Transcript Brain and Cranial Nerves

Anatomy and Physiology, Sixth Edition
Rod R. Seeley
Idaho State University
Trent D. Stephens
Idaho State University
Philip Tate
Phoenix College
Chapter 13
Lecture Outline*
*See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.
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Chapter 13
Brain and Cranial Nerves
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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
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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
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ANS control
Endocrine control
Muscle control
Temperature regulation
Regulation of food and
water intake
• Emotions
• Regulation of sleepwake 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
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Olfactory (I)
Optic (II)
Oculomotor (III)
Trochlear (IV)
Trigeminal (V)
Abducens (VI)
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Facial (VII)
Vestibulocochlear (VIII)
Glossopharyngeal (IX)
Vagus (X)
Accessory (XI)
Hypoglossal (XII)
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