Nervous System

• The study of the structure and function of the nervous system is Neurology.

• Doctors who study it are called Neurologists.

• The basic unit of the nervous system is the Neuron which consists of two parts.

• The body(gray) matter which is called the Nerve Cell.

• And the long fibers extending from the body called the processes – Axons or Dendrites (white matter)

• The central nervous system is often referred to as the Cerebro-Spinal System, and has 3 main functions

– 1. Control Consciousness

– 2. control the voluntary functions of the 5 senses

– 3. control voluntary muscle actions

• The nervous system is further divided into the:

– 1. Autonomic: which consists of the sympathetic and parasympathetic systems and controls the involuntary body functions.

– 2. Peripheral: which carries messages to and from the CNS.

The nervous system has 3 principle parts:

• 1. brain

• 2. spinal cord

• 3. Nerves

• The brain is the control center of the body. It receives internal and external messages, and then responds by sending messages controlling the body’s activities.

The brain is divided into 3 parts, each part controlling different activities

• 1. Cerebrum:

–The largest part.

•Controls senses, thoughts, memory learning, voluntary muscles

1 Gyrus rectus 2 Superior frontal gyrus 3 Cingulate gyrus 4 Cingulate sulcus 5 Paracentral sulcus 6 Central sulcus 7 Precuneus 8 Cuneus 9 Lingual gyrus

1 Frontal pole 2 Temporal pole 3 Olfactory tract & sulcus 4 Orbital gyri 5 Gyrus rectus 6 Inferior temporal sulcus 7 Inferior temporal gyrus 8 Occipitotemporal sulcus 9 Fusiform gyrus 10 Collateral sulcus 11 Lingual gyrus 12 Uncus 13 Calcarine sulcus

1 Central sulcus 2 Precentral gyrus 3 Postcentral gyrus 4 Precentral sulcus 5 Postcentral sulcus 6 Middle frontal gyrus 7 Superior frontal gyrus 8 Superior parietal lobule 9 Occipital gyri 10 Longitudinal fissure

• 2. Cerebellum:

–In the back of the brain

•Controls body movements and balance

1 Cerebral peduncle 2 Basilar groove 3 Olive 4 Pyramid 5 Trigeminal nerve 6 Abducent nerve

• 3. Medulla: (the smallest part)

– Thick stalk at base of skull, connects brain to spinal cord.

• Controls vital involuntary functions (breathing, digestion, heartbeat) , and sneezing and blinking.

1 Anterior median fissure 2 Olive 3 Pyramids 4 Cerebellum

The brain is covered by 3 Meninges

• 1. Pia Mater: covers brain and spinal cord. – The first, innermost layer

• 2. Dura Mater: – the outermost and toughest layer

• 3. Arachnoid Mater– Middle layer, web like.

• If the meninges become infected with a virus or bacteria, a serious condition called Meningitis results.

• The spinal cord is the main passageway for the transmission of messages to and from all other parts of the body.

• Nerves are long, white cords made of cell processes that carry messages from one part of the body to another.

Nerves are divided into 3 types• 1. Sensory (aka Afferent)– Carries messages to brain from sense organs

• 2. Motor (aka efferent)– Carries messages from brain to muscle

• 3. Mixed – Combination of sensory and motor nerves