Central Nervous System A&P Spring,

Cerebrum: highly folded, largest volume, problem solving, memory, personality, sensory interpretation, initiates motor activity Cerebellum: posterior, inferior, coordination of body movements, motor memory Brain Stem: homeostasis (HR, RR, control of hormone secretions), primitive emotions General Organization of the Brain

Basic Landmarks of the Cerebrum Gyrus: ridge on the cerebrum (increases surface area and provides more space for neurons) Sulcus: groove in between the gyri. Fissure: a deep sulcus Central Sulcus Lateral Fissure Transverse Fissure Frontal Lobe Parietal Lobe Temporal Lobe Occipital Lobe

Frontal Lobe personality problem solving motor aspects of speech initiation of movements (pre-central gyrus – somatomotor area) Parietal Lobe experience and interpretation of touch (post-central gyrus – somatosensory area) association of hearing, touch, vision Occipital Lobe Vision – perception and interpretation Temporal Lobe hearing interpretation of vision and hearing

Corpus Callosum Contains commisural fibers Thalamus primarily a relay of sensory info to the cerebrum (projection fibers) Hypothalamus control of pituitary gland body temperature weight, hunger and thirst regulation of reproduction Midbrain motor pathways from cerebrum to spinal cord coordinates visual and auditory reflexes Pons feeds info in and out of cerebellum Part of Reticular Activating System (RAS) Medulla Oblongata Cardiac Control Center Respiratory Control Center Decussation of Ascending Pathways Part of RAS

Basal Nuclei Below Cerebrum and surrounding the thalamus Important for fine control of body movements (Parkinson’s Disease) Caudate nucleus, putamen, globus pallidus, substantia nigra, red nucleus

Thalamus Pineal Gland Superior colliculus Inferior colliculus Pons Medulla Brain Stem

The Limbic System Cingulate gyrus Hippocampus Amygdala Hypothalamus Basic, emotional responses to the environment The Four “F’s” feeding fighting fear reproduction

Coronal Section Showing Post- Central Gyrus Sensory Mapping of the Somatosensory Area For each touch receptor on the body, there is a coresponding neuron in the brain. Areas of the skin with higher densities of receptors will require more neurons on the somatosensory area. Homunculus

Location of spinal cord inside canal of vertebra

Gray matter White matter Dorsal root Dorsal root ganglion Ventral root

Spinal nerve dorsal root Dorsal root ganglion sensory motor Sensory neuron cell body Motor neuron cell body Organization of the Spinal Cord Ventral root

Simple Knee Jerk Reflex Coordinated by the Spinal Cord Sensory neuron Quadriceps muscle Motor neuron Dorsal root ganglion Dorsal root Ventral root

Withdrawal Reflex interneuron

Quickie Review

A B C D E F G H

A B C D E

1.What do the Basal Nuclei do? 2.What does the limbic system do? 3.What does the Reticular Activating System do? 4.What is the difference between a knee jerk reflex and a withdrawal reflex?

Peripheral Nervous System

Olfactory nerve Optic nerve Oculomotor nerve Trochlear nerve Trigeminal nerve Abducens Facial Vestibulocochlear Glossopharengeal Vagus Accesory Hypoglossal Cranial Nerves: provide sensory and motor control to the head, senses, facial expressions, control of the tongue.

Spinal Nerves and Nerve Plexes C1-C5 = cervical T1-T12 = thoracic L1-L5 = Lumbar S1-S6 = Sacral A “plexus” is a gathering of spinal nerves in a specific area of the body. Here the nerves are reorganized and form the major nerves leading to the arms and legs. cervical brachial lumbar sacral

QUICKIE REVIEW 1.In general, what are the functions of the cranial nerves? 2.Which cranial nerve descends into the thoracic and abdominal cavities? 3.If a person injured their L-2 spinal nerve, where is it located (precisely)? 4.What does it mean to say that a cranial or spinal nerve is a “mixed” nerve? 5.What is the name of the largest plexus leading to the arm? 6.Which region of the spinal cord doesn’t give rise to plexes? 7.What are four specific changes that occur when the sympathetic nervous system becomes stimulated? 8.Which division of the autonomic nervous system has its ganglia on or near the target organ? 9.Which division of the autonomic nervous system uses norepinephrine as it’s post-ganglionic neurotransmitter? 10. If a motor activity for the foot is initiated in the pre-central gyrus, all of the following will become active except (more than one answer) thalamusmidbrainmedulladescending tract dorsal rootventral rootlumbar or sacral plexusthoracic plexus