Week 3 - topic 2 Flashcards
Main structures of the CNS
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The forebrain
The forebrain is located rostrally (towards the nose) and has two main divisions:
- Telencephalon
- Diencephalon
Telencephalon
Cerebrum = Left and Right Cerebral Hemisphere
Cerebral hemispheres =
Cerebral cortex
Limbic system
Basal ganglia
Cerebral cortex
The cerebral cortex surrounds the two cerebral hemispheres Folded/Convoluted: - sulci (small grooves) - fissures (large grooves) - gyri (bulges in between grooves)
Lobes of the central cortex
Frontal
Parietal
Temporal
Occipital
There are two of each lobe in the brain (one in each hemisphere)
Cerebral cortex - sensory cortex
Sensory Cortex: Three areas of the cerebral cortex receive information from sensory organs
Primary visual cortex
Primary auditory cortex
Primary somatosensory cortex
Cerebral cortex - contralateral connections
Contralateral Connections
For all senses except taste and smell:
- Sensory information from the left goes to the right cerebral hemisphere
- Sensory information from the right goes to the left cerebral hemisphere
Cerebral cortex - primary motor cortex
- The primary motor cortex is the region of the cerebral cortex most directly involved in the control of movement
- Contralateral connections
Cerebral cortex - association cortex
Association Cortex
- Sensory Association Cortex
- Motor Association Cortex
Sensory association cortex
- Each primary sensory area of the cerebral cortex sends information toadjacent regions for further processing
- Regions further away receive information from more than one sensorysystem – allows us to connect information across senses
Brain diagram
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Basal ganglia
- Collection of nuclei below the cerebral cortex
nuclei = an identifiable group of cell bodies in the CNS - Involved in motor control
Limbic system
- Widespread group of brain nuclei that innervate each other to form a network
- Involved in learning, memory, and emotions
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Limbic cortex and singular gyrus
- located around medial edge of cerebral hemisphere
- a form of cerebral cortex
Hippocampus
- learning and memory
- medial temporal lobe structure
- part of limbic system
Amygdala
- important for processing emotions
- interior of rostral temporal lobe
- forms part of limbic system
- processing feelings and expressions of emotions, emotion memories and recognising signs of emotions in others
Fornix and mammillary bodies
- fibre bundle connecting the hippocampus to other parts of the brain, including the mammillary bodies of the hypothalamus
- part of limbic system
Lateralization in the cerebral cortex - left side processing
- The left hemisphere is related to analysis of information (extracting elements that make up an experience)
- This makes the left hemisphere well suited for processing serial events (things that happen one after the other), and controlling behaviour sequences
- As you can imagine, this means that the left hemisphere is important for language processing
Lateralization in the cerebral cortex - right side processing
- The right hemisphere is related to synthesis of information
- This makes the right hemisphere good at combining things for holistic processing
- This type of functionality is important for drawing and reading maps
Corpus callosum
- The corpus callosum is a large bundle of axons that interconnects corresponding regions of association cortex on each side of the brain. The left and right frontal lobes are connected, as are the left and right temporal, parietal, and occipital lobes.
- The corpus callosum allows the two sides to talk to one another, and because of this, each part of the association cortex has an idea about what is happening in the corresponding region on the opposite side
Thalamus
- The largest portion of the diencephalon
- Located above the hypothalamus
- Main function = a relay station
Thalamus nuclei (groups of neural cell bodies)
- Lateral geniculate nucleus (LGN) = visual relay
- Medial geniculate nucleus = auditory relay
- Ventrolateral nucleus = motor relay
- Other nuclei receive and send information to and from the cerebral cortex
Hypothalamus
- Located underneath the thalamus
- Controls the autonomic nervous system (regulates bodily functions)
- Controls the endocrine system (hormones)
- Small, but complex structure with many nuclei
- part of diencephalon
Mesencephalon
The mesencephalon is the midbrain and it has two major components:
- Tectum
- Tegmentum
Tectum
Dorsal portion of mesencephalon
Two main structures:
-> Superior colliculi = visual system/visual reflexes
-> Inferior colliculi = auditory system
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Brain diagram - brain stem
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Tegmentum
Located beneath the Tectum Structures: - Part of the Reticular Formation - The Periaqueductal Gray Matter - Red Nucleus and the Substantia Nigra - Nuclei related to controlling eye movements
The hindbrain
The hindbrain surrounds the fourth ventricle and has two major parts:
- Metencephalon - (Pons and Cerebellum)
- Myelencephalon - (Medulla)
Cerebellum
- Cerebellar cortex + cerebellar nuclei
- Cerebellar peduncles (little feet) attach the cerebellum to the pons
- Motor control and smooth, coordinated movement
Pons
- Looks like a big lump on the brain stem
- It contains part of the reticular formation
- Relays information from cerebral cortex to cerebellum
Medulla oblongata
- The main structure in the myelencephalon is the medulla oblongata
- Contains part of the reticular formation: specifically nuclei that control vital functions such as regulation of the cardiovascular system, respiration, and skeletal muscle tone
The spinal cord
- The Spinal Cord is a long, tubelike structure of nervous tissue that extends caudally (away from the front of the face) from the medulla oblongata in the hindbrain.
- The main function of the spinal cord is that it distributes motor fibers to the effector organs of the body (glands and muscles) and collects somatosensory information (e.g. pressure, touch) to pass onto the brain
Vertebral column
- The spinal cord is protected by the vertebral column.
- The column is composed of 24 vertebrae (interlocking bones) across three main regions; cervical (neck), thoracic (chest); lumbar (lower back), as well as fused vertebrae that make up the sacral and coccygeal sections.
- The spinal cord passes through a hole in each of the vertebrae which is called the spinal formamen
Spinal roots
- The spinal cord isn’t as long as the vertebral column - the rest is filled by spinal roots.
- A spinal root is a bundle of axons surrounded by connective tissue.
- Spinal roots occur in pairs which fuse and form a spinal nerve
Dorsal and ventral spinal roots
Dorsal Root: The spinal root that contains incoming sensory fibres
Ventral Root: The spinal root that contains outgoing motor fibres
