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Unit 3C/D Answers
1) The cerebral hemispheres function differently:
Left Hemisphere (in most)
Right Hemisphere (in most)
Right hand control (body)
Left hand control (body)
Language
Music & Art
Numeric & Scientific skill
Space & Pattern Perception
Reasoning
Insight
Comparing
2) The White Matter of the Cerebrum contains Association fibers found between gyri in the
same hemisphere, they do not exist in the cerebral hemisphere, while Commissural fibers found in
the corpus callosum connect the right and left hemispheres, and finally the Projection fibers
connect the cerebrum to the rest of the brain and spinal cord.3C 8
3) The Cerebral Nuclei or Basal Ganglia are composed of gray matter deep inside the cerebrum.
Interneurons provide connection of the cerebral cortex with the brainstem, the thalamus and the
hypothalamus. Its functions are to influence muscular activity, regulate attention and cognition,
also regulate the intensity of slow or stereotyped movements and inhibit antagonistic and
unnecessary movements. 3C 8-9
4) The Diencephalon is made up of the Thalamus, Hypothalamus and the Epithalamus. 3C 9
5) The thalamus gland is the relay station for sensory input, except for smell, to the cerebrum.
Its role is in mediating sensation, motor activities, cortical arousal, learning, and memory. It has
four groups of nuclei on each side: anterior, ventral, dorsal, and posterior.3C 9
6) The Hypothalamus senses sound, taste, smell, and somatic sensations. It monitors the body
providing homeostasis and connects the nervous system to the endocrine system and controls it.
7) The epithalamus region is located on the roof of the third ventricle. The pineal gland is found
here and is part of the endocrine system and it secretes the hormone melatonin. The choriod
plexus also forms CSF from the blood. 3C 9
8) The midbrain contains cerebral peduncles which are located on the ventral side and are
composed of white matter. This contains motor fibers from the cerebral cortex that go to the
pons and the spinal cord and also sensory fibers from the spinal cord to the thalamus for sorting.
The tectum is located on the dorsal side and contains reflex centers that receive visual input and
cause head and neck movement and receive auditory input that causes head and trunk movement.
9) The midbrain also contains the cell bodies for cranial nerves such as Oculomotor III,
Trochlear, and Abducens VI nerve. 3C 10
10) The pons connects the medulla oblongata, and the spinal cord to the brain, it is in control of
respiration with the medullary respiratory center. Nuclei for cranial nerves within the pons are
the Trigeminal V, the Adbucens VI, the Facial VII, the Vestibulocochlear VIII. 3C10
11) In the Autonomic Nervous System (ANS) motor neurons innervate the viscera of smooth and
cardiac muscle and also glands, as it regulates the viscera to ensure homeostasis during body
activities. It is very hard to override the ANS voluntarily as it operates subconsciously.
12) The Autonomic Nervous System (ANS) has two branches, the Sympathetic and the
Parasympathetic. The Sympathetic NS which is referred to as the Fight or Flight response called
for during exercise, excitement, emergencies, and embarrassment. It works with the Somatic
Nervous System (SNS) to provide oxygen and fuel to the skeletal muscles. While the
Parasympathetic NS is referred to as the rest and digest, which conserves energy during
relaxation, mostly controlling digestion, defecation, and diuresis. 3D1