Ear Anatomy and Histology Flashcards
Cutaneous innervation of the EAM
Superior part: CN VII
Anterior part: CN V (via auriculotemporal)
Posterior part: Great auricular (C3)
Inferior part: CN X (via Arnold N.)
Blood supply of the external ear:
Posterior auricular, superficial temporal (branches into anterior auricular arteries)
What type of epithelium lines the EAM
Keratinized stratified squamous epithelium (integument)
Draw the cutaneous innervation of the external ear:
Refer to drawings
Arnold Nerve:
Supplies innervation to the floor of the EAM. Branch of the the Vagus nerve which triggers the cough reflex
Which nerves are involved in the cough reflex?
Efferent: Vagus and Phrenic (diaphragm)
Afferent: Vagus N. (via Arnold N.)
Properties of the External acoustic meatus:
Outer 2/3 = soft connective tissue and cartilage
Inner 1/3 = just skin and bone (skin directly over the bone, no connective tissue etc., bleeds easily)
EAM has ceruminous glands, sebaceous glands and hair follicles
What type of epithelium line the outer and inner layers of the tympanic membrane?
Outer is stratified squamous, inner is simple cuboidal
Properties of the tympanic membrane:
Tip of the malleus is the umbo, section 2 has the cone of light
Has both flaccid and tense part, moves with sound and transmits signals to ossicles
Middle ear:
Location
Parts
Located at petrous part of the temporal bone
Tympanic cavity proper (mesotympanum)
Epitympanic recess (attic)
Walls of the tympanic cavity:
Roof: Tegmental wall Floor: Jugular wall Lateral: Membranous wall Medial: Labyrinthine wall Posterior: Mastoid wall
Draw the organization of the middle ear:
Refer to drawings
Pharyngotympanic tube:
Connects tympanic cavity with nasopharynx (back of throat)
Distal 2/3 is bony while the proximal 1/3 is cartilage (opposite of EAM)
Functions to equalize pressures (ear popping sensation)
Muscles that expand the PT:
Levator veli palatini - contracts longitudinally and pushes one wall
Tensor veli palatini - pulls the other wall of the PT
Pharyngotympanic tube is lined with ….
Pseudostratified epithileum
Auditory ossicles:
Malleus, incus and stapes
Connects the tympanic membrane to oval window
Short process of the incus connected to posterior wall. Base of stapes connected to oval window
Bony labyrinth and membranous labyrinth:
Separated by?
Bony: lined with endosteum
Membranous: made of small sacs of tubes, enclosed with epithelium
Perilymph