Cranial and Spinal Nerves Overview

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Questions and Answers

How many pairs of cranial nerves are there that originate from the brain?

8 pairs

14 pairs

12 pairs (correct)

10 pairs

Which cranial nerve is unique in its origin as it arises from both the brain and the spinal cord?

10th cranial nerve

12th cranial nerve

9th cranial nerve

11th cranial nerve (correct)

What is the total number of spinal nerves present in the human body?

35 pairs

30 pairs

24 pairs

31 pairs (correct)

Where do all cranial nerves exit from the cranial cavity?

Through foramina in the cranium Signup and view all the answers

What is the primary exit pathway for spinal nerves?

Through intervertebral foramina Signup and view all the answers

What is the neurotransmitter used by the first motor axon from the CNS to the autonomic ganglion?

Acetylcholine Signup and view all the answers

Which motor axon is associated with the autonomic ganglion?

Second motor axon Signup and view all the answers

After the autonomic ganglion, which neurotransmitters can potentially be released by the second motor axon?

Acetylcholine or Norepinephrine Signup and view all the answers

How many motor axons are involved in the autonomic pathway described?

Two motor axons Signup and view all the answers

What is the primary function of the preganglionic nerve in the autonomic nervous system?

To transmit signals from CNS to autonomic ganglion Signup and view all the answers

What response does the sympathetic nervous system trigger?

Fight or flight response Signup and view all the answers

Where are the cell bodies of preganglionic neurons in the sympathetic nervous system located?

Lateral horn of gray matter from T1-L2 Signup and view all the answers

Which of the following functions is associated with the parasympathetic nervous system?

Triggering rest-and-digest response Signup and view all the answers

What is the structural term for the sympathetic nervous system?

Thoracolumbar system Signup and view all the answers

What type of fibers are the preganglionic fibers in the sympathetic nervous system?

Short and myelinated Signup and view all the answers

How do the sympathetic and parasympathetic nervous systems operate with respect to one another?

Operate in conjunction with antagonistic control Signup and view all the answers

What is characteristic of postganglionic fibers in the sympathetic nervous system?

Long and non-myelinated Signup and view all the answers

What are the locations of the postganglionic neurons in the sympathetic nervous system?

Paravertebral and prevertebral ganglia Signup and view all the answers

What are the three possible courses of preganglionic fibers in the sympathetic nervous system?

Remain at the same level, ascend or descend, pass through the ganglion without synapsing. Signup and view all the answers

Which structure is an exception in the sympathetic nervous system regarding preganglionic sympathetic fibers?

Adrenal gland Signup and view all the answers

How do postganglionic axons reach the abdominal pelvic organs?

By following arteries to the organs. Signup and view all the answers

What do modified postganglionic neurons in the adrenal medulla release into the blood vessels?

Epinephrine and norepinephrine. Signup and view all the answers

Which statement about splanchnic nerves is correct?

They do not synapse and pass through the ganglion. Signup and view all the answers

What is the primary function of the cells in the adrenal medulla?

To release neurotransmitters for a widespread sympathetic response. Signup and view all the answers

What happens during an 'adrenaline surge' in emergency situations?

Both epinephrine and norepinephrine are released directly into blood vessels. Signup and view all the answers

Which of the following accurately describes the sympathetic trunk?

It allows for the ascend and descent of some preganglionic fibers. Signup and view all the answers

What is the primary neurotransmitter released by preganglionic neurons in the autonomic nervous system?

Acetylcholine Signup and view all the answers

Where are the cell bodies of postganglionic neurons located?

In the autonomic ganglia Signup and view all the answers

Which part of the nervous system is responsible for the involuntary control of heart rate?

Autonomic nervous system Signup and view all the answers

Which type of neuron in the autonomic nervous system is always myelinated?

Preganglionic neuron Signup and view all the answers

What type of muscle is primarily influenced by the autonomic nervous system?

Cardiac muscle Signup and view all the answers

How does the control of motor neurons differ between the somatic and autonomic nervous systems?

Somatic is excitatory only, autonomic can be both excitatory or inhibitory Signup and view all the answers

What is the main function of the autonomic nervous system?

Regulate bodily functions automatically Signup and view all the answers

Which of the following statements is true about the autonomic nervous system?

It influences smooth and cardiac muscles Signup and view all the answers

Study Notes

Cranial Nerves

All 12 pairs of cranial nerves arise from the brain except the 11th cranial nerve which arises from the brain and spinal cord.
All cranial nerves exit the cranial cavity through foramina in the cranium.

Spinal Nerves

31 pairs of spinal nerves (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal nerves).
All exit the vertebral column through intervertebral foramina.

Autonomic Nervous System

Part of the Peripheral Nervous System that controls involuntary actions.
Contains two nerve cells:
- Preganglionic: with cell body located in the brain stem or spinal cord, always myelinated, neurotransmitter is acetylcholine
- Postganglionic: with cell body located in an autonomic ganglion, non-myelinated, neurotransmitter is acetylcholine, epinephrine, or norepinephrine

Somatic vs. Autonomic Nervous System

Somatic Nervous System:
- Sensory neuron (afferent pathway): Somatic senses & special senses
- Effector: Skeletal muscle
- Control of motor neuron and effect: Voluntary control, excitatory effect
- Motor Neuron (efferent pathway) and neurotransmitter: One motor axon from CNS to effector. NT is Acetylcholine
Autonomic Nervous System:
- Sensory neuron (afferent pathway): Located in blood vessel & visceral organ
- Effector: Smooth muscles, cardiac muscles and glands
- Control of motor neuron and effect: Involuntary control, excitatory or inhibitory effect
- Motor Neuron (efferent pathway) and neurotransmitter: First motor axon from CNS to autonomic ganglion (preganglionic nerve). Second motor axon from autonomic ganglion to effector (postganglionic nerve). NT can be acetylcholine or norepinephrine

Subdivision of Autonomic Nervous System

Sympathetic Nervous System:
- Prepares the body to function under stress (exercise, excitement, emergencies).
- Triggers fight or flight response.
- Prepares the body for intense muscle activity.
- Cell bodies of preganglionic neurons are in lateral horn of gray matter of spinal cord from T1-L2 (L3).
- Cell bodies of postganglionic neurons occur in two locations:
  - Paravertebral ganglia: either side of the vertebral column, form sympathetic trunks (chains).
  - Prevertebral ganglia: located in plexus that surround the origins of main branches of abdominal aorta.
- Preganglionic fibers are short and myelinated.
- Postganglionic fibers are long and non-myelinated.
Parasympathetic Nervous System:
- Maintenance functions.
- Triggers "Rest-and-digest" response.
- Counterbalances sympathetic function.

Sympathetic Nervous System (Continued)

Course of preganglionic fibres:
- Remain at same level: Synapse with postganglionic neuron of paravertebral ganglia.
- Ascend or descend within sympathetic trunk: Synapse with a paravertebral postganglionic neuron.
- No synapse: Pass through paravertebral ganglion without synapse, form splanchnic nerve. Synapse in prevertebral ganglion.
Adrenal gland exception:
- Preganglionic sympathetic fibres do not synapse in prevertebral ganglia and terminate directly in the cells of adrenal medulla.
- These cells act as modified postganglionic neurons and release the NT (epinephrine/norepinephrine) directly into the blood vessels. This causes a widespread sympathetic response (adrenaline "surge" in emergency).

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Description

This quiz explores the anatomy and function of cranial and spinal nerves, as well as the autonomic nervous system. Test your knowledge about the 12 cranial nerves, 31 spinal nerves, and the differences between the somatic and autonomic systems. Perfect for students of neuroscience and anatomy.