Cranial Nerves & Peripheral Nervous System
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Questions and Answers

What does PNS stand for?

Peripheral Nervous System

How many pairs of nerves are in the PNS?

43

What type of messages do cranial nerves transmit?

  • Neither Motor nor Sensory
  • Motor or Sensory (correct)
  • Motor only
  • Sensory only

    • All cranial nerves originate from the midbrain.

    <p>False</p> Signup and view all the answers

    What is the function of the olfactory nerve (I)?

    <p>Smell</p> Signup and view all the answers

    What is the function of the optic nerve (II)?

    <p>Vision</p> Signup and view all the answers

    What is the function of the oculomotor nerve (III)?

    <p>Extraocular eye movement, pupillary constriction, and upper eyelid elevation</p> Signup and view all the answers

    What is the function of the trochlear nerve (IV)?

    <p>Extraocular eye movement (inferior medial)</p> Signup and view all the answers

    What is the function of the trigeminal nerve (V)?

    <p>Sensory: transmitting stimuli from face and head, corneal reflex. Motor: chewing, biting, and lateral jaw movements</p> Signup and view all the answers

    What is the function of the abducent nerve (VI)?

    <p>Extraocular eye movement (lateral)</p> Signup and view all the answers

    What is the function of the facial nerve (VII)?

    <p>Sensory: taste receptors (anterior two-thirds of tongue); Motor: Facial muscle movement, including muscles of expression (those in the forehead and around the eyes and mouth)</p> Signup and view all the answers

    What is the function of the vestibulocochlear nerve (VIII)?

    <p>Sensory: hearing, sense of balance</p> Signup and view all the answers

    What is the function of the glossopharyngeal nerve (IX)?

    <p>BOTH: swallowing movements; Sensory: sensations of throat; taste receptors (posterior one-third of tongue)</p> Signup and view all the answers

    What is the function of the vagus nerve (X)?

    <p>BOTH) Motor - movement of palate, swallowing, gag reflex; activity of the thoracic and abdominal viscera, such as heart rate and peristalsis. Sensory: sensations of throat, larynx, and thoracic and abdominal viscera (heart, lungs, bronchi, and GI tract)</p> Signup and view all the answers

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

    <p>Motor: shoulder movement, head rotation</p> Signup and view all the answers

    What is the function of the hypoglossal nerve (XII)?

    <p>Motor: tongue movement</p> Signup and view all the answers

    The somatic nervous system controls voluntary movement.

    <p>True</p> Signup and view all the answers

    The autonomic nervous system is responsible for controlling involuntary functions like breathing and heart rate.

    <p>True</p> Signup and view all the answers

    What is the neurotransmitter released by somatic motor neurons?

    <p>Acetylcholine</p> Signup and view all the answers

    What is the function of the sympathetic nervous system?

    <p>Fight or Flight</p> Signup and view all the answers

    Sympathetic and parasympathetic effects are always opposite in all organs.

    <p>False</p> Signup and view all the answers

    The adrenal medulla is a part of the sympathetic nervous system.

    <p>True</p> Signup and view all the answers

    What are the two main neurotransmitters released by the autonomic nervous system?

    <p>Acetylcholine and Norepinephrine</p> Signup and view all the answers

    Norepinephrine is the same thing as noradrenaline.

    <p>True</p> Signup and view all the answers

    Nicotinic receptors are found at the neuromuscular junction of skeletal muscles.

    <p>True</p> Signup and view all the answers

    Muscarinic receptors are found in the postganglionic neurons of the sympathetic nervous system.

    <p>False</p> Signup and view all the answers

    What is the name of the toxin produced by certain mushrooms that is an agonist for muscarinic receptors?

    <p>Muscarine</p> Signup and view all the answers

    What is the name of the antagonist for muscarinic receptors?

    <p>Atropine</p> Signup and view all the answers

    Study Notes

    Cranial Nerves & Peripheral Nervous System

    • The peripheral nervous system (PNS) transmits signals between the central nervous system (CNS) and receptors/effectors throughout the body.
    • Axons are bundled together to form nerves.
    • The PNS comprises 43 pairs of nerves: 12 pairs of cranial nerves and 31 pairs of spinal nerves. These connect to the spinal cord.
    • Cranial nerves primarily connect the brain/brainstem to the head and neck. They carry motor or sensory or both types of messages.
    • Cranial nerves (except olfactory and optic) arise from the midbrain, pons, or medulla oblongata.

    Cranial Nerve Functions

    • Olfactory (I): Sensory, smell
    • Optic (II): Sensory, vision
    • Oculomotor (III): Motor, extraocular eye movement (superior, medial, and inferior lateral), pupillary constriction, and upper eyelid elevation.
    • Trochlear (IV): Motor, extraocular eye movement (inferior medial)
    • Trigeminal (V): Both, sensory (face and head, corneal reflex), motor (chewing, biting, lateral jaw movements).
    • Abducens (VI): Motor, extraocular eye movement (lateral)
    • Facial (VII): Both, sensory (taste anterior 2/3 of tongue), motor (facial muscle movement, including expression).
    • Vestibulocochlear (VIII): Sensory, hearing and balance
    • Glossopharyngeal (IX): Both, sensory (throat, taste posterior 1/3 tongue), motor (swallowing)
    • Vagus (X): Both, sensory (throat, larynx, thoracic and abdominal viscera), motor (palate movement, swallowing, gag reflex, and activity of thoracic/abdominal viscera - heart, lungs, and GI tract)
    • Accessory (XI): Motor, shoulder movement, head rotation
    • Hypoglossal (XII): Motor, tongue movement

    Somatic Nervous System

    • The somatic portion of the PNS carries signals from the CNS to skeletal muscle cells.
    • Axons in this system are large, myelinated, and pass directly to target muscles without synapses.
    • The neurotransmitter released by these neurons is acetylcholine.
    • Excitation of motor neurons causes muscle contractions.
    • Muscle relaxation occurs through the inhibition of motor neurons within the spinal cord.

    Autonomic Nervous System (ANS)

    • The ANS controls involuntary actions in internal organs.
    • It's typically comprised of two neuron chains (pre and postganglionic) connecting the CNS to effector cells (e.g cardiac muscle, smooth muscles glands).
    • The synapse between the two neurons occurs outside the CNS in structures called ganglia.
    • There are two main branches: sympathetic and parasympathetic.

    Autonomic Nervous System Divisions

    • Sympathetic Division:
      • Fibers originate from the thoracic (chest) and lumbar regions of the spinal cord.
      • Often called thoracolumbar division.
      • Associated with "fight or flight" responses.
    • Parasympathetic Division:
      • Fibers originate from the brainstem and sacral portion of the spinal cord.
      • Often called craniosacral division.
      • Associated with maintaining homeostasis (e.g., digestion).

    ANS Neurotransmitters

    • The main neurotransmitters of the ANS are acetylcholine and norepinephrine.
    • Acetylcholine is used by preganglionic neurons in both sympathetic and parasympathetic divisions, and by postganglionic neurons in the parasympathetic system.
    • Norepinephrine is released by postganglionic sympathetic neurons except for those connecting to sweat glands.

    Autonomic Receptors

    • Cholinergic receptors bind acetylcholine.
    • Nicotinic receptors are found at neuromuscular junctions of skeletal muscle, postganglionic neurons, and neurons in the brain.
    • Muscarinic receptors are found at neuromuscular junctions of cardiac and smooth muscle, glands, and some sympathetic neurons.
    • Adrenergic receptors respond to norepinephrine and epinephrine.
    • Different adrenergic receptor subtypes (α1, α2, β1, β2, β3) impact target effectors differently.

    ANS Physiological Effects

    • Physiological effects depend on whether sympathetic or parasympathetic activities are dominant.
    • Effects can be localized or widespread (eg. heart rate increases during stress via widespread sympathetic response).

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    Related Documents

    PNS Physiology PDF

    Description

    Test your knowledge about cranial nerves and the peripheral nervous system. This quiz covers the functions of each cranial nerve and their role in connecting the brain to various body parts. Challenge yourself to recall the sensory and motor functions associated with each nerve.

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