Ear Flashcards
What are the two parts of the external ear?
Auricle and external acoustic meatus
Describe the course of the external acoustic meatus
Travels from the deepest part of the concha and the tympanic membrane. Lateral third is cartilaginous and the medial two thirds is bony tunnel
What is the innervation of the auricle, external acoustic meatus and tympanic membrane?
Auricle: Superficially-cervical plexus and V3. Deep-CN10 and 7
External acoustic meatus: V3, CN10 and 7
Tympanic membrane: Outer-V3, CN10, 7 and 9. Inner-9
What is the roof of the middle ear?
Roof-Tegmental wall (tegmen tympani bone)
What innervates the middle ear?
Tympanic plexus (formed by CN9 and sympathetic plexus)
What is the middle ear’s arterial supply?
Branches of external carotid
What is a risk with a middle ear infection?
May spread posteriorly to mastoid antrum and mastoid cells and into the cranium, leading to meningitis
Which nerve is most often damaged during middle ear surgery and how is it obvious if this has occurred?
Chorda tympani-patients have changes in taste and dryness of the mouth. Runs posterior to tympanic membrane
What is the floor of the middle ear?
Floor-Jugular wall (branch of CN9 enters)
Lateral wall of middle ear
Lateral-Membranous wall (tympanic membrane and lateral wall of epitympanic recess)
Posterior wall of middle ear
Posterior-Mastoid wall (aditus to mastoid antrum leaves a hole. Tendon of stapedius-pyramidal eminence and branch CN7-chorda tympani nerve enter)
Anterior wall of middle ear
Anterior-Carotid wall (pharyngotympanic tube and tensor tympani muscle and branches from internal carotid plexus enter. Chorda tympani nerve exits)
Medial wall of middle ear
Medial-Labyrinthine wall (oval and round windows, promontory containing tympanic plexus. Lesser petrosal nerve leaves)
Tympanic membrane parts
Umbo Handle of malleus Posterior malleolar fold Anterior malleolar fold Lateral process of malleus Pars flaccida Cone of light
