Questions: Neuroanatomy: Brain, Spinal Cord, and Peripheral Nervous System

Question 1

A patient suffers damage to the cerebellum. Which of the following deficits is most likely?

• A. Loss of the ability to form new memories
• B. Inability to initiate voluntary movement
• C. Loss of coordination and balance, with movements becoming jerky and imprecise
• D. Loss of language production due to disruption of Broca's area

Answer: (C)

The cerebellum does not initiate movement — that is the role of the motor cortex. Instead, it receives copies of motor commands and sensory feedback, then fine-tunes the output to make movements smooth, coordinated, and accurate. Cerebellar damage produces ataxia (impaired coordination), dysmetria (difficulty judging distances in movement), and balance problems. Memory and language are associated with cortical and limbic structures, not the cerebellum.

Question 2

The cerebellum is the primary region that initiates voluntary movements in response to sensory input.

• T. True
• F. False

Answer: False

Voluntary movement is initiated by the motor cortex (in the cerebrum's frontal lobe). The cerebellum's role is coordination and error correction — it receives copies of motor commands and proprioceptive feedback, then adjusts motor output to make movements accurate and smooth. A useful analogy: the motor cortex is the composer, and the cerebellum is the editor that removes the wrong notes.

Question 3

How is the peripheral nervous system subdivided, and what types of targets does each subdivision control?

Model answer: The PNS is divided into the somatic nervous system (voluntary control of skeletal muscles and conscious sensory input) and the autonomic nervous system (ANS, involuntary control of internal organs, glands, and smooth muscle). The ANS is further split into sympathetic (fight-or-flight: increases heart rate, dilates pupils, inhibits digestion) and parasympathetic (rest-and-digest: slows heart rate, stimulates digestion, constricts pupils) branches.

The somatic/autonomic distinction maps onto voluntary vs. involuntary control. Because most organs receive both sympathetic and parasympathetic innervation, the ANS achieves fine-grained control through the balance between the two, not by switching one entirely off. This dual innervation also explains why the sympathetic and parasympathetic systems are not simply opposing on/off switches — they operate simultaneously at different levels of tone.