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Questions and Answers

What are the three parts of the brainstem?

Medulla oblongata, Pons, Midbrain

What is the main function of the brainstem?

It contains cranial nerve nuclei, vital centers for respiration and cardiac activities, and acts as a conduit for ascending and descending tracts.

What are the cranial nerves that contain parasympathetic outflow?

The cranial nerves that contain parasympathetic outflow are III, VII, IX, and X.

What is the clinical sign of an olfactory nerve lesion?

Loss of the sense of smell (anosmia) Signup and view all the answers

What is the clinical sign of an optic nerve lesion?

Blindness or visual field defects Signup and view all the answers

What is the clinical sign of an oculomotor nerve lesion?

Dilated pupil, ptosis (drooping eyelid), and diplopia (double vision) Signup and view all the answers

What is the clinical sign of a trochlear nerve lesion?

Diplopia (double vision), particularly when looking straight downward Signup and view all the answers

What is the clinical sign of a trigeminal nerve lesion?

Sensory deficits in the face, loss of the corneal reflex, and flaccid paralysis of the mastication muscles. Signup and view all the answers

What is the clinical sign of an abducens nerve lesion?

Inability to move the eye laterally, causing convergent strabismus, with the eye deviating towards the nose. Signup and view all the answers

What is the clinical sign of a facial nerve lesion depending on the location of the lesion?

Lower motor neurone lesion (LMN) may result in total facial weakness, while upper motor neurone lesions (UMN) cause forehead sparing weakness. Signup and view all the answers

What is the clinical sign of a vestibulocochlear nerve lesion?

Deafness, tinnitus, and/or vertigo. Signup and view all the answers

What is the clinical sign of a glossopharyngeal nerve lesion?

Impaired gag reflex, loss of sensation in the posterior one-third of the tongue, and difficulty swallowing. Signup and view all the answers

What is the clinical sign of a vagus nerve lesion?

Impaired gag reflex, soft palate deviation, and difficulty swallowing. Signup and view all the answers

What is the clinical sign of a spinal accessory nerve lesion?

Weakness in turning the head, difficulty shrugging the shoulders, and drooping of one shoulder. Signup and view all the answers

What is the clinical sign of a hypoglossal nerve lesion?

Tongue deviation toward the affected side when protruded. Signup and view all the answers

Which of the following cranial nerves is responsible for the sense of smell?

Olfactory Signup and view all the answers

Which of the following cranial nerves is responsible for controlling eye movements?

Abducens Signup and view all the answers

Which of the following cranial nerves is responsible for controlling taste?

Glossopharyngeal Signup and view all the answers

Which of the following cranial nerves is responsible for swallowing?

Glossopharyngeal Signup and view all the answers

Which of the following cranial nerves is responsible for hearing and balance?

Vestibulocochlear Signup and view all the answers

Study Notes

Brainstem and Cranial Nerve

The brainstem is the connecting part between the forebrain and the spinal cord
It occupies the posterior cranial fossa
The brainstem has three parts: medulla oblongata, pons, and midbrain (arranged from bottom to top)
The brainstem contains cranial nerve nuclei (CN III-XII) and vital centers (respiration and cardiac activities)
It acts as a conduit for ascending and descending tracts

Major Brain Subdivision

The prosencephalon (forebrain) is comprised of the telencephalon (cerebrum) and diencephalon (thalamus and hypothalamus)
The mesencephalon (midbrain) lies between the diencephalon and rhombencephalon
The rhombencephalon (hindbrain) includes the metencephalon (pons and cerebellum) and myelencephalon (medulla oblongata)

Parts of the Brainstem

The medulla oblongata extends from just above the origin of C1 nerve, is about 3cm long, and 2cm wide
The pons is a bridge connecting the two cerebellar hemispheres, measuring 2.5 cm in length
The midbrain connects the pons and cerebellum to the forebrain, ascending through the tentorium cerebelli

Arterial Supply

The arterial supply to different regions is detailed, with specific arteries supplying the medulla oblongata, pons, and midbrain
For example, the vertebral artery supplies the pons; the basilar artery is present in the pons area

External Features (Anterior View)

Key structures like the pyramids, olive, and anterolateral sulcus are identifiable on the anterior view of the medulla oblongata
The location and function of cranial nerves (CNs) IX, X, XI, XII and C1 nerve are described.

External Features (Lateral View)

Structures such as the pyramids, olives, posterolateral sulcus, and hypoglossal nerve, CN XII, are prominent
The location of nerves such as glossopharyngeal nerve, CN IX; vagus nerve, CN X, are shown, and their relationship to other brain structures.

External Features (Posterior View)

Key structures such as the posterior median fissure, gracile and cuneate tubercles are evident
The location of the various structures like the hypoglossal trigone, vagal trigone, sulcus limitans, and various columns are shown

Cranial Nerves - Definition

Cranial nerves emerge directly from the brain or brainstem
Spinal nerves emerge from the spinal cord

Cranial Nerves - Features

Each cranial nerve is paired, existing on both sides of the brain and present in twelve pairs
The cranial nerves are numbered I to XII based on their emergence point in the brain, from front to back
They have diverse functions, classification into motor, sensory, and mixed,

Cranial Nerves

Twelve pairs of cranial nerves are part of the peripheral nervous system
They have various functions, including sensory (nose, eyes) motor (muscles), mixed (face, taste)

Organisation of Cranial Nerves

Cranial nerves are categorized into entirely sensory, entirely motor, mixed, and parasympathetic outflow

Lesions of Specific Cranial Nerves

Olfactory nerve (I): Loss of smell (anosmia) - caused by fracture of anterior cranial fossa, or cerebral tumors
Optic nerve (II): Partial or complete blindness, nasal/bitemporal hemianopia, caused by optic neuritis, traumas
Vestibulocochlear nerve (VIII): Deafness, tinnitus, vertigo, nystagmus, due to cochlear or vestibular nerve disorders
Oculomotor nerve (III): Drooping eyelid (ptosis), fixed/dilated pupils, impaired eye movement
Trochlear nerve (IV): Double vision when looking straight downward, eye deviating medially and downward
Abducens nerve (VI): Inability to move eye laterally (convergent strabismus), compressed by aneurysm or cavernous sinus thrombosis
Trigeminal nerve (V): Loss of face sensation, corneal reflex impairment, Deviation of jaw to the weak side; and difficulties in chewing
Facial nerve (VII): Various motor functions of facial muscles impaired, possible symptoms of Bell's Palsy
Glossopharyngeal nerve (IX): Loss of sensation in posterior third of tongue, including taste, unilateral gag reflex; difficulties in swallowing
Vagus nerve (X): Uvula deviates away from lesion side
Spinal accessory nerve (XI): Weakness in turning head to opposite side and drooping shoulder.
Hypoglossal nerve (XII): Tongue deviates towards the paralyzed side when protruded