Ear and Orbits

What are the divisions of the ear?

External parts, Middle parts, Internal parts.

What is the primary function of the external and middle ear?

Mainly concerned with the transference of sound to the internal ear.

What is the role of the internal ear?

Contains organs for equilibrium (balance) and hearing.

What is the tympanic membrane (eardrum)?

A structure that separates the external ear from the middle ear.

What is the function of the pharyngotympanic (auditory) tube?

Joins the middle ear to the nasopharynx.

What are the smallest bones in the body?

The ossicles:

• malleus

• incus

• stapes

What are the ossicles, and how are they shaped?

• Malleus (like a mallet)

• Incus (like an anvil)

• Stapes (like a stirrup or horse staple).

Which cranial nerve is associated with hearing and balance?

Vestibulocochlear nerve (Cranial Nerve VIII).

Which cranial nerve innervates the tensor tympani muscle?

Mandibular branch of the trigeminal nerve (Cranial Nerve V3).

Which cranial nerve innervates the stapedius muscle?

Facial nerve (Cranial Nerve VII).

How is the vestibulocochlear nerve clinically tested?

Hearing:

• Whisper test or tuning fork test (Rinne and Weber tests).

Balance:

• Observing gait, Romberg test.

What are common pathologies affecting the ear?

Otitis media (middle ear infection), tinnitus, hearing loss, vestibular disorders (e.g., vertigo).

What is the clinical significance of the tympanic membrane?

Its appearance can indicate infections, fluid accumulation, or perforations in the ear.

What are the orbits?

Pyramidal, bony cavities in the facial skeleton that house and protect the eyeballs.

What is the function of the orbits?

Contain and protect the eyeballs, muscles, nerves, and vessels, along with most of the lacrimal apparatus.

What fills the space in the orbits not occupied by structures?

Orbital fat.

Which bones contribute to the orbit?

• Ethmoid

• Lacrimal

• Sphenoid

• Frontal

• Maxilla

• Palatine

• Zygomatic.

Which bones do NOT contribute to the orbit?

Nasal bone.

How are the orbits oriented?

• Bases (orbital openings)

• Apices

Bases (orbital openings) {How are the orbits oriented}

• are directed anterolaterally

Apices {How are the orbits oriented}

• posteriomedially

What structures are protected within the orbits?

Eyeballs, extraocular muscles, optic nerve (Cranial Nerve II), vessels, lacrimal apparatus.

What is the primary role of orbital fat?

Fills spaces not occupied by structures, providing cushioning and support for the eyeball.

What is the proximal attachment of the lateral rectus muscle?

Common tendinous ring (at the apex of the orbit).

What is the proximal attachment of the medial rectus muscle?

Common tendinous ring (at the apex of the orbit).

What is the proximal attachment of the superior rectus muscle?

Common tendinous ring (at the apex of the orbit).

What is the proximal attachment of the inferior rectus muscle?

Common tendinous ring (at the apex of the orbit).

What is the proximal attachment of the superior oblique muscle?

Body of the sphenoid bone.

What is the proximal attachment of the inferior oblique muscle?

Anterior part of the orbital floor.

What is the distal attachment of the lateral rectus muscle?

Lateral sclera, just posterior to the corneoscleral junction.

What is the distal attachment of the medial rectus muscle?

Medial sclera, just posterior to the corneoscleral junction.

What is the distal attachment of the superior rectus muscle?

Superior sclera, just posterior to the corneoscleral junction.

What is the distal attachment of the inferior rectus muscle?

Inferior sclera, just posterior to the corneoscleral junction.

What is the distal attachment of the superior oblique muscle?

Sclera, posterior to the superior rectus, after passing through the trochlea.

What is the distal attachment of the inferior oblique muscle?

Sclera, posterior to the lateral rectus.

What movements are performed by the lateral rectus muscle?

Abducts the eyeball.

What movements are performed by the medial rectus muscle?

Adducts the eyeball.

What movements are performed by the superior rectus muscle?

Elevates, adducts, and medially rotates the eyeball.

What movements are performed by the inferior rectus muscle?

Depresses, adducts, and laterally rotates the eyeball.

What movements are performed by the superior oblique muscle?

Depresses, abducts, and medially rotates the eyeball.

What movements are performed by the inferior oblique muscle?

Elevates, abducts, and laterally rotates the eyeball.