Somato - Vestibular Flashcards
External ear
Function for channeling sound waves to middle ear
Middle ear
Converting waves in air to waves in fluid
Inner ear
Converts mechanical stimuli into action potentials
Structures of middle ear - ossicles
Hammer - malleus
Anvil - incus
Stirrup - stapes
Nearby nerves of middle ear
Facial nerve (CN VII)
Sympathetic nerve to the eye
Inner ear function
Convert mechanical stimuli (vibration, acceleration, position relative to gravitational field) into neural signals
Parts of inner ear sensory
Cochlea - detection of sound
Semicircular canals - detection of angular acceleration
Otolith organs - detection of linear acceleration & position
Mechanoreceptors in inner ear
Shared cell type - hair cell, cilia moved by fluid or membrane to open or close channels = increased or decreased rates of action
CN of inner ear
Cochlear and vestibular nerves rolled into one
Vestibulocochlear VIII
Structure layers of middle ear
Petrous temporal bone
Periosteum
Perilymph
Endolymph
Sensory epithelium
Vestibule
Divided into two parts
Utricle
Saccule
Apical sterocilia
Movement of cilia = hyperpolarization or depolarization
Release neurotransmitters which binds to sensory neurons
Mammal hair cells do not regenerate
Transduction
Depolarization of hair cell
Release of neurotransmitter (glutamate)
Binds to receptors on sensory neuron
If depolarization is sufficient, action potential fires
Tip link
Thin band of protein, that binds tips of sterocilia together so they move in flow
Occurrence when short cilia move towards tall
Occurrence when tall cilia move towards short
What causes the depolarization in hair cells
Potassium (cation)
Spiral ganglion
Located at center of cochlea
Bipolar neurons received signals for hair cells
Project to brainstem via cochlear nerve
Synapse on neurons in cochlear nuclei
Pathway of spiral ganglion
5 neurons
Bipolar from hair cells to vestibular nuclei
Second order from vestibular nuclei to inferior colliculus
Third order from inferior colliculus to thalamus
Forth order from thalamus to auditory cortex
Hair cell damage
Breakage of length
Damage to sterocilia
Damage to synapse
High frequency hair cells get lost first
Semi circular canals
3 fluid filled canals
Oriented at right angels
Detect angular acceleration
Each has dilation called the ampulla
Anterior semicircular canal
Detects pitch or the nodding up and down motion of the head
Lateral semicircular canal
Detects “yaw” motion or shaking your head no/side to side
Posterior semicircular canal
Detects roll motion, tipping head side to side
