Anatomy - Clinical Anatomy of the Ear Flashcards
What is the thinnest part of the skull?
Pterion
Why is a fracture at the pterion very dangerous?
The middle meningeal artery is located behind it
Trauma to this artery can cause an epidural haematoma
The temporal bone is comprised of which two parts?
Squamous and petrous
The zygomatic process is associated with which bone?
Temporal
Which bones form the anterior cranial fossa?
- Frontal
- Ethmoid
- Sphenoid
Which bones form the middle cranial fossa?
- Sphenoid
- Temporal
Which bones form the posterior cranial fossa?
- Temporal
- Occipital
Which cranial nerve(s) enter the cranial cavity via the anterior cranial fossa?
Olfactory nerve
(via cribriform plate of the ethmoid bone)
Which cranial nerves enter the cranial cavity in the middle cranial fossa?
- CN II
- CN III
- CN IV
- CN V (V1, V2 and V3)
- CN VI
CN VII enters the cranial cavity via which orifice?
Internal acoustic meatus
(in posterior cranial fossa)
CN V2 enters the cranial cavity via which orifice?
Foramen rotundum
Which cranial nerve(s) enter the cranial cavity via the superior orbital fissure?
- CN III
- CN IV
- CN V1
- CN VI
CN V3 enters the cranial cavity via which orifice?
Foramen ovale
Which cranial nerves enter the cranial cavity in the posterior cranial fossa?
- CN VII
- CN VIII
- CN IX
- CN X
- CN XI
- CN XII
Which cranial nerve(s) enter the cranial cavity via the internal acoustic meatus?
- CN VII
- CN VIII
Which cranial nerve(s) enter the cranial cavity via the jugular foramen?
- CN IX
- CN X
- CN XI
Which cranial nerve(s) enter the cranial cavity via the hypoglossal foramen?
CN XII
By which term is the eardrum referred to?
Tympanic membrane
Which areas can lymphatics from the ear drain firstly based on their location in the auricle?
- Lateral surface of superior half - Parotid lymph nodes
- Cranial surface of superior half - Mastoid lymph nodes and deep cervical
- Rest of auricle and lobe - Superficial cervical lymph nodes
All lymphatic drainage from the auricle will eventually follow which path?
- Deep cervical lymph nodes
- Thoracic duct or right lymphatic duct
- Venous angle
What is the name given to the thinnest aspect of the tympanic membrane?
Pars flaccida
What is the name given to the thickest part of the tympanic membrane?
Pars tensa
What is the name given to the most inwardly depressed area of the tympanic membrane?
Umbo
What supplies general sensory supply to the external surface of the tympanic membrane?
CN V3
What supplies general sensory supply to the internal surface of the tympanic membrane?
CN IX
What are the bones which can be found in the middle ear?
- Malleus
- Incus
- Stapes
What creates the umbo?
Handle of malleus ataches at this point pulling in the tympanic membrane
What is the name of the opening to the internal ear?
Oval window
Why can tonsillitis or pharyngitis minic ear ache?
They have a shared sensory supply (CN IX)
This is referred pain
What connects the middle ear cavity to the nasopharynx?
Eustachian tube
What is the function of the Eustachian tube?
Equalise pressure in the nasal and middle ear cavities
Why may mastoiditis occur during a middle ear infection?
The mastoid process is a (posterior) boundary to the middle ear cavity
Infection can easily spread
How does CN VII connect to the CNS?
Brainstem at junction between pos and medulla
What is the intracranial part of the course of CN VII?
Passes directly into internal acoustic meatus in posterior cranial fossa
What is the temporal bone course of CN VII?
Through internal acoustic meatus
Enters stylomastoid foramen
How can CN VII act on the stapedius?
Reduces stapes movement to protect the inner ear from excessive noise
Which branch comes off of CN VII in the middle ear cavity?
Chorda tympani
What does the chorda tympani supply?
- Taste buds of anterior 2/3rd of tongue
- Parasympathetic supply to submandibular and sublingual glands
When CN VII travels within the petrous aspect of the temporal bone, which canal does it lie within?
Facial
The vestibulocochlear nerve is in which two parts?
- Cochlear nerve - hearing
- Vestibular nerve - balance
The otic capsule will lie within which bone?
Temporal
What does the otic capsule contain?
Bony labyrinth
(fluid (perilymph) filled spaces inside the otic capsule)
What 3 things are suspended within the perilymph of the bony labyrinth?
- Membranous labyrinth
- Communicating sacs and ducts
- Endolymph fluid
How many turns is there in the cochlea?
2.5
What is the apex of the cochlear spiral called?
Cupula
How many canals can be found in the otic capsule?
3
(anterior, lateral, posterior)
Action potentials from the semicircular ducts in the otic capsule will be conducted to the brainstem via which nerve?
Vestibular
At which point do CN VII and CN VIII connect with the brainstem?
Junction between the pons and medulla oblongata
Which structure can prevent dislocation at the TMJ?
Zycomatic process of the temporal bone
Which canal transmits taste fibres to the anterior 2/3rd of the tongue
Facial canal
What innervates the palatine tonsils?
CN IX
What is the sensory innervation of the Eustachian tube?
CN IX
Which 4 structures pass through the jugular foramen?
- Jugular vein
- CN IX
- CN X
- CN XI
Where can the opening of the internal acoustic meatus be found?
Posterior cranial fossa
A Le Fort type 1 fracture is most likely to damage what?
Nasolacrimal duct
What is the smallest muscle in the body?
Stapedius
