convert into electrical signals
Bony labyrinth - vestibule, three semi circular canals and the cochlea. Vestibule contains saccule and utricle to detect linear motion.
Semicircular canals - rotatory movements
Cochlear contains organ of corti containing epithelial cells converting sound waves to electrical impulses
What is ear trauma commonly related to?
Sports injuries
Violence
How severe is ear trauma normally?
Normally uncomplicated and treatable under local anaesthetic
How should a laceration with exposed cartilage be managed?
Cover any exposed cartilage with skin
What may be done if there is skin loss or a skin laceration can’t be closed by primary closure?
Plastic reconstructive surgery
What is the main risks with bites to the ear?
Infection from skin commensal or oral commensal of offending creature/person
Staph epidermis and S hominid are most prevalent coagulase negative commensals
How would you manage a patient with an ear bite?
Take a good history - work out likely organism
Leave wound open
Irrigate wound thoroughly
Antibiotics
Why are pinna haematoma’s dangerous?
Disrupt blood supply to cartilage as it normally obtains nutrients via diffusion from vessels in the perichondrium.
Can lead to avascular necrosis
What is cauliflower ear?
Cartilage undergoes avascular necrosis which stimulates the formation of new cartilage but it grows asymmetrically
What can cause a tympanic membrane perforation?
Blunt force - trauma to side of head
Penetrating trauma - e.g. cotton bud
Otitis media
Barotrauma - explosion/scuba diving
How does a tympanic membrane perforation present?
Pain
Conductive hearing loss (possibly)
Can get tinnitus and serosanguineous discharge
How can tympanic membrane perforation be managed?
Most heal within 8 weeks- monitoring
Antibiotics if contamination
Keep clean and cry
Not healing after 6 months or hearing loss/recurrent infection - myringoplasty
What can cause haemotympanum?
Basal skull fracture - most common
Nasal packing
Bleeding disorders/anticoagulants
Recurrent ear infections
How does haemotympanum present?
Seen through tympanic membrane
Associated with conductive hearing loss
Sense of fullness in ear
Pain
How is haemotympanum managed?
Treat conservatively but follow up to ensure no residual hearing loss
However commonly associated with other issues - head trauma
What is otitis externa and causes?
Inflammation of the skin of the external ear canal
Acute - less than three weeks, chronic >3
Swimmer’s ear - water causes inflammation in ear
Bacterial infection, fungal, eczema, seborrhoeic dermatitis, contact dermatitis