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Anatomy and Physiology, Sixth Edition

Rod R. SeeleyIdaho State UniversityTrent D. StephensIdaho State UniversityPhilip TatePhoenix College

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

*See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.

Chapter 13Chapter 13

Lecture OutlineLecture Outline**

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Brain and Cranial Nerves

Chapter 13

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Brain and Cranial Nerves

• Brain– Part of CNS contained in cranial cavity– Control center for many of body’s functions– Much like a complex computer but more

• Parts of the brain– Brainstem– Cerebellum– Diencephalon– Cerebrum

• Cranial nerves– Part of PNS arise directly from brain

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Brainstem

• Connects spinal cord to brain• Parts

– Medulla oblongata– Pons– Midbrain

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Brainstem

• Medulla oblongata or medulla– Regulates: Heart rate, blood vessel diameter,

respiration, swallowing, vomiting, hiccupping, coughing, and sneezing

– Pyramids: Decussate

• Pons– Sleep and respiratory center

• Midbrain– Integral part of auditory pathways in CNS

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Brainstem and Diencephalon

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Cerebellum

• Involved in control of: balance, posture, locomotion, and fine motor coordination producing smooth flowing movements

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Diencephalon

• Components– Thalamus, Subthalamus, Epithalamus, Hypothalamus

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Diencephalon• Thalamus

– Largest part of diencephalon

– Most sensory input projects to here

– Influences mood and actions as fear or rage

• Subthalamus– Involved in controlling

motor functions

• Epithalamus– Pineal gland may influence

sleep-wake cycle

• Hypothalamus– Functions

• ANS control

• Endocrine control

• Muscle control

• Temperature regulation

• Regulation of food and water intake

• Emotions

• Regulation of sleep-wake cycle

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Cerebrum

• Largest portion of brain• Divisions

– Right

– Left

– Lobes: Frontal, parietal, occipital, temporal, insula

• Cortex: Outer surface• Medulla: Center

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Basal Nuclei and Limbic System

• Basal nuclei– Motor function control

• Limbic system– Basic survival

functions as memory, reproduction, nutrition

– Emotions

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Limbic System

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Meninges

• Connective tissue membranes– Dura mater: Superficial

– Arachnoid mater

– Pia mater: Bound tightly to brain

– Spaces • Subdural: Serous fluid

• Subarachnoid: CSF

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Ventricles

• Ventricles: Lateral ventricles (2), third ventricle, fourth ventricle

• Choroid plexuses produce CSF which fills ventricles and other parts of brain and spinal cord– Blood-cerebrospinal fluid barrier: Substances do not pass between

cells but through due to tight junctions of blood endothelial cells

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Cerebrospinal Fluid (CSF)

• Similar to serum with most of proteins removed

• Bathes brain and spinal cord

• Provides a protective cushion around CNS

• Provides some nutrients to CNS tissues

• Produced by ependymal cells

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Flow of CSF

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Brain Blood Supply

• Brain – Requires tremendous amount of blood– Receives 15-20% of blood pumped by heart– Interruption can cause unconsciousness and irreversible

brain damage– High metabolic rate and dependence on constant supply

of oxygen and glucose– Receives blood through arteries

• Blood-Brain barrier– Capillary endothelial cells along with astrocytes and

basement membrane– To be considered when developing drugs

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Formation of the Neural Tube

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Development of Brain Segments and Ventricles

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Cranial Nerves

• Indicated by Roman numerals I-XII from anterior to posterior

• May have one or more of 3 functions– Sensory (special or general)

– Somatic motor (skeletal muscles)

– Parasympathetic (regulation of glands, smooth muscles, cardiac muscle)

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Cranial Nerves

• Olfactory (I)• Optic (II)• Oculomotor (III)• Trochlear (IV)• Trigeminal (V)• Abducens (VI)

• Facial (VII)• Vestibulocochlear (VIII)• Glossopharyngeal (IX)• Vagus (X)• Accessory (XI)• Hypoglossal (XII)