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Figure

The cerebellum, which is located below the occipital lobes of the cerebrum, communicates with other parts of the nervous system by means of the cerebellar peduncles.

Figure

A sagittal section of the brain showing the cerebrum, diencephalon, brain stem, and cerebellum (see also plate 76).

ure 11.23

Figure

A sagittal section of the brain showing the cerebrum, diencephalon, brain stem, and cerebellum (see also plate 76).

pe-dung'k'ls) (fig. 11.23). One pair, the inferior peduncles, brings sensory information concerning the actual position of body parts such as limbs and joints to the cerebellum via the spinal cord and medulla oblongata. The middle peduncles transmit information from the cerebral cortex about the desired position of these body parts. After integrating and analyzing the information from these two sources, the cerebellum sends correcting impulses from the dentate nucleus via the superior peduncles to the midbrain (fig. 11.22). These corrections are incorporated into motor impulses that travel downward through the pons, medulla oblongata, and spinal cord in the appropriate patterns to move the body in the desired way.

Overall, the cerebellum integrates sensory information concerning the position of body parts and coordinates skeletal muscle activity and maintains posture. It receives sensory impulses from receptors in muscles, tendons, and joints (proprioceptors) and from special sense organs, such as the eyes and ears (see chapter 12, p. 461). For example, the cerebellum uses sensory information from the semicircular canals of the inner ears concerning the motion and position of the head to help maintain equilibrium. Damage to the cerebellum is likely to result in tremors, inaccurate movements of voluntary muscles, loss of muscle tone, a reeling walk, and loss of equilibrium.

Table 11.7 summarizes the characteristics and functions of the major parts of the brain. Clinical Application 11.6 discusses how brain waves reflect brain activity.

H Where is the cerebellum located?

What are the major functions of the cerebellum?

What kinds of receptors provide information to the cerebellum?

Part

Characteristics

Functions

Part

Characteristics

Functions

1. Cerebrum

2. Basal nuclei (ganglia)

3. Diencephalon

4. Brain stem a. Midbrain b. Pons c. Medulla oblongata

5. Cerebellum

Largest part of the brain; two hemispheres connected by the corpus callosum

Masses of gray matter deep within the cerebral hemispheres

Includes masses of gray matter (thalamus and hypothalamus)

Connects the cerebrum to the spinal cord Contains masses of gray matter and bundles of nerve fibers that join the spinal cord to higher regions of the brain A bulge on the underside of the brain stem that contains masses of gray matter and nerve fibers An enlarged continuation of the spinal cord that extends from the foramen magnum to the pons and contains masses of gray matter and nerve fibers

A large mass of tissue located below the cerebrum and posterior to the brain stem; includes two lateral hemispheres connected by the vermis

Controls higher brain functions, including interpreting sensory impulses, initiating muscular movements, storing memory, reasoning, and determining intelligence Relay stations for motor impulses originating in the cerebral cortex and passing into the brain stem and spinal cord The thalamus is a relay station for sensory impulses ascending from other parts of the nervous system to the cerebral cortex; the hypothalamus helps maintain homeostasis by regulating visceral activities and by linking the nervous and endocrine systems

Contains reflex centers that move the eyes and head, and maintains posture

Relays nerve impulses to and from the medulla oblongata and cerebrum; helps regulate rate and depth of breathing Conducts ascending and descending impulses between the brain and spinal cord; contains cardiac, vasomotor, and respiratory control centers and various nonvital reflex control centers

Communicates with other parts of the CNS by nerve tracts; integrates sensory information concerning the position of body parts; and coordinates muscle activities and maintains posture

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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