Lecture 1

Question 1

The vertebral column is divided into 5 sections:

Answer 1

Cervical (7) Rostral
Thoracic (12)
Lumbar (5)
Sacrum (Composite, 5 pieces)
Coccyx (Composite, 4 pieces) Caudal

Question 2

The curved shape of the spine is created when infants:

Answer 2

Are learning to look up and sit up (Born with a straight/non curved vertebral column

Question 3

Name the 3 anatomical sections of the vertebral column (Transverse view)

Answer 3

Body (Large anterior section), Spinous process (Posterior bony projection), Vertebral canal (Hollow center section holding the spinal cord - only about 50-75% of the space taken up by it)

Question 4

The spinal nerves (Off of the spinal cord) are divided into 5 sections:

Answer 4

Cervical (8 pairs) - C1->C7 above vertebrae, C8->S5 below vertebrae
Thoracic (12 pairs)
Lumbar (5 pairs)
Sacral (5 pairs)
Coccygeal (1 pair)

Question 5

Name and locate the landmarks of the spinal cord (4)

Answer 5

Cervical Enlargement - C4 vertebrae, C5 nerves (Brachial plexus)

Lumbar Enlargement - T12 vertebrae, L1/L2 nerves (Lumbar plexus)

End of the spinal cord - L2 vertebrae (S5 nerves)

Cauda Equina - No longer spinal cord, but spinal nerves off the spinal cord extend creating this “horses tail”

Question 6

Spinal cord cross section: Ventral roots

Answer 6

Anterior side
Carries motor info out towards muscle

Question 7

Spinal cord cross section: Dorsal roots

Answer 7

Posterior side
Carries sensory info back towards spinal cord

Question 8

Spinal cord cross section: Gray matter

Answer 8

Anterior horn - muscle contraction
Lateral horn - cell bodies, autonomic nervous system
Posterior horn - taking in sensory info

Gray due to cell bodies of the neurons

Question 9

Spinal cord cross section: White matter

Answer 9

Dorsal, ventral, lateral columns

White due to axons travelling down covered in myelin sheath

Question 10

Types of info carried in spinal cord

Answer 10

Motor travels DOWN the spinal cord

Sensory travels UP the spinal cord

Question 11

2 types of motor information and differences between them

Answer 11

Somatic
- Contraction of:
-Skeletal muscle
-Joints
-Aware and in control/voluntary

Autonomic
- Smooth muscle, cardiac muscle, or gland
-Not always in control/involuntary (Not
consciously in control
-Ex. Contraction of bladder
- 2 types of autonomic info

Question 12

2 types of autonomic information and differences between them

Answer 12

Sympathetic
- Fight or flight

Parasympathetic
- More important at rest

Question 13

What is a dermatome?`

Answer 13

An area of skin supplied by a group of sensory axons (the same group) of a particular spinal segment (all innervated by the same nerve)

Explains where sensory info goes to first before travelling to brain (T3 = nipple line, T10 = belly button

Question 14

What is a myotome?

Answer 14

The group of muscles innervated by a particular segment

Most segments innervate more than one muscle, and most muscles are innervated by more than one segment

Question 15

What are the tracts of the spinal cord?

Answer 15

Very organized multi-lane highway going up and down bringing specific info in each lane

Ascending tract - sensory info to brain

Descending tract - motor info from brain to muscles

Question 16

Ascending tracts of spinal cord have how many neurons to reach the brain? Examples?

Answer 16

Sensory info takes primary, secondary and tertiary neurons

Most names explain where it travels to (Spinothalamic tract - spinal cord to thalamus, etc)

Dorsal column**

Question 17

Descending tracts of spinal cord have how many neurons to go from brain to muscles? Examples?

Answer 17

Motor info takes just 2 neurons to get to the muscles (Upper and lower motor neurons AKA spinal, or peripheral nerves)

Corticospinal tract - cortex to spinal cord info transfer

Question 18

What are the 3 different groups of Ascending tracts in the spinal cord?

Answer 18

1. Spinothalamic system
   - Lateral spinothalamic
   - Anterior spinothalamic
2. Dorsal Columns (medial-Lemniscal system)
   - Fasciculus gracilis
   - Fasciculus cuneatus
3. Spinocerebellar system
   - Posterior spinocerebellar tract
   - Anterior spinocerebellar tract

Question 19

What are the 2 different groups of Descending tracts in the spinal cord?

Answer 19

1. Direct pathways (Pyramidal)
   - Corticospinal
2. Indirect pathways (Extrapyramidal)
   - Rubrospinal tract

Question 20

What are the 2 sections of the Spinothalamic system (Ascending tract) and their purposes?

Answer 20

1. Lateral spinothalamic tract
   - Carries pain and temperature sensations from periphery to brain
2. Anterior spinothalamic tract
   - Carries light touch (Wind, light brushing, NOT poking), pressure, tickle and itch sensations from periphery to brain

Question 21

What are the 2 sections of the dorsal column (Medial-Lemniscal), their level of sensation, and purpose? (Ascending tract)?

Answer 21

Carries fine touch, proprioception, pressure and vibration sensations from the periphery to brain

1. Fasciculus Gracilis
   - Sensation below T6 dermatome
2. Fasciculus Cuneatus
   - Sensation from dermatome T6 and above

Question 22

What are the 2 sections of the Spinocerebellar system (Ascending tract) and their purposes?

Answer 22

Carries proprioceptive information from periphery to cerebellum (Used for coordination of movements and maintenance of posture

1. Posterior spinocerebellar tract
   - Info from lower extremities
2. Anterior spinocerebellar tract
   - Info from L2 and above

Question 23

What are the purposes of the direct (pyramidal) pathways, and why are they direct? (Descending tract)

Answer 23

Maintenance of muscle tone and controlling the speed and precision of skilled movements

• Direct since upper motor neurons synapse directly with lower motor neurons in spinal cord

Question 24

What are the purposes of the indirect (extrapyramidal) pathways and why are they indirect? (Descending tract)

Answer 24

Involved in less precise motor control such as overall body coordination

• Indirect since upper motor neurons synapse in some intermediate nucleus (Group of cell bodies) rather than directly synapsing with lower motor neurons

Question 25

What are the 2 sections of the corticospinal system and their purposes? (Direct, Descending tract)

Answer 25

Upper motor neurons originate in cerebral cortex, descend in brainstem until caudal medulla 1. Lateral corticospinal tract - 75-85% of the neurons cross at pyramidal decussation and descend into this lateral corticospinal tract - Used in contralateral limb movements (Since crosses over) 2. Anterior corticospinal tract - 15-25% of the neurons descend uncrossed in spinal cord as the anterior corticospinal tract - Used in trunk neck and shoulder movements Both used for maintenance of muscle tone and controlling the speed and precision of skilled movements

Question 26

How does the Autonomic nervous system function? (4 steps)

Answer 26

Preganglionic neuron Synapses Autonomic ganglia (Group of cell bodies) Synapses Postganglionic neuron Synapses Effector organ

Question 27

What is a ganglion?

Answer 27

A group of neuron cell bodies (connected by synapses to different systems) - Like a PRE drink - Excites the transmission sending a signal to a specific area

Question 28

Sympathetic nervous system divergence and ganglionic neurons and purpose?

Answer 28

This system prepares body for fight or flight - Excitatory towards things that will be helpful (heart rate) - Inhibitory towards things that won't be (digestion) Preganglionic neurons originate in gray matter between T1 and L2 There is a lot of divergence from preganglionic -> postganglionic - Mass activation, so one preganglionic leads to many postganglionic Has short preganglionic neurons, and long postganglionic neurons - Due to preganglionic neurons being close to spinal cord, so longer to reach the target organs from there, but signal is fast to get to cord

Question 29

Parasympathetic nervous system divergence, ganglionic neurons and purpose?

Answer 29

This system is predominant at rest - Excitatory towards things that will be helpful (Bile secretion, blinking) - Inhibitory towards things to relax better (Decrease heart rate) Preganglionic neurons originate in brainstem and gray matter between S2 and S4 There is less divergence from preganglionic -> postganglionic - Due to picking and choosing what is activated at rest, not mass activation/everything at once like sympathetic Has long preganglionic neurons and short postganglionic neurons - Due to being postganglionic neurons being close to target organs, so longer to get to spinal cord, but very close to organs after 75% of outflow is from the vagus nerve

Question 30

What happens if only one system is affected by a spinal cord injury (Ex. Just the sympathetic nervous system?)

Answer 30

Still causes many issues since usually a good balance of the two working, causing different issues through the organs and body

Question 31

What is a reflex and give an example of the process of a somatic reflex (5 steps)

Answer 31

An involuntary motor response to a sensory stimulus 1. Sensory receptor (Feel tap on patellar tendon) 2. Afferent neuron (Sends message to cord) 3. Association neuron (Allows synapse) 4. Efferent neuron (Message to kick out leg) 5. Effector cells (Contracts muscles to kick the leg out)

Question 32

Afferent vs. Efferent

Answer 32

Afferent - Sends sensory feedback to spinal cord/towards CNS Efferent - Motor neurons that carry impulses from CNS to muscles to cause movement

Question 33

What could an example of an autonomic reflex/baroreflex be?

Answer 33

Balancing blood pressure by increasing or decreasing heart rate whenever the baroreceptors detect a large enough change