Ear Flashcards
Where does the frontal sinus drain?
via frontonasal duct into the semilunar hiatus of the middle meatus
Where does the ethmoid sinus drain
into the middle and superior meatus
Where does the sphenoidal sinus drain?
into the sphenoethmoidal recess
Where does the maxillary sinus drain?
it drains into the semilunar hiatus into the middle meatus
CN 5 V1
innervates lateral wall and anterior septum of the nose as well as parts of the sensation of the upper face
Choanae
opening at the back of the nasopharynx
muscle of the soft palate
tensor veli palatini
Muscles of the Middle Ear
- stapedius muscle
- tensor tympani muscle
Anatomy of the Tympanic Membrane
Describe the pathway of hearing sensation
- oval window vibrates the perilymph fluid in the inner ear which is then transferred to the endolymph fluid within the Organ of Corti within the cochlea which stimulates hair cells
- hair cells transmit sound information to the CNS via CN VIII
- CNS: CN VIII → medulla oblongata→inferior colliculus of midbrain → superior olives → thalamus → auditory cortex
Semicircular canals
- filled with endolymph
- respond to rotation of the head in 3 planes
- hair cells at the base of the semicircular canals are distorted when the head moves in the x, y, z planes
Vestibule
- made up utricle and saccule
- hair cells within the vestibule are pressed down by gravity, or if gravity /accelearation changes → hair cells become distorted
Vestibular pathway
- for balance and sensation of balance
- vestibular hair cells send signals via CN VIII (vestibulocochlear)
- received by pons and medulla oblongata → cerebellum and cerebral cortex
Nystagmus
- rapid, involuntary eye movement as a result of activation of the vestibular system (usually side to side)
CN V3
mandibular brach: motor control of the tensor tympani muscle
CN VII: Ear
somatic snesation of the external acoustic meatus, motor control of the stapedius muscle of the middle ear
CN VIII
hearing, vestibular sensation
CN IX: Ear
- somatic sensation of the external ear and middle ear
Risk factors of otitis Media
smoking
family hx of OM
bottle feeding
attending daycare
Bacteria associated with otitis externa and risk factors
- Bacterial:
- Pseudomonas aerugonisa, Proteus vulgaris, staph aureus, or E. coli
- Fungal:
- Aspergillus niger
- Candida albicans
- Risk factors:
- allergies
- psoriasis
- eczema
- seborrheic dermatitis
- decreased canal acidity (possibly due to repeated presence of water)
- irritants (e.g. hair spray/dye)
- **skin maceration that sets the stage for bacterial infection **
Non-syndromic Hearing Loss
- partial or total hearing loss that not associated with other s/sxs
- classifications:
- Autosomal Dominant (DFNA)
- Autosomal Recessive (DFNB)
- X-linked (DFNX)
- each has subtypes number in the order they were discovered
- Mostly sensorineural but can less commonly be conductive
- Mixed inner and middle ear hearing loss. = DFNX2
- called mixed hearing loss
Primary Immunodeficiencies in ENT
- s/sxs: recurrent ENT infections
- whether its viral, bacterail, or fungal depends on which genes are involved
- early onset PIDs often have mendelian inheritance patterns
- many are X-linked →occurring more commonly in boys
Syndromic Hearing Loss
- hearing loss in addition to other medical issues
- characterized by mode of inheritance:
- autosomal recessive (AR)
- autosomal dominant (AD), or x-linked
- 3 major syndromes:
- Usher syndrome: retinitis pigmentosa and senorineural hearing loss
- Pendred syndrome: abnormal iodine metabolism in addition to hearing loss
- Jervell and Lange-Nielsen syndrome: profound sensorineural hearing loss, cardiac arrhythmias caused by prolonged QT interval
Waardenurg Syndrome
- ***Most common form of autosomal dominant sensorineural hearing loss***
- 3% of childhood hearing loss
- bilateral or unilateral sensorineural hearing loss, pigment abnormalities, and defining features of the face
- white hair in front, differently colored irises (heterochromia irides), graying early, and vitiligo
- face features: widely spaced medial canthi, broad nasal root, and unibrow (synophrys)
- tx: cochlear implant
Vestibular Schwannoma and Neurofibromatosis 2
- benign tumors of the vestibularcochlear nerve (CNVIII)
- NF2 = changes in the NF2 gene
- regulations proteins production that functions as a tumor suppressor
- usually caused by spontaneous mutation of the NF2 gene
- otherwise inherited via autosomal dominant
- S/Sxs:
- problems with balance, tinnitys and gradual hearing loss
- people with NF2 have less cafe-au-lait spots on the skin than those who have NF1
- Tx: surgical removal if possible
- radiation therapy
- VEGF inhibitor bevacizumab (VERY EXPENSIVE)
Environmental Impacts on Hearing
- noise
- aging
- presbycusis
- ototoxic drugs
- aminoglycosides
- can synergistically act with noise to cause severe hearing problems
- aminoglycosides
- viral and bacterial infections
- Rubella (less so with vaccine and rhogam)
- Cytomegalovirus is most common cause of congenital deafness*****
- diet, stress, drugs, certain diseases and life styles
3 Major Syndromes associated with Autosomal Recessive inheritance
- Usher Syndrome:
- retinitis pigmentosa and sensorineural hearing loss
- Pendred Syndrome:
- abnormal iodine metablism with hearing loss
- Jervell and Lange-Nielsen Syndrome:
- profound hearing loss
- cardiac arrhythmias caused by prolonged QT intervals
Waardenburg Syndrome
- Autosomal dominant sensorineural hearing loss
- white forelock, heterochromia, premature graying, vitiligo
- unilateral sensorineural hearing loss
- tx: cochlear implant
Neurofibramatosis 2
- noncancerous tumors of the nerves vestibular cochlear nerves
- bilateral acoustic neuromas/vestibular schwannomas
- mutation of the NF2 gene → tumor suppresor gene
- less cafe au lait spots than in NF1
- Autosomal Dominant
- gradual hearing loss, tinnitus, balance problems
With the advent of vaccines what is the most common cause of congential deafness
- cytomegalovirus
