Motor & Integrative Neurophysiology: Spinal Reflexes

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Questions and Answers

What is the primary function of the spinal cord?

To facilitate digestion

To produce hormones

To store memories

To conduct nerve impulses to and from the brain (correct)

Which type of neurons is responsible for transmitting impulses to higher CNS levels?

Second-order sensory neurons (correct)

Alpha motor neurons

Interneurons

First-order sensory neurons

How is the gray matter of the spinal cord arranged?

In a circular pattern

In a straight line

Scattered randomly

In three distinct horns (correct)

Which part of the spinal cord encloses the nerve cell bodies?

Gray matter Signup and view all the answers

What characterizes the white matter of the spinal cord?

Conducts nerve impulses to and from the brain Signup and view all the answers

What type of spinal nerve provides sensory perception and motor function for the upper trunk?

Thoracic nerves Signup and view all the answers

Alpha motor neurons are primarily located in which area of the spinal cord?

Ventral horn Signup and view all the answers

How many segments does the spinal cord have?

31 Signup and view all the answers

What is the primary inhibitory neurotransmitter released by Purkinje cells in the cerebellar cortex?

GABA Signup and view all the answers

Which cerebellar structure is primarily involved in controlling posture and equilibrium?

Fastigial nuclei Signup and view all the answers

What function is primarily associated with the cerebrocerebellum?

Coordination and sequencing of motor activities Signup and view all the answers

Which of the following statements about the cerebellum is true?

It acts as a monitor and modulator of movement. Signup and view all the answers

How does the archicerebellum affect muscle tone?

It inhibits muscle tone. Signup and view all the answers

What pathway does the interpositus nuclei utilize to communicate with the motor cortex?

Cortico-ponto-cerebello-dento-thalamo-cortical circuit Signup and view all the answers

Which of the following cerebellar nuclei is responsible for controlling agonist and antagonist muscles?

Interpositus nuclei Signup and view all the answers

What is the purpose of the fastigiospinal tract?

To control posture Signup and view all the answers

What is the primary function of the lateral vestibulospinal tract?

Facilitate the activity of extensor muscles Signup and view all the answers

Which statement about upper motor neurons (UMNs) is accurate?

They extend from the cerebral cortex to the motor neuron pool. Signup and view all the answers

What is the primary source of cerebrospinal fluid (CSF) production?

Choroid plexus in the lateral ventricles Signup and view all the answers

Where does the cerebrospinal fluid (CSF) flow after the fourth ventricle?

Subarachnoid space Signup and view all the answers

How does CSF formation occur at the cellular level?

By an active pump of Na ions Signup and view all the answers

Which type of neuron is responsible for relaying signals from the brain to the skeletal muscles?

Lower motor neuron (LMN) Signup and view all the answers

What role do perivascular spaces play in the brain?

They act as a specialized lymphatic system for the brain. Signup and view all the answers

Which of the following structures predominantly contains the white matter of the spinal cord?

Anterior white column Signup and view all the answers

Study Notes

Spinal Cord Overview

A long, slender cylinder of nerve tissue extending from the brain stem.
Approximately 45 cm in males and 43 cm in females, with a diameter of 2 cm.
Enclosed by the protective vertebral column and covered by meninges.
Comprised of 31 segments correlating with 31 pairs of spinal nerves.

Spinal Nerves

8 Cervical nerves control sensory perception and motor function in the back of the head, neck, and arms.
12 Thoracic nerves innervate the upper trunk.
5 Lumbar nerves serve the lower trunk and legs.
5 Sacral nerves provide innervation for the lower trunk and legs.
1 Coccygeal nerve is the terminal spinal nerve.

Functions of Spinal Cord

Conducts nerve impulses to and from the brain.
Processes sensory input from skin, joints, and muscles of the trunk and limbs.
Initiates reflex responses to sensory input.

Internal Structure of Spinal Cord

Divided into inner gray matter and outer white matter.
Gray matter contains nerve cell bodies, dendrites, and parts of axons, resembling a butterfly or the letter 'H'.
Gray matter has three horns: ventral (anterior), dorsal (posterior), and lateral gray horns.

Neurons in Gray Matter

Second-order sensory neurons are located in the dorsal horn, receiving input from first-order sensory neurons.
Somatic motor neurons are found in the ventral horn, with two types:
- Alpha motor neurons innervate skeletal muscle fibers to induce contraction.
- Lateral vestibulospinal tract modulates extensor and flexor muscle activity.

Upper and Lower Motor Neurons

Upper motor neurons extend from the cerebral cortex to the motor neuron pool in the brainstem and spinal cord.
Lower motor neurons make up the motor neuron pool, sending axons to skeletal muscles.

Cerebrospinal Fluid (CSF) Overview

Total volume in the cranial cavity: 1600-1700 ml; volume of CSF: 150 ml.
CSF is found in the brain's ventricles, cisterns around the brain, and subarachnoid space.
Functions include protective cushioning, floating the brain, and serving as a medium for exchange.

Formation and Pathway of CSF

CSF is primarily produced by the choroid plexus in lateral ventricles at a rate of 500 ml/day.
It follows a specific pathway from lateral ventricles to subarachnoid space, ultimately entering venous sinuses.

Perivascular Spaces and CSF

Perivascular spaces serve as a lymphatic system for the brain, contributing to nutrient exchange and waste removal.

Efferent Connections from the Cerebellum

Fastigeal nuclei control posture via fastigiospinal tract.
Interpositus nuclei help coordinate and sequence motor activities, regulating muscle tone.
Outputs from the cerebellar cortex are primarily from Purkinje cells, which provide inhibitory control using GABA.

Functions of the Cerebellum

Monitors and modulates movement rather than initiating it.
Plays a crucial role in maintaining posture, equilibrium, and muscle tone, adjusting to sensory feedback.
Engages in predictive functions during rapid motion or direction changes.

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Description

This quiz focuses on the motor and integrative aspects of neurophysiology, specifically related to spinal reflexes. It covers the structure and function of the spinal cord, including its segments and their connection to spinal nerves. Test your knowledge on this essential neurological component.