The Ear

Question 1

Divisions of the Ear

External (outer)

Answer 1

Auricle, external auditory meatus, external surface of the tympanic membrane

Question 2

Divisions of the Ear

MIddle

Answer 2

Internal surface of the tympanic membrane, tympanic cavity, ossicles, pharyngotympanic tube

Question 3

Divisions of the Ear

Internal (inner)

Answer 3

Auditory apparatus, vestibular apparatus, internal auditory meatus, vestibulococchlear nerve (CN VIII), oval window, round window

Question 4

Relations of the Ear

Answer 4

Question 5

External Ear

Auricle

Answer 5

Elastic cartilage

Muscles of facial expression but vestigal in humans

Lymph to parotid and cervical lymph nodes

Question 6

Auricle Arteries

Answer 6

Question 7

Auricle Innervation

Answer 7

Question 8

External Ear

External Auditory Meatus

Answer 8

About 2.5cm long

Lateral third has elastic cartilage, hair follicles, sweat and sebaceous glands

Medial two-thirds is bone lined with stratified squamous epithelium

Blood from branches of external carotid (auricular)

Nerves are mainly auriculo-temporal from CN V3 but also auricular branches from CN VII and CN X

Question 9

Tympanic Membrane

Answer 9

Roughly 8mm diameter circle

Outer is stratified squamous and inner is mucous membrane

Chorda tympani across medial surface

Malleus attached to inner surface

Lateral surface - auriculotemporal nerve (CN V3) and auricular branch of vagus (CN X)

Medial surface - tympaic branches of glossopharyngeal nerve (CN IX)

Question 10

Tympanic Cavity

Answer 10

Question 11

Internal Ear

Answer 11

Question 12

Muscles and Neuro-vascular supply to ear

Answer 12

Question 13

Bones of Middle Ear

Answer 13

Question 14

Facial Nerve

Answer 14

Question 15

Chorda Tympani

Answer 15

Crosses medial surface of tympanic membrane and handle of malleus

Leaves tympanic cavity via petrotympanic fissure

Joins lingual nerve

Parasympathetic - sub-lingual and sub-mandibular salivary glands

Special sense of taste for the anterior 2/3 of the tongue

Question 16

Auditory Tube

Answer 16

Connects nasopharynx with tympanic cavity

Lateral - Bony canal lined with mucosa

Medial - Cartilagenous and membranous tube

Normally closed but lumen opens when tensor veli palatini contract (swallow, yawn etc)

Equalises pressure on both sides of tympanic membrane

Sensory via CN IX

Question 17

Inner Ear

Answer 17

Question 18

Ear overview

Answer 18

Question 19

Labrynths

Bony

Answer 19

Surrounded by otic capsule

Otic capsule very dense bone within petrous temporal bone - not bony labyrinth but surrounds it

System of canals filled with perilymph

Cochlea

Vestibule

Semicircular canals

Question 20

Labrynths

Membranous

Answer 20

Continuous system of ducts and sacs inside bony labyrinth

Suspended in perilymph but contains endolymph

Perilymph and endolymph conduct sound vibrations and respond to mechanical forces (movement and acceleration)

Question 21

Cochlea

Answer 21

Question 22

Cochlea

Answer 22

Question 23

Semi-Circular Canals

Answer 23

Lie posterior and lateral to vestibule

Each canal 2/3 of a circle

Anterior, posterior and lateral

Anterior posterior sit at right angles with lateral being horizontal

Contain semi-circular ducts (continuous with utricle)

Each duct swells at the end (amupullae)

Question 24

Ampulla, Utricle and Saccule

Answer 24

Each ampulla houses crista ampullaris which respond to angular movements of head

Vestibule is a bony labyrinth, inside of which are two membranous sacs - the utricle and saccule

These house equilibrium receptors called maculae which respond to the pull of gravity and changes in head positon

Otoliths

Question 25

Cochlear Vasculature

Answer 25