Ears Flashcards
What bone is the external acoustic meatus in?
Squamous part of temporal bone
What bone is the internal acoustic meatus in?
Petrous part of the temporal bone
What are the primordial origins of the temporal bone?
Mesoderm from first two branchial arches, occipital somites
What parts of the temporal bone form via intramembranous ossification?
Squamous and tympanic parts (from first pharyngeal arch)
How are the malleus and incus formed?
Endochondrally from first branchial arch cartilage
How are the stapes and styloid process formed?
Endochondrally from second branchial arch cartilage
How are the petrous temporal and mastoid processes formed?
Endochondrally from occipital somite cartilage
What is A?
Squamous part of temporal bone
What is B?
Articular eminence
What is C?
Mandibular fossa
What is D?
Zygomatic process
What is E?
Styloid process of the temporal bone
What is F?
Tympanic plate
What is G?
External auditory meatus
What is H?
Mastoid process of temporal bone
What is A?
External auditory meatus
What is B?
Tympanic membrane
What is C?
Middle ear cavity
What is D?
Auditory tube
What is E?
Cochlea
What is G?
Semicircular canal
What is H?
Ear ossicles
What primordia develops into the skin of the external auditory meatus and outer surface of tympanic membrane?
Ectoderm of the first branchial groove
What primordia gives rise to the cartilages of the auricle?
Condensations of pharyngeal arch 1 & 2 mesenchyme
What primordia gives rise to the auditory tube, middle ear cavity, aditus, mastoid antrum, mastoid air cells, and inner surface of tympanic membrane?
Endoderm of first pharyngeal pouch
What primordia gives rise to the cochlea and vestibular apparatus (semicircular canals) of the inner ear?
Ectoderm of the otic placode/otocyst
What are the parts of the ear drum?
Main part = pars tensa
Upper part = pars flaccida (more mobile)
What are the main features of the eardrum?
Handle of malleus
Umbo (central depression in the ear drum)
What is the function of the cochlea?
Hearing
What is the function of the semicircular canals?
Balance, equilibrium, and rotational motion
What is the sound wave conduction sequence?
Tympanic membrane –> malleus –> incus –> stapes –> oval window –> scala vestibuli perilymph –> cochlear endolymph fluid –> tectorial membrane in cochlear duct –> shearing forces on hair cell stereocilia –> cochlear nerve stimulation
What muscles dampen ossicle vibrations? What is their innervation?
Stapedius (facial nerve) and tensor tympani (trigeminal nerve)
How are hair cells in the utricle and saccule stimulated?
By calcium carbonate otoliths that exert force on hair cells by gravity or linear acceleration of the head in any direction
What is A?
Tensor Tympani
What is B?
Tegmen Tympani
What is C?
Malleus
What is D?
Incus
What is E?
To mastoid air cells
What is F?
Stapes
What is G?
Tympanic membrane
What is H?
Auditory tube
What is I?
Internal carotid artery
What is J?
Jugular bulb
What is K?
Facial nerve and chorda tympani
What is L?
Lesser petrosal nerve