Brain and Spinal Cord

Question 1

Gyrus

Answer 1

• ridge

- plural: gyri

Question 2

Sulcus

Answer 2

• shallow groove

- plural: sulci

Question 3

Fissure

Answer 3

-deep groove

Question 4

Central sulcus

Answer 4

-separates the precentral gyrus of the frontal lobe and the postcentral gyrus of the parietal lobe

Question 5

Longitudinal fissure

Answer 5

-separates the two hemispheres

Question 6

Lateral sulcus

Answer 6

-separates temporal lobe and parietal lobe

Question 7

Transverse cerebral fissure

Answer 7

-separates the cerebrum and the cerebellum

Question 8

Cerebral cortex

Answer 8

• thin (2-4mm) superficial layer of gray mater
• composed of interneurons (cell bodies, unmyelinated)
• site of conscious mind
• each hemisphere connects to contralateral side of the body
• there is lateralization of cortical function in the hemispheres

Question 9

Conscious mind

Answer 9

• awareness
• sensory perception
• voluntary motor initiation
• communication
• memory storage
• understanding

Question 10

6 cortical layers of the neocortex

Answer 10

1. Molecular layer
2. external granular layer
3. external pyramidal layer
4. internal granular layer
5. internal pyramidal layer
6. multiform layer

Question 11

Layers 1-3 of the neocortex

Answer 11

• intracortical communication
• association or commissural fibers
• sensory input

Question 12

Layer 4 of the neocortex

Answer 12

• input from thalamus

- output to cortical layers 2/3

Question 13

Layers 5 + 6 of the neocortex

Answer 13

• input from layers 2 and 3

- outputs: 5 to basal nuclei/SC/BS and 6 to thalamus

Question 14

Three types of functional areas of the cerebral cortex

Answer 14

1. Motor areas
2. Sensory areas
3. Association areas
   - conscious behavior involves ENTIRE cortex

Question 15

Motor areas

Answer 15

• control voluntary movement
• primary (somatic) motor cortex
• premotor cortex (controls learned motor skills
• Broca’s area (one side (left), motor speech area)
• frontal eye field (eye movements)

Question 16

Sensory areas

Answer 16

• conscious sensation
• primary somatosensory cortex
• somatosensory association cortex
• visual areas (occipital)
• auditory areas (temporal)
• olfactory cortex (insula)
• gustatory cortex (insula)
• visceral sensory area (insula)
• vestibular cortex (insula)

Question 17

Association areas

Answer 17

-integrate diverse information

Question 18

Primary motor cortex

Answer 18

• large pyramidal cells of the precentral gyri
• long axons (pyramidal/corticospinal tracts in spinal cord)
• allows conscious control of precise, skilled, voluntary movement
• control opposite side of body
• not a 1:1 ratio of neuron to muscle

Question 19

Motor homunculi of primary motor cortex

Answer 19

• upside-down caricatures representing the motor innervation of body regions
• face on lateral side (largest region)
• hands to feet (lateral to medial; hands 2nd largest)

Question 20

Primary somatosensory cortex

Answer 20

• in the postcentral gyri
• receives sensory information from the skin, skeletal muscles, and joints
• capable of spatial discrimination (identification of body region being stimulated)

Question 21

Motor homunculi of somatosensory cortex

Answer 21

• Face, teeth, gums, pharynx, and GI on lateral side (face is largest)
• Hands to feet (lateral to medial; hands and feet largest)
• Genitals most medial

Question 22

Lateralization

Answer 22

• division of labor between hemispheres

- left and right hemispheres communicate via fiber tracts in the cerebral white matter

Question 23

Cerebral dominance

Answer 23

-designates the hemisphere dominant for language (left hemisphere in 90% of people–> usually right-handed)

Question 24

Left hemisphere

Answer 24

-controls language, math, and logic

Question 25

Right hemisphere

Answer 25

-insight, visual-spatial skills, intuition, and artistic skills

Question 26

Cerebral white matter

Answer 26

• myelinated fibers and their tracts

- responsible for communication

Question 27

Commissures

Answer 27

• connect gray matter of the two hemispheres

- corpus callosum, anterior and posterior commissures

Question 28

Association fibers

Answer 28

-connect different parts of the same hemisphere

Question 29

Projection fibers

Answer 29

• connect the hemispheres with lower brain or spinal cord

- corona radiata: from internal capsule coming from brain stem

Question 30

Spinal cord white matter

Answer 30

-ascending and descending motor and sensory tracts

Question 31

Spinal cord gray matter

Answer 31

-divided into 12 laminae; multiple nuclei

Question 32

Sensory/ascending spinal tracts

Answer 32

• usually three neuron chains
  1. First order neuron in ganglion
  2. Second order neuron in dorsal horn
  3. Third order neuron in thalamus

Question 33

Spinocerebellar tract

Answer 33

• ventral and dorsal
• sensory info from muscle and tendon stretch to cerebellum
• stays on same side of brain hemisphere/spinal cord

Question 34

Spinothalamic tract

Answer 34

• lateral: pain and temp.
• ventral: crude touch and presure
• opposite side: cross at level of spinal cord

Question 35

Dorsal column-medial lemniscal tract

Answer 35

• discriminative touch, proprioception and vibration sensation
• opposite side of body (crosses in medulla)
• fasciculus gracilis: medial portion of dorsal funiculus (lower limb and trunk)
• fasciculus cuneatus: lateral portion of dorsal funiculus (upper limb and trunk

Question 36

Descending/motor spinal tracts

Answer 36

• two neuron chains (usually)
  1. Upper motor neuron: pyramidal cells in motor cortex
  2. Lower motor neuron: in ventral horn, innervate muscle

Question 37

Pyramidal (corticospinal) tracts

Answer 37

• skilled motor
• lateral: voluntary movement; crosses at decussation of pyramids of the medulla
• ventral: voluntary movement; crosses at the level of the spinal cord
• opposite side

Question 38

Rubrospinal tract

Answer 38

• muscle tone of distal limbs (flexors)

- opposite sides (cross in midbrain)