Nervous System VII Flashcards

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Questions and Answers

What are spinal nerves?

31 pairs of mixed nerves named for point of issue from spinal cord.

What is a mixed nerve?

A mixed nerve contains both sensory and motor neurons.

What do spinal nerves do?

Supply all body parts but head and part of neck (cranial nerves).

Where do spinal nerves exit?

At the intervertebral foramen. Signup and view all the answers

What are the two roots that connect to the spinal cord?

Ventral roots and dorsal roots. Signup and view all the answers

How do spinal nerves form?

Dorsal and ventral roots unite to form spinal nerves. Signup and view all the answers

What are the branches of spinal nerves called?

Dorsal ramus and ventral ramus. Signup and view all the answers

What does RRNR stand for?

Rootlet - Root - Nerve - Ramus. Signup and view all the answers

What are the ventral rami except T2-T12 known for?

Forming interlacing nerve networks called nerve plexuses. Signup and view all the answers

What are the two types of paralysis mentioned?

Quadriplegia and paraplegia. Signup and view all the answers

What happens to mature neurons regarding regeneration?

They are amitotic and do not divide. Signup and view all the answers

What causes gait problems related to a herniated disc?

Damage to the obturator nerve. Signup and view all the answers

What is the autonomic nervous system?

The motor division of the peripheral nervous system that controls body activities involuntarily. Signup and view all the answers

What are the two arms of the autonomic nervous system?

Sympathetic and parasympathetic. Signup and view all the answers

What is the craniosacral division?

Parasympathetic motor nerves. Signup and view all the answers

Sympathetic motor nerves originate from thoracic and lumbar spinal nerves. It is also called the _____________ division.

Thoracolumbar. Signup and view all the answers

What are the two types of neurons in the autonomic nervous system?

Pre-ganglionic neuron and post-ganglionic neuron. Signup and view all the answers

Where do parasympathetic pre-ganglionic neurons travel?

To distant ganglia close to the tissue affected. Signup and view all the answers

Where do sympathetic pre-ganglionic neurons travel?

Primarily to ganglia in the sympathetic trunk via white rami communicans. Signup and view all the answers

What neurotransmitter is released by preganglionic axons of both parasympathetic and sympathetic divisions?

Acetylcholine (ACH). Signup and view all the answers

What neurotransmitter do postganglionic axons of parasympathetic neurons release?

Acetylcholine (ACH). Signup and view all the answers

What neurotransmitters do postganglionic axons of sympathetic neurons release?

Epinephrine and norepinephrine. Signup and view all the answers

What do cholinergic fibers release?

Neurotransmitter acetylcholine (ACH). Signup and view all the answers

What type of receptors bind acetylcholine (ACh)?

Cholinergic receptors. Signup and view all the answers

What are the two types of cholinergic receptors?

Nicotinic and muscarinic. Signup and view all the answers

Study Notes

Spinal Nerves

31 pairs of spinal nerves; mixed nerves named for their exit point from the spinal cord.
Contain both sensory and motor neurons, making them mixed nerves.
Supply all body regions except the head and part of the neck.
Distribution includes 8 cervical (C1-C8), 12 thoracic (T1-T12), 5 lumbar (L1-L5), 5 sacral (S1-S5), and 1 coccygeal (C0) nerve.

Exit and Structure of Spinal Nerves

Spinal nerves exit the spinal column through the intervertebral foramen.
Neuronal connections to the spinal cord are through ventral and dorsal roots.
Dorsal and ventral roots unite to form spinal nerves.

Rami of Spinal Nerves

Each spinal nerve branches into mixed rami: a shorter dorsal ramus and a larger ventral ramus.
Ventral rami, except T2-T12, form interlacing nerve networks known as nerve plexuses (cervical, brachial, lumbar, sacral).
Dorsal rami do not form plexuses, ensuring different muscle innervation.

Nerve Plexuses and Their Importance

Nerve fibers within plexuses criss-cross, resulting in branches containing fibers from various spinal nerves.
Each limb muscle typically receives nerve innervation from multiple spinal nerves, providing redundancy in case of damage.

Paralysis Conditions

Quadraplegia refers to paralysis from the neck down, as seen in Christopher Reeve's case.
Paraplegia refers to paralysis from the waist down, exemplified by Franklin D. Roosevelt.

Nerve Fiber Regeneration

Mature neurons do not divide; damage to cell bodies prevents regeneration.
Peripheral axon damage may allow regeneration; the closer the severed ends, the higher the chance of success.

Autonomic Nervous System (ANS)

ANS is the motor division of the peripheral nervous system controlling involuntary activities.
Consists of two arms: sympathetic (fight or flight) and parasympathetic (rest and digest).
Most tissues receive innervation from both sympathetic and parasympathetic neurons, which have opposing effects.

Autonomic Nervous System Divisions

Parasympathetic division: originates from cranial nerves and sacral spinal nerves; also called the craniosacral division.
Sympathetic division: originates from thoracic and lumbar spinal nerves; referred to as the thoracolumbar division.

Neuron Structure in the ANS

Efferent motor neurons follow a two-neuron circuit: pre-ganglionic neuron and post-ganglionic neuron.
Parasympathetic pre-ganglionic neurons are longer, reaching distant ganglia close to the target tissue.
Sympathetic pre-ganglionic neurons are shorter, mainly connecting to ganglia in the sympathetic trunk.

Neurotransmitters in the ANS

Both divisions' pre-ganglionic axons release acetylcholine (ACh).
Parasympathetic post-ganglionic axons also release ACh.
Sympathetic post-ganglionic axons release epinephrine and norepinephrine (adrenaline and noradrenaline).

Receptors and Their Functions

Cholinergic fibers release acetylcholine; all parasympathetic post-ganglionic axons are cholinergic.
Adrenergic fibers release norepinephrine.
Two types of cholinergic receptors exist: nicotinic (binds ACh) and muscarinic (also binds ACh); both are named after drugs that mimic ACh effects.

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Description

This quiz focuses on spinal nerves and mixed nerves, crucial components of the nervous system. It includes definitions and functions, providing key insights into how these nerves contribute to bodily functions. Perfect for students looking to enhance their understanding of nervous system anatomy.