5: Spinal cord Flashcards
Where does the spinal cord end?
L1-L2
Conuc medullaris= termination point of spinal cord
General length and width of spinal cord?
42cm long
14mm wide
The shorter length is due to the fact that the spinal cord stops growing at four but the spinal column keeps growing with age.
Conus medularis
spinal cord termination point L1-L2
Filum terminale
anchors spinal cord to coccyx
- stables spinal cord during movement
What are the 5 regions of the spinal cord.
Cervical 8 Thoracic 12 lumbar 5 sacral 5 coccygeal 1
How many vertebrae do we have?
31
What occurs in terms of nerves at T12-L2
the lumbar, sacral and coccyx nerves branch off. They cant do it in their bone regions as the spinal cord terminates before it reaches them.
Name and number of spinal nerves
1 spinal nerves comes off with each vertebrate but because the spinal cord terminated at L1-L2, the rest banch off early creating cauda equina
Cervical 8 Thoracic 12 lumbar 5 sacral 5 coccygeal 1
Cauda equina
lumbar, sacral and coccygeal nerve roots travel beyond the conus medullaris to reach the vertebral region from which the lumbar, sacral and coccygeal spinal nerves emerge.
How do peripheral nerves enter the spinal cord and become tract?
via dorsal and ventral routes
Dorsal=
- first in the alphabet so up higher
- S= sensory
Describe a mixed nerve
Can spinal nerves carry both sensory and motor axons.
Spinal cord nerves are mixed.
Define a ganglion
cluster of cell bodies
Explain the dorsal root ganglion
a cluster of cell bodies on the dorsal root (upper nerve entering spinal cord)
- the point where fist and second order neurons synapse.
Think about the fact you can see it in all diagrams so it is close to the spinal cord! remember this for you have to describe length of pre and post ganglions
Ventral root carrier…
motor axons
v= verchile motor
- motor output leaves spinal cord
Dorsal root carries….
sensory axons
- inout enter spinal cord
sensory input comes first so this is up top
Damage to sensory neurons in dorsal root, ganglion or spinal nerve can cause
loss of sensation, sharp stabbing pains or abnormal sensations such as burning, stinging, pickling or tingling.
Damage to Motor neurons in a ventral root or spinal nerves can result in
muscle weakness, loss of movement and autonomic disfunction- e.g. loss of bladder and bowel control
What mechanisms protect the spinal cord?
- vertebral column
- CSF (also nourishes neural tissue and removes water products)
- spinal meningies
Describe the structure and function of spinal meningies
- continuation of cranial meninges
- extend beyond spinal cord
Where is the needle of a lumbar puncture or epidural placed?
subarachnoid space
needle inserted between L4 and L5. At this point there is no spinal cord so the spinal nerves drift away from the needle in the CSF so there is little chance of damaging the nerves.
take some CSF for texting for bacterial infection e.g. mengitis
List the layers of the meninges
durs mata sub dural scape arachnoid mater sub arachnoid space pia mater
Describe the epidural space
space between dura mater and vertebral column