Lecture 16 (4/2) Flashcards
Spinal Cord
Spinal Cord (General)
In the spinal cord the white matter is outside and the grey matter is inside - which is opposite of the brain
Funiculi
Tracts that connect the white matter of the spinal cord
Four Funiculi:
1 Dorsal Funiculus
1 Ventral Funiculus
2 Lateral Funiculi
Dorsal Funiculus
There is 1
Contains numerous sensory neurons and has dorsal horn
Ventral Funiculus
There is 1
Contains numerous motor neurons and has a ventral horn
Lateral Funiculi
There are 2
Upper Motor Neurons
Found in the cortex
Lower Motor Neurons
Found in the spinal cord
Central Canal
A cavity that extends throughout the length of the spinal cord
Filled with CSF
Continuous with the fourth ventricle in the medulla
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
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
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
Dorsal Ramus
The contribution that carries sensory information
Anterior Ramus
The contribution that carries motor information
Mixed nerves
Spinal nerves that carry both sensory and motor information
Dorsal Root
The entry point for the rami into the spinal cord
Ventral Root
The entry point into the spinal cord
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
Extroreceptors
One of two types receptors - sensory input for the spinal cord originates here
Have 2 main subtypes
Non-pain receptors
Pain receptors
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
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
C-Fibers
A type of pain receptor that is less than 1 micrometer in diameter
They are so small they are un-myelinated
A-Delta Fibers
A type of pain receptor that is 1-6 micrometers in diameter
Myelinated
Proprioceptors
One of two types of sensory receptors
Found in the muscles, tendons, and joints
Consist of specialized receptor organs called muscle spindles
Muscle Spindles
Specialized receptor organs; a type of proprioceptor
Senses the stretch of muscles
Deals with the awareness of limb position in space
Golgi Tendon Organs
Specialized receptor organs, a type of proprioceptor
Very sensitive to tension on the tendons caused by muscle contraction
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
Motor Neurons
Part of the efferent system
Two types:
Alpha Motor Neurons
Gamma Motor Neurons
Alpha Motor Neurons
One of two types of motor neurons
Big cells that innervate big muscle fibers
12 micrometers in diameter
Gamma Motor Neurons
One of two types of motor neurons
Innervate muscle spindles
Tiny
