spinal cord Flashcards
Spinal Nerve
31 pairs, 2 for each spinal cord segment
Rootlets (anterior and posterior) -> Anterior and posterior Roots
Ventral (anterior) roots motor (efferent) - segregated, messages are leaving the CNS to the PNS
Dorsal (posterior) roots sensory (afferent) - coming in from the outside, going up to the brain and we perceive that as pain
Near the intervertebral foramen is DRG
Lateral to the dorsal root or spinal ganglion we will have the ventral and dorsal roots come together
Prior to that they are completely segregated, dorsal roots are sensory and the ventral roots are motor
Once we come together, later to that dorsal root ganglion the dorsal and the ventral roots fuse and they become a spinal nerve
Spinal nerve exists for only an 8th of an inch and splits into primary dorsal and ventral rami
Dorsal and ventral rami are integrated , both have sensory and motor components
Spinal Cord
The reflex center and conduction pathway between brain and body
Begins at medulla oblongata ( reflex center , HR and RR center primitive brain)
Ends at conus medularis ( L1,L2) - end of spinal cord (below it for lumbar puncture)
Cervical and lumbar enlargement correspond to a lot of ventral nerves that are going to our upper and lower extremities
Lumbar sacral roots form cauda equina - stringy nerves that hang down vertebral column
In the middle coming off the conus medularis , is the filum terminale that attaches to coccygeal ligament that is a redundancy that tethers the spinal cord so its not bouncing all over the place
how 31 pairs?
7 cervical, 12 thoracic, 5 lumbar, 5 sacral = 29
But really 8 cervical nerves and 1 coccygeal nerve so it will equal 31
Dermatomes
each one of these segments has a deficit
example deficit in C2 , sensory deficit in this area
This all has been mapped out , do a neural test and find the specific spinal cord segment
No C1 at the dermatome
C1 is the Suboccipital nerve , motor and the sensory component is propioception so does not come out here
C2 is the greater Suboccipital nerve , doesnt really innervate any muscles just sensory to the back of the head
Feeling of the face is from a cranial nerve
Meninges
surround, support, and protect spinal cord
space outside the CNS is called the epidural space- vertebral plexuses in here ( valveless) and fat
-receive an epidural will diffuse into CNS and cause pain relieve during things like childbirth
Meninges- Dura Mater
It s a a thick fibrous CT and elastic fibers
Forms a dural sac runs entire length of vertebral canal
Extend out laterally surrounds dorsal and ventral roots
Thick dura has blood vessels which can cause epidural hematoma
Meninges- Arachnoid Mater
Below the dura mater, delicate avascular made of fibrous and elastic CT
Neural tissue
Very thin
Meninges Space - Subdural Space
between the Dura and the Arachnoid Mater
head trauma = subdural hematoma can cause coma and death
The dura will push out and get in contact with the bones of the skull, and as the blood pools it can compress the brain and can cause death
Meninges Space - Subarachnoid Space
Find the CSF
Between the arachnoid and the pia mater
Can get also a Subarachnoid hemorrhages - fatal
Lumbar cisternae - enlargment of the SAS between L2-sacrum
Arachnoid Trabeculae
Connect the arachnoid mater to the pia mater
Meninges - Pia Mater
Innermost vascular covering of the spinal cord
Directly on the neural tissue
Has Denticulate ligaments - attach spinal cord to dura mater and help suspend spinal cord in dural sac ;
tethering it posteriorly along with coccygeal ligament , help stabilize it
20-22 between dorsal and ventral roots
Denticulate ligament help whether a root or rootlet is anterior, posterior, or ventral
Usually seen posterior aspect see dorsal root, above or superior to denticulate ligament. one deep to it is the ventral root
Dorsal is above and ventral is deep in
Vasculature of Spinal Cord
Anterior spinal artery supplies ventral 2/3 of spinal cord
Paired posterior spinal arteries from supplies dorsal 1/3 of spinal cord
Come from segmental arteries from vertebral
Spinal Arteries
Segmentak arteries from vertebral, deep cervical, ascending cervical, posterior, intercostal,lumbar and lateral ->sacral -> medullary arteries
-> spinal arteries
Spinal Arteries - 2
Medullary arteries enter intervertebral foramina and -> anterior and posterior radicular arteries to roots
Great radicular artery/great anterior segmental medullary artery ( of Adamkiewicz)
- Largest on the left from posterior intercostal or lumbar T10-L2
- Main blood supply to lower spinal cord
Spinal Arteries - 3
Medullary arteries -> redicular arteries -> that supply the spinal nerves and roots
Anterior and posterior redicular arteries
medullary continues as spinal artery supplying the actual spinal cord
