Special Senses Flashcards
What nerve supplies general sensation to the anterior 2/3 of the tongue?
The Lingual nerve which is a sensory nerve that arises from the mandibular division of the trigeminal nerve (cranial nerve V)
What nerve supplies taste for the anterior 2/3 of the tongue?
The facial nerve. Specifically the branch called the chorda tympani.
What nerve supplies taste and sensation for the posterior 1/3 of the tongue?
The glossopharyngeal nerve.
What is the pathway of sound from beginning to end?
Sound enters through the pinna > funnels through the external acoustic meatus > vibrate the tympanic membrane > these vibrations pass through the ossicles > ossicles amplify the sound waves and focus the vibrations into the oval window > vibrates fibres on the basilar membrane > this triggers hairs on the Organ of Corti > creates an action potential that passes along the auditory pathway to the brain.
What are the 3 chambers of the cochlea?
The scala vestibuli, the scala media and the scala tympani.
What does the basilar membrane do?
When the ossicles send pressure waves through the inner fluid, sections of the basilar membrane vibrate back and forth (these are the fibres that recognise high and low pitch).
What pitch vibrates the shorter fibres at the base of the basilar membrane?
High pitch.
What pitch vibrates the longer fibres at the end of the basilar membrane?
Low pitch.
How do vibrations in fibres on the basilar membrane get transduced?
When these vibres fibrate, they trigger ‘hairs’ on the Organ of Corti which causes Na+ channels to open, this causes action potentials to form which are then passed from the Organ of Corti, along the cochlear nerve, up the auditory pathway, to the cerebral cortex.
How does the brain know the volume of the sound it has recieved?
As louder sounds move the hair cells more (moving the inner hair cells) and softer sounds move the hair cells less (just the outer hair cells).
What do the vestibular canals do?
Detect the different types of head rotation through hair cells (held within the utricle and saccule within each canal) and give the brain information on the acceleration of the head -
Where does sound energy come out of the cochlea?
The round window.
What is the olfactory pathway?
Olfactory receptor cells (in the olfactory epitheliium) recognise odorants > olfactory nervesmove through the foramina in the cribriform plate > information from receptor cells pass to the olfactory tract > olfactory cortex (cerebral cortex and amygdala)
