Chapter 6 The Nervous System 211
The left frontal lobe also includes Broca’s
area, which controls the tongue and lip
movements required for speech. Damage to
this area in stroke patients produces diffi culty
with speaking. The association cortex on the most
anterior portion of the frontal lobe is believed to
be responsible for intellect.
The parietal (pa-RIGH-eh-tal) lobes are
immediately posterior to the frontal lobes. The
parietal lobes include the primary somatic
sensory cortex, which interprets sensory
impulses received from the skin, internal organs,
muscles, and joints. The display of body parts in
the somatic sensory part of Figure 6.10 represents
the density, or amount, of sensory neural input
received from different parts of the body. Notice
that the fi ngertips and lips, in particular, have a
lot of sensory receptors. This is why they occupy
large portions of the sensory cortex.
The occipital (ahk-SIP-i-tal) lobes, posterior
to the parietal lobes, are responsible for vision.
The lateral sulci divide the temporal (TEHM-
poh-ral) lobes, the most inferior lobes, from the
frontal and parietal lobes above them. The
temporal lobes are involved in speech, hearing,
vision, memory, and emotion. The region
responsible for speech is located at the
intersection of the occipital, temporal, and
parietal lobes.
Diencephalon
The diencephalon (DIGH-ehn-SEHF-
a-lahn), also known as the interbrain, is
located deep inside the brain, enclosed by the
cerebral hemispheres (Figure 6.12). It includes
several important structures—the thalamus,
hypothalamus, and epithalamus.
1. List the four major anatomic regions of
the brain.
2. Describe the relationship between gyri
and sulci.
3. List the four lobes of the brain and state
their locations.
4. List the function(s) of each lobe.
Check Your Understanding
• The thalamus (THAL-a-mus) serves as
a relay station for communicating both
sensory and motor information between the
body and the cerebral cortex. It also plays a
major role in regulating the body’s states of
arousal, including sleep, wakefulness, and
high-alert consciousness.
• Only about the size of a pearl, the
hypothalamus (HIGH-poh-THAL-a-mus) is
a key part of the autonomic nervous system,
regulating such functions as metabolism,
heart rate, blood pressure, thirst, hunger,
energy level, and body temperature. The
centers for sex, pain, and pleasure also lie
within the hypothalamus.
• The epithalamus (EHP-i-THAL-a-mus)
includes the pineal gland and regulates the
sleep-cycle hormones that it secretes.
Brain Stem
Approximately the size of a thumb, the
brain stem is shaped somewhat like a stem and
includes three structures: the midbrain, pons,
and medulla oblongata (Figure 6.12).
• The midbrain on the superior end of the
brain stem serves as a relay station for
sensory and motor impulses. Specifi cally,
it relays information concerning vision,
hearing, motor activity, sleep and wake
cycles, arousal (alertness), and temperature
regulation.
• The pons (pahnz), located immediately
below the midbrain, plays a role in
regulating breathing.
• Inferior to the pons, the medulla oblongata
(meh-DOOL-a AHB-lawn-gah-tah) regulates
heart rate, blood pressure, and breathing,
and controls the refl exes for coughing,
sneezing, and vomiting.
The reticular (reh-TIK-yoo-lar) formation
is a collection of gray matter that extends the
length of the brain stem. The reticular formation
regulates waking from slumber, as well as
heightened states of awareness. Individuals with
severe brain injuries can continue to live as long
as the brain stem remains functional and they
receive suffi cient hydration and nutrition.