Lab 1: Spinal Cord and Spinal Nerves
descending pathways
The systems of neurons that bring motor information from the brain down to the appropriate spinal level. Signals travel along two neurons. An example is the corticospinal tract.
sympathetic chain
Distributes neurons of the communicating rami and sends branches towards the thoracic and abdominal cavities. Runs parallel to the spinal cord.
visceral sensory
From the viscera to the dorsal horn.
somatic motor
To skeletal muscles from the ventral horn.
visceral motor
To smooth muscle and glands from the lateral horn.
vertebral foramen
A hole within the vertebra through which the spinal cord passes.
dorsal root ganglion
A large collection of cell bodies. Forms due to the unique structure of the unipolar sensory neurons in which the cell body is in the middle of the course of the axon.
stretch reflex
A monosynaptic reflex. An example is the patellar (or knee-jerk) reflex.
plexus
A network of nerves formed by the joining of the spinal nerve's ventral rami.
intercostal nerves
A pattern of ventral rami along the inferior surface of teh ribs that send small branches to nearby muscles, bones, and skin.
polysynaptic reflex
A reflex invovling one or several interneurons.
vertebral canal
A tube formed from successive vertebral foramina that houses the spinal cord.
withdrawal reflex
An example of a polysynaptic reflex.
spinal cord
Begins as the medulla oblongata exits the skull and enters the vertebral foramen of the first cervical vertebra.
dorsal ramus
Branch off of spinal nerve that carries somatic motor information to and somatic sensory information from the posterior body wall.
ventral ramus
Branch off of the spinal nerve that carries somatic motor information to and somatic sensory information from the lateral and anterior body wall.
communicating rami
Branch off of the spinal nerve that carries visceral motor and visceral sensory neurons to and from the viscera. Can be myelinated or unmyelinated.
sympathetic chain ganglia
Bulges on the sympathetic chain composed of neuronal cell bodies.
cauda equina
Bundle of spinal nerves beyond the conus medularis that resembles a horse's tail.
ventral root
Carries motor information with their cell bodies in the ventral and lateral horns of the spinal cord.
dorsal root
Carries sensory information to the dorsal horn of the spinal cord.
spinal nerves
Exit the vertebral column through the intervertebral foramina. They supply structures in the body with innervation at regular intervals and are numbered according to the vertebral level from which they take their exit from the vertebral canal. They form from the joining of two major tributaries, the dorsal and ventral roots.
filum terminale
Extension of the pia mater that lies within the cauda equina. It is a thin thread that anchors the end of the spinal cord to the sacrum.
brachial plexus
Formed of C5-T1 spinal nerve rami. Supplies the upper limb.
lumbosacral plexus
Formed of L2-S2 rami. Supplies the lower limb.
somatic sensory
From skin, skeletal muscles, and joints to the dorsal horn.
spinal reflexes
Involuntary circuits in which the brain is not involved in the response to the stimulus.
monosynaptic reflexes
Involve a sensory neuron and its synapse with a motor neuron. An example is the stretch reflex.
central canal
Located at the center of the spinal cord and is continuous with the ventricles of the brain.
lumbar enlargement
Located in the spinal cord in the region of the lower limb. This structure results from many more neurons sending and receiving information to and from the limbs.
cervical enlargement
Located in the spinal cord in the region of the upper limb. This structure results from many more neurons sending and receiving information to and from the limbs.
pia mater of the spinal cord
Menix that is in direct contact with the spinal cord.
visceral
Refers to the interior cavities of the body (digestive, respiratory, cardiovascular systems).
somatic
Refers to the outer body (bones, skeletal muscles, skin)
denticulate ligaments
Specializations of the pia mater that anchor the spinal cord to the dura mater and limit the movement of the cord.
meninges
Structures that cover and protect the brain as well as the spinal cord.
epidural space
Surrounds the dura mater of the spinal cord (but not the dura of the brain). It is a space filled with fat and is a common site for the injection of anesthetic during labor.
conus medularis
The cone-shaped termination of the spinal cord.
gray matter
The inner region of the spinal cord that contains the unmyelinated neurons of the CNS. These include the interneurons as well as portions of sensory and motor neurons. It is organized into three columns: the dorsal horn, the ventral horn, and the lateral horn.
Epineurium
The outer most layer of a nerve.
white matter
The outer region of the spinal cord that consists of myelinated axons that are oriented vertically to communicate with higher or lower regions of the CNS. The white matter is roughly grouped into 3 columns on each side of the sagittal plane.
dura mater of the spinal cord
The outermost and toughest layer menix covering the spinal cord.
ascending pathways
The systems of neurons that bring information up to the brain. Signals travel along three neurons. An example is the spinothalamic tract.
anterior median fissure
a small division on the anterior side of the spinal cord (different from the central canal)
dermatome
the region of your skin that is innervated by a particular pair of spinal nerves
decussation
to cross the midsagittal plane to the contralateral side.