Spinal Pathways (dense material)

Question 1

What is the function of the primary motor cortex?

Answer 1

Initiates voluntary movement (efferent output)

Question 2

What is the function of the primary somatosensory cortex?

Answer 2

Receives and processes sensory information (afferent input)

Question 3

What is the function of the thalamus?

Answer 3

Major relay center for sensory and motor signals; also involved in attention, awareness, memory, and movement

Question 4

What is meant by contralateral control in the brain?

Answer 4

Right side of the body is controlled by the left cortex, and left side of the body by the right cortex

Question 4

Why do hands and face have larger cortical representation than legs?

Answer 4

They perform more precise, complex movements requiring greater neural control

Question 5

What is found in the anterior (ventral) horn?

Answer 5

Somatic motor nuclei (controls skeletal muscle)

Question 5

What is found in the posterior (dorsal) horn?

Answer 5

Somatic and visceral sensory nuclei

Question 6

What is found in the lateral horn?

Answer 6

Visceral motor nuclei (preganglionic sympathetic neurons); only present from T1–L2/L3

Question 7

What is white matter composed of?

Answer 7

Myelinated axons

Question 8

What are columns in white matter?

Answer 8

Large regions of white matter

Question 8

What is the function of the dorsal column?

Answer 8

Carries ascending sensory information

Question 9

What are tracts?

Answer 9

Smaller bundles of axons within columns

Question 10

What is found in anterior and lateral columns?

Answer 10

Both ascending (sensory) and descending (motor) tracts

Question 11

What is the anterior white commissure?

Answer 11

Area where axons cross (decussate) to the opposite side

Question 12

What are the functions of the somatic nervous system?

Answer 12

Conscious sensation and voluntary control of skeletal muscles

Question 13

Where are somatic sensory receptors located?

Answer 13

Skin, muscles, and joints

Question 14

Where are visceral sensory receptors located?

Answer 14

Internal organs (monitor hunger, stretch, etc.)

Question 15

What does the somatic motor division control?

Answer 15

Voluntary skeletal muscle movement

Question 16

What does the visceral motor division control?

Answer 16

Involuntary actions (smooth muscle, cardiac muscle, glands)

Question 17

How many neurons are in a sensory pathway?

Answer 17

Three: 1st order, 2nd order, 3rd order

Question 18

What does the 1st order neuron do?

Answer 18

Carries signal from sensory receptor to spinal cord or brainstem

Question 19

What does the 2nd order neuron do?

Answer 19

Carries signal from spinal cord/brainstem to thalamus

Question 20

What does the 3rd order neuron do?

Answer 20

Carries signal from thalamus to primary somatosensory cortex

Question 21

Where do sensory neurons enter the spinal cord?

Answer 21

Through the dorsal root

Question 22

What type of information does the dorsal column pathway carry?

Answer 22

Fine touch, light pressure, proprioception

Question 23

Where does the dorsal column pathway decussate?

Answer 23

Medulla oblongata

Question 24

Dorsal column pathway sequence?

Answer 24

Receptor → 1st order neuron to medulla → decussates → 2nd order neuron to thalamus → 3rd order neuron to somatosensory cortex

Question 25

What type of information does the anterolateral pathway carry?

Answer 25

Pain and temperature

Question 26

Where does the anterolateral pathway decussate?

Answer 26

In the spinal cord at the level of entry

Question 27

Anterolateral pathway sequence?

Answer 27

Receptor → 1st order neuron to dorsal horn → decussates → 2nd order neuron to thalamus → 3rd order neuron to somatosensory cortex

Question 28

Difference between dorsal column vs anterolateral pathways?

Answer 28

Dorsal column = fine touch/proprioception, decussates in medulla Anterolateral = pain/temp, decussates in spinal cord

Question 29

How many neurons are in motor pathways?

Answer 29

Two: upper motor neuron (UMN) and lower motor neuron (LMN)

Question 30

What does the upper motor neuron do?

Answer 30

Carries signal from primary motor cortex to spinal cord

Question 31

What does the lower motor neuron do?

Answer 31

Carries signal from spinal cord to skeletal muscle

Question 32

Where do lateral corticospinal tracts decussate?

Answer 32

Medulla oblongata (pyramids)

Question 32

What is the function of corticospinal tracts?

Answer 32

Control voluntary skeletal muscle movement

Question 33

What do lateral corticospinal tracts control?

Answer 33

Appendicular muscles (limbs)

Question 34

What do anterior (ventral) corticospinal tracts control?

Answer 34

Axial muscles (trunk)

Question 35

Where do anterior corticospinal tracts decussate?

Answer 35

At the spinal cord level

Question 36

What do corticobulbar tracts control?

Answer 36

Muscles of the face, jaw, tongue, and pharynx

Question 37

Where do corticobulbar tracts synapse?

Answer 37

Motor nuclei of cranial nerves in the brainstem

Question 38

What initiates a pain reflex (e.g., touching a hot object)?

Answer 38

Activation of sensory receptors

Question 39

What neuron carries the signal to the spinal cord?

Answer 39

Sensory (afferent) neuron

Question 40

What pathway carries pain to the brain?

Answer 40

Anterolateral pathway

Question 41

What happens at the spinal cord during a reflex?

Answer 41

What happens at the spinal cord during a reflex?

Question 42

What is the immediate response?

Answer 42

Synapse directly with motor neuron → rapid withdrawal

Question 43

What is the delayed response?

Answer 43

Signal sent to brain via interneurons for conscious perception (“ouch”)

Question 44

How does the motor neuron exit the spinal cord?

Answer 44

Through the ventral root

Question 45

Are meninges the same in brain and spinal cord?

Answer 45

Yes: dura mater, arachnoid mater, pia mater

Question 45

What is the final step in a reflex?

Answer 45

Effector muscle contracts

Question 45

What happens to nerve signals in spinal cord injury?

Answer 45

Transmission is blocked in both directions at the level of injury

Question 46

What is different about the epidural space in spinal cord vs brain?

Answer 46

Spinal cord: real space Brain: potential space

Question 46

Why is permanent spinal cord damage irreversible?

Answer 46

Neurons in the CNS do not regenerate

Question 47

Why can some spinal cord function recover?

Answer 47

Temporary damage from edema/inflammation may resolve