Functional Components Of Cranial Nerves Flashcards

1
Q

What are the functional components of cranial nerves?

A

Motor (efferent): GSE, GVE, SVE

Sensory (afferent): GSA, GVA, SVA, SSA
*NoSSE

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2
Q

What is the function of CN I (Olfactory nerve)?

A

CN I is responsible for the special sensory function of smell (SVA). It enters the cranial cavity through the cribriform plate and synapses in the olfactory bulb.

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3
Q

What is the function of CN II (Optic nerve)?

A

CN II is responsible for the special sense of vision (SSA). It carries visual information from the retina to the lateral geniculate body and then to the primary visual cortex.

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4
Q

What are the functions of CN III (Oculomotor nerve)?

A

GSE: Innervates extraocular muscles (superior, medial, and inferior recti, inferior oblique, and levator palpebrae superioris).

GVE: Parasympathetic innervation to the sphincter pupillae and ciliary muscles.

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5
Q

What is the function of CN IV (Trochlear nerve)?

A

CN IV innervates the superior oblique muscle, which moves the eye down and out (GSE).

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6
Q

What is the function of CN VI (Abducens nerve)?

A

CN VI innervates the lateral rectus muscle, which is responsible for lateral movement of the eye (GSE).

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7
Q

What are the functions of CN V (Trigeminal nerve)?

A

GSA: General sensation from the face.

SVE (Branchial motor): Innervates muscles of mastication.

GSE: Proprioceptive fibers.

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8
Q

What are the functions of CN VII (Facial nerve)?

A

SVE: Muscles of facial expression.

GVE: Parasympathetic innervation to lacrimal, submandibular, and sublingual glands.

SVA: Taste from the anterior 2/3 of the tongue.

GSA: Sensation to part of the external ear.

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9
Q

What is the function of CN VIII (Vestibulocochlear nerve)?

A

CN VIII is responsible for hearing and balance (SSA). It carries sensory information from the cochlea (hearing) and semicircular canals (balance).

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10
Q

What are the functions of CN IX (Glossopharyngeal nerve)?

A

SVE (BM): Innervates the stylopharyngeus muscle.

GVE: Parasympathetic innervation to the parotid gland.

GVA: Sensation from the posterior 1/3 of the tongue, oropharynx, and carotid body.

SVA: Taste from the posterior 1/3 of the tongue.

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11
Q

What are the functions of CN X (Vagus nerve)?

A

SVE (BM): Innervates muscles of the palate, pharynx, and larynx.

GVE: Parasympathetic innervation to thoracic and abdominal organs.

GSA: Sensation from the auricle and external acoustic meatus.

GVA: Sensation from thoracic and abdominal organs.

SVA: Taste from the epiglottis.

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12
Q

What is the function of CN XI (Spinal accessory nerve)?

A

CN XI innervates the sternocleidomastoid and trapezius muscles (GSE).

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13
Q

What is the function of CN XII (Hypoglossal nerve)?

A

CN XII innervates the muscles of the tongue (GSE).

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14
Q

Where are the nuclei of cranial nerves located?

A

All cranial nerve nuclei, except CN I and CN II (which are extensions of the forebrain), are located in the brainstem (midbrain, pons, and medulla oblongata).

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15
Q

What is the corneal reflex, and which cranial nerves are involved?

A

The corneal reflex tests the sensory function of CN V (Trigeminal nerve) and the motor function of CN VII (Facial nerve). It checks if a patient winks when the cornea is touched.

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16
Q

What is the difference between upper motor neuron (UMN) and lower motor neuron (LMN) lesions in CN VII (Facial nerve)?

A

UMN lesion: Affects the contralateral lower face (forehead spared).

LMN lesion: Affects the entire ipsilateral face (forehead and lower face).

17
Q

What is the role of the Edinger-Westphal nucleus

A

The Edinger-Westphal nucleus is responsible for the parasympathetic (GVE) component of CN III, controlling the sphincter pupillae and ciliary muscles for pupil constriction and lens accommodation.

18
Q

Which cranial nerves are involved in taste sensation?

A

CN VII (Facial nerve): Taste from the anterior 2/3 of the tongue.

CN IX (Glossopharyngeal nerve): Taste from the posterior 1/3 of the tongue.

CN X (Vagus nerve): Taste from the epiglottis.

19
Q

How are cranial nerve nuclei organized in the brainstem?

A

They are organized into six discontinuous columns: three sensory (GSA, GVA/SVA, SSA) and three motor (GSE, GVE, SVE).

20
Q

Which cranial nerves exit through the superior orbital fissure?

A

CN III (Oculomotor), CN IV (Trochlear), CN V1 (Ophthalmic branch of Trigeminal), and CN VI (Abducens).

21
Q

Which cranial nerves exit through the jugular foramen?

A

CN IX (Glossopharyngeal), CN X (Vagus), and CN XI (Accessory).

22
Q

What is the clinical significance of a CN III (Oculomotor) palsy?

A

It causes ptosis (drooping eyelid), dilated pupil, and inability to move the eye medially, upward, or downward.

23
Q

Which cranial nerves are involved in the gag reflex?

A

CN IX (Glossopharyngeal) for sensory and CN X (Vagus) for motor.

24
Q

Which cranial nerves are involved in the pupillary light reflex?

A

CN II (Optic) for sensory and CN III (Oculomotor) for motor.

25
Q

What is the ciliary ganglion, and which cranial nerve is it associated with

A

The ciliary ganglion is a parasympathetic ganglion associated with CN III (Oculomotor). It controls the sphincter pupillae and ciliary muscles.

26
Q

What is the otic ganglion, and which cranial nerve is it associated with?

A

The otic ganglion is a parasympathetic ganglion associated with CN IX (Glossopharyngeal). It controls the parotid gland.

27
Q

What is the clinical significance of anosmia?

A

Anosmia (loss of smell) can result from damage to CN I (Olfactory nerve) due to head trauma or neurodegenerative diseases like Parkinson’s or Alzheimer’s.

28
Q

What is the clinical significance of vertigo and balance issues?

A

These can result from damage to the vestibular branch of CN VIII (Vestibulocochlear nerve).

28
Q

Which cranial nerves have nuclei in the pons?

A

CN V (Trigeminal), CN VI (Abducens), CN VII (Facial)and CN VIII (Vestibulocochlear).

28
Q

What is the clinical significance of hoarseness and dysphagia?

A

These can result from damage to CN X (Vagus nerve), which innervates the larynx and pharynx.

28
Q

Which cranial nerves have nuclei in the midbrain?

A

CN III (Oculomotor) and CN IV (Trochlear).

29
Q

Which cranial nerves have nuclei in the medulla oblongata?

A

CN IX (Glossopharyngeal), CN X (Vagus), CN XI (Accessory), and CN XII (Hypoglossal).

30
Q

What is unique about CN IV (Trochlear) compared to other cranial nerves?

A

t is the only cranial nerve that exits the brainstem dorsally.