Podcast
Questions and Answers
What type of muscle is primarily innervated by the autonomic nervous system?
What type of muscle is primarily innervated by the autonomic nervous system?
Which cranial nerve is NOT involved in the parasympathetic supply to the head and neck?
Which cranial nerve is NOT involved in the parasympathetic supply to the head and neck?
What is the primary role of sympathetic visceral efferent fibers?
What is the primary role of sympathetic visceral efferent fibers?
Which ganglion is associated with the smooth muscle of the eye?
Which ganglion is associated with the smooth muscle of the eye?
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Which function is NOT typically associated with the parasympathetic nervous system?
Which function is NOT typically associated with the parasympathetic nervous system?
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From which spinal segments do the sympathetic preganglionic fibers originate?
From which spinal segments do the sympathetic preganglionic fibers originate?
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What is a general function of the parasympathetic nervous system?
What is a general function of the parasympathetic nervous system?
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Which structure do the postganglionic fibers of the parasympathetic system distribute through?
Which structure do the postganglionic fibers of the parasympathetic system distribute through?
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Which muscle is NOT innervated by the oculomotor nerve (CN III)?
Which muscle is NOT innervated by the oculomotor nerve (CN III)?
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What type of fibers are found in the Edinger-Westphal nucleus?
What type of fibers are found in the Edinger-Westphal nucleus?
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Which symptom is characteristic of CN III palsy?
Which symptom is characteristic of CN III palsy?
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Where does the oculomotor nerve primarily emerge from the brain?
Where does the oculomotor nerve primarily emerge from the brain?
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Which of the following muscles is involved in raising the eyelid?
Which of the following muscles is involved in raising the eyelid?
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What is the pathway of the oculomotor nerve after it leaves the midbrain?
What is the pathway of the oculomotor nerve after it leaves the midbrain?
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Which of the following is NOT a function of the oculomotor nerve?
Which of the following is NOT a function of the oculomotor nerve?
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The oculomotor nerve divides into which of the following divisions?
The oculomotor nerve divides into which of the following divisions?
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What is the function of the motor root of the trigeminal nerve?
What is the function of the motor root of the trigeminal nerve?
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Which ganglia are suspended by the trigeminal nerve?
Which ganglia are suspended by the trigeminal nerve?
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What does the supratrochlear nerve innervate?
What does the supratrochlear nerve innervate?
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Which of the following is the smallest division of the trigeminal nerve?
Which of the following is the smallest division of the trigeminal nerve?
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Which of the following statements about the trigeminal ganglion is correct?
Which of the following statements about the trigeminal ganglion is correct?
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Which function does the long ciliary nerve carry?
Which function does the long ciliary nerve carry?
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What is the primary role of the tensor tympani muscle?
What is the primary role of the tensor tympani muscle?
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How does the nasociliary nerve contribute to the overall function of the trigeminal nerve?
How does the nasociliary nerve contribute to the overall function of the trigeminal nerve?
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Which division of the trigeminal nerve primarily provides sensation to the forehead and scalp?
Which division of the trigeminal nerve primarily provides sensation to the forehead and scalp?
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What type of fibers are carried by the trigeminal nerve from the anterior 2/3 of the tongue?
What type of fibers are carried by the trigeminal nerve from the anterior 2/3 of the tongue?
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What type of nerve fibers are carried by the infratrochlear nerve?
What type of nerve fibers are carried by the infratrochlear nerve?
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Which nerve provides general sensory innervation to the lacrimal gland?
Which nerve provides general sensory innervation to the lacrimal gland?
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Which of the following nerves carries hitchhiking sympathetic fibers to the iris?
Which of the following nerves carries hitchhiking sympathetic fibers to the iris?
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Which branch of the maxillary nerve primarily provides sensation to the nasal and palatal mucosa?
Which branch of the maxillary nerve primarily provides sensation to the nasal and palatal mucosa?
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What is the primary function of the short ciliary nerve?
What is the primary function of the short ciliary nerve?
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How does the zygomatic nerve relate to the lacrimal nerve?
How does the zygomatic nerve relate to the lacrimal nerve?
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Which of the following best describes the route of the maxillary nerve?
Which of the following best describes the route of the maxillary nerve?
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Which branch of the ophthalmic nerve is responsible for sensory innervation to the forehead?
Which branch of the ophthalmic nerve is responsible for sensory innervation to the forehead?
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Study Notes
Autonomic Nervous System
- Innervates smooth muscles (blood vessels, iris), cardiac muscle, and glands
- Two types of fibers:
- Visceral afferent: brings sensory info from internal organs
- Visceral efferent: carries motor signals to internal organs
- Visceral afferent fibers: carry sensory info from carotid body and sinus (CN IX)
- Visceral efferent fibers
- Sympathetic: releases "fight or flight" hormones (epinephrine and norepinephrine) to stimulate energy expenditure
- Parasympathetic: promotes energy conservation and restorative functions
Oculomotor Nerve (CN III)
- Responsible for striated eye and eyelid muscle movement and parasympathetic innervation of smooth eye muscles
- Striated muscles innervated by CN III:
- Levator palpebrae superioris (raises eyelid)
- Superior, inferior, and medial rectus (eye movement)
- Inferior oblique (rotates the eye)
- Smooth muscles innervated by CN III:
- Pupillary sphincter muscle (constricts pupil)
- Ciliary muscle (focuses the lens)
- Two nuclei located in midbrain:
- Oculomotor nucleus: controls striated muscle innervation
- Edinger-Westphal nucleus: controls parasympathetic innervation of eye muscles
- Pathway:
- Exits the midbrain
- Travels lateral to the posterior communicating artery
- Enters the cavernous sinus wall
- Divides into superior and inferior divisions anterior to the cavernous sinus
- Enters the superior orbital fissure (SOF)
- Passes through annulus of Zinn
Trigeminal Nerve (CN V)
- Largest cranial nerve
- Sensory root: carries sensory information from the face, head, and neck
- Motor root: controls muscles of mastication and other facial muscles
- Trigeminal ganglion (semilunar ganglion): houses cell bodies of sensory fibers
- Located in Meckel’s cave (trigeminal cave) on the petrous portion of the temporal bone
- Covered by meninges and surrounded by CSF
Trigeminal Nerve Divisions
- V1: Ophthalmic Nerve
- Smallest division
- Only carries sensory information (general afferent)
- Branches:
-
Frontal Nerve:
- Supraorbital: innervates forehead, upper eyelid, scalp, and frontal sinus
- Supratrochlear: innervates medial eyelid, forehead, and conjunctiva
-
Nasociliary Nerve:
- Infratrochlear: innervates conjunctiva, medial eyelid, lacrimal sac, caruncle, and side of nose
- Short ciliary: innervates ciliary body, iris sphincter, and carries hitchhiking fibers (parasympathetic and sympathetic)
- Long ciliary: innervates cornea and carries hitchhiking sympathetic fibers
- Anterior and Posterior Ethmoidal: innervate ethmoid sinuses and nasal cavity
-
Lacrimal Nerve:
- Innervates lacrimal gland, conjunctiva, and lateral eyelid
- Receives hitchhiking parasympathetic fibers from pterygopalatine ganglion
-
Tentorial Nerve:
- Innervates meninges
-
Frontal Nerve:
- V2: Maxillary Nerve
- Only carries sensory information (general afferent)
- Suspends pterygopalatine ganglion and carries hitchhiking fibers:
- Postganglionic parasympathetic fibers to the lacrimal gland and nasal and palatal mucosa
- Postganglionic sympathetic fibers from the internal carotid artery to the same targets
- Pathway:
- Trigeminal ganglion
- Lateral wall of cavernous sinus
- Foramen rotundum
- Pterygopalatine fossa
- Divides into several branches
- Branches:
-
Zygomatic Nerve:
- Zygomaticofacial nerve: sensation from cheek skin
- Zygomaticotemporal nerve: sensation from temporal region skin
- Conveys hitchhiking postganglionic parasympathetic fibers from the pterygopalatine ganglion to the lacrimal nerve
-
Infraorbital Nerve:
- Innervates lower eyelid, cheek, upper lip, and teeth
- Greater Palatine Nerve: -Innervates posterior palate and palatine tonsil
-
Lesser Palatine Nerve:
- Innervates soft palate and palatine tonsil
-
Nasopalatine Nerve:
- Innervates anterior palate and nasal septum
-
Meningeal Branch:
- Innervates dura mater
-
Zygomatic Nerve:
- V3: Mandibular Nerve
- Carries both sensory and motor information
- Innervates muscles of mastication
- Branches:
-
Motor branches:
- Masseter
- Temporalis
- Lateral and Medial Pterygoids
- Tensor Tympani
- Anterior Belly of Digastric
- Mylohyoid
- Tensor Veli Palatini
-
Sensory branches:
- Auriculotemporal nerve: innervates temporomandibular joint, TMJ, part of ear, skin over temporalis
- Inferior alveolar nerve: innervates lower teeth and lower gums, carries hitchhiking fibers to submandibular ganglion
- Lingual nerve: innervates anterior ⅔ of tongue, carries hitchhiking fibers from chorda tympani (for taste)
- Mental nerve: innervates lower lip and chin
- Buccal nerve: innervates buccal mucosa
- Inferior Dental Plexus: innervates all lower teeth
-
Motor branches:
Trigeminal Nerve Function Summary
- Carries general afferent (GA) fibers from most of the head and neck
- Carries general efferent (GE) fibers that motor innervate muscles of mastication
- Suspends four parasympathetic ganglia:
- Ciliary: smooth eye muscles
- Pterygopalatine: lacrimal gland
- Otic: parotid gland
- Submandibular: submandibular and sublingual glands
- Carries hitchhiking fibers:
- Special afferent (SA) fibers: taste from anterior ⅔ of tongue and palate (chorda tympani)
- Sympathetic fibers from internal carotid artery: innervation of smooth eye muscles and blood vessels
- Parasympathetic fibers from CN III, VII, and IX
Clinical Considerations
- CN III palsy: drooping eyelid (ptosis), eye turned down and out, dilated pupil that doesn’t react to light
- Usually caused by an intracranial aneurysm and requires immediate medical attention
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Description
Test your knowledge on the autonomic nervous system and the functions of the oculomotor nerve (CN III). This quiz covers the innervation details of smooth muscles, cardiac muscles, and glands, along with the roles of sympathetic and parasympathetic fibers. Challenge yourself to recall important concepts related to muscle movement and sensory pathways.
