Cranial Nerves Overview and Functions
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Questions and Answers

Which condition is most likely to cause painless vision loss immediately postoperative?

  • Optic nerve compression
  • Central retinal artery occlusion
  • Corneal abrasion
  • Ischemic optic neuropathy (correct)

What is a common postoperative ocular injury encountered after surgery?

  • Corneal abrasion (correct)
  • Ischemic optic neuropathy
  • Trochlear nerve injury
  • Oculomotor nerve injury

Which factor is NOT considered a risk for ischemic optic neuropathy during surgery?

  • Prolonged surgeries
  • Active lifestyle (correct)
  • Diabetes
  • Hypertension

What position of the eye is indicative of oculomotor nerve (CN III) injury?

<p>Down and out (B)</p> Signup and view all the answers

Which cranial nerve is responsible for both sensory and motor functions?

<p>Trigeminal Nerve (CN V) (A)</p> Signup and view all the answers

Which cranial nerve injury can lead to ageusia?

<p>Facial Nerve (CN VII) (C)</p> Signup and view all the answers

Damage to which cranial nerve may result in vision loss or changes?

<p>Optic Nerve (CN II) (B)</p> Signup and view all the answers

What is the main function of the carotid sinus nerve?

<p>Regulates blood pressure and monitors oxygen levels (A)</p> Signup and view all the answers

Which of the following symptoms is NOT associated with glossopharyngeal nerve (CN IX) injury?

<p>Irregular heart rate (A)</p> Signup and view all the answers

Which branch of the glossopharyngeal nerve provides sensory innervation to the palatine tonsils?

<p>Tonsillar branch (C)</p> Signup and view all the answers

How does Hering's nerve relate to the glossopharyngeal nerve?

<p>Hering's nerve is a branch of the glossopharyngeal nerve that specifically conveys sensory information from the carotid sinus to the brainstem (A)</p> Signup and view all the answers

What condition can lead to dysfunction of cranial nerve IX? (select all that apply)

<p>Styloid fracture (A), Eagle syndrome (B), Iatrogenic injury from LMA (C), Posterior cranial fossa tumor (D)</p> Signup and view all the answers

What is the primary sensory function of the ophthalmic branch of CN V?

<p>Sensory to the superior aspect of the face and eyeball (A)</p> Signup and view all the answers

What triggers the oculocardiac reflex mediated by the ophthalmic branch of CN V?

<p>Traction of extraocular muscle (A), Pressure applied to the eye (C)</p> Signup and view all the answers

Which of the following symptoms is NOT associated with injury to the abducens nerve (CN VI)?

<p>Loss of taste on the front two-thirds of the tongue (C)</p> Signup and view all the answers

Which branch of the facial nerve (CN VII) is responsible for innervating the muscles associated with the forehead?

<p>Temporal branch (C)</p> Signup and view all the answers

What is a common treatment option for trigeminal neuralgia?

<p>Tegretol (carbamazepine) (B)</p> Signup and view all the answers

Which cranial nerve mediates the efferent portion of the oculocardiac reflex?

<p>Vagus nerve (CN X) (A)</p> Signup and view all the answers

Which condition is characterized by idiopathic facial palsy and is associated with CN VII?

<p>Bell's palsy (C)</p> Signup and view all the answers

In which instance might vestibular neuritis develop?

<p>Due to herpes simplex virus (HSV) (D)</p> Signup and view all the answers

What is the primary sensory role of the vagus nerve?

<p>Providing sensory information from internal organs to the solitary nucleus (B)</p> Signup and view all the answers

Which muscle is not innervated by the recurrent laryngeal nerve (RLN)?

<p>Cricothyroid muscle (C)</p> Signup and view all the answers

What reflex is mediated by the vagus nerve in response to lung expansion?

<p>Hering-Breuer reflex (C)</p> Signup and view all the answers

What is a consequence of increased vagal tone during surgery?

<p>Bradycardia (C)</p> Signup and view all the answers

Which factor is least likely to cause increased vagal tone in a perioperative setting?

<p>State of deep anesthesia (C)</p> Signup and view all the answers

What typically happens to the tongue when the hypoglossal nerve is damaged? (select all that apply)

<p>Tongue exhibits atrophy and decreased mobility (B), Tongue deviates towards the damaged side (C)</p> Signup and view all the answers

Where is cranial nerve CN II located?

<p>In the optic canal (B)</p> Signup and view all the answers

Where is cranial nerve I (olfactory) located?

<p>Cribriform plate (A)</p> Signup and view all the answers

Which cranial nerves pass through the superior orbital fissure?

<p>Cranial Nerve III (Oculomotor), Cranial Nerve IV (Trochlear), Cranial Nerve V1 (Ophthalmic), Cranial Nerve VI (Abducens) (A)</p> Signup and view all the answers

Where does the maxillary branch of the trigeminal nerve exit the brain?

<p>Foramen rotundum (B)</p> Signup and view all the answers

Where does the mandibular branch of the trigeminal nerve exit the brain?

<p>foramen ovale (B)</p> Signup and view all the answers

Where are the facial nerve and vestibulocochlear nerve located?

<p>Internal acoustic meatus (A)</p> Signup and view all the answers

Which cranial nerves are associated with exiting the brain through the jugular foramen? (Select all that apply)

<p>Glossopharyngeal (CN IX) (A), Vagus (CN X) (B), Accessory (CN XI) (C)</p> Signup and view all the answers

Which cranial nerve is directly attached to the cerebrum?

<p>Olfactory Nerve (Cranial Nerve I) (A)</p> Signup and view all the answers

Which cranial nerve is attached to the hypothalamus?

<p>Optic nerve (CN II) (B)</p> Signup and view all the answers

Which cranial nerves are associated with the mesencephalon?

<p>Cranial Nerve III (Oculomotor) (A), Cranial Nerve IV (Trochlear) (B)</p> Signup and view all the answers

Which cranial nerves are associated with the pons?

<p>Trigeminal nerve (CN V) (A), Abducens nerve (CN VI) (B), Facial nerve (CN VII) (C), Auditory nerve (CN VIII) (D)</p> Signup and view all the answers

Which cranial nerves attach in the medulla? (Select all that apply)

<p>Glossopharyngeal (CN IX) (A), Vagus (CN X) (B), Accessory (CN XI) (C), Hypoglossal (CN XII) (D)</p> Signup and view all the answers

Which cranial nerves are responsible for the parasympathetic fibers of the peripheral nervous system?

<p>Oculomotor, Facial, Glossopharyngeal, Vagus (3, 7. 9, 10) (A)</p> Signup and view all the answers

What is anosmia?

<p>The loss of the sense of smell (A)</p> Signup and view all the answers

What is ageusia?

<p>Loss of the sense of taste (A)</p> Signup and view all the answers

Which of the following anesthetic agents are known causes of anosmia?

<p>Both Intranasal Ketamine and Intranasal 4% Lidocaine (C)</p> Signup and view all the answers

Which of the following are anesthetic causes of ageusia? (Select all that apply)

<p>LMA over inflation (A), Long use of LMA (B)</p> Signup and view all the answers

What is a potential complication of a CN II nerve block?

<p>Unintentional injection resulting in partial or total brainstem anesthesia (A)</p> Signup and view all the answers

Why is the optic nerve vulnerable to compression?

<p>It is located near the pituitary gland and circle of Willis (C)</p> Signup and view all the answers

Difficulty in moving the eye in which direction is indicative of trochlear nerve injury?

<p>Downward (B), Laterally (D)</p> Signup and view all the answers

What mediates the afferent portion of the oculocardiac reflex (5 and dime reflex)?

<p>Ophthalmic branch of CN V (A)</p> Signup and view all the answers

What is a consequence of an injury to the Abducens Nerve (CN VI)?

<p>Inability to move the eye outward/laterally/abduction (A)</p> Signup and view all the answers

5 branches of facial nerve = Two Zebras Bit My Cookie = Temporal, Zygomatic, Buccal, Marginal Mandibular, Cervical

<p>True (A)</p> Signup and view all the answers

What are the treatment options for the oculocardiac reflex?

<p>All of the above (D)</p> Signup and view all the answers

Which branch of the facial nerve is responsible for the motor component of the corneal reflex?

<p>Zygomatic branch (B)</p> Signup and view all the answers

Trochlear nerve palsy results in what impairment?

<p>Vertical diplopia (B)</p> Signup and view all the answers

Abducens nerve palsy results in what impairment?

<p>Horizontal diplopia (A)</p> Signup and view all the answers

Where is the onset of neuromuscular blockade best measured?

<p>Facial nerve via orbicularis oculi (A)</p> Signup and view all the answers

What is nystagmus?

<p>A condition characterized by involuntary eye movements (A)</p> Signup and view all the answers

Meclizine is used to treat palsy in which cranial nerve?

<p>Vestibulocochlear nerve (VIII) (D)</p> Signup and view all the answers

Which of the following drugs are known to be ototoxic? (Select all that apply)

<p>Loop diuretics (A), Certain antibiotics (B), NSAIDs (C), PDE5 inhibitors (D), Platinum agents (E), Quinine (F)</p> Signup and view all the answers

What is the carotid sinus nerve a branch of?

<p>Glossopharyngeal nerve (B)</p> Signup and view all the answers

What is an alternate name for the carotid sinus nerve?

<p>Hering's nerve (A)</p> Signup and view all the answers

Which branch of cranial nerve IX (glossopharyngeal nerve) carries parasympathetic fibers?

<p>Tympanic branch (A)</p> Signup and view all the answers

Which stroke syndromes are known to cause dysfunction of cranial nerve IX? (Select all that apply)

<p>Vernet syndrome (A), Collet-Sicard syndrome (B), Villaret syndrome (C)</p> Signup and view all the answers

A deviated uvula indicates dysfunction in which cranial nerves?

<p>Cranial Nerve IX and X (A)</p> Signup and view all the answers

Where do the vagus parasympathetic fibers originate?

<p>Dorsal vagus motor nucleus (A)</p> Signup and view all the answers

Where do the vagus parasympathetic fibers that innervate the heart originate?

<p>Nucleus ambiguus (A)</p> Signup and view all the answers

What is the primary function of the cricothyroid muscle?

<p>Tenses the vocal cords (B)</p> Signup and view all the answers

What is the action of the posterior cricoarytenoid muscle?

<p>Abduction of the vocal cords (B)</p> Signup and view all the answers

What is the action of the lateral cricoarytenoid muscle?

<p>Adducts the vocal cords (B)</p> Signup and view all the answers

What is the action of the thyroarytenoid muscle?

<p>Relaxes the vocal cords (B)</p> Signup and view all the answers

What is the Hering-Breuer reflex?

<p>A reflex that prevents over-inflation of the lungs by inhibiting inspiration. (A)</p> Signup and view all the answers

What provides sensory innervation to the Hering-Breuer reflex?

<p>Vagus nerve (A)</p> Signup and view all the answers

Which branch of the vagus nerve innervates the SA node?

<p>Right vagus nerve (B)</p> Signup and view all the answers

Which component of the spinal accessory nerve is considered to be part of the vagus nerve?

<p>Cranial component due to functional overlap (A)</p> Signup and view all the answers

What is the only tongue muscle not innervated by the hypoglossal nerve?

<p>Palatoglossus (D)</p> Signup and view all the answers

Which cranial nerve innervates the palatoglossus muscle?

<p>Vagus Nerve (CN X) (B)</p> Signup and view all the answers

Lesions in which area will cause the tongue to deviate away from the injury?

<p>Supranuclear region (A)</p> Signup and view all the answers

Why are bilateral hypoglossal nerve lesions worse than unilateral ones? (select 2)

<p>Bilateral lesions cause complete loss of tongue movement, affecting speech and swallowing. (A), Unilateral lesions are typically asymptomatic and have minimal impact due to compensation from the other nerve (B)</p> Signup and view all the answers

What disease process causes tongue fasciculations due to atrophy?

<p>Motor Neuron Disease (A)</p> Signup and view all the answers

What is neck-tongue syndrome?

<p>A condition involving pain with rapid movement in the ipsilateral neck and tongue area due to CN II damage. (A)</p> Signup and view all the answers

What is dysarthria?

<p>Slurred speech due to muscle weakness affecting articulation (A)</p> Signup and view all the answers

What does CRAO stand for?

<p>Central Retinal Artery Occlusion - vessel problem (A)</p> Signup and view all the answers

Which cranial nerve innervates the pharyngeal muscles (except the stylopharyngeus)?

<p>Vagus nerve (A)</p> Signup and view all the answers

Which muscle of the pharynx is innervated by the glossopharyngeal nerve?

<p>Stylopharyngeus (A)</p> Signup and view all the answers

Flashcards

What are Cranial Nerves?

Cranial nerves are a set of 12 nerve pairs originating from the brain, controlling sensory, motor, and autonomic functions throughout the head and neck. They are part of the Peripheral Nervous System (PNS) except for Cranial Nerve II (CN II), which is located in the meninges.

How are Cranial Nerves numbered?

Cranial nerves are numbered from I to XII based on their position, starting with the most superior (CN I) and ending with the most inferior (CN XII).

What are the categories of functions for Cranial Nerves?

Cranial nerves can be classified based on their primary function: sensory (CN I, II, VIII), motor (CN III, IV, VI, XI, XII), or both (CN V, VII, IX, X).

Where do Cranial Nerves originate?

Cranial nerves originate at different levels of the brain: CN I from the cerebrum, CN II near the hypothalamus, CN III-IV from the mesencephalon, CN V-VIII from the pons, and CN IX-XII from the medulla.

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Which Cranial Nerves are involved with the parasympathetic nervous system?

Certain cranial nerves (CN III, VII, IX, X) contain parasympathetic fibers, which control involuntary functions like heart rate, digestion, and pupil size.

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What are some common causes of Cranial Nerve injuries?

Cranial nerve injuries can result from various causes, including head trauma, infections, strokes, tumors, diabetes, hypertension, and autoimmune diseases.

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What are the symptoms of an Olfactory Nerve (CN I) injury?

Loss of smell (anosmia), decreased sense of smell (hyposmia), loss of taste (ageusia), reduced taste perception (hypogeusia), and altered taste (dysgeusia) are potential symptoms of olfactory nerve (CN I) injury.

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What are the symptoms of an Optic Nerve (CN II) injury?

Visual impairments, such as loss of vision or changes in visual perception, can occur due to optic nerve (CN II) injury. The optic chiasm, where optic nerve fibers cross, is a critical point for vision.

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What are the symptoms of an Oculomotor Nerve (CN III) injury?

Double vision (diplopia), a drooping eyelid (ptosis), and pupil dilation are common symptoms of oculomotor nerve (CN III) injury.

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What are the symptoms of a Trochlear Nerve (CN IV) injury?

Difficulty moving the eye downward and inward, often accompanied by a head tilt, can be a sign of trochlear nerve (CN IV) injury.

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What are the symptoms of a Trigeminal Nerve (CN V) injury?

Facial pain, loss of sensation in the face, and chewing problems can be caused by trigeminal nerve (CN V) injury.

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What are the symptoms of an Abducens Nerve (CN VI) injury?

Inability to move the eye laterally (outward), resulting in double vision (diplopia) and strabismus (crossed eyes), is a common sign of abducens nerve (CN VI) injury.

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What are the symptoms of a Facial Nerve (CN VII) injury?

Facial weakness, drooping, and loss of taste on the front two-thirds of the tongue are symptoms of facial nerve (CN VII) injury.

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What are the symptoms of a Vestibulocochlear Nerve (CN VIII) injury?

Hearing loss, balance issues, and dizziness are common symptoms of vestibulocochlear nerve (CN VIII) injury.

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What are the symptoms of a Glossopharyngeal Nerve (CN IX) injury?

Difficulty swallowing (dysphagia) and loss of taste on the back of the tongue are signs of glossopharyngeal nerve (CN IX) injury.

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What are the symptoms of a Vagus Nerve (CN X) injury?

Voice changes, difficulty swallowing, and problems with internal organ functions are potential symptoms of vagus nerve (CN X) injury.

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What are the symptoms of a Spinal Accessory Nerve (CN XI) injury?

Weakness in shoulder and neck muscles, affecting movements like turning the head or lifting the arm, can be a sign of spinal accessory nerve (CN XI) injury.

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What are the symptoms of a Hypoglossal Nerve (CN XII) injury?

Difficulty speaking (dysarthria), swallowing, and tongue movement, often presenting as tongue deviation towards the affected side, are symptoms of hypoglossal nerve (CN XII) injury.

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

The olfactory nerve (CN I) is responsible for the sense of smell. It carries signals from the olfactory bulb in the brain to the olfactory epithelium in the nose.

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

The optic nerve (CN II) transmits visual information from the eye to the brain. It is connected to the optic chiasm, where nerve fibers cross over to allow for perception in both eyes.

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What is the function of the Oculomotor Nerve (CN III)?

The oculomotor nerve (CN III) controls eye movement and eyelid elevation. It also regulates pupil size.

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

The trochlear nerve (CN IV) controls the superior oblique muscle, which helps to rotate the eye downward and inward. This assists in downward gaze.

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What is the function of the Trigeminal Nerve (CN V)?

The trigeminal nerve (CN V) has three branches: ophthalmic, maxillary, and mandibular. It's responsible for sensory functions of the face and motor control of chewing.

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

The abducens nerve (CN VI) controls the lateral rectus muscle, which is responsible for outward eye movement. This allows you to look laterally.

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What is the function of the Facial Nerve (CN VII)?

The facial nerve (CN VII) controls facial expressions, taste on the front two-thirds of the tongue, and tear and saliva production.

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

The vestibulocochlear nerve (CN VIII) is responsible for hearing and balance. It has two branches: vestibular (balance) and cochlear (hearing).

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What is the function of the Glossopharyngeal Nerve (CN IX)?

The glossopharyngeal nerve (CN IX) controls swallowing, taste on the back of the tongue, and regulates blood pressure by influencing the carotid sinus reflex.

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What is the function of the Vagus Nerve (CN X)?

The vagus nerve (CN X) innervates internal organs, controlling heart rate, digestion, and breathing. It also contributes to the Hering-Breuer reflex, which regulates lung volume.

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What is the function of the Spinal Accessory Nerve (CN XI)?

The spinal accessory nerve (CN XI) controls neck and shoulder movements, innervating the sternocleidomastoid and trapezius muscles.

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

The hypoglossal nerve (CN XII) controls tongue movements, which are essential for speech, chewing, and swallowing.

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Study Notes

Cranial Nerves Overview

  • Cranial nerves are part of the Peripheral Nervous System (PNS) except for Cranial Nerve II (CN II), which is located in the meninges.
  • Primary functions: sensory (CN I, II, VIII), motor (CN III, IV, VI, XI, XII), or both (CN V, VII, IX, X).
  • Cranial nerves are named from superior to inferior based on their brain origins.

Cranial Nerve Attachments

  • CN I: Cerebrum
  • CN II: Optic Chiasm, near the hypothalamus
  • CN III-IV: Mesencephalon
  • CN V-VIII: Pons
  • CN IX-XII: Medulla

Parasympathetic Fiber Cranial Nerves

  • Relevant nerves with parasympathetic fibers: CN III (Oculomotor), CN VII (Facial), CN IX (Glossopharyngeal), CN X (Vagus).

Causes and Symptoms of Cranial Nerve Injuries

  • Injury causes include head trauma, infections, strokes, tumors, diabetes, hypertension, and autoimmune diseases.

Olfactory Nerve (CN I)

  • Injury leads to anosmia (loss of smell), hyposmia (decreased sense of smell), ageusia (loss of taste), hypogeusia (reduction in taste sensations), and dysgeusia (altered taste).
  • Olfactory cells can regenerate.

Optic Nerve (CN II)

  • Injury results in vision loss or changes. The optic chiasm is crucial in crossing the optic nerve.
  • Vulnerable to compression near the pituitary gland; common causes of permanent loss include CRAO and ischemic optic neuropathy.
  • CN II nerve block types include retrobulbar, sub-tenon, and peribulbar techniques.

Oculomotor Nerve (CN III)

  • Injury causes double vision, droopy eyelid, and pupil dilation.
  • Controls eye movement and eyelid elevation.

Trochlear Nerve (CN IV)

  • Injury results in difficulty moving the eye downward or inward, often noted by a head tilt.

Trigeminal Nerve (CN V)

  • Injury causes facial pain, loss of sensation, and chewing difficulties.
  • Composed of three branches: ophthalmic (sensory), maxillary (sensory), and mandibular (motor and sensory).
  • Trigeminal neuralgia treated with Tegretol (carbamazepine) or surgical decompression.

Abducens Nerve (CN VI)

  • Injury leads to inability to move the eye laterally.
  • Symptoms include diplopia and strabismus.

Facial Nerve (CN VII)

  • Injury results in facial weakness, drooping, and loss of taste on the front two-thirds of the tongue.
  • Has five branches: Temporal, Zygomatic, Buccal, Marginal Mandibular, Cervical.
  • Bell's palsy is a common form of facial nerve paralysis.

Vestibulocochlear Nerve (CN VIII)

  • Injury leads to hearing loss and balance issues; consists of vestibular and cochlear branches.
  • Vulnerable to basilar skull fractures; vestibular neuritis can arise from HSV.

Glossopharyngeal Nerve (CN IX)

  • Injury results in dysphagia (difficulty swallowing) and loss of taste on the back of the tongue.
  • Carries parasympathetic fibers and plays a role in carotid sinus reflex regulation.

Vagus Nerve (CN X)

  • Injury leads to voice changes and swallowing difficulties.
  • Innervates internal organs and regulates heart rate and digestive processes.
  • Mediation of the Hering-Breuer reflex involving lung stretch receptors.

Spinal Accessory Nerve (CN XI)

  • Injury causes weakness in shoulder and neck muscles.
  • Innervates sternocleidomastoid and trapezius muscles; often presents in iatrogenic conditions.

Hypoglossal Nerve (CN XII)

  • Injury results in difficulty speaking, swallowing, and moving the tongue.
  • Controls all tongue muscles except palatoglossus; damage leads to tongue deviation towards the affected side.

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Test your knowledge on cranial nerves and their functions with this quiz. Explore the attachment points, roles in sensory and motor functions, and implications of injuries. Ideal for students of anatomy and neuroscience.

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