Questions and Answers
What are the three parts of the ear?
What is the auricle also known as?
Pinna
The auricle is entirely made of bone.
False
What is the length of the external acoustic meatus (EAM)?
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The tympanic membrane separates the EAM from the _____ ear.
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What part of the tympanic membrane is considered lax and thin?
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What is the primary function of the middle ear?
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The tympanic cavity is about 20 mm in diameters.
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Which wall of the tympanic cavity is largely made by the tympanic membrane?
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What supplies the nerve innervation for the middle ear?
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Match the following ear parts with their descriptions:
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Study Notes
Introduction to the Ear
- The ear serves as the organ responsible for hearing and balance.
- Functions include collection, conduction, modification, amplification, and analysis of sound waves.
Parts of the Ear
- The ear consists of three main parts:
- External ear
- Middle ear
- Internal ear
External Ear Structure
- Auricle (Pinna): Located on the side of the head, made of cartilage covered by skin, featuring various elevations and depressions.
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Key Features:
- Helix: The outer rim, extending to the fleshy lobule, which lacks cartilage support.
- Antihelix: Curved prominence that divides into two crura.
- Scaphoid Fossa: Curved depression between the helix and antihelix.
- Concha: Hollowed center of the auricle leading to the external acoustic meatus (EAM).
- Tragus: Located anterior to the EAM, with the antitragus positioned above the lobule.
Musculature
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Extrinsic Muscles:
- Anterior, superior, and posterior auricular muscles attach the auricle to the skull.
- Innervated by the facial nerve, with vascular supply from posterior auricular artery.
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Intrinsic Muscles:
- Include helicis major and minor, tragicus, and others, also innervated by the facial nerve.
External Acoustic Meatus (EAM)
- A S-shaped canal measuring approximately 2.5 cm from the concha to the tympanic membrane (TM).
- Divided into:
- Cartilaginous Part: The lateral third, about 8 mm long, C-shaped, lined with hair and glands.
- Osseous Part: The medial two-thirds, 16 mm long, narrower than the cartilaginous part.
Nerve and Blood Supply
- Anterior and superior walls: Innervated by the auriculotemporal branch of the mandibular nerve.
- Posterior and inferior walls: Supplied by the auricular branch of the vagus nerve.
- Arterial supply includes posterior auricular and superficial temporal arteries.
Tympanic Membrane (TM)
- Separates the EAM from the middle ear, thin and semi-transparent.
- Oval shape, broader at the top than the bottom, angled at approximately 55 degrees.
- Dimensions: 9-10 mm (anteroinferior) and 8-9 mm (shortest diameter).
- Divided into pars flaccida (lax, upper part) and pars tensa (taut, major part).
- Maximum convexity known as UMBO; innervated by auriculotemporal, vagus, and glossopharyngeal nerves.
Middle Ear
- An air-filled space in the temporal bone housing ossicles that transmit sound vibrations from the TM to the inner ear.
- The tympanic cavity measures around 15 mm in anteroposterior and vertical diameters and has a biconcave lens shape.
Walls of Tympanic Cavity
- Lateral Wall: Formed mainly by the TM.
- Roof (Tegmental Wall): Composed of a thin petrous bone layer that separates the middle ear from the cranial fossa.
- Floor (Jugular Wall): Located above the jugular fossa.
Clinical Relevance
- Conditions such as otitis media, foreign body impaction, and inflammation are associated with the ear's anatomy and function.
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Description
This quiz explores the anatomy and functions of the ear, covering its three main parts: the external ear, middle ear, and internal ear. Learn how the ear acts as a receptor for sound waves and maintains balance. It's an essential resource for those studying human physiology.
