Spinal Cord Flashcards
Where does the spinal cord end?
Around L1 vertebrae.
Why are lumbar punctures performed at L4-L5 and definitely below L3?
Because the spinal cord ends before then. If performed lower, then the nerves move out of the way and there is easier access to the cerebral spinal fluid.
How many arteries supply the spinal cord?
3.
What artery supplies the anterior 2/3rds of the cord?
The anterior spinal artery.
What arteries supply the posterior 1/3rd of the cord?
The two posterior spinal arteries.
Ascending pathways carry what types of signals?
Sensory.
Descending pathways carry what types of signals?
Motor.
What does the dorsal spinocerebral pathway do?
Provides proprioceptive and muscle sense information from individual muscles.
What does the ventral spinocerebral pathway do?
Provides propioceptive and muscle sense information from limbs as a whole.
Is the spinocerebral pathway ipsilateral or contralateral?
Ipsilateral.
What does the dorsal column-medial lemniscus (DCML) pathway do?
Provides discriminate touch, light pressure, and is highly localized.
Where is the first order neuron located in the DCML pathway? Where does the signal enter after that? Where does the signal ascend?
In the dorsal root ganglia (DRG). Afterwards, they enter the posterior horn of the spinal cord. It ascends uncrossed in dorsal columns.
If the DCML pathway crosses, where does it cross?
In the brainstem.
What is the function of the anterolateral (ALS) pathways?
Pain, temperature, crude touch, and deep pressure.
What are the receptors in the anerolateral (ALS) pathways?
Free nerve endings in the skin.
Where is the first order neuron in the anterolateral pathways? Where is the second order neuron?
The dorsal root ganglia (DRG). In the dorsal horn.
If the anterolateral pathway crosses, where does it cross? Where does it ascend at?
It crosses the midline at each spinal segment and ascend at the aterolateral fasciculus.
What is the function of the corticospinal tracts (CT)?
Execute and control voluntary motor activity.
If the corticospinal tract crosses, where does it cross? Where does it descend to?
It crosses the midline at the pyramidal descussation in the brainstem. It descends within the spinal cord to synapse with lower motor neurons in the anterior horn.
Where do lateral corticospinal tract nerves provide function to?
Limb muscles.
Motor tracts consist of what two neurons?
The upper and the lower motor neuron.
Dorsal root ganglia contain what kind of nerves?
Sensory nerves.
What do dorsal roots contain?
The afferent axons from nerves in the dorsal root ganglia.
Why are spinal nerves classified as mixed nerves?
Because they contain both sensory and motor nerve fibers.
What are the meningeal three layers?
- The dura mater. 2. Arachnoid mater. 3. Pia mater.
What is the dura mater?
A tough, fibrous layer that forms the outermost covering of the spinal cord and brain.
What space contains the cerebralspinal fluid?
The subarachnoid space.
What is the pia mater?
A connective tissue membrane that covers the surface of the CNS.
The blood vessels supplying the nerves in the spinal cord are found in which meningeal layer?
The pia mater.
What are horns?
Gray matter that project toward the outer surface of the spinal cord.
What forms the H-shape?
A mass of gray matter.
What is a nerve tract?
A bundle of axons in the CNS.
What is a nerve?
A bundle of axons in the PNS.
What are the four regions of the spinal cord? (Top to bottom)
- Cervical. 2. Thoracic. 3. Lumbar. 4. Sacral.
What is the conus medullaris?
The tapered, lower end of spinal cord.
What is the cauda equina?
Fibers of the filum terminale and the long ventral and dorsal roots (when seen in gross dissection).
What is cervical enlargement?
The relative enlargement of the cervical portion of the spinal cord due to the abundance of CNS neurons involved with motor control of the arms.
What does the cervical enlargement supply nerves to?
The pectorial girdle and upper limbs.
What does the lumbosacral enlargement supply nerves to?
To the pelvis and lower limbs.
Where is the central canal located?
Within the horizontal bar of the H.
What do gray commissures contain? How many are there?
Axons decussating (crossing) from one side of the cord to the other. There are two of them.
All spinal nerves form what two branches?
- A dorsal ramus. 2. A ventral ramus.
What is the function of dorsal (posterior) ramus?
Receives sensory innervation from, and sends motor innervation to, the skeletal muscles of the back.
What is the function of the ventral (anterior) ramus?
Supplies innervation to the ventrolateral body surface, structures in the body wall, and the limbs.
What is a dematome?
A sensory region monitored by the posterior rami of a single spinal segment.
When are the symptoms of a spinal cord injury ipsilateral.
When it crosses in the brain.
When are the symptoms of an injury to the spinal cord contralateral?
When it crosses in the spinal cord.
