The Spinal Cord Flashcards
How long and how wide is the spinal cord?
18 inches long and 1/2 inch wide
Where does CNS tissue (spinal cord) end?
between vertebrae L1 and L2
Conus medullaris
termination of spinal cord
thecal (dural) sac
membranous sheath tube of dura mater that surrounds the spinal cord and the cauda equina. contains CSF which provides nutrients and buoyancy to the spinal cord.
Where does the thecal sac end?
S2
Name the meninges
Dura Mater
Arachnoid Mater
Pia Mater
Arachnoid Mater
delicate membrane made of fibrous and elastic tissue that lines the dural sac and the dural root sleeves. Encloses the CSF-filled subarachnoid space containing the spinal cord, spinal nerve roots, and spinal ganglia. It is held against the dura but separable from it.
Lumbar cistern
the subarachnoid space in the lower lumbar spinal canal. It is an enlargement of the subarachnoid space in the dural sac, distal to the conus medullaris. It contains CSF and the nerve roots of the cauda equina.
Pia Mater
innermost covering membrane of the spinal cord. Closely follows the entire spinal cord and directly covers the roots of spinal nerves and the spinal blood vessels. Inferior to the conus medullaris, the pia continues as the filum terminale.
Denticulate ligaments
specializations of pia mater. Form separate dorsal and ventral rootlets. Extend laterally from cord and attaches to the dura by way of 21 pairs of denticulations, they suspend the spinal cord in the subarachnoid space.
How many pairs of spinal nerves are there?
31 pairs
Spinal Nerves
contain both sensory and motor axons identified by the first letter of the spinal cord part and number.
How many cervical nerves are there?
8 cervical nerves even though there are 7 cervical vertebrae. Starts above each vertebra. Nerve C8 is above T1.
How many thoracic nerves are there?
12
How many lumbar nerves are there?
5
How many sacral nerves are there?
5
How many coccygeal nerves are there?
1
Spinal nerves pass through the
intervertebral foramen
Intervertebral foramen
opening between the pedicles of the adjacent vertebra. It is the opening for the passage of the spinal nerves out from the spinal cord.
Intervertebral Disc
- fibrocartilaginous joint of the motion segment
- make up 1/4 length of the spinal column
- present at levels C2-C3 to L5-S1
- Allows compressive, tensile, and rotational motion
- largest avascular structures in the body
Annulus Fibrosis
- outer portion of the intervertebral disc
- made up of lamellae
- great tensile strength
Lamellae
- layers of collagen fibers
- arranged obliquely 30 degrees
- reversed contiguous layers