ch 8 book questions

Question 1

Know the different structures of the cerebral hemispheres (cortex, fissures, gyri, etc.)

Answer 1

• longitudinal fissure: separates left and right hemispheres (interhemispheric/sagittal)
• cortex: visible surface, mostly complex/sophisticated part of brain
• gyri: ridges sulci: dips fissure: deep sulcus
• corpus callosum: massive bundle of tissue connecting structures across hemispheres

Question 2

What is one of the main differences between the brain of humans and the brain of animals?

Answer 2

humans have relatively deep and numerous sulci defining the cortical surface

Question 3

Familiarize yourself with the hidden cortical surface

Answer 3

• the deeps sulci are infolding of cortical surface, forming hidden walls of tissue that contribute to a greater volume of cortical cells in the human brain relative to other animals
• the hidden cortical surface area and its corresponding thickness add to human cognitive and performance power

Question 4

Somatotopic representations- understand the size of cortical tissue devoted to different regions/structures of the body (which body parts are associated with the biggest/smallest areas of cortical tissue)

Answer 4

• the size of the face and and its associated structures (tongue, lips, larynx) is exceptionally large compared to the size of the feet or trunk
• a disproportionate number of cells in the primary motor cortex are devoted to control of the structures that play a major role in speech production and swallowing
• there’s a disproportionate representation of cells that control movements of orofacial structures (jaw, tongue, lips) and laryngeal structures

Question 5

Location of Broca’s Area

Answer 5

the inferior frontal gyrus, on the lateral surface of the left frontal lobe and immediately above the front end of the sylvian fissure

Question 6

Role of Broca’s Area

Answer 6

• central role in the planning and organization of motor behavior required for speech production
• the site where speech expression is controlled

Question 7

Know the specific names of the descending projection tracts

Answer 7

• corticobulbar tract: fibers originating in cortical neuron cell bodies that make a first synapse in one of the several brainstem motor nuclei
• corticospinal tract: fibers originating in the cortex that make a first synapse in motor cells of the spinal cord
• and tracts running from cortical regions to the thalamus: corticothalamic tracts

Question 8

Know the two major somatosensory pathways for stimuli sensed below the neck

Answer 8

posterior column-medial lemniscal tract & anterolateral tract

Question 9

Know the functions of the two major somatosensory pathways

Answer 9

• posterior column-medial lemniscal tract: carries sensory information from one side of the body. this sensory information enters the spinal cord after making a first synapse in a dorsal root ganglion.
• anterolateral tract: carries information on pain, temperature, and “crude” touch and coveys it to the cortex on the side opposite to the stimulation
• both tracts eventually send their information to the thalamus where synapses are made and fibers sent to the cortex

Question 10

Know where upper and lower motor neuron lesions occur

Answer 10

• upper motor neuron lesions: in the cortical motor neurons or in the axons they issue prior to making synapses with the motor neurons in the brainstem or spinal cord
• lower motor neuron lesions: in the nuclei of the brainstem or motor cells of the spinal cord, or in the axons they issue and the peripheral nerves in which those axons travel, or even at the location of the nerve-muscle fiber connection

Question 11

Know the results of upper and lower motor neuron lesions

Answer 11

• upper: muscles with excessive muscle tone while at rest and hypersensitive reflexes
• lower: loss of muscle mass (wasting or atrophy) small muscle twitches visible to the naked eye (fasciculations) and in some cases low muscle tone at rest
• both: affected muscles tend to be weak