Spinal cord Flashcards
What is found at the cervicomedullary junction?
nucleus gacil and cuneate tuberlces (nuceli forming dorsal columns)
where do nerve exit in the cervical region?
above nerve root (ie. between C7 and T1 is nerve root 8)
where do nerve roots exit in lumbar and thoracic regions?
below level of vertebrae ie. between T6 and T7 is nerve T6
Number of vertebrae and nerves in cervical region?
7 vertebrae
8 nerves
Number of vertebrae and nerves in thoracic region?
12 vertebrae
12 nerves
Number of vertebrae and nerves in lumbar region?
5 vertebrae
5 nerves
Number of vertebrae and nerves in sacral region?
Sacrum vertebrae
5 nerves
Number of vertebrae and nerves in coccygeal region?
Coccyx vertebrae
1 nerve
how many nerves are in the spinal cord?
31
What is the relative ascent of the spinal cord?
-vertebral column elongates more rapidly than spinal cord during fetal life
- spinal segmental levels lie superior to their corresponding vertebral levels (nerves run superiorally and obliquely
what are the longest nerve roots?
lumbrosacral roots (constitute cauda equina)
what is the conus medullaris?
slight swelling, more aoxns (where spinal cord ends)
what is filum terminale and whats its role?
-where conus medullaris tapers into a filament
- lies in middle of cauda equina
- stops cord rebounding
where are the two regions of expansion in the spinal cord and what do they correspond?
- cervical expansion (C4-T1) corresponds to nerve supply to the arms
- lumbrosacral expansion (L2-S3) corresponds to the nerve supply to the distal limbs
what is the obex?
point in which 4th ventricle narrows to become central canal of spinal cord
what is the ventriculus terminalis?
small focal dilation of the central canal in conus medullaris
- rarely seen in adults (seen in about 3% children under 5)
how is the spinal cord suspended in dural sheath?
denticulate ligament on each side
- attached to lateral surface of the cord midway between the dorsal and ventral roots
where does dura mater extend from and to?
from formen magnum to S2 level
what is the spinal cord protected by?
vertebrae, ligaments, meninges and CSF
what makes up the grey matter of the spinal cord?
dorsal horn (axons form ascending white matter fasciculi)
intermediate zone (interneurons involved in local circuitry)
ventral horn (motor cells innervate skeletal muscle)
lateral horn (preganglionic sympathetic efferetn neurons)
intermediolateral
what makes up the white matter of the spinal cord?
- dorsal funiculus (medial gracile and lateral cuneate fasciculus)
- lateral funiculus (dorsolateral and ventrolateral)
- ventral funiculus
Pattern of white matter down spinal cord?
white matter increases as you descend the cord due to increase in number of nerve fibres
why are cervical and lumbar regions enlarged?
- more grey matter in ventral horns due to increased motor neurons due to increased limb movements
what is laminae of Rexed?
laminae numbered 1-10 dorsal to ventral
- each laminae composed of a different cell type
what does an absent tendon jerk mean?
afferent and efferent neurons of the stretch reflex are damaged
what does an exaggerated tendon jerk indicate?
loss of inhibition of motor neurons by descending tracts
what will a patient with abnormal signal in dorsal columns complain of?
- loss of light touch vibration and proprioception in feet and hands
- Rombergs sign positive
- legs may be weak and leg reflexes lost
what can cause abnormal signals in dorsal column?
- vit. B12 deficiency
- syphilis
- MS
- HIV
what does the spinothalamic tract carry?
- pain and temperature
when does spinothalamic tract decussate?
- immediately
what does dorsal column medial lemniscus pathway carry?
- joint position sense and vibration
where does dorsal column medial lemniscus pathway decussate?
in lower medial into medial lemniscus
What is brown sycard syndrome?
- hemisection of the cord can take out pain and temperature on one side of the body and joint and position sense in the other side
