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.
