Spinal Cord Morphology

Question 1

Shallow longitudinal groove in which dorsal rootlets enter the spinal cord on its posterolateral surface

Answer 1

posterolateral sulcus

Question 2

Ventral rootlets leave spinal cord from these structures

Answer 2

anterolateral sulcus

Question 3

Contains the cell bodies of the primary sensory neurons of that particular spinal nerve

Answer 3

dorsal root ganglion

Question 4

Join to form spinal nerves

Answer 4

Dorsal and ventral roots

Question 5

Portion of the spinal cord that gives rise to a spinal nerve

Answer 5

segment

Question 6

Breakdown of the 31 spinal segments of the spinal cord

Answer 6

8 - cervical
12 - thoracic
5 - lumbar
5 - sacral
1 - coccygeal

Question 7

Cervical enlargement (spinal cord)

Answer 7

Supplies the upper extremities, extends from C5-T1

Question 8

Lumbar enlargement (spinal cord)

Answer 8

Supplies the lower extremities, extends from L2-S3

Question 9

What are funiculi generally in the spinal cord?

Answer 9

white matter columns in between the gray mater areas

You have the anterior, lateral, and posterior funiculi

Question 10

Where do you have lateral gray horns in the spinal cord?

Answer 10

Levels of the 12 thoracic and upper 2 or3 segments of lumbar nerve roots

Question 11

Structure through which the corticospinal tract descends

Answer 11

Lateral funiculus

Principle targets are neurons in the anterior gray horn concerned with activation of skeletal muscles

Question 12

Structures through which the posterior column of medial lemniscus (PCML) ascend

Answer 12

Gracile and cuneate fasciculi

Question 13

Composition of fasciculi

Answer 13

Composed of the central processes of peripheral sensory neurons supplying muscles, joints, and skin

Question 14

Areas of the body from which processes enter the gracile fasciculus and cuneate fasciculus, respectively

Answer 14

Processes entering from the lower part of the body form the gracile fasciculus; those from the upper part form the cuneate fasciculus

Question 15

Gray matter columns in the spinal cord

Answer 15

1) Posterior (Dorsal) Horn
2) Intermediate Gray / Intermediate Zone
3) Anterior Horn

Question 16

Column/root containing alpha and gamma (lower) motor neurons

Answer 16

Ventral Gray Column / Ventral Horn

Question 17

Spinal cord structures containing preganglionic cells for the autonomic nervous systems

Answer 17

Intermediolateral gray columns/horns

Question 18

These segments give rise to sympathetic axons that leave the spinal cord within the ventral roots and then travel to the sympathetic ganglia via the white rami communicantes

Answer 18

T1-L2

Question 19

From segments S2-4, these axons leave the spinal cord within the sacral ventral roots

Answer 19

Sacral parasympathetic neurons

Question 20

Lissauer’s Tract

Answer 20

Compact bundle of small fibers which are part of the pain pathway in the dorsolateral fasciculus of the spinal cord

Question 21

Where is the proportion of gray to white matter greatest in the spinal cord

Answer 21

lumbar and cervical enlargements

Question 22

General trend with spinal lamina (what is where generally?)

Answer 22

Dorsal: sensory
Intermediate Areas: autonomics
Ventral: motor

Question 23

Describe the medial stream of afferent fibers into lamina of rexed

Answer 23

• Comprised of medium/large fibers which divide within posterior funiculus into asc/desc branches
• Branches swing into the post. gray horn and synapse in Lamina II, III, IV
• Largest ascending fibers run all the way to the posterior column nuclei in the medulla oblongata
• Long fibers form bulk of gracile/cuneate fasciculi

Question 24

Describe the lateral stream of afferent fibers into lamina of rexed

Answer 24

• Comprised of small (Aδ and C) fibers which divide into short ascending/descending branches with the posterolateral tract of Lissauer
• Synapse upon neurons in the Marginal Zone (Lamina I) and Substantia Gelatinosa (Lamine II)
• Some fibers synapse upon dendrites of Laminae III-V

Question 25

Give rise to anterior and posterior spinal arteries (respectively, I think)

Answer 25

Vertebral and Radicular (esp Great Radicular Artery of Adamkiewicz) Arteries

Question 26

Give rise to spinal arterial plexus

Answer 26

Anterior and Posterior Spinal Arteries

Question 27

Knee-Jerk Reflex. ___ type fiber endings in quadriceps muscle spindles are exited and in turn excite quadriceps ____ motor neurons

Answer 27

Ia type fibers

alpha motor neurons

Question 28

General principle of reciprocal inhibition in reflexes

Answer 28

Reflex activity in a given muscle produces similar activity in its ipsilateral synergists and the opposite activity in its ipsilateral antagonists.

Question 29

Principal Cord Segment Tested: biceps reflex

Answer 29

C5

Question 30

Principal Cord Segment Tested: brachioradialis reflex

Answer 30

C6

Question 31

Principal Cord Segment Tested: triceps reflex

Answer 31

C7

Question 32

Principal Cord Segment Tested: knee-jerk reflex (patellar)

Answer 32

L4

Question 33

Principal Cord Segment Tested: ankle-jerk reflex (achilles)

Answer 33

S1

Question 34

Autogenic inhibition

Answer 34

Alpha motor neurons that innervate the muscle connected to the relevant golgi tendon organ are inhibited via inhibitory interneuron between the afferent and efferent fibers.

Question 35

Two ways which flexor reflex pathways spread over multiple spinal segments

Answer 35

1) Primary afferent fibers bifurcate on entering the spinal cord and their processes then extend one or more segments in both rostral and caudal directions
2) flexor pathway includes at least one interneuron, which itself may have processes extending over several segments

Question 36

Crossed effects of a flexor reflex

Answer 36

Simultaneous and opposite pattern of activity in the contralateral limb; As the left left leg flexes and withdraws, the right leg extends and is thus better able to support the body