ENT Ear Anatomy Flashcards
What are the 3 parts of the Ear?
External Ear
Middle Ear
Inner Ear
What bone is the Inner 2/3 of the Ear Canal (EAM) embedded in?
Temporal Bone
Has Squamous and Petrous parts
What are the functions of the ear?
Hearing
Balance
What anatomical structures does the Temporal Bone contain?
Middle Ear Cavity Inner Ear (Organs of Hearing and Balance)
CN VII
CN VIII
What is the thinnest part of the skull?
Pterion
H-Shaped Suture of the Temporal, Frontal, Parietal and Sphenoid Bones.
What structures is the Ear Canal made up of?
1/3 Cartilage (Avascular so recieves blood supply from skin)
2/3 Bone (Temporal)
The Ear Canal is horizontally straight. True/False?
False!
Has a loose S curve to it so needs to be pulled at auricle to straighten it out
Which glands secrete ear wax?
Ceruminous Glands
What is the main nerve supply to the auricle?
Cervical Spinal Nerves 2 and 3
Some innervation with CN V3 also present
What is the nerve supply to the External Tympanic Membrane and EAM?
CN X (Inferior Parts of EAM and 1/3 of EXTERNAL Surface of Tympanic Membrane)
Auriculotemporal Branch of CN V3 (Superior Parts of EAM as well as the 2/3 of EXTERNAL Surface of the Tympanic Membrane.
Also some CN VII Involvement for Sensation.
What is the nerve supply to the INTERNAL surface of the Tympanic Membrane?
CN IX
What is the Lymphatic Drainage of the Auricle?
Lateral Surface of the Superior Half drains into the Parotid Lymph Nodes
Cranial Surface of the Superior Half drains into the Mastoid and Deep Cervical Lymph Nodes
Remainder of the Auricle/Pinna drains into the Superficial Cervical Lymph Nodes
What are other innervations of CN IX?
Middle Ear Cavity Eustachian Tube Nasopharynx Posterior 1/3 of Tongue Parotid Glands Tonsils
What are the 2 muscles of the Ossicles?
Stapedius
Tensor Tympani
What are the main structures of the Middle Ear Cavity?
Tympanic Membrane Ossicles Oval Window Round Window Eustachian Tube Epitympanic Recess (source of Mastoiditis) Aditus Chorda Tympani of CN VII Internal Carotid Artery at Anterior Wall
What are the functions of the Eustachian Tube?
Equalise Air Pressure in the Middle Ears
Ventilate Middle Ear Mucosa
Source of Infection Tracking into Middle Ear
How does Chorda Tympani nerve arise?
CN VII will travel in the IAM, until it reaches the Temporal Bone where it splits into the Chorda Tympani Nerve and CN VII
Chorda Tympani branches off whilst CN VII continues through IAM
What are the Chorda Tympani innervations?
Taste Sensation to Taste Buds on Anterior 2/3 of Tongue
Parasympathetic Innervation to Submandibular and Sublingual Salivary Glands but NOT the Parotid Salivary Gland
What are the CN VII innervations?
Motor Innervation to the Muscles of Facial Expression
Which part of the Temporal Bone is the Inner Ear found in?
Petrous Part
What are the 2 branches of CN VIII?
Vestibular Nerve
Cochlear Nerve
What is the name given to the cochlear and vestibular apparatus?
Otic Capsule
What fluid does the bony labyrinth contain?
Perilymph
What fluid is contained within the Membranous Labyrinth?
Endolymph
What is the tip of the Cochlea called?
What sound frequencies does it detect?
Cupula (Apex)
Low Frequencies
What are the Ampullae?
End-Dilations of the Semicircular Canals where the Balancing Sensory Cells are held
What are the Maculae?
Regions containing clusters of hair cells that sense Endolymph Movement
What do the Semicircular Canals detect?
Changes in the Velocity of Angular Motion.
What changes in movement does the Saccule detect?
Vertical Movement Change
What changes in movement does the Utricle detect?
Horizontal Movement Change
