Lecture 9: Nervous System 1

The Brain

• The brain has several regions, each with specific functions, and are linked to allow maximum functional integration.
• The brain is built layer by layer, with the most complex functions being controlled at the highest levels.

Lateralization of Brain Function

• The left and right cerebral hemispheres control the opposite sides of the body.
• Sensory pathways decussate (cross-over) from one side of the CNS to the other.
• Motor pathways decussate from one side of the CNS to the other.

Lobes of the Cortex

• Frontal lobe: responsible for higher executive functions, including emotional regulation, planning, reasoning, and problem-solving.
• Parietal lobe: responsible for integrating sensory information, including touch, temperature, pressure, and pain.
• Temporal lobe: responsible for processing sensory information, particularly important for hearing, recognizing language, and forming memories.
• Occipital lobe: the major visual processing center in the brain.

Forebrain Regions

• Thalamus: processes sensory information.
• Hypothalamus: the major control center of the autonomic motor system, involved in hormonal activity, and regulates homeostasis.
• Pineal gland: produces the hormone melatonin, regulating sleep-wake cycles.

Spinal Cord

• Composed of grey matter and white matter.
• White matter is composed of fibre tracts of myelinated sensory and motor axons.
• Knowledge of tract locations and functions allows localization of damage.

Cranial Nerves and Spinal Nerves

• Cranial nerves: 12 pairs, responsible for transmitting information to and from the brain.
• Spinal nerves: 31 pairs, emerging from the spinal cord, controlling various functions and sensations.

Autonomic Nervous System

• Functions without conscious control to maintain homeostasis.
• Divided into sympathetic (fight or flight) and parasympathetic (rest and digest) systems.
• Controls cardiac muscle, smooth muscle, exocrine glands, and endocrine glands.

Central Nervous System

• Consists of the brain and spinal cord.
• The peripheral nervous system is made up of cranial nerves and spinal nerves.

Brain Structure

• The forebrain is the largest region, containing the cerebral cortex, thalamus, hypothalamus, pineal gland, and limbic system.
• The hindbrain includes the brainstem and cerebellum.
• The brainstem connects the forebrain to the spinal cord and cerebellum.

Cerebral Cortex

• Divided into right and left cerebral hemispheres, connected by the corpus callosum.
• Each hemisphere is divided into four lobes: frontal, parietal, temporal, and occipital.

Cerebellum

• Coordinates gait, maintains posture, controls muscle tone, and voluntary muscle activity.
• Receives information from the cerebral cortex and muscles, tendons, and joints.

Brainstem

• Connects the forebrain to the spinal cord and cerebellum.
• Responsible for many vital functions, including breathing, consciousness, blood pressure, heart rate, and sleep.