ENT Anatomy Flashcards
(29 cards)
External Ear:
What type of cartilage is present?
Elastic Cartilage
External Ear:
Innervation
- Greater auricular nerve
(branch of cervical plexus) - Lesser occipital nerve
(branch of cervical plexus) - Auriculotemporal nerve
(branch of mandibular nerve) - branches of Facial and Vagus nerve
External Ear:
Lymphatic drainage
Lateral surface of the superior half of the auricle drains to the:
- Superficial Parotid Lymph nodes
Cranial surface of the superior half of the auricle drains to the:
- Mastoid Lymph nodes
- Deep Cervical Lymph nodes
Remainder of the auricle, including the lobule, drains into:
- Superficial Cervical Lymph nodes
External Acoustic Meatus:
Name 4 features that help protect the auditory canal
Hair
Cerumen
Curvature and Shape
Tightness of skin
Which direction should you pull the auricle if examining the ear with an otoscope in an adult vs. child?
Adults:
- pull auricle gently upward and backward
Children:
- downward and backward
Middle Ear:
What foramen leads to middle cavity from the cranial cavity?
Internal Acoustic Meatus
Middle Ear:
Which bone is the Internal Acoustic Meatus foramen in?
Petrous part of the Temporal bone
Middle Ear:
Which nerves pass through the Internal Acoustic Meatus foramen?
Facial (VII)
Vestibulocochlear (VIII)
Middle Ear:
Where is the Facial nerve travelling to and what does it innervate?
- closely associated with the Vestibulocochlear nerve in the Internal Acoustic Meatus
- after exiting IAM, the facial nerve continues its course through the Facial canal within the Temporal bone
- eventually exiting the Skull via the Stylomastoid foramen
- innervates muscles of facial expression and carries taste sensation from anterior 2/3s of the tongue
Middle Ear:
What is the Vestibulocochlear nerve responsible for?
Where is the nerve travelling to and what does it innervate?
- responsible for transmitting sensory information related to balance (vestibular) and hearing (cochlear)
- after exiting IAM, the Vestibulocochlear nerve splits into 2 branches
- Vestibular nerve innervates the vestibular apparatus (in the inner ear)
- Cochlear nerve innervates the cochlea (organ of hearing)
Tympanic Membrane:
What are the identifying features that can help orientate the image?
- Malleolar folds are superior
- umbo is inferior
Tympanic Membrane:
Name 5 features of Otitis Media (glue ear)
- opaque/cloudy appearance
- tympanic membrane may bulge outward
- presence of fluid behind membrane can restrict its movement, leading to reduced mobility or immobility
- fluid may be visible
- yellowish/amber colour
Tympanic Membrane:
Where is the safest to make incisions in the Tympanic membrane?
Either:
- anteroinferior quadrant
Or
- posteroinferior quadrant
Ossicles:
Function
Play a crucial role in the:
transmission, amplification, and protection of sound signals
(as the signals travel from the external environment to the inner ear, where they are processed and interpreted as auditory sensations)
Ossicles:
Which 2 small muscles attach to the ossicles?
Tensor Tympani
Strapedius Muscle
Middle Ear:
Attachment, Origin, Innervation, Role of Tensor Tympani
- attaches to the handle of the malleus (ossicle)
- originates from wall of the auditory tube and inserts onto malleus
- innervated by Trigeminal nerve V
- plays a role in dampening loud sounds by tensing the TM
Middle Ear:
Attachment, Origin, Innervation, Role of Strapedius Muscle
- muscle attaches to the stapes
- originates from the posterior wall of the middle ear cavity and inserts onto the neck of the stapes
- innervated by Facial nerve VII
- plays a role in reducing the amplitude of sound transmission to protect the inner ear from loud sounds
Middle Ear:
Walls of the middle ear (6)
- Lateral wall = tympanic membrane
- Medial wall = round and oval window (lateral wall of inner ear)
- Superior wall = tegmen tympani
- Inferior wall = jugular bulb
- Posterior wall = mastoid process of temporal bone
- Anterior wall = carotid canal
Middle Ear:
Contents of the middle ear (6)
- 3 auditory ossicles = malleus, incus and stapes
- tympanic cavity (the air-filled space itself)
- chorda tympani nerve
- tensor tympani muscle
- strapedius muscle
- opening of the auditory tube (Eustachian tube)
Middle Ear:
Discuss the passage of the chord tympani nerve (5)
Origin - chorda tympani nerve starts from the Facial nerve VII within the temporal bone
Middle Ear Passage - it travels through middle ear, running between the incus and malleus bones
Exit - it exits the middle ear through the Petrotympanic fissure
Joining - it merges with the Lingual nerve in the Infratemporal fossa
Tongue sensation - together, carry taste sensations from the anterior 2/3s of the tongue
Middle Ear:
What is the Chorda Tympani a branch of?
Facial nerve VII
Middle Ear:
What does the Chorda Tympani innervate?
Sensory = taste from anterior 2/3s of the tongue
Parasympathetic = innervates sublingual and submandibular glands
Discuss the process of Sound Conduction (12)
1) sound wave enters the EAM
2) wave strikes the TM = moving it medially
3) Handle of the Malleus is attached to this membrane = also moves medially
4) this moves the Head of the Malleus laterally
5) Heads of the Malleus and Incus articulate = head of Incus is moved laterally
6) this pushes the long process of the incus medially
7) the long process articulates with stapes = stapes moves medially; oval window moves medially
8) this action converts large-amplitude, low force, airborne wave that vibrates the TM into a small-amplitude, high force vibration of the oval window = which generates a wave in the fluid-filled Scala Vestibuli of the cochlea
9) wave in perilymph of the Scala Vestibuli moves through the cochlea = outward bulging of the Secondary tympanic membrane covering the round window
10) causes Basilar membrane to vibrate
11) this causes stimulation of receptor cells in the spiral organ
12) the receptor cells send impulses back to the brain through the Cochlear part of the VIII nerve - where they are interpreted as sound
What are Paranasal Sinuses?
How many pairs are there?
Air-filled extensions of the nasal cavity
There are 4 paired sinuses - named accordingly to the bone in which they are located
