Section 8-8
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Questions and Answers

What structure is formed by the bundling of PNS axons wrapped in connective tissue?

  • Cranial Nerves
  • Peripheral Nerves (correct)
  • Spinal Nerves
  • Ganglia

Which of the following best describes the primary function of the olfactory nerves (N I)?

  • Control muscle movement in the face
  • Carry auditory information
  • Transmit visual data from the eyes
  • Relay special sensory information for smell (correct)

What is the name given to the clusters of cell bodies found in the PNS?

  • Nuclei
  • Ganglia (correct)
  • Nerves
  • Tracts

Which cranial nerve is directly attached to the cerebrum?

<p>Olfactory nerve (N I) (D)</p> Signup and view all the answers

What is the general function of the optic nerves (N II)?

<p>Transmit visual data (B)</p> Signup and view all the answers

Which of the following is NOT a correct description of a cranial nerve's function?

<p>A nerve that carries information about hormone levels (D)</p> Signup and view all the answers

Which of the following best describes how cranial nerves are generally designated?

<p>By a letter and a Roman numeral indicating the position along the brain (C)</p> Signup and view all the answers

Besides sensory and motor functions, which additional role do some cranial nerves have?

<p>Carrying autonomic fibers to PNS ganglia (C)</p> Signup and view all the answers

Which nerve provides voluntary control of tongue movements?

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

Which muscle group is controlled by the external branch of a certain nerve (as mentioned in the text)?

<p>Sternocleidomastoid and trapezius muscles (A)</p> Signup and view all the answers

Damage to a spinal nerve or dorsal root ganglion can cause a loss of sensation in a specific area, known as a:

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

Which nerve plexus innervates the muscles of the neck and controls the diaphragm?

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

The laryngeal muscles, which control the vocal cords, are innervated by what branch of a specific nerve?

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

A mild, temporary palsy, such as when your arm or leg 'falls asleep', is an example of:

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

How many pairs of spinal nerves are classified as sacral nerves?

<p>5 (A)</p> Signup and view all the answers

The brachial plexus has what area of innervation?

<p>Pectoral girdles and upper limbs (A)</p> Signup and view all the answers

Which cranial nerve does not have motor nuclei located in the midbrain?

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

What is the primary function of the abducens nerve?

<p>To move the eyeball laterally away from the midline. (B)</p> Signup and view all the answers

Which cranial nerve provides sensory information for the posterior third of the tongue?

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

Which nerve carries sensory information from the auricle and external acoustic meatus?

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

Which of the following is not a branch of the trigeminal nerve?

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

Which nerve carries autonomic fibers to the muscles that control the amount of light entering the eye?

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

The vestibulocochlear nerve is responsible for:

<p>Monitoring sensory receptors of the internal ear (B)</p> Signup and view all the answers

Which cranial nerve provides motor control over the chewing muscles?

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

Which of the following is not innervated by the oculomotor nerve?

<p>Lateral rectus muscle (D)</p> Signup and view all the answers

Which of the following is innervated by the trochlear nerve?

<p>Superior oblique muscle (A)</p> Signup and view all the answers

Which nerve fibers originate in the spinal cord in addition to the medulla oblongata?

<p>Accessory nerves (B)</p> Signup and view all the answers

Which of the following does the mandibular branch of the trigeminal nerve not provide sensory information from?

<p>Upper gums and teeth (A)</p> Signup and view all the answers

The nuclei of the abducens nerves are located in the:

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

Which two locations contain nuclei associated with the vestibulocochlear nerves?

<p>Pons and medulla oblongata (A)</p> Signup and view all the answers

Which cranial nerve provides taste sensation from the anterior two-thirds of the tongue and controls muscles of facial expression?

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

Flashcards

What is the PNS?

The peripheral nervous system (PNS) connects the central nervous system (CNS) to the rest of the body. It carries sensory information and motor commands.

What are nerves?

Bundles of axons in the PNS wrapped in connective tissue. They carry signals to and from the CNS.

What are cranial nerves?

Nerves that originate from the brain and control functions like sight, taste, and hearing.

What are spinal nerves?

Nerves that connect to the spinal cord and control bodily functions like movement and sensation.

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What is a ganglion?

A cluster of neuron cell bodies located outside the CNS.

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How are cranial nerves classified?

Cranial nerves can be classified as sensory, motor, or mixed, depending on the type of information they carry.

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What are the olfactory nerves (N I)?

The olfactory nerves (N I) are the only cranial nerves attached to the cerebrum and are responsible for the sense of smell.

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What are the optic nerves (N II)?

The optic nerves (N II) carry visual information from the eyes to the brain.

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What is the role of the internal branch of the accessory nerve?

A cranial nerve that innervates the voluntary swallowing muscles of the soft palate and pharynx, as well as the laryngeal muscles.

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What controls the sternocleidomastoid and trapezius muscles?

A cranial nerve that controls the sternocleidomastoid and trapezius muscles, which are involved in movement of the shoulder and neck.

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What nerve controls tongue movements?

A cranial nerve (N XII) that supplies voluntary control over movements of the tongue.

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What is a dermatome?

A specific region of the body surface monitored by a pair of spinal nerves.

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What are nerve plexuses?

Areas where several spinal nerves come together to form networks, allowing for complex innervation of specific body regions.

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What is the function of the cervical plexus?

The cervical plexus innervates the neck muscles and the diaphragm.

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What does the brachial plexus innervate?

The brachial plexus innervates the pectoral girdle and upper limbs.

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What do the lumbar and sacral plexuses innervate?

The lumbar plexus and sacral plexus supply the pelvic girdle and lower limbs.

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Optic Chiasm

The point where optic nerves from each eye cross.

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Oculomotor Nerves (CN III)

Nerves that control the movement of the eyeball.

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Trochlear Nerves (CN IV)

Nerves that control the superior oblique muscle of the eye, responsible for downward and outward eye movement.

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Trigeminal Nerve (CN V)

The largest cranial nerve, responsible for sensory input from the face and motor control of chewing.

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Ophthalmic Branch

The branch of the trigeminal nerve that provides sensory information for the orbit of the eye, nasal cavity, and skin around the forehead and nose.

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Maxillary Branch

The branch of the trigeminal nerve that provides sensory information for the lower eyelid, upper lip, cheek, and upper teeth.

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Mandibular Branch

The largest branch of the trigeminal nerve, providing sensory information for the lower teeth, temples, and tongue, and motor control for chewing.

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Abducens Nerve (CN VI)

The nerve that controls the lateral rectus muscle, responsible for outward movement of the eyeball.

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Facial Nerves (CN VII)

Mixed nerves responsible for facial expressions, taste sensation on the anterior tongue, and control of tear and salivary glands.

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Vestibulocochlear Nerves (CN VIII)

Nerves that monitor sensory input from the inner ear, responsible for balance and hearing.

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Glossopharyngeal Nerves (CN IX)

Mixed nerves that innervate the tongue and pharynx, responsible for taste, swallowing, and blood pressure monitoring.

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Vagus Nerve (CN X)

The longest cranial nerve, responsible for sensory information from the auricle, diaphragm, and various internal organs, and motor control of the pharynx, esophagus, and visceral organs.

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Accessory Nerves (CN XI)

Motor nerves that innervate muscles in the neck and back, involved in head movement.

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Vestibule

The part of the internal ear responsible for balance sensations, monitored by the vestibular nerve.

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Cochlea

The part of the inner ear responsible for hearing, monitored by the cochlear nerve.

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Study Notes

Peripheral Nervous System (PNS)

  • Links central nervous system (CNS) neurons to body
  • Carries sensory info and motor commands via PNS axons
  • Axons bundled in connective tissue form peripheral nerves
  • Cranial nerves originate in brain, spinal nerves in spinal cord
  • PNS includes cell bodies (ganglia) and axons of sensory/motor neurons in autonomic nervous system (ANS)

Cranial Nerves

  • 12 pairs connect to brain
  • Named based on appearance/function, designated N+Roman numeral
  • Example: N I (olfactory nerves)
  • Classified as sensory, motor, or mixed (often with secondary functions)
  • Some cranial nerves (III, VII, IX, X) also carry autonomic fibers to PNS ganglia, similar to spinal nerves.

Olfactory Nerves (N I)

  • Only cranial nerves attached to cerebrum
  • Carry special sensory info for smell
  • Originate in nasal cavity epithelium, penetrate ethmoid bone & synapse in olfactory bulbs
  • Axons travel to olfactory centers via olfactory tracts

Optic Nerves (N II)

  • Carry visual info from eyes
  • Pass through optic foramina, intersect at optic chiasm ("crossing")
  • Continue as optic tracts to nuclei of left/right thalamus

Oculomotor Nerves (N III)

  • Midbrain motor nuclei control N III & IV
  • Innervate 4 extrinsic eye muscles (superior, medial, inferior rectus & inferior oblique)
  • Also carry autonomic fibers to intrinsic eye muscles (controlling light & lens shape)

Trochlear Nerves (N IV)

  • Smallest cranial nerves
  • Innervate superior oblique eye muscle
  • Motor nuclei located in midbrain
  • Name refers to pulley-shaped ligament sling

Trigeminal Nerves (N V)

  • Largest cranial nerves (originate in pons)
  • Sensory info from face & head, motor control over chewing muscles
  • Three branches:
    • Ophthalmic (sensory: orbit, nose, foreheard)
    • Maxillary (sensory: lower eyelid, upper lip, palate)
    • Mandibular (largest, sensory - lower face, gums, tongue , motor- chewing)

Abducens Nerves (N VI)

  • Innervate lateral rectus eye muscle (responsible for abduction)
  • Nuclei in pons
  • Emerge at border of pons & medulla oblongata
  • Travel with oculomotor and trochlear nerves within the orbit

Facial Nerves (N VII)

  • Mixed nerves of face
  • Sensory & motor roots emerge from pons sides
  • Sensory fibers monitor facial muscles, facial pressure, taste (anterior 2/3 tongue)
  • Motor fibers control facial expressions, muscles around ear
  • Carry some autonomic fibers (control tear & salivary glands.)

Vestibulocochlear Nerves (N VIII)

  • Monitor sensory receptors in inner ear
  • Two parts:
    • Vestibular nerve (balance, position, movement)
    • Cochlear nerve (hearing)

Glossopharyngeal Nerves (N IX)

  • Mixed nerves, innervate tongue & pharynx
  • Sensory & motor nuclei in medulla oblongata
  • Sensory: taste (posterior 1/3 of tongue), blood pressure, dissolved gases
  • Motor: swallowing muscles
  • Carry autonomic fibers (control parotid salivary glands)

Vagus Nerves (N X)

  • "Wandering" nerves
  • Sensory info from ear, diaphragm, pharynx, esophagus, respiratory tract, abdominal organs
  • Sensory nuclei in medulla oblongata; vital for autonomic visceral control (not consciously perceived)
  • Motor: control skeletal muscles (soft palate, pharynx, esophagus) and also affect cardiac, smooth muscle of digestive system

Accessory Nerves (N XI)

  • Motor nerves for neck & back muscles
  • Some fibers originate in spinal cord (cervical segments)
  • Join together in cranium, exit as N XI; divide into two branches:
    • Internal branch (joins vagus, controls voluntary swallowing, larynx, speech)
    • External branch (controls sternocleidomastoid & trapezius muscles of pectoral girdle)

Hypoglossal Nerves (N XII)

  • Provide voluntary control over tongue movements
  • Nuclei located in medulla oblongata

Spinal Nerves

  • 31 pairs, grouped by vertebral column region
  • Cervical (8), Thoracic (12), Lumbar (5), Sacral (5), Coccygeal (1)
  • Each pair monitors a specific body surface area called a dermatome
  • Dermatome importance: clinical diagnosis of damage or infection to a spinal nerve/dorsal root ganglia

Nerve Plexuses

  • Skeletal muscle fusion often results in innervation by multiple spinal nerves.
  • Networks (plexuses) provide nerve trunks.
  • Four major plexuses: cervical, brachial, lumbar, sacral (sometimes called lumbosacral)
  • Innervate muscles of neck, pectoral girdles, upper limbs, pelvic girdle, and lower limbs.
  • Also contain sensory and motor fibers.
  • Peripheral neuropathies (peripheral nerve palsies) result from nerve trauma/compression.

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Description

Explore the key components and functions of the Peripheral Nervous System (PNS), including cranial nerves and their classifications. This quiz covers the connections between the PNS and CNS, detailing the sensory and motor roles of cranial nerves. Test your knowledge on the structure and function of these essential nerve pathways.

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