Spinal Cord Anatomy Flashcards
What is the spinal cord derived from?
Neural tube
What vtimain affects neural tube formation?
Folic acid in 1st trimester
What is the neural tube dervived from?
ectoderm
When does the neural tube start to develop?
3rd week of gestation
What occurs during neural tube formation?
dorsal plates –> sensory neurons
ventral plates –> motor neurons
neural canal –> central canal
WHen does the neural tube close?
4th week of gestation
What do neural crest cells give rise to?
- Dorsal Root Ganglia
- Adrenal Medulla
- Melanocytes
- Microglia
- Meninges (arach and pia)
- Enteric neurons
- Schwann cells
- Sympathetic ganglia
Where does the spinal cord begin and end?
- foramen magnum
to
-L1/2 in an adult
What segments of the spinal cord are enlarged?
- Cervical @ C6 b/c brachial plexus
- Lumbarsacral b/c lumbosacral plexus
What is the dilated end of the spinal cord called?
- conus medularis
What are the nerves at the end of the spinal cord?
- Cauda equina
What are the coverings of the spinal cord from outer to deep?
- dura
- arachnoid matter
- pia matter
What space does the arachnoid matter leave under the CSF?
subarachnoid space
What makes up the pia matter?
- filum terminale
- dentate ligaments
Function of dentate ligaments?
archor the spinal cord to the spinal dura
Where does the dural sac end?
S2
What are the two parts of the filum terminale?
- filum terminale interna
- filum terminale externa
Where does the filum terminale intera begin and end?
from conus medularis to end of dural sac @ S2
Where does the filum terminale externa begina and end?
fuses with dura and extends to coccyx
How many segments are there of the spinal cord?
31
What are the 3 budles of fasciculi (spinal cord tracts)?
- posterior
- anterior
- lateral
What forms fasciculi?
fast conducting myelinated axons
What are the gilial cells?
- oligodendrocytes
- astrocytes
In the ascending dorsal columns where do the fibers from the lower limb synapse?
nucleus gracilis
In the ascending dorsal columns where do the fibers from the upper limb synapse?
nucleus cuneatus
What sensation do the dorsal columns carry?
- vibration –> Pacinian corpuscles)
- fine touch (2 point discrimination) –> Meissner’s corpuscles
- joint position sense –> Ruffini endings
What do the spinocerebellar tracts carry?
- unconcious proprrioception
- -> golgi tendon organs, muscle spindles
What do the lateral spinothalamic tracts carry?
- pain –> naked nerve ending
- temperature –> naked nerve ending
What do the anterior spinothalamic tracts carry?
- crude touch – Merkel cells
- pressure –> Merkel cells
What functions do descending tracts control?
- skeletal motor
- smoot muscle
- secretory glands
What is the non motor descending tract?
- raphespinal, modulates nociception
How does the Ascending dorsal column synapse?
- 1st order: mechanoreceptors, vibration and fine touch
- 2nd order: Nuclei gracilis and cuneatus
Decussate @ Medulla - VPL of Thalamus
How does the Spinothalamic tract synapse?
- 1st order: Nociceptors, thermoreceptors, light toouch receptors
- 2nd order: lamina 1 & 2 in the dorsal horn of the grey matter
Decussate @ spinal cord at level of nerve - 3rd order: VPL of nucleus
How does the Dorsal Spinocerebellar tract synapse?
- 1st order: unconscious proprioception from lower limb
- 2nd order: Clarke’s nucleus
Decussate, DOES NOT - 3rd order: cerebellum via inferior cerebellar peduncle
How does the Ventral Spinocerebellar tract synapse?
- 1st order: unconscious proprioception from both upper and lower limb
- 2nd order:
