Brain and Cranial Nerves

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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 bodys 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)