Lecture 16 (4/2) Flashcards Preview

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Flashcards in Lecture 16 (4/2) Deck (29):
1

Spinal Cord (General)

In the spinal cord the white matter is outside and the grey matter is inside - which is opposite of the brain

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Funiculi

Tracts that connect the white matter of the spinal cord

Four Funiculi:
1 Dorsal Funiculus
1 Ventral Funiculus
2 Lateral Funiculi

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Dorsal Funiculus

There is 1

Contains numerous sensory neurons and has dorsal horn

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Ventral Funiculus

There is 1

Contains numerous motor neurons and has a ventral horn

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Lateral Funiculi

There are 2

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Upper Motor Neurons

Found in the cortex

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Lower Motor Neurons

Found in the spinal cord

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Central Canal

A cavity that extends throughout the length of the spinal cord

Filled with CSF

Continuous with the fourth ventricle in the medulla

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Spinal Nerves

There are 31 Pairs of spinal nerves, divided into 5 regional groups

8 Cervical
12 Thoracic
5 Lumbar
5 Sacral
1 Coccygeal

The nerves are formed by two contributions, 1 from the anterior portion, 1 from the posterior portion, which are joined together to form 1 nerve

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Intervertebral Foramen

A hole that the spinal nerves travel through to get to the spinal cord

The nerves that innervate the arms and legs leave the cord through the cervical and lumbar/saccral regions respectively

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Rami (Ramus singular)

The name of the contributions that form the nerves of the spinal cord.

They are not visible because they are inside the bones. You can only see the nerve as they connect outside the intervertebral foramen

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Dorsal Ramus

The contribution that carries sensory information

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Anterior Ramus

The contribution that carries motor information

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Mixed nerves

Spinal nerves that carry both sensory and motor information

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Dorsal Root

The entry point for the rami into the spinal cord

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Ventral Root

The entry point into the spinal cord

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Afferent System

Afferent fibers carry only sensory information

Located in the dorsal root ganglia traveling to the somatosensory cortex and enter the spinal cord through the dorsal root

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Extroreceptors

One of two types receptors - sensory input for the spinal cord originates here

Have 2 main subtypes
Non-pain receptors
Pain receptors

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Non-Pain Receptors/ A-beta Fibers

One of 2 subtypes of extroreceptors

Consist of receptors that are sensitive to mechanical stimulation

Found throughout the skin

Respond to touch, hair-bending, and temperature changes

Associated with afferent fibers that are 6-12 micrometers in diameter and are myelinated.

Called A-beta Fibers

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Pain Receptors

One of 2 subtypes of extroreceptors

Found in the skin, muscles, blood vessels, and many other tissues in the body

Respond to painful stimuli or stimuli that causes tissue damage (spanking)

Two types:
C-fibers
A-delta fibers

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C-Fibers

A type of pain receptor that is less than 1 micrometer in diameter

They are so small they are un-myelinated

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A-Delta Fibers

A type of pain receptor that is 1-6 micrometers in diameter

Myelinated

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Proprioceptors

One of two types of sensory receptors

Found in the muscles, tendons, and joints

Consist of specialized receptor organs called muscle spindles

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Muscle Spindles

Specialized receptor organs; a type of proprioceptor

Senses the stretch of muscles

Deals with the awareness of limb position in space

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Golgi Tendon Organs

Specialized receptor organs, a type of proprioceptor

Very sensitive to tension on the tendons caused by muscle contraction

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Efferent System

Efferent fibers carry only motor information

Efferent fibers leave the ventral horn through the ventral root

The cell bodies of the neurons going to the muscles lie in the ventral horn

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Motor Neurons

Part of the efferent system

Two types:
Alpha Motor Neurons
Gamma Motor Neurons

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Alpha Motor Neurons

One of two types of motor neurons

Big cells that innervate big muscle fibers

12 micrometers in diameter

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Gamma Motor Neurons

One of two types of motor neurons

Innervate muscle spindles

Tiny