KAAP220 Lecture Notes - Lecture 21: Medulla Oblongata, Cerebral Cortex, Primary Motor Cortex
11 May 2018
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Lecture 21
• Chapter 13 - Brain
• Brain anatomy
• ~1200 mL in volume; size varies; size doesn’t indicate intelligence
• Male brain is on average slightly larger but more a result of their average size being overall larger
• Brain development
• CNS begins as a hollow cylinder - neural tube - brain is visible by 4th week of development
• Primary brain vesicles = 3 swellings at cephalic end of tube; brain starts as 3 swellings
• Prosencephalon - forebrain; anterior tip of neural tube; subdivides into -
• Diencephalon - becomes major relay/processing center for information headed to/from
cerebrum
• Telencephalon - expands rapidly; forms cerebrum
• Cerebrum
• Mesencephalon - midbrain; caudal to prosencephalon
• Rhombencephalon - hindbrain; most caudal part; continuous with spinal cord; subdivides into -
• Metencephalon - caudal to midbrain (mesencephalon); forms cerebellum and pons of adult
brain
• Myelencephalon - becomes medulla oblongata
• Brain regions
• Cerebrum - the outer and largest most portion
• Cerebellum - mini brain, inferior to the posterior part of the brain (the occipital lobes)
• Diencephalon - thalamus and hypothalamus
• Brainstem
• Cerebrum
• Left and right cerebral hemispheres; divided by deep fissures
• Surface
• Gyri (folds) and sulci (grooves) - increase surface area
• The folds are the worms
• The sulci are the grooves in the worms
• There’s a central sulcus - coronal groove
• Longitudinal fissure - mid-saggital; fissures are really deep; can take the L and R lobes and put our
fingers down into that and separate the 2 lobes
• Cerebral cortex - superficial most layer of cerebrum
• Superficial layer of gray matter
• Very thin; primarily cell bodies
• Major functions - conscious thought, some memory storage and lots of processing, sensory
processing, control of skeletal muscles
• Cerebellum
• Partially hidden by cerebral hemispheres
• Second largest brain structure
• It’s small but dense - only 10% of brain’s volume, but 50% of its neurons
• Contains over 50% of the neurons within the brain - so they’re jam-packed in there
• Functions - coordination/modulation of motor commands from cerebral cortex
• Diencephalon
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Document Summary
Diencephalon - becomes major relay/processing center for information headed to/from. Prosencephalon - forebrain; anterior tip of neural tube; subdivides into - cerebrum. Telencephalon - expands rapidly; forms cerebrum: mesencephalon - midbrain; caudal to prosencephalon. Rhombencephalon - hindbrain; most caudal part; continuous with spinal cord; subdivides into - Metencephalon - caudal to midbrain (mesencephalon); forms cerebellum and pons of adult brain. Gyri (folds) and sulci (grooves) - increase surface area. Nuclei involved in respiration: brainstem, 3 parts - midbrain, pons, and medulla oblongata, midbrain contains nuclei that, pons - connects cerebellum/brainstem, medulla oblongata, corpus callosum - archway over the thalamus and hypothalamus; connection between the 2. Relays ascending sensory information through brainstem and to the thalamus. Relays all descending motor information to spinal cord. Cardiovascular and respiratory functions cerebral hemispheres: cerebrum, hemispheres subdivided into lobes. Each cerebral hemisphere divided into lobes - named after overlying bones of the skull (except for the insula)
