This document provides an overview of the anatomy of the middle ear, including the ossicles (malleus, incus, stapes), intratympanic muscles (tensor tympani and stapedius), arterial and venous supply, nerve supply, and the tympanic plexus. It also discusses some clinical applications like causes of hyperacusis and otosclerosis.
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EAR-III.pdf
1. EAR - III
Presented by:-
Dr. Sushma Tomar
Associate Professor
Department of Anatomy
5-8-2020
2. Lesson Plan
Ear Ossicles:
• Malleus
• Incus
• Stapes
Intratympanic muscles & their applied aspects
• Tensor Tympani
• Stepedius
Arterial supply of middle ear
Venous and Lymphatic drainage of middle ear
Nerve supply of middle ear & its applied aspects
Tympanic plexus
4. Malleus
Shape- Hammer shaped.
Parts-
• Head
• Neck
• Handle (Manubrium/ Long process)
• Lateral process
• Anterior process
Head articulates with body of Incus.
Incudo-malleolar joint is saddle variety of
synovial joint.
5. Incus
Shape- ‘Anvil’ shaped.
Parts-
• Body
• Short process
• Long process.
Bulbous tip of long process articulates
with head of Stapes.
Incudo-stapedial joint is Ball and
Socket variety of synovial joint.
6. Stapes
Shape- ‘Stirrup’ shaped.
Parts-
• Head
• Neck
• Anterior crus
• Posterior crus
• Footplate (Base)
Footplate is attached to the margin of oval
window by annular ligament.
7. Intratympanic Muscles
• Tensor tympani
• Stapedius
Tensor Tympani-
Origin-
• Cartilaginous part of auditory tube.
• Sulcus tubae.
Insertion-
• Handle of Malleus.
Nerve Supply-
• Nerve to Medial pterygoid.
Actions-
• Tenses the tympanic membrane.
9. Stapedius
Origin-
• Interior of Pyramidal eminence.
Insertion-
• Neck of Stapes.
Nerve Supply-
• Facial nerve
Actions-
• Draws the stapes laterally.
10. Applied Aspects
Hyperacusis-
• Abnormally increased power of hearing.
• Whispering sound appears as noise.
• It occurs due to paralysis of Stapedius
muscle.
Otosclerosis-
• Abnormal ossification of annular
ligament.
• Impeded movements of Stapes.
Symptoms-
• Deafness.
• It is the most common cause of deafness
in adults.
11. Arterial Supply of Middle Ear
6 arteries:
1. Anterior tympanic artery.
2. Stylomastoid artery.
3. Petrosal branch of middle meningeal artery.
4. Superior tympanic branch of middle meningeal artery.
5. Branch from artery of pterygoid canal.
6. Tympanic branch of Internal Carotid Artery.
13. Nerve Supply of Middle Ear
• Tympanic branch of Glossopharyngeal nerve.
• Superior Carotico-tympanic nerve.
• Inferior Carotico-tympanic nerve.
• Facial nerve [ Motor to Stapedius]
• Mandibular nerve [Motor to Tensor Tympani].
Superior and Inferior Carotico-tympanic nerves-
• These nerves are sympathetic nerves and derived from sympathetic plexus around Internal Carotid Artery.
• These nerves are vasomotor.
14. Tympanic Plexus
It is a nerve plexus.
Location-
Promontory on medial wall of middle ear.
Contributing Nerves-
• Tympanic branch of Glossopharyngeal nerve
[Jacobson’s nerve].
• Superior and Inferior Carotico-tympanic nerves.
• A branch from geniculate ganglion of Facial nerve.
It supplies mucous membrane of:
• Middle ear.
• Mastoid air cells.
• Bony Eustachian tube.
Branches-
• Lesser Petrosal Nerve.
Tympanic Plexus
15. Applied Aspects
Otalgia [ Pain in the Ear]-
In the ear pain can be referred from:
• Tongue.
• Teeth.
• Tonsil.
• Pharynx.
These are the areas supplied by
Trigeminal, Glossopharyngeal and
Vagus nerves.
These nerves also supply external and
middle ear.