The Spinal Cord

Question 1

How long and how wide is the spinal cord?

Answer 1

18 inches long and 1/2 inch wide

Question 2

Where does CNS tissue (spinal cord) end?

Answer 2

between vertebrae L1 and L2

Question 3

Conus medullaris

Answer 3

termination of spinal cord

Question 4

thecal (dural) sac

Answer 4

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.

Question 5

Where does the thecal sac end?

Answer 5

S2

Question 6

Name the meninges

Answer 6

Dura Mater
Arachnoid Mater
Pia Mater

Question 7

Arachnoid Mater

Answer 7

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.

Question 8

Lumbar cistern

Answer 8

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.

Question 9

Pia Mater

Answer 9

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.

Question 10

Denticulate ligaments

Answer 10

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.

Question 11

How many pairs of spinal nerves are there?

Answer 11

31 pairs

Question 12

Spinal Nerves

Answer 12

contain both sensory and motor axons identified by the first letter of the spinal cord part and number.

Question 13

How many cervical nerves are there?

Answer 13

8 cervical nerves even though there are 7 cervical vertebrae. Starts above each vertebra. Nerve C8 is above T1.

Question 14

How many thoracic nerves are there?

Answer 14

12

Question 15

How many lumbar nerves are there?

Answer 15

5

Question 16

How many sacral nerves are there?

Answer 16

5

Question 17

How many coccygeal nerves are there?

Answer 17

1

Question 18

Spinal nerves pass through the

Answer 18

intervertebral foramen

Question 19

Intervertebral foramen

Answer 19

opening between the pedicles of the adjacent vertebra. It is the opening for the passage of the spinal nerves out from the spinal cord.

Question 20

Intervertebral Disc

Answer 20

• 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

Question 21

Annulus Fibrosis

Answer 21

• outer portion of the intervertebral disc
• made up of lamellae
• great tensile strength

Question 22

Lamellae

Answer 22

• layers of collagen fibers
• arranged obliquely 30 degrees
• reversed contiguous layers

Question 23

The intervertebral disc is made up of

Answer 23

Annulus Fibrosis

Nucleus Pulposus

Question 24

Nucleus Pulposus

Answer 24

• inner structure of the intervertebral disc
• gelatinous
• high water content
• resists axial forces

Question 25

Blood supply to the intervertebral disc

Answer 25

- intervertebral discs have no significant vascular structures - they receive their blood supply by diffusion through the vertebral body endplates - a network of vessels located centrally in the endplate allows nutrients to diffuse into the nucleus pulposus and annulus fibrosis.

Question 26

Anterior longitudinal ligament

Answer 26

the ligament that runs from superior to inferior along the anterior surface of the body of the vertebrae. It helps attach the bodies of the vertebrae to each other

Question 27

Posterior longitudinal ligament

Answer 27

- weaker than anterior - runs from the axis (C2) caudally to the sacrum - narrow at the levels of the vertebrae, but the fibers extend laterally at the disc level

Question 28

The attachment of the posterior longitudinal ligament to the intervertebral disc helps...

Answer 28

to reinforce the posterior aspect of the annulus fibrosis. However, because the ligament thins laterally, most disc herniations occur in a posterolateral direction.

Question 29

The _______ _______ connects each adjacent spinous process.

Answer 29

interspinous ligament

Question 30

In the cervical spine, the interspinous ligament becomes part of the ______ _______, which extends cranially to insert into the occiput.

Answer 30

ligamentum nuchae

Question 31

The _____ _____ is a very strong band connecting the tips of contiguous spinous processes. It extends from C7 to the sacrum. Above C77 these fibers are part of the ligamentum nuchae.

Answer 31

supraspinous ligament

Question 32

Ligamentum flavum

Answer 32

- also known as the yellow ligament - consists of elastic fibers oriented vertically that extend from the anterior inferior surface of the lamina above to the superior posterior surface of the lamina below - tends to thicken as it progresses down the spine, beginning at the axis (C2) and extending to the sacrum

Question 33

Lumbar Puncture travels through

Answer 33

skin, subcutaenous layer, back muscles, supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space, dura mater, arachnoid mater, and into the subarachnoid space where there is CSF.

Question 34

The nucleus pulposus is a _______ structure, not liquid.

Answer 34

cargilaginous

Question 35

______ _____ act as shock absorbers between the vertebral bodies.

Answer 35

intervertebral discs

Question 36

Where is there no intervertebral disc found?

Answer 36

between the C1 and C2, and between L5 and S1

Question 37

Intervertebral discs are _____ joints.

Answer 37

cartilagenous

Question 38

Is the intervertebral disc penetrated to perform a spinal tap?

Answer 38

no, only the subarachnoid space is needed.

Question 39

Herniated disc

Answer 39

- herniation of the nucleus pulposis through a weakened anulus fibrosis, usually posterolaterally - commonly puts pressure on the nerve roots or dorsal root ganglion exiting the intervertebral foramen at or below this level, leading to the symptoms of a "slipped disc"; these occur most frequently in the cervical and lumbar regions due to these segments being the most mobile

Question 40

If a herniated disk presses the nerve between the C5 and C6 vertebrae, it will be compressing the ____ nerve, which emerges above the ____ vertebra.

Answer 40

C6; C6

Question 41

If a disc herniates in the lumbar region, ex. between L5 and S1, it will be affecting the _____ spinal nerve.

Answer 41

S1; this is because the L5 nerve lies immediately below the L5 pedicle, above the herniating disc and is not affected. However, the S1 nerve roots are already proceeding laterally toward the S1 intervertebral foramen, so it is usually caught by the herniating L50S1 disc.

Question 42

pseudounipolar neurons are (sensory/motor)?

Answer 42

sensory (afferent)

Question 43

multipolar neurons are (sensory/motor)?

Answer 43

motor (efferent)

Question 44

The ____ _____ _____ supplies sensory innervation to the skin of the back and motor innervation to the true back muscles.

Answer 44

dorsal primary ramus

Question 45

Which muscles are considered true muscles of the back and why?

Answer 45

Intrinsic (Erector spinae, suboccipital, and splenius) muscles. Primary function is to produce movements of the vertebral column.

Question 46

Extrinsic back muscles

Answer 46

- lie most superficially on the back - muscles of the upper limb that have migrated to the back during fetal development - divided into superficial and intermediate

Question 47

Superficial extrinsic back muscles

Answer 47

Trapezius, rhomboid major & minor, Latissimus dorsi, levator scapulae

Question 48

intermediate extrinsic back muscles

Answer 48

serratus posterior inferior and serratus posterior superior

Question 49

Intrinsic back muscles movements

Answer 49

- flexion (touching toes) - extension (bending backward) - lateral bending - rotation (head and neck or entire torso)

Question 50

Ventral rami of C1-T1 and T12-S5 contribute to the formation of:

Answer 50

plexuses

Question 51

ventral rami of T2-T11 continue as

Answer 51

intercostal nerves

Question 52

Dermatome

Answer 52

the area of skin innervated by the cutaneous branches of a single spinal nerve

Question 53

CSF function

Answer 53

- colorless fluid that occupies the subarachnoid space surrounding the brain, spinal cord, and ventricular system - provides mechanical and immunological protection for the brain, spinal cord, and thecal sac

Question 54

CSF production

Answer 54

-produced by the choroid plexus in the third, fourth, and lateral ventricles of the brain.

Question 55

CSF is an ultrafiltrate of ____ ____ through the permeable capillaries of the choroid plexus.

Answer 55

blood plasma

Question 56

how much CSF is formed each day?

Answer 56

~500 mL per day; total amount turned over 3-4 times per day