2.4 A Guided Tour of the Brain

Question 1

Spinal cord

Answer 1

The spinal cord is a long, cylindrical bundle of nerve tissue that extends from the base of the brain, down the vertebral canal, and terminates around the first or second lumbar vertebra in the lower back. It serves as a vital part of the central nervous system (CNS) along with the brain.

Question 2

Brainstem

Answer 2

contains groups of motor and sensory nuclei, nuclei of widespread modulatory neurotransmitter systems, and white matter tracts of ascending sensory information and descending motor signals.

Question 3

Medulla

Answer 3

Th e brainstem’s most caudal portion. The medulla is
continuous with the spinal cord and contains the prominent,
dorsally positioned nuclear groups known as the gracile and
cuneate nuclei (which relay somatosensory information fr om
the spinal cord to the brain) and the ventral pyramidal tracts
(which contain descending projection axons fr om the brain
to the spinal cord). Various sensory and motor nuclei are
found in the medulla.

Question 4

Pons

Answer 4

is latin for ‘bridge’ and it is named that way because it is the main connection between the brain and the cerebellum. The pons is important for some eye movement as well as movements of the face and mouth. The reticular formation as three colomns of nuclei: raphe nuclei, parvocellular reticular nuclei, gigantocellular nuclei.

Question 5

cerebellum

Answer 5

clings to the brainstem at the level of the pons. Most of the fibers arriving at the cerebellum project to the cerebellar cotex, conveying information about motor outputs and sensory inputs describing body position.

Question 6

Midbrain

Answer 6

lies superior tot he pons and can only be seen in medial view. Large fiber tracts course through the midbrain’s ventral region from the forebrain to the spinal cord, cerebellum and other parts of the brainstem. The midbrain also contains some of the cranial nerve ganglia and the superior and inferior colliculus - they play a important role in perceiving objects and locating and orienting towards auditory stimuli.

Question 7

thalamus

Answer 7

almost exactly in the center of the brain and perched on top of the brainstem. It is divided in two parts: one in the right hemisphere and one in the left - that straddle the third ventricle. The thalamus has been referred to as the ‘gateway to the cortex’ because all of the sensory (except the olfactory nerve) modalities make synaptic relays in the thalamus before continuing to the primary cortical sensory receiving areas.

Question 8

hypothalamus

Answer 8

is the chief site for hormone production and control. It lies on the floor of the third ventricle. The hypothalamus controls the functions necessary for maintaining the normal state of the body: basal temperature and metabolic rate, glucose levels, hormonal state, sexual phase, cicadian cycle etc. It accomplishes much of this work through the endocrine system via control of the pituitary gland. The hypothalamus produces hormones as well as factors that can regulate those hormones.

Question 9

limbic system

Answer 9

The limbic system is a group of interconnected brain structures that play a fundamental role in regulating emotions, memory, and behavior. It consists of several key components, including the amygdala, hippocampus, hypothalamus, and cingulate gyrus. Here’s a summary of the limbic system:

Question 10

basal ganglia

Answer 10

a collection of nuclei bilaterally located deep in the brain beneath the anterior portion of the lateral ventricles, near the thalamus. They include: the caudate nucleus, putamen, globus pallidus, subthalamic nucleus and substantia nigra. The caudate nucleus and the putamen together are known as the striatum. It plays a crucial role in motor control, coordination, and the regulation of voluntary movements.