ANATOMY - Ear Flashcards
What are the three main divisions of the ear?
External ear
Middle ear
Inner ear
What are the two components of the external ear?
Auricle (pinna)
External acoustic meatus
What is the function of the superficial auricularis muscles of the auricle?
Superficial auricularis muscles allow the auricle to be orientated towards and localise sound
What is the name of the cartilage which makes up the auricle?
Auricular cartilage
What anchors the auricular cartilage of the auricle to the base of the skull?
Annular cartilage
What is the tragus?
Tragus is the point where the auricular cartilage meets to form a cone at the base of the auricle
On which side of of the auricle do the blood vessels run?
External surface of the auricle
What are the borders of the external acoustic meatus?
Tragus to the tympanic membrane
Which two gland types are found within the skin lining the external acoustic meatus?
Sebaceous glands
Tubular ceruminous glands
What is produced by tubular ceruminous glands?
Wax (cerum)
Which four structures are a part of the middle ear?
Tympanic membrane
Tympanic cavity
Auditory ossicles
Auditory tube
Which structure divides the external acoustic meatus from the middle ear?
Tympanic membrane
What lines the external surface of the tympanic membrane?
Epithelium
What lines the internal surface of the tympanic membrane?
Mucosa
Which skull bone is the tympanic cavity embedded in?
The tympanic cavity is embedded in the temporal bone
What are the dorsal and ventral divisions of the tympanic cavity?
Dorsal: Epitympanic recess
Ventral: Tympanic bulla
(T/F) The tympanic bulla consists of fluid in a healthy animal
FALSE. The tympanic bulla consists of air in a healthy animal
What are the three auditory ossicles?
Malleus
Incus
Stapes
Which auditory ossicle is attached to the medial surface of the tympanic membrane?
Malleus
What are the two muscles associated with the auditory ossicles?
Tensor tympani
Stapedius
What is the function of the muscles associated with the auditory ossicles?
Contraction of the tensor tympani and stapedius muscles reduces the ability of the ossicles to vibrate and thus reduces the amplitude of sound waves
What are the two functions of the auditory tube?
Drains fluid secreted by the tympanic membrane into the nasopharynx
Equalises air pressure in the middle ear
How does the auditory tube equalise pressure in the middle ear?
The auditory tube connects the middle ear to the nasopharynx and is usually collapsed but during swallowing and yawning, the tube is opened to small amounts or air, allowing for the equalisation if air pressure between the environment and the middle ear
What is the outpouching of the auditory tube seen in horses?
Guttural pouch
What are the dorsal and ventral openings of the middle ear into the inner ear?
Dorsal: Vestibular window (oval window)
Ventral: Cochlear window (round window)
Which skull bone completely encloses the inner ear?
Petrous temporal bone
What are the two labyrinths found in the inner ear?
Osseous labyrinth
Membranous labyrinth
What fluid is found between the osseous and membranous labyrinth?
Perilymph
What fluid is found within the membranous labyrinth?
Endolymph
What are the two central cavities of the membranous labyrinth?
Utriculus
Sacculus
Which three ducts extend from the utriculus in the membranous labyrinth?
Anterior semicircular duct
Posterior semicircular duct
Lateral semicircular duct
What is the name of the enlargements at the base of the semicircular ducts?
Ampullae
Which duct extends from the sacculus in the membranous labyrinth?
Cochlear duct
What is the central chamber of the osseous labyrinth which contains the utriculus and sacculus?
Vestibule
Which structures of the osseous labyrinth contain the semicircular ducts?
Semicircular canals
Which structure of the osseous labyrinth contains the cochlear duct?
Cochlea
What is the central, conical shaped structure in the cochlea?
Modiolus
Which structure projects from the modiolus of the cochlea?
Spiral lamina
What are the three fluid-filled channels within the cochlea?
Scala vestibuli
Cochlear duct
Scala tympani
Which structure separates the scala vestibuli from the cochlear duct?
Vestibular membrane
Which structure is located within the cochlear duct?
Organ of corti
Which structure separates the cochlear duct from the scala tympani ?
Basilar membrane
Which artery supplies the external ear?
Caudal auricular artery
Which artery supplies the middle and internal ear?
Occipital artery
Which artery do the caudal auricular artery and the occipital artery branch from?
External carotid artery
Which vein does the external ear drain into?
Maxillary vein
What is an aural haematoma?
A blood filled swelling within the auricle
What is the main cranial nerve which innervates the ear?
Cranial nerve VIII (vestibulocochlear nerve)
Which nerve innervates the tensor tympani muscle?
Mandibular nerve (branch of CNV)
Which nerve innervates the stapedius muscle?
Cranial nerve VII (facial nerve)
What is otitis?
Inflammation of the ear
What are three methods that can be used to image the ear?
Radiography
Advanced imaging
Otoscope