Chapter 13: Spinal Cord And Spinal Nerves

Question 1

3 layers of protection for CNS

Answer 1

Skull & vertebrae
Meninges
CSF

Question 2

Dura mater

Answer 2

Outermost layer.
Dense irregular connective tissue.
Continuous with epineurium.

Question 3

Arachnoid mater

Answer 3

Middle layer. Thin, avascular. Composed of cells and loosely arranged collagen and elastic fibres.

Question 4

Pia mater

Answer 4

Innermost layer. Adheres to brain and spinal cord. Consist of cuboidal or squamous cells within collagen and some elastic fibres.
Contains many blood vessels.

Question 5

Denticulate ligaments

Answer 5

Thickenings of pia mater. Project laterally and fuse with arachnoid mater and inner surface of dura mater.
Protects spinal cord from sudden displacement.

Question 6

Cervical enlargement

Answer 6

Extends from C4 to T1.

Question 7

Lumbosacral enlargement

Answer 7

Extends from T9-T12

Question 8

Conus medullaris

Answer 8

Tapering of spinal cord, ending between L1 and L2

Question 9

Filum terminale

Answer 9

Extension of the pia mater that extends inferiorly and fuses with arachnoid mater and dura mater. Anchors spinal cord to the coccyx.

Question 10

Number of spinal nerves (pairs)

Answer 10

8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
31 in total

Question 11

Roots

Answer 11

Connects spinal nerve to a segment of the spinal cord via rootlets.

Question 12

Posterior root and rootlets

Answer 12

Contains only sensory axons.

Question 13

Dorsal spinal root ganglion

Answer 13

Contains cell bodies of sensory neurons.

Question 14

Anterior root and rootlets

Answer 14

Contains axons of motor neurons.

Question 15

Anterior median fissure

Answer 15

Wide groove on the ventral part of spinal cord.

Question 16

Posterior median sulcus

Answer 16

Narrow furrow on the dorsal side of spinal cord.

Question 17

Gray matter of spinal cord

Answer 17

Contains dendrites and cell bodies of neurons, unmyelinated axons, and neuroglia.

Question 18

Gray commissure.

Answer 18

Forms the cross bar of the “H” in the gray matter.
Contains central canal filled with CSF, and which is continuous with the 4th ventricle

Question 19

Anterior white commissure

Answer 19

Connects the white matter of the spinal cord between left and right sides.

Question 20

Posterior gray horn

Answer 20

Contains axons of sensory neurons as well as cell bodies and axons of interneurons

Question 21

Anterior gray horn

Answer 21

Contains somatic motor nuclei.

Question 22

Lateral gray horn

Answer 22

Present in thoracic, lumbar, and mid sacral regions.
Containers autonomic motor nuclei.

Question 23

3 funiculi

Answer 23

Anterior white funiculi
Posterior white funiculi
Lateral white funiculi

Question 24

Funiculi

Answer 24

Contains bundles of axons having a funiculus origin or destination.
Bundles known as tracts (or fasciculi)

Question 25

Endoneurium

Answer 25

Consists of collagen, fibroblasts, and macrophages. Covers individual axons.

Question 26

Nerve fascicle

Answer 26

Groups of axons with their endoneurium held together in bundles.

Question 27

Perineurium

Answer 27

Wraps around nerve fascicles. Consists of up to 15 layers of fibroblasts within a network of collagen.

Question 28

Epineurium

Answer 28

Outermost layer. Consists of fibroblasts and thick collagen fibres. Fuses with dura mater. Fills spaces between nerve fascicles.

Question 29

Rami

Answer 29

Division of spinal nerves shortly after it passes through intervertebral foramen.

Question 30

Posterior ramus

Answer 30

Serves deep muscles and skin of the posterior surface of the trunk.

Question 31

Anterior ramus

Answer 31

Serves muscles and structures of the upper and lower limbs and skin of the lateral and anterior surfaces of the trunk.

Question 32

Meningeal branch

Answer 32

Reenters the vertebral cavity through the intervertebral foramen. Supplies the vertebrae, vertebral ligaments, blood vessels of spinal cord, and meninges.

Question 33

Communicating rami

Answer 33

Supplies components of the ANS

Question 34

5 plexuses

Answer 34

Cervical Brachial Lumbar Sacral Coccygeal

Question 35

Intercostal nerves

Answer 35

Anterior rami of spinal nerves T2-T12 since they do not enter into a plexus. Directly connects to the structures they supply.

Question 36

Cervical plexus

Answer 36

Formed by roots of C1-4 and some of C5. Supplies skin and muscle of head, neck, superior shoulders and chest, and phrenic nerve. Also runs parallel to CN XI and XII

Question 37

Brachial plexus

Answer 37

Roots of C5-8, and T1. Forms superior, middle, and inferior trunks. Trunks diverge into anterior and posterior divisions. Divisions unite to lateral, medial, and posterior cords.

Question 38

5 terminal branches of brachial plexus

Answer 38

Axillary nerve Musculocutaneous nerve Radial nerve Median nerve Ulnar nerve.

Question 39

Lumbar plexus

Answer 39

Roots of L1-4. Supplies anterolateral abdominal wall, external genitals, and part of lower limbs.

Question 40

Sacral plexus

Answer 40

Root of L4-5 and S1-4. Sciatic nerve arises from this plexus.

Question 41

Coccygeal plexus

Answer 41

Roots of S4-5, and coccygeal nerves. Anococcygeal nerves arise from this plexus.