Anatomy - ENT Flashcards
What is the function of the ear canal/external auditory meatus?
Receives sound and transmits it medially towards the tympanic membrane
What is the function of the auricle?
Localises sound in different positions in space
Which nerve innervates the posterioinferior aspect of the outer ear?
Vagus
Which nerve innervates the anteriosuperior aspect of the outer ear?
Branch of V3
What portion of the external acoustic meatus is cartilagenous?
Lateral 1/3
What portion of the external acoustic meatus is bony?
Medial 2/3
What quadrant is the cone of light normally seen?
Antero-inferior quadrant
What are the margins of the middle ear?
Tympanic membrane to petrous part of temporal bone
What is the space above the tympanic membrane called?
Epitympanic recess
What does the epitympanic recess communicate with?
mastoid air cells
What is the function of the auditory/Eustachian tube?
Allows equilisation of pressure between the middle ear and the atmosphere
What structures does the auditory tube communicate with?
Middle ear communicates with auditory tube which connects to nasopharynx
In what direction does the auditory tube project?
anteroinferiorly to the nasopharynx
What is the clinical significance of a more horizontal auditory tube in infants?
Because auditory tube connects to the nasopharynx, bacteria from the nasopharynx can easily enter the middle ear. Since the auditory tube is more horizontal, it is more difficult for the bacteria to drain back into the nasal cavity
What is the clinical significance of inflammation in the middle ear?
Inflammation in the middle ear will impact the ossicles which transmit sound vibration and may impair hearing
Why can pain in the outer ear cause referred pain to the lower teeth?
The lower teeth are innervated by a branch of V3 and a portion of the outer ear is innervated by another branch of V3
What is the clinical significance of pressure build-up in the middle ear?
The pressure build-up may push the tympanic membrane out and therefore change the shape and concavity of the tympanic membrane. As a result, the cone of light will move to another quadrant
What are the 3 ossicles?
From lateral to medial:
Malleus
Incus
Stapes
Which ossicle attaches to the tympanic membrane?
Handle of the malleus
What is a protective mechanism to loud sounds?
Reflex contraction of the muscles which attach to the ossicles
Which muscle attaches to stapes and what is its innervation?
Stapedius innervated by CN VII (seventh for stapedius)
Which muscle attaches to malleus and what is its innervation?
Tensor tympani innervated by CN V (T for tensor and trigeminal)
What is the clinical significance of an acoustic neuroma situated near CN VII and VIII within the internal acoustic meatus?
The neuroma may compress CN VII causing inactivation of VII
As a result, the efferent arch of the reflex muscle contraction in the middle ear is obliterated.
Loud sounds may no longer be dampened and the hair cells within the inner ear may consequently be damaged by excessive energy transmission
What is the function of the round window?
It is an opening from the inner ear which allows the energy transmitted into the inner ear to be released back into the middle ear
Which nerve carries parasympathetic fibres to salivary glands and carries sensory info about taste from the tongue to the CNS?
Chorda tympani (branch of facial nerve)
What does chorda tympani transmit?
Carries parasympathetic fibres to salivary glands
Carries sensory info about taste from tongue to CNS
What is the promontory?
A bulge in the medial wall of the middle ear created by the basal turn of the cochlea
Where does the oval window lie in relation to the promontory?
Oval window is superior and posterior to the promontory
Where is the round window in relation so the promontory?
The round window is inferior and posterior to the promontory
Which vessel is close to the middle ear?
Internal carotid artery runs underneath the middle ear
What is the function of the bony labyrinth?
It transmits mechanical energy from vibration into the inner ear
Where are the sensory receptors for dynamic equilibrium (directional head movement) located?
Within the ampulla
What is the membranous labyrinth?
It is a closed sac filled with endolymph
Where are the sensory receptors for hearing located?
Within cochlear duct
Where are sensory receptors for static equilibrium (head position) located?
Within the utricle
Which bones form the bridge of the nose?
Nasal bones
What structures do the nasal bones articulate with?
Frontal bone and frontal process of maxilla
Which cartilage forms most of the boundaries of the nostril?
Alar cartilage
What is the function of the posterior nares?
Allows communication between the nasal cavity and other airways
Which structures complete the nasal septum?
Vomer, ethmoid bone and septal cartilage
Which structure allows communication between nasal cavity and other airways?
Posterior nares
What are possible consequences of a nose break involving the ethmoid bone?
- Bacteria from nasal cavity can spread to the meninges
- Blood may extend into the meninges and possibly involve the subarachnoid space
- Rhinorrhea
What are features of the medial wall of the nasal cavity?
-Olfactory area constitutes the top third of the cavity: contains
olfactory epithelium and primary afferent neurons
-Respiratory area constitutes pseudostratified columnar epithelium
-Lined by highly vascular mucous membrane
-Vestibule lined by skin and hair
What is the function of highly vascular mucous membranes in the nasal cavity?
- warms and humidifies air to prevent smooth muscle spasms
- mucous production
- lines most of nasal cavity except vestibule
What are features of the lateral wall of the nasal cavity?
- Turbinate bones (superior, middle and inferior concha)
- Vestibule
- Lined by highly vascular mucous membrane
What is the function of turbinate bones?
Produce turbulent air in order to increase air exposure to vascular mucosa
Which sinuses are innervated by V1 of trigeminal?
Frontal
Ethmoid
Sphenoid
Which sinus is innervated by V2 of trigeminal?
Maxillary
Which duct opens into the inferior meatus?
Nasolacrimal duct
What is the blood supply to the superior aspects of both lateral and nasal walls of nasal cavity?
Anterior an posterior ethmoidal arteries
What is the blood supply to the posterior aspect of both lateral and nasal walls of the nasal cavity?
Sphenopalatine artery
What is the blood supply to the inferior aspect of both the lateral and nasal walls of the nasal cavity?
Great palatine artery
What is the blood supply to the anterior aspect of both the lateral and nasal walls of the nasal cavity?
Lateral wall - facial artery
Nasal wall - labial artery
What is the nerve supply to the anterosuperior half of the nasal cavity?
V1 of trigeminal - nasociliary nerve
What is the nerve supply to the posteroinferior half of the nasal cavity?
V2 of trigeminal - greater and lesser palatine nerves
What are the boundaries of the pharynx?
Base of skull to C6/lower border of cricoid cartilage
What is the role of the constrictor muscles in the pharynx?
Contraction encourages bolus of food down into oesophagus
Create a sling to close off the nasal cavity, oral cavity and larynx during swallowing
What are the boundaries of the nasopharynx?
- Sphenoid bone superiorly
- Superior constrictor muscle posteriorly
- Soft palate and uvula inferiorly
Where are the pharyngeal tonsils (adenoids)?
Just deep to the mucosa at the roof of the nasopharynx
Which muscle opens the auditory tube when contracted?
Salpingopharyngeus
Which bones form the hard palate?
Maxilla and palatine bone
Which structures make up the roof of the mouth?
- Alveolar arch
- Hard palate
- Soft palate
- Uvula
Which bones form the floor of the mouth?
Mandible and hyoid bone
What muscles attach mandible to hyoid bone?
- Digastic
- Mylohoid
- Geniohyoid
What are the divisions of the tongue and what delineates these divisions?
Anterior 2/3 and posterior 1/3
Divided by sulcus terminalis
Which muscle retracts the tongue?
Styloglossus
What muscle elevates the tongue?
Palatoglossus
What muscle protrudes the tongue?
Genioglossus
What muscle depresses the tongue?
Hypoglossus
What are the extrinsic muscles of the tongue?
- Styloglossus
- Palatoglossus
- Genioglossus
- Hypoglossus
What nerve innervates styloglossus?
XII
What nerve innervates palatoglossus?
CN X
What extrinsic tongue muscles does CN XII innervate?
- Styloglossus
- Genioglossus
- Hypoglossus
What extrinsic tongue muscle does CN X innervate?
Palatoglossus
What nerve innervates genioglossus?
XII
What nerve innervates hypoglossus?
XII
Which nerve innervates the intrinsic muscles of the tongue?
XII
What is the sensory innervation to the posterior 1/3 of the tongue?
Glossopharygeal
What portion of the tongue does glossopharyngeal provide sensory innervation?
Posterior 1/3
Which nerve provides taste info from anterior 2/3 of tongue?
Chorda tympani (branch of CN VII)
Which nerve provide general sensory info from anterior 2/3 of tongue?
Lingual nerve (branch of V3 of trigeminal)
Which nerve innervate the teeth of the maxilla (upper teeth)?
Posterior superior alveolar nerve
Which nerve innervates the teeth of the mandible (lower teeth)?
Inferior alveolar nerve
What are the 3 pairs of salivary glands?
- Parotid
- Sublingual
- Submandibular
Which gland wraps around the free posterior edge of mylohyoid muscle?
Submandibular
Which muscle does submandibular gland wrap around?
Myelohyoid
What structures are in the oropharynx?
- Palatal arches (palatoglossal and palatopharyngeal)
- Palatine tonsils
- Uvula
- Palatoglossal muscle
- Palatopharyneal muscle
Where are the palatal arches in relation to each other?
Palatoglossal arch sits anterior to palatopharyngeal arch
Where are the palatine tonsils located?
Between palatoglossal and palatopharyngeal arches
What are the functions of the soft palate?
- When elevated, seals nasal cavity during swallowing, coughing and suction
- When depressed, seals oral cavity to allow unimpeded breathing during chewing
Which nerve innervates tensor veli palatini?
Trigeminal
What nerve innervates the muscles which move the soft palate?
Pharyngeal branches of vagus (excl. tensor veli palatini)
Which muscle that attaches to the soft palate is innervated by trigeminal?
Tensor veli palatini
What is Waldeyer’s ring?
Incomplete ring of lymphoid tissue
What are the boundaries of the larynx?
Begins at epiglottis and ends at inferior border of cricoid cartilage at level of C6
What are the structures of the laryngeal skeleton?
From superior to inferior:
- Hyoid bone
- Thyroid cartilage
- Cricoid cartilage
What attaches to the arytenoid cartilage and where?
Vocal ligaments attach to anterior vocal proccess
What attaches to muscular process of the arytenoid cartilage?
Intrinsic muscles of the larynx
What are the processes of the arytenoid cartilage and where are they?
Vocal process is anterior and muscular process is posterior
What are the movements displayed by the arytenoid cartilages?
Swivelling
Sliding towards each other
Where do the vocal ligaments attach?
Attach to vocal processes of arytenoid cartilage
What are the 2 folds of mucosa in the larynx?
Vestibular fold is false vocal cord which is superior to the true vocal fold
To produce phonation how should the vocal ligaments move?
Adducted
To allow for breathing, how should the vocal folds move?
Abducted
Which muscle abducts the vocal ligaments to allow for breathing?
Posterior cricoarytenoid
Which muscle adducts the vocal ligaments to allow for phonation?
Lateral cricoarytenoid
Which nerve supplies cricothyroid muscle?
External laryngeal
Which nerve supplies the intrinsic muscles aside from cricothyroid?
Inferior laryngeal
Which nerves provides sensory innervation to the intrinsic muscles of the larynx?
Recurrent laryngeal
What is the blood supply of the larynx?
Superior thyroid arteries
Inferior thyroid veins
Which nerve forms the afferent arc of the gag reflex?
CN IX
What is the sensory supply of the nasopharynx?
Pharyngeal branches of V2
What is the sensory supply of oropharynx?
Pharyngeal branches of CN IX
What is the sensory supply of the laryngopharynx?
Vagus
Which nerve is involved in swallowing and in the efferent arc of the gag reflex?
Vagus
What is the motor nerve supply to the pharynx?
Mostly from pharyngeal branches of the vagus excl. stylopharyngeus
Which nerve innervates stylopharyngeus?
Glossopharyngeal
Which nerve supplies the larynx?
Branches of vagus
