Ear Flashcards
What is the location and shape of the middle ear?
The middle ear is an air-filled cavity in the petrous part of the temporal bone, shaped like a biconcave disc.
What are the boundaries of the middle ear?
Roof: Tegmen tympani; Floor: Jugular wall; Lateral: Tympanic membrane; Medial: Inner ear wall; Anterior: Eustachian tube opening; Posterior: Mastoid antrum.
What are the contents of the middle ear?
Ear ossicles (malleus, incus, stapes), muscles (tensor tympani, stapedius), chorda tympani nerve, and the tympanic plexus.
What is the nerve supply of the middle ear?
Innervated by the tympanic plexus, derived from the glossopharyngeal nerve (CN IX) and sympathetic fibers.
What is the applied anatomy of the middle ear?
Otitis media, conductive hearing loss, perforation of the tympanic membrane, and mastoiditis.
What is the tympanic membrane?
A thin, oval, semi-transparent membrane that separates the external ear from the middle ear.
What are the layers of the tympanic membrane?
Outer: Skin; Middle: Fibrous layer; Inner: Mucous membrane.
What is the external auditory meatus?
A canal extending from the auricle to the tympanic membrane, conducting sound waves.
What are the parts of the internal ear?
Bony labyrinth (vestibule, semicircular canals, cochlea) and membranous labyrinth (utricle, saccule, semicircular ducts, cochlear duct).
What are the ear ossicles?
Malleus, incus, and stapes—tiny bones that transmit sound vibrations from the tympanic membrane to the inner ear.
What is the nerve supply of the pinna?
Auriculotemporal nerve (V3), great auricular nerve (C2, C3), lesser occipital nerve (C2), and auricular branch of vagus (CN X).
What are the contents of the middle ear?
Ear ossicles, muscles (tensor tympani, stapedius), chorda tympani nerve, and tympanic plexus.
What are the parts of the internal ear?
Cochlea, vestibule, semicircular canals, utricle, saccule, and endolymphatic duct.
Which diagrams should be drawn for the ear?
External tympanic membrane (otoscope view), lateral auricle surface, and medial wall of the middle ear.
What is the tympanic membrane?
A thin, oval, semi-transparent membrane that separates the external ear from the middle ear and transmits sound vibrations.
What are the parts of the tympanic membrane?
Pars tensa (main tense portion) and pars flaccida (small, lax portion near the anterior-superior quadrant).
What are the surfaces of the tympanic membrane?
Outer (lateral) surface facing the external auditory canal and inner (medial) surface facing the middle ear.
What is the arterial supply of the tympanic membrane?
Branches of the deep auricular artery (from maxillary artery) and anterior tympanic artery (from external carotid system).
What is the venous drainage of the tympanic membrane?
Drains into the pterygoid venous plexus and external jugular vein.
What is the nerve supply of the tympanic membrane?
Outer surface: Auriculotemporal nerve (V3) and auricular branch of vagus (CN X). Inner surface: Glossopharyngeal nerve (CN IX).
What are the layers of the tympanic membrane?
Outer epidermal layer (continuous with external auditory canal), middle fibrous layer, inner mucosal layer (continuous with middle ear).
How is the tympanic membrane examined?
Using an otoscope to assess color, position, light reflex, and presence of perforations or fluid behind the membrane.
What are common findings in tympanic membrane examination?
Normal: Pearly gray with a visible light reflex. Abnormal: Bulging (infection), retraction (Eustachian tube dysfunction), perforation, or fluid accumulation.
How does the tympanic membrane develop embryologically?
Develops from all three germ layers: Ectoderm (external layer), mesoderm (fibrous layer), and endoderm (inner mucosal layer). Forms from the first pharyngeal membrane.
What is the clinical importance of tympanic membrane development?
Congenital anomalies can lead to hearing defects. Perforations or scarring can affect sound conduction.
