Spinal Cord Anatomy

Question 1

How many cranial, thoracic, lumbar, sacral, and coccygeal nerves?

Answer 1

8 cranial, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal.

Question 2

Where are the cervical and lumbar enlargements?

Answer 2

Cervical: C5-T1. Lumbar: L1-S2.

Question 3

Where does the fetal spinal cord end? Adult spinal cord?

Answer 3

L3. L1/L2

Question 4

What are the dermatomes for back of head, thumb and index finger, nipples, umbilicus, knee cap, and lateral foot?

Answer 4

C2=back of head
C6=thumb and index finger
T4=nipples
T10=umbilicus
L3=kneecap
S1=lateral foot

Question 5

What are the three gray matter regions?

Answer 5

Posterior (dorsal) horn, intermediate gray, and anterior (ventral) horn.

Question 6

Describe alar and basal plates

Answer 6

Alar=afferent, sensory. Basal=efferent, motor.

Question 7

Describe substantia gelatinosa

Answer 7

In dorsal horn, modify sensory input. Valve for pain.

Question 8

Describe nucleus proprius

Answer 8

In dorsal horn, contains cells that form spinothalamic tract, which is most important pain pathway.

Question 9

Describe nucleus dorsalis

Answer 9

In intermediate gray, projects to cerebellum as dorsal spinocerebellar tract. Helps with proprioception/coordination.

Question 10

Describe interomediolateral (IML) nucleus

Answer 10

In intermediate gray, origin of preganglionic sympathetic efferents. Only T1-L3. GVE

Question 11

Describe medial and lateral motor nuclei

Answer 11

Medial controls trunk/shoulders. Lateral does fingers etc.

Question 12

Where is there more white matter in the spinal cord?

Answer 12

More in cervical cord than lumbar or thoracic cord.

Question 13

Describe free nerve endings

Answer 13

Nonencapsulated. Pain/temp

Question 14

Describe Merkel’s disk.

Answer 14

Nonencapsulated. Touch in feet, hands, genitalis, lips

Question 15

Describe hair follicles.

Answer 15

Nonencapsulated and fast adapting. Touch

Question 16

Describe meissner’s corpuscle

Answer 16

Encapsulated and fast adapting. 2 point discrimination

Question 17

Describe Pacinian corpuscle

Answer 17

Encapsulated and fast adapting. Vibration

Question 18

Describe Ruffini ending

Answer 18

Encapsulated. Pressure/stretch

Question 19

Describe joint receptor

Answer 19

Encapsulated. Joint position

Question 20

Describe neuromuscular spindle

Answer 20

Encapsulated. Muscle stretch

Question 21

Describe golgi tendon organs

Answer 21

Encapsulated. Muscle tension

Question 22

Describe myelination of lateral and medial divisions of dorsal root afferents.

Answer 22

Lateral: lightly myelinated, pain and temp.
Medial: heavily myelinated, 2-point touch, limb position, and muscle stretch.