Brain anatomy

Question 1

5 Divisions of the brain

Answer 1

Forebrain
1. Telencephalon
2. Diencephalon
Midbrain
3. Mesencephalon
Hindbrain
4. Myelencephalon (or medulla)
5. Metencephalon

Question 2

Myelencephalon (medulla)

Answer 2

Most posterior division of the brain. Composed largely of tracts carrying signals between the rest of the brain and the body. Contains the reticular formation

Question 3

Reticular formation

Answer 3

Complex network of about 100 tiny nuclei that occupies the central core of the brain stem from the posterior boundary of the myelencephalon to the anterior boundary of the midbrain.

Question 4

Metencephalon

Answer 4

Houses many ascending and descending tracts and part of the reticular formation. These structures create a bulge, called the pons, on the brain stem’s ventral surface. The pons and cerebellum (little brain) are the major divisions of the metencephalon

Question 5

Cerebelum

What does damage to the cerebelum cause?

Answer 5

• Large, convoluted structure on the brain stem’s dorsal surface. It is an important sensorimotor structure.
• Cerebellar damage eliminates the ability to precisely control one’s movements and to adapt them to changing conditions. It also produces a variety of cognitive deficits (e.g., deficits in decision making and in the use of language) suggesting that the functions of the cerebellum are not restricted to sensorimotor control.

Question 6

Pons

Answer 6

Located on the brain stem’s ventral surface. The pons is one major division of the metencephalon

Question 7

Mesencephalon

Answer 7

Located in the midbrain, the mesencephalon has 2 divisions - tectum and the tegmentum

Question 8

Tectum

Answer 8

The dorsal surface of the midbrain. In mammals, the tectum is composed of two pairs of bumps, the colliculi (little hills).
The posterior pair, called the inferior col­liculi, have an auditory function. The anterior pair, called the superior colliculi, have a visual-motor function, specifically to direct the body’s orientation toward or away from particular visual stimuli

Question 9

Tegmentum

What are the 3 structures within the Tegmentum?

Answer 9

Division of the mesencephalon ventral to the tectum. In addition to the reticular formation and tracts of passage.

1. the periaqueductal gray (gray matter situated around the cerebral aqueduct. It helps to mediate the analgesic (pain-reducing) effects of opioid drugs.
2. the substantia nigra (important component of the sensorimotor system)
3. red nucleus (important component of the sensorimotor system)

Question 10

Diencephalon

Answer 10

Located in the forebrain the diencephalon is composed of two structures: the thalamus and the hypothalamus

Question 11

Thalamus

Answer 11

The large, two-lobed structure that constitutes the top of the brain stem. One lobe sits on each side of the third ventricle, and the two lobes are joined by the massa intermedia, which runs through the ventricle. Visible on the surface of the thalamus are white lamina (layers) that are composed of myelinated axons.

Question 12

Sensory relay nuclei

Answer 12

Located in the thalamus these nuclei receive signals from sensory receptors, process them, and then transmit them to the appropriate areas of sensory cortex.
E.g. lateral geniculate nuclei, medial geniculate nuclei, and the ventral posterior nuclei are important relay stations in the visual, auditory, and somatosensory systems, respectively.

Question 13

Hypothalamus

3 important structures in the hypothalamus?

Answer 13

Located just below the anterior thalamus. It plays an important role in the regulation of several motivated behaviours (e.g., eating, sleep, and sexual behaviour).
- Pituitary glands, optic chiasm and the mammillary bodies

Question 14

Optic chiasm

Answer 14

The point at which the optic nerves in each eye come together. The X shape is created because some of the axons of the optic nerve decussate (cross over to the other side of the brain) via the optic chiasm.
The decussating fibers are said to be contralateral (projecting from one side of the body to the other), and the nondecussating fibers are said to be ipsilateral (staying on the same side of the body).

Question 15

Mammillary bodies

Answer 15

The mammillary bodies, considered to be part of the hypothalamus, are a pair of spherical nuclei located on the inferior surface of the hypothalamus, just behind the pituitary.