Lecture 20: Hearing And Equilibrium Flashcards
According to the Langdon table, what is characteristic of the auditory system in early tetrapods?
Inner ear sensitive to sound vibrations
-stapes involved in palatal, spiracular manipulations
(Spiracle=primitive opening into inner ear)
According to the Langdon table, what is characteristic of the auditory system in early therapsids?
Articular, quadrate, and stapes bones involved in conduction
According to the Langdon table, what is characteristic of the auditory system in the primitive mammals?
Dentary-squamosal joint established
Articular and quadrate bones specialized for transmitting vibrations
What is the transition from the quadrate-articular jointed jaw to a dentary-squamosal joint and what happens to the quadrate and articular bone?
Quadrate-articular–> quadrate-articular + dentary-squamosal–> dentary-squamosal
Quadrate and articular bones become reduced and eventually evolve into the incus and malleus
According to the Langdon table, what is characteristic of the auditory system in the advanced mammals?
- quadrate becomes incus**
- articular becomes malleus **
- angular becomes tympanic bone**
- middle ear sealed off behind tympanic membrane
- development of pinna (outer ear feature)
- sound localization
- sensitivity to high frequency
**=bolded on slide
What is another name for the tympanic bulla (bone)?
Auditory bulla
Where is the tympanic bulla found and what is it formed by?
Feature of squamosal bone; formed by tympanic part of temporal bone that houses the tympanic ring (bone)(angular)
In primates, what is the auditory bulla formed by?
Petrosal bone (Petrous part of temporal bone)
What ear ossicles develop from arch 1?
Malleus and incus
What ear ossicle develops form arch 2?
Stapes
Where is the tympanic/ectotympanic ring (angular) found in mammals and specifically in primates?
Position varies among mammals
In primates, may be within or outside the auditory bulla
Where does the tympanic/ectotympanic ring (angular) lie in lemurs?
Within auditory bulla cavity
Where does the tympanic/ectotympanic ring (angular) lie in lorises?
Attached to inside wall of bulla cavity
Where does the tympanic/ectotympanic ring (angular) lie in new world platyrrhines?
Attached outside wall of bulla
Where does the tympanic/ectotympanic ring (angular) lie in old wold catarrhines and tarsiers?
It is attached to outside wall of bulla but forms a bony ring (auditory tube=external auditory meatus)
What do the dryolestes, an early Jurassic mammal, show in their cochlea
Shows beginnings of modern therian mammal inner ear anatomy
According to the Langdon table, what is characteristic of the auditory system in humans?
- Specialized for hearing frequencies of human voice
- specializations for pitch, volume, direction, and language discrimination
- Broca’s area
- wernicke’s area
Where is the membranous labyrinth located?
In the petrous part of temporal bone
What is the pathway for the auditory system?
Primary auditory cortex–>wernickes area–> Broca’s area–> motor area
What enters through the internal acoustic meatus?
Vestibulaocochlear nerve and facial nerve
What is the function of the external ear?
Captures and funnels acoustic signals through the tympanic membrane to the middle ear
What does the middle ear contain and what is the function?
Contains a complex of small bones that then transmit sound vibrations to the inner ear where the organs of hearing and equilibrium are found
What is typically found in the inner ear?
Organs of hearing and equilibrium is found
Where is the middle ear found?
Found within the petrous part of temporal bone behind the tympanic membrane (ear drum)
