23 Ear Flashcards
A patient has pain in his ear. His throat is red and inflammed, conforming pharyngitis. Which structure provides a pathway for the infxn to spread to the tympanic cavity (middle ear)?
The pharyngotympanic (eustachian) tube connects the middle ear and the nasopharynx and is the conduit for spreading infxns.
There was concern a patient might have injured the nerve that principally innervates the external surface of the tympanic membrane. Which test is performed during examination to check for injury to this nerve?
The external surface of the tympanic membrane is innervated by the auriculotemporal nerve (branch of V3). Damage to this nerve would result in painful movements of the TMJ bc this joint receives innervation from the same nerve.
What is the most direct route for the spread of an infxn from the upper respiratory tract to the middle ear cavity?
The eustachian/pharyngotympanic tube is a mucosal-lined tube that provides direct connection from the nasopharynx to the middle ear cavity.
Which nerve is responsible for the sensory innervation of the inner surface of the tympanic membrane?
The inner surface of the tympanic membrane is supplied by the glossopharyngeal nerve.
The auricular branches of the facial and vagus nerves and the auriculotemporal branch of V3 innervate the external surface fo the tympanic membrane.
Radiographs reveals a tumor in the middle ear cavity, invading through the bony floor. Which structure will most likely be affected?
The sigmoid sinus collects venous blood from the transverse sinuses and empties it into a small cavity known as the jugular bulb, the inferior portion oh which is located beneath the bony floor of the middle ear cavity.
Which nerve are compressed by an acoustic neuroma (vestibular schawnnoma)?
V, VII and VIII
Vestibular schawnnoma = benign tumor of VIII
What is the embryologic origin of the structure that allows infxns to spread from the pharynx to the middle ear cavity?
The first pharyngeal pouch gives rise to the tympanic recess, with its membrane giving rise to the tympanic membrane. The tympanic recess itself gives rise to the tympanic cavity and the mastoid antrum. The pharyngotympanic tube, a part of the tympanic cavity, connects the tympanic cavity to the pharynx.
A patient has a red and bulging tympanic membrane with purulent effusion. Assuming this area is now infected, which venous channel is most at risk for thrombosis as a direct result of proximity to the infected/inflamed bone?
The area indicated by the arrow is the mastoid air cells of the mastoid process. The infxn likely spread via mastoid emissary veins, which passed through the mastoid foramen of the temporal bone to the sigmoid sinus. The sigmoid sinus begins beneath the temporal bone and travels to the jugular foramen, at which point it joins the inf. petrosal sinus to form the jugular vein.
A physician palpates the mastoid process of a patient complaining of pain behind the ear. Which bone is the physician palpating?
The temporal bone parts include mastoid, petrous, squamous and tympanic portions.
