The Brain

• brain and spinal cord protected by the cranium and vertebrae
• also protected by the meninges and cerebrospinal fluid (CSF)

the tough, thick, outermost part which forms four partitions

• falx cerebri-extends between the cerebral hemispheres, attaches to the crista galli (ethmoid)
• tentorium cerebelli-between the cerebrum and cerebellum
• epidural space- (spinal cord) between bone and dura mater
• subdural space-between dura and arachnoid

• thin, middle portion
• some subarachnoid space is filled with CSF

very thin, vascular, adheres to the surface

inflammation of the meninges due to bacteria or virus. bacterial is usually more serious, viral is generally self-limiting. also fungal

inflammation of the brain

network of capillaries in the ventricles which produce CSF. CSF circulates through the ventricles and sub-arachnoid space then in reabsorbed by the arachnoid granulations

water on the brain, excess CSF

• only 2% of body weight, but uses 20% of the oxygen supply..
• 1,000,000,000,000,000 synapses for the 25 billion neurons
• blood delivered by 2 carotid arteries and 2 vertebral arteries which branch into the Circle of Willis
• the brain is one of the most metabolically active organs of the body, and when deprived of blood, irreversible damage may occur
• the brain has a limited carbohydrate resources, so a continuous supply of glucose is mandatory

allows glucose, O2, amino acids, and certain ions to pass rapidly, but slows or stops many other substances. substances that do not cross are small and require a carrier molecule.

forebrain

• telencephalon-cerebrum
• diencephalon-thalamus, hypothalamus

midbrain

hindbrain

• metencephalon- cerebellum, pons
• myelencephalon- medulla

medulla + pons + midbrain

• posterior, medulla and spinal cord
• cerebral aqueduct connects it with the third ventricle

• within diencephalon
• the interventricular foramina connects it with the lateral ventricles

in cerebrum

myelinated, conducting portion

large masses of cell bodies, dendrites of association, unmyelinated axons

• contains white and gray matter
• pyramidal tracts contain axons from the cerebrum, major motor pathways (descending)
• fasciculi gracilus and faciculi cuneatus- ascending tracts (touch, pressure)
• peduncle-thick bundle of nerve fibers containing: cardiac centers, vasomotor centers (blood pressure), and respiratory centers
• 4 of 12 cranial nerves originate at the medulla: 9th, 10th, 11th, and 12th.

• superior to the medulla
• helps regulate respiration
• reflexes from the trigeminal (5), abducens (6), and facial (7)

• contains cerebral peduncles
• nerve fibers contain much dopamine (involved with Parkinson's)
• red nucleus-neurons conveying impulses of muscle tone
• superior colliculi-visual reflex centers
• inferior colliculi-relays for auditory info
• many other reflexes integrated here

pineal gland or Epiphysis-endocrine gland

• influence emotions
• either side of the 3rd ventricle
• relay station for all sensory into except smell

inferior to the thalamus

crossing of optic nerve, floor of the hypothalamus

connects hypothalamus to pituitary

involved with feeding reflexes

• link between nervous and endocrine systems
• link between cerebrum and lower autonomic centers
• regulate temperature
• helps maintain H2O balance (ADH)
• influences emotional and sexual behavior
• regulates appetite

separated from the cerebrum by the transverse fissure

• the two hemispheres are connected by the vermis and partially separated by the falx cerebelli
• mostly white matter under a layer of gray
• when cut, appears as the arbor vitae
• 30 million purkinje cells (cortex area) helps to integrate info for motor activity
• inferior cerebellar peduncle:spinal cord to cerebellar cortex
• middle cerebellar peduncle: pons to cerebellar cortex
• superior cerebellar peduncle: cerebellum to CNS

• making muscle movement smooth and coordinated
• maintain posture (muscle tone)
• maintain equilibrium

uncoordinated muscle movement

convolutions

shallow grooves

deep grooves

thin outer layer of gray matter of Cerebrum

• Frontal Lobe: motor cortex (Broca's area for speech)
• Parietal Lobe: receives sensory info and integrates it
• Occipital Lobe: receives and interprets visual info
• Temporal Lobe: receives and interprets auditory info; also emotion, personality, behavior, and memory
• Central Lobe: autonomic and somatic activities
• Limbic Lobe: offaction and emotional behavior

transmit impulses within a hemisphere

connects hemispheres

connects the neocortex of the two hemispheres

connects the old cortex with the thalamus

pathways to and from the brain

• gray areas in the white matter
• responsible for subconscious movements such as swinging the arms while walking

• Sensory
• Motor
• Associative (intellectual activities, memory)

map of brain and functions

formation of words

inability to express oneself through words

generally dominant for motor skills, right handedness, language, intellectual skills

may be dominant for creative abilities and spaciotemporal matters

emotions, sexuality, biological rhythms, autonomic responses, motivation, reward and punishment centers

• Consists of:
• Limbic Lobe
• Hippocampus (area of old cortex)
• Amygaala (nuclei near optic tract)
• Oflactory Structures
• parts of Thalamus
• parts of Hypothalamus (mammillary body)
• Fornix (connects mammillary to hippocampus)

Electroencephalogram

monitor brain activity

reticular activating system

maintain consciousness (when its activity slows, you may become sleepy)