External and Middle Ear Flashcards
Function of the Ear
Hearing
Balance
Divisions of the Ear
External Ear
Middle Ear
Internal Ear
All the parts of the ear lie within the …
temporal bone of the skull
External Ear
Function
Collect and Conduct Sound towards the Middle Ear
External Ear
Parts
Auricle
External Auditory Canal
Tympanic Membrane
External Ear: Auricle
Parts of the Auricle
Helix
Anti-Helix
Scaphoid Fossa
Concha
Tragus
Lobule
External Ear: Auricle
What is the Helix?
Curved Rim of Auricle
External Ear: Auricle
Anterior Part of the Helix is called the …
Crus of the Helix
External Ear: Auricle
What is the Anti-Helix?
Curved Rim anterior to Helix
External Ear: Auricle
Anteriorly, the Anti-Helix divides into …
2 Crura
External Ear: Auricle
Scaphoid Fossa location
Between Helix and Anti-Helix
External Ear: Auricle
Concha location
Anteroinferior to Antihelix
External Ear: Auricle
What is the Tragus?
Curved Flap projecting Posteriorly
External Ear: Auricle
Lobule location
Lowest Part of Auricle
External Ear: Auricle
Lobule formation
Soft Tissue without Cartilaginous Skeleton
External Ear: External Auditory Canal
Extent
From External Acoustic Meatus to Tympanic Membrane
External Ear: External Auditory Canal
Shape
S-Shaped
External Ear: External Auditory Canal
Parts
Outer Cartilaginous Part (1/3rd)
Inner Boney Part (2/3rd)
External Ear: External Auditory Canal
Length
24mm
External Ear: Tympanic Membrane
What is the Tympanic Membrane
Oval Disc on the Medial End of the External Auditory Canal
External Ear: Tympanic Membrane
It forms the Greater Part of the …
Lateral Wall of the Tympanic Cavity
Middle Ear
What is the Middle Ear?
Air-Filled, Mucous Membrane-Linked Space
Middle Ear
Limited by …
Laterally: Tympanic Membrane
Medially: Internal Ear
Middle Ear
Function
Transmit Vibrations of Tympanic Membrane to Internal Ear
Middle Ear
Communications
Mastoid Area posteriorly
Nasopharynx via Eustachian Tube anteriorly
Middle Ear
Walls
Anterior: Eustachian Tube
Posterior: Mastoid Antrum
Superior: Tegmen Tympani
Inferior: Fundus Tympani
Medial: Medial Wall
Lateral: Tympanic Membrane
Middle Ear
Anterior/Carotid Wall features
Attachment of Tensor Tympani Muscle
Opening of Eustachian Tube
Related to Internal Carotid Artery
Middle Ear
Posterior/Mastoid Wall features
Aditus to Mastoid Antrum
Pyramid gives origin to Stapedius Muscle
Middle Ear
Roof/Tegmental Wall features
Thin Layer of Bone (Tegmen Tympani) separating Middle Ear from Middle Cranial Fossa
Middle Ear
Floor/Jugular Wall features
Separates Middle Ear from Internal Jugular Vein
Contains Tympanic Branch of Glossopharyngeal Nerve
Middle Ear
Medial/Labyrinthine Wall features
Promontry (bulge) produced by Cochlea
Tympanic Plexus covering Promontry
Oval Window Superior to Promontry
Round Window Inferior to Promontry
Facial Canal (for Facial Nerve) Posterior to Oval Window
Middle Ear
The Medial Wall is also the …
Lateral Wall of the Internal Ear
Middle Ear
Lateral Wall consist of …
tympanic membrane
Middle Ear
Contents
Auditory Ossicles (Malleus, Incus, Stapes)
Muscles (Tensor Tympani and Stapedius)
Middle Ear
What are the Auditory Ossicles?
3 Interconnected Movable Bones between Tympanic Space and Internal Ear
Middle Ear
Function of the Tympanic Cavity Muscles
Decrease sound intensity before reaching inner ear
Middle Ear
Motor Nerve Supply of Tympanic Cavity Muscles
Tensor Tympani: Trigeminal Nerve
Stapedius: Facial Nerve
Middle Ear
The Eustachian Tube connects the ____ to the ____
__Middle Ear__
__Nasopharynx__
Middle Ear
Eustachian Tube length
36mm
Middle Ear
Eustachian Tube consists of …
Bony Part (1/3rd)
Cartilaginous Part (2/3rd)
Middle Ear
Function of Eustachian Tube
Equalizes pressure across Tympanic Membrane
Drains Mucous from Middle Ear into Pharynx
Middle Ear
Eustachian Tube opened during ____ by ____
__deglutition__
__the Tensor Palati and Levator Palati__
Middle Ear
Nerve Supply of Lateral Surface of Auricle
Upper 2/3: Auriculotemporal Nerve
Lower 1/3: Great Auricular Nerve
Middle Ear
Nerve Supply of External Auditory Canal
Anterosuperior Wall: Auriculotemporal Nerve
Posteroinferior Wall: Vagus
Middle Ear
Nerve Supply of the Outer Surface of Tympanic Membrane
Anterior Half: Auriculotemporal Nerve
Posterior Half: Vagus
Middle Ear
Nerve Supply of the Tympanic Cavity and Inner Surface of Tympanic Membrane
Glossopharyngeal Nerve