Ch3: The Hindbrain, Midbrain, and Forebrain

the hindbrain, the midbrain, and the forebrain

The brain has 3 major divisions …

Diencephalon (“between brain”) - Thalamus and hypothalamus

Telencephalon (“end brain”) - Cerebral cortex, hippocampus, basal ganglia

Major structures in forebrain

tectum, tegmentum, superior colliculus, inferior colliculus, substantia nigra

Major structures in the midbrain

medulla, pons, cerebellum

Major structures in the hindbrain

hindbrain

the posterior part of the brain

brainstem

the medulla, pons, midbrain, and central structure of the forebrain; reptillian/primitive brain

medulla

hindbrain structure located just above the spinal cord; could be regarded as an enlarged extension of the spinal cord MEG; continuation of reticular formation; vital reflexes

cranial nerves

nerves that control sensations from the head, muscle movements in the head, and much of the parasympathetic output in the organ

pons

hindbrain structure that lies anterior and ventral to the medulla; a “bridge” so that left hemisphere controls the right side and right hemisphere controls the left side; continuation of reticular formation; motor control

cerebellum

highly folded hindbrain structure that is important for behaviors that depend on accurate timing; important for movement, balance, and coordination; really affected by alcohol

midbrain

middle part of the brain; more prominent in reptiles, amphibians, and fish

tectum

roof of the midbrain; contains the superior colliculus and inferior colliculus; dorsal side

superior colliculus

swelling on either side of the tectum; important to visual processing

inferior colliculus

swelling on the surface of the tectum that contributes to hearing

tegmentum

under the tectum; intermediate level of the midbrain; VTA (ventral tegmental area); substantia nigra; start of reticular formation

substantia nigra

a midbrain structure that gives rise to a pathway releasing dopamine; involved with Parkinson’s disease and the frozen patients

forebrain

most anterior part of the brain; consists of two cerebral hemispheres

limbic system

interlinked structures that form a border around the brainstem; structures are important for motivations and emotions

amygdala

temporal lobe structure important for evaluating emotional information, especially fear

thalamus

a pair of structures in the center of the forebrain; most sensory (minus olfactory) info goes through here first; many nuclei

hypothalamus

small area near the base of the brain, ventral to the thalamus; conveys messages to the pituitary gland, altering its release of hormones; damage to this area leads to abnormalities in motivated behaviors, like feeing, drinking, temperature regulation, sexual behavior, fighting, or activity level; the 4 F’s (fight, flight, food, f***); controls autonomic NS; controls pituitary gland

pituitary gland

an endocrine (hormone-producing) gland attached to the base of the hypothalamus; synthesizes hormones that the blood carries to organs throughout the body

basal ganglia

a group of subcortical forebrain structures lateral to the thalamus; includes 3 major structures: the caudate nucleus, the putamen, and the globus; circuits with cortex modulate motor and cognitive function

nucleus basalis

a forebrain structure that lies on the ventral surface; receives input from the hypothalamus and basal ganglia; sends axons to areas in the cerebral cortex; key part in arousal, wakefulness, and attention; inactivity/deterioration of this causes Parkinson’s, Alzheimers, and other diseases related to impairments of attention and intellect

hippocampus

a large structure located toward the posterior of the forebrain, between the thalamus and the cerebral cortex; important in learning and memory

Hindbrain: cerebellum, medulla, and pons.

Midbrain: substantia nigra, superior and inferior colliculi, tectum, and tegmentum.

Forebrain: basal ganglia, hippocampus, hypothalamus, pituitary, and thalamus

Of the following, which are in the hindbrain, which in the midbrain, and which in the forebrain: basal ganglia, cerebellum, hippocampus, hypothalamus, medulla, pituitary gland, pons, substantia nigra, superior and inferior colliculi, tectum, tegmentum, thalamus?

thalamus

Which area is the main source of input to the cerebral cortex?

ventricles

four fluid-filled cavities within the brain

cerebrospinal fluid (CSF)

a clear fluid similar to blood plasma produced by choroid plexus in the brain ventricles

meninges

membranes that surround the brain and spinal cord

dura mater - outside membrane

arachnoid membrane

pia mater

What are the layers of the meninges?

hyrdocephalus

a condition caused by accumulation of CSF within the ventricles or the subarachnoid space, increasing pressure on the brain; if occurring in infants, the skull bones spread, causing an overgrown head; can lead to mental retardation

1. cerebrospinal fluid (CSF)

2. meninges (a layer of membranes)

3. blood-brain barrier

How is the brain protected?

toward the stomach

What does ventral mean?

ipsilateral

If two structures are both on the left side, or both on the right, what is their relationship?

a groove that separates one gyrus from another?

What is a sulcus?

They receive sensory input

What is the function of the dorsal roots of the spinal cord?

vegetative activities

What does the parasympathetic nervous system control?

b. the cranial nerves

Which of these controls breathing, heart rate, and salivation?

a. the hippocampus

b. the cranial nerves

c. the basal ganglia

d. the pituitary gland

a. hippocampus

Which of these is part of the forebrain?

a. hippocampus

b. medulla

c. pons

d. cerebellum

c. thalamus

Which structure provides most of the direct input to the cerebral cortex?

a. cranial nerves

b. medulla

c. thalamus

d. pineal gland

c. cerebrospinal fluid

What do the ventricles contain?

a. densely packed neuron cell bodies

b. glia

c. cerebrospinal fluid

d. long axons