Lecture #17 Chapter 11 (Spinal Cord) Flashcards
What are the two functions of the spinal cord?
-Pathway for impulses to and from the brain
-Center for spinal reflexes
What is the spinal cord?
A slender column of the nervous tissue that runs continuously with the brainstem
Where does the spinal cord begin at?
Foramen magnum
What does the spinal cord extend downward through?
The vertebral canal which is the vertebral foramen of the vertebra
Where does the spinal cord terminate at?
Between the L1 and L2 vertebrae space
How many spinal nerves are there?
31 pairs/segments
What are the two bulges in the spinal cord?
The cervical enlargement and the Lumbar enlargement
What is the end of the spinal cord called?
Conus medullaris
Cauda equina?
A structure at the end of the spinal cord that resembles a horses tail which contains the lumbar and sacral spinal nerves
What is the filum terminale?
A thin cord of connective tissue that anchors the spinal cord to the coccyx
What are the seven landmarks of the spinal cord from superior to inferior?
-Begins at the foramen magnum
-Cervical enlargement
-Spinal cord within the vertebral canal
-Lumbar enlargement
-Conus Medullaris
-Cauda equina
-Filum terminale
What runs through the middle of the spinal cord?
Central canal
What is the horizontal bar of gray matter in the middle of the spinal cord called?
Gray commissure
What is the spinal cord divided by anteriorly?
A deep anterior median fissure
What is the spinal cord divided by posteriorly?
A shallow posterior median sulcus
What are the three regions of white matter in the spinal cord?
-Posterior funiculus
-Lateral funiculus
-Anterior funiculus
What are the three areas of gray matter in the spinal cord?
-Posterior horn
-Lateral horn
-Anterior horn
What are the two roots of the spinal cord?
The dorsal root and the ventral root
Which root of the spinal cord has a ganglion?
The dorsal root
Which root do sensory neurons pass through?
Dorsal root
Which root do motor neurons pass through?
Ventral root
Where are the cell bodies of the unipolar sensory neurons located in the spinal cord?
The dorsal root ganglion
What is a reflex?
An automatic, subconscious response to stimuli within or outside the body
What is a reflex arc?
A neural pathway that consists of a sensory receptor + 2 or more neurons + an effector
What is a simple reflex arc?
Sensory + motor neurons
What does the most common reflex arc consist of?
Sensory neuron + interneurons + motor neurons
What five components make up a reflex arc?
-Receptor
-Sensory neuron
-Interneuron
-Motor neuron
-Effector
What is a monosynaptic (stretch) reflex?
-Monosynaptic = only 1 synapse
-Consists of 2 neurons (sensory + motor)
What is an example of a monosynaptic (stretch) reflex?
Knee-jerk reflex
When does a withdrawal reflex occur?
When you touch or step on something painful
What is the function of a withdrawal reflex?
Prevents tissue damage by removing limb from source of injury
The withdrawal reflex is ____ in that the pathway involves ____ neurons (and thereby ____ synapses)?
-Polysynaptic
-3
-2
What is reciprocal innervation?
-Flexors contract
-Extensors are inhibited
[Innervation so that the contraction of a muscle or set of muscles (as of a joint) is accompanied by the simultaneous inhibition of an antagonistic muscle or set of muscles.]
What is the crossed extensor reflex?
Occurs when flexors on the affected side contract and extensors on the contralateral (opposite) side also contract to stabilize the body during the withdrawal reflex
This helps shift body weight to ensure you don’t fall during this reflex response