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229 Cards in this Set
- Front
- Back
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Name the three major functions of the nervous system.
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1. Sensory
2. Motor 3. Integration |
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How is the control exerted by the nervous system different from that exerted by the endocrine system?
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The endocrine system is slower acting and uses hormones to communite versus neurotransmitters.
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What structures make up the Central Nervous System (CNS)?
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Brain
Spinal Cord |
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What structures make up the Peripheral Nervous System (PNS)?
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12 pairs of Spinal Nerves
31 pairs of Cranial Nerves Autonomic Pathways |
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What is a nerve?
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Each nerve is a cordlike structure that contains many axons. These axons are often referred to as “fibres”. Within a nerve, each axon is surrounded by a layer of connective tissue called the endoneurium. The axons are bundled together into groups called fascicles, and each fascicle is wrapped in a layer of connective tissue called the perineurium. Finally, the entire nerve is wrapped in a layer of connective tissue called the epineurium.
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What is a mixed nerve?
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Contains sensory AND motor components.
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What is a sensory nerve?
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Carries impulses from a receptor to the CNS.
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What is a motor nerve?
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Carries impulses from the CNS to the effector.
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Which type of nerve is most common?
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Mixed nerves (i.e., spinal nerves) are the most common.
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What is another term for sensory pathways?
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Afferent Pathways
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What is another term for motor pathways?
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Efferent Pathways
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What is the role of a sensory receptor in a sensory pathway?
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A structure in the body that senses change and changes it into a nerve impulse.
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What is the role of the effector organ in a motor pathway?
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A structure that performs the response. Effectors are skeletal muscle, cardiac muscle, smooth muscle and glands.
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What is the role of the CNS in these pathways?
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Performs "integration" ... decides what the response to a stimulus should be and sends that information to the effector.
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Name the two motor divisions of the PNS.
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Somatic Motor
Autonomic Motor |
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What are the effector organs of the motor division of the PNS?
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Somatic Motor ... skeletal muscle.
Autonomic Motor ... cardiac muscle, smooth muscle and glands. |
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To what extent is it accurate to describe one motor system as voluntary and the other as involuntary?
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Each system is PRIMARILY one or the other but there are no absolutes.
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In what ways are those descriptions inaccurate regarding peripheral motor systems?
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One example ... reflexes. This is an example of skeletal muscle (Somatic Motor System) being involuntary.
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What is a visceral effector?
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An organ that carries out the action directed by the CNS.
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What are the two divisions of the autonomic nervous system?
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Sympathetic ... Thoracolumbar
Parasympathetic ... Craniosacral |
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How can you summarize the effects of each division ... sympathetic and parasympathetic?
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Sympathetic (Thoracolumbar) ... "fight or flight" ... performs functions that expend energy.
Parasympathetic (Craniosacral) ... "rest and digest" ... performs functions that conserve energy. |
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What are the two kinds of cells which make up the nervous system?
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1. Neurons
2. Glial Cells |
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Which are specialized to conduct impulses?
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Neurons
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What to the other cells do in general?
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Glial Cells ... known as "nerve glue" ... provide protection, structure and support.
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Give a brief description of each type of glial cell in the CNS.
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CNS Glial Cells ...
1. Astrocyte ... star shaped cell that attaches to capillaries for nourishment. Creates the blood-brain barrier. 2. Oligodendrocyte ... looks like an astrocyte but functions as a Schwann cell without the regenerative properties of the Schwann. 3. Ependymal Cell ... ciliated epithelial cells that line the ventricles and central canal of the spinal cord. Produces and circulates CSF. 4. Microglia ... specialized WBCs that eat debris and dead cells. |
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Give a brief description of each type of glial cells in the PNS.
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PNS Glial Cells ...
1. Schwann Cells or Neurolemmocytes ... insulates the neuron with a fat called myelin that helps to speed up conduction. This myelin can also help PNS neurons regenerate their processes when damaged. |
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Which cells produce myelin sheaths in the CNS?
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Oligodendrocytes
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Which cells produce myelin sheaths in the PNS?
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Schwann Cells or Neurolemmocytes
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What is a myelin sheath made of and what are its functions?
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Myelin is made of a fatty substance that helps conduct impulses AND holds neurons in place.
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What is the neurilemma and what does it enable the cell it covers to do?
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The neurilemma is the outermost level of the myelin sheath. It enables neurons in the PNS to regenerate after injury to its processes.
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What are the nodes of Ranvier and what takes place there?
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Spaces between the myelin on the neurons' processes. This is site of saltatory conduction ... the impulse can jump from Node of Ranvier to Node of Ranvier which is fastest type of conduction.
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What is saltatory conduction?
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An impulse can jump from Node of Ranvier to Node of Ranvier which is the fastest type of conduction.
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Name and describe the three major structures of a neuron.
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1. Dendrites ... short process that carry impulses towards the cell body.
2. Soma (cell body) ... contains the neuron's organelles. 3. Axon ... usually a long single process that carries the impulse away from the soma. |
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What is a nerve fiber?
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An elongated process from the neuron. Usually means the axon.
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How long may an axon be?
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There is no limit on the length of an axon.
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What is the normal pathway of an impulse as it moves through a neuron?
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Dendrite - Soma - Axon
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Describe the structures at the terminal end of an axon.
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1. Axon Collateral
2. Telodendria (Axon Terminals) 3. Synaptic End Bulbs (hold synaptic vescicles) 4. Synaptic Vescicles (hold NTs) |
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Classify neurons by structure and function.
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Function ... sensory/afferent, motor (efferent)
Structure ... unipolar, bipolar, multipolar |
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Sensory/Afferent Neuron
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Carries impulses from a receptor to the CNS.
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Motor/Efferent Neuron
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Carries impulses from the CNS to the effector.
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Unipolar Neuron
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SENSORY PNS NEURONS. Cell body is on the side of one long integrated dendrite and axon. Cell body can be protected by ganglion. No axon hillock
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Bipolar Neuron
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SPECIAL SENSES ONLY. Dendrite, cell body and axon appear as one long process. MOST RARE. No axon hillock.
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Multipolar Neuron
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MOST COMMON. Most PNS motor, CNS motor and CNS sensory neurons. Has an axon hillock (trigger zone).
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What is an association neuron?
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An integration neuron ... or a decision making neuron.
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How do these structure/function categories overlap?
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Two examples are ... PNS neurons ... are sensory OR motor AND multipolar. PNS sensory neurons are also unipolar.
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What is meant by a membrane potential?
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The difference between the ions inside and outside the cell.
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What is meant by a resting potential?
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Resting Potential At rest the cell membrane is polarized maintaining a negative interior charge of -70mv. This is called the electrical gradient. There is about ten times more sodium (Na+) on the outside and twenty times more potassium (K+) on the inside. This is called the concentration gradient.
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How is the resting potential established by the cell?
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Pumps on the cell membrane are used to push 3 sodium ions OUT of the cell and 2 potassium ions IN to the cell. This will result in a more negative charge on the inside of the cell ... -70mV
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What is a pump?
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A pump works against the concentration gradient and uses energy to transport ions.
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What is a channel membrane?
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A channel membrane is a passive channel that works with the concentration gradient.
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Explain what is meant by the terms depolarized, hyperpolarized and repolarized.
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Depolarized ... depolarization is a change in a cell's membrane potential, making it more positive, or less negative.
Hyperpolarized ... Hyperpolarization is a change in a cell's membrane potential that makes it more negative. It is the opposite of a depolarization. Repolarization ... repolarization refers to the change in membrane potential that returns the membrane potential to a negative value after the depolarization phase of an action potential has just previously changed the membrane potential to a positive value. |
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What happens when the neuron is stimulated, and how is it stimulated?
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When a neuron is stimulated, it causes the gated channels to open. A stimulus is any change in the environment.
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Describe the steps in the generation of the impulse.
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1. Stimulus causes the sodium gates to open.
2. Influx of sodium makes the interior of the cell more positive. 3. When interior cell reaches -55 mV, the axon hillock allows firing of an impulse. 4. When interior cell reaches +30 mV, the sodium gate closes and the potassium gate opens. 5. Potassium rushes out of the cell, creating a more negative environment. |
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What is the all or nothing principle?
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The neuron either reaches threshold or it doesn't ... there is no partial firing of an impulse.
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How are differences in stimuli strength translated by the nervous system?
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The stronger a stimulus ... the faster it will bring a neuron to threshold.
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What determines the speed of an impulse in different axons?
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1. Diameter
2. Myelination 3. Body Temperature |
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What is a synapse?
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A junction between ...
1. two neurons 2. neuron and muscle 3. neuron and gland |
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Where is the pre-synaptic membrane?
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The membrane of a pre-synaptic neuron ,,, this is a neuron that carries the signal TO the synapse.
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Where is the post-synaptic membrane?
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The membrane of a post-synaptic neuron ... neuron that receives the signal. Any part of the post synaptic neuron can receive the signal.
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What is the synaptic cleft?
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The space in between a pre- and post-synaptic neuron.
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Describe how an impulse may be transmitted across the synaptic cleft?
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At the synaptic end bulb, calcium follows sodium into the membrane and pushes the vescicles to the cell membrane and releases NTs via exocytosis. The NTs attach to the post-synaptic receptors.
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What is the excitatory synapse?
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The NTs open the sodium gates on the post-synaptic neuron ... moving the neuron closer to threshold.
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What is inhibitory synapse?
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The NTs open the potassium gates on the post-synaptic neuron ... moving the neuron further away from threshold.
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What determines if an impulse will be generated in the post-synaptic neuron?
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Whether of not threshold is met at the axon hillock.
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What is the importance of the inhibitory synapse?
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The balance between EPSPs and IPSP is very important in the integration of electrical information produced by inhibitory and excitatory synapses.
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What is a neurotransmitter? Name two.
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Neurotransmitters are the chemicals which allow the transmission of signals from one neuron to the next across synapses.
Acetycholine & Dopamine |
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What is meant by summation of impulses?
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The sum of all inhibitory and excitatory charges.
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What is facilitation?
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Phenomenon that occurs when two or more neural impulses that alone are not enough to trigger a response in a neuron combine to trigger an action potential.
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How many axons can synapse with a single post synaptic neuron?
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Many
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What do you call a junction of a motor neuron and a muscle cell?
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Neuromuscular junction.
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What do you call the junction of a motor neuron and a gland?
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Neurogladular junction.
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What happens to NTs after they cross the synaptic cleft?
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Enzymes allow the NTs to be taken back into the pre-synaptic neuron via endocytosis.
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Can an impulse flow in both directions in an axon?
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No
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Can an impulse flow in both directions across a synapse?
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No
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What do you call a cluster of gray matter in the brain?
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Nucleus
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What do you call a cluster of gray matter in the spinal cord?
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Gray Matter ... Posterior Gray Horn, Anterior Gray Horn, Lateral Gray Horn, Gray Commissure
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What do you call a cluster of gray matter in the PNS?
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Ganglion
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What do you call a cluster of axons (usually myelinated) in the CNS?
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White Matter ... Columns that contain Tracts
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What do you call a cluster of axons (usually myelinated) in the PNS?
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Nerve
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Where does the spinal cord begin and end?
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The cord begins at the foramen magnum and travels down to L2.
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Name and locate the two enlargements of the spinal cord.
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Cervical and Lumbar Enlargements
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What are the functions of the cervical and lumbar enlargements?
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They provide attachments sites for the upper extremities nerves (Cervical Enlargement) and lower extremities nerves (Lumbar Enlargement)
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What is the Conus Medullaris?
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Inferior border of the spinal cord at L2.
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What is the Cauda Equina?
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"Horses Tail" ... spinal nerves extending from the inferior end of the spinal cord to the intervertebral foramina or the sacral foramina.
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How many pairs of spinal nerves are there?
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31 pairs of spinal nerves
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How many segments of the cord?
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31 segments of the spinal cord
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What is a dermatome, mytome, scleratome?
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Dermatome ... area of skin innervated by a segment of the spinal cord.
Myotome ... area of muscles innervated by a segment of the spinal cord. Scleratome ... area of connective tissue innervated by a segment of the spinal cord. |
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Where do spinal nerves exit from the vertebral column?
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Intervertebral forament
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What are ascending tracts?
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Groups of nerve fibers in the spinal cord that transmit sensory impulses upward to the brain.
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What are descending tracts?
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A nerve tract in the spinal cord that carries impulses away from the brain.
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Describe the difference between long tracts and short tracts.
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Long tracts ... white matter. Connects the spinal cord and brain.
Short tracts ... white matter. Connects different segments of the cord to coordinate movements and reflexes. |
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What are the tracts functions?
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They are either sensory or motor. They are NOT mixed like the spinal nerves.
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What occurs in the gray matter of the cord?
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Gray matter is where synapses occur in the spinal cord.
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What is found in the anterior horn?
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AGH ... CNS motor neurons synapse with PNS motor neurons (lower motor neurons)
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What is found in the posterior horn?
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PGH ... PNS sensory neurons synapse with CNS sensory neurons
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What is found in the lateral horn?
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LGH ... autonomic pre-ganglionic neurons begin.
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Does every segment of the cord contain lateral horns?
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No ... only the thoracolumbar spinal cord.
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What are meninges?
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Connective tissues that cover the brain and spinal cord.
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Name and describe the three different layers starting from the outermost layer.
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1. Pia Mater ... inner most layer that attaches directly to the cord. "Gentle Mother"
2. Arachnoid Mater ... middle layer; fibrous and vascular. "Spider Mother" 3. Dura Mater ... outer most layer that is dense connective tissue. "Tough Mother" |
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Where is the CSF found within the meninges?
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CSF is found in the sub arachnoid space which is below the arachnoid and above the pia mater.
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What are the filum terminale and denticulate ligaments?
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Filum Terminale ... string like continuation of the pia mater from the conus medullaris (inferior border of cord proper) to the sacrum.
Denticulate ligaments ... "tooth like" ligaments that attach the pia mater to outer layers and hold the spinal cord in the center of the canal. |
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Which layer of the meninges do the filum terminale and denticulate ligaments originate?
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Pia mater
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Where does the first pair of spinal nerves emerge from the vertebral canal?
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The excepted first pair of cervical spinal nerves, finds its way through the opening between the occipital bone, which belongs to the skull, and the atlas.
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Are spinal nerves mixed nerves?
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Yes
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How are spinal nerves grouped?
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There are eight paired cervical nerves (C1-C8), twelve thoracic (T1-T12), five lumbar (L1-L5), five sacral (S1-S5), and one coccygeal (Co1).
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How many pairs are in each group?
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There are eight paired cervical nerves (C1-C8), twelve thoracic (T1-T12), five lumbar (L1-L5), five sacral (S1-S5), and one coccygeal (Co1).
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Name the rami of a spinal nerve.
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1. Anterior Ramus
2. Posterior Ramus |
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What area of the body does each branch innervate?
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Anterior Ramus ... contains the neurons that will eventually inntervate all the other areas of the body that the Posterior Ramus does not innervate.
Posterior Ramus ... contains neurons that innervate the skin and mucles in a small strip just lateral to the vertebral column (paraspinal muscles) |
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Which are the only branches to enter into the nerve plexus?
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Cervical
Lumbar Sacral |
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Name the four major plexuses formed by the anterior rami of the spinal nerves.
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Cervical
Brachial Lumbar Sacral |
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What is a plexus?
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A nerve plexus is a network of intersecting nerves. They combine sets of spinal nerves that serve the same area of the body into one large grouped nerve.
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Do thoracic nerves form a plexus?
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No
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Cervical Plexus
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Nerves: C1-C4<BR>Terminal Nerves: Phrenic, Ansa Cervicals, Segmental Branches<BR>Areas Innervated: muscles of swallowing, diaphragm, anterior neck, levator scapula, scalenes.
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Brachial Plexus
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Nerves: C5-T1
Terminal Nerves: Radial, Axillary, Median, Musculotaneous, Ulnar Areas Innervated: Upper Extremities |
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Lumbar Plexus
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Nerves: L1-L4
Terminal Nerves: Femoral, Obturator, Illiohypogastric, Illioinguinal Body Areas Innervated: anteriolateral abdominal wall, external genitals, part of lower extremity. |
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Sacral Plexus
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Nerves: L4-S3
Terminal Nerves: Superior gluteal, Inferior gluteal, Sciatic, Tibial, Common Peroneal, Deep Peroneal, Superficial Peroneal. |
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Phrenic Nerve
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Plexus: Cervical
Entrapment Sites: ? Muscles: Diaphragm |
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ANSA Cervicals (Cervical Loop)
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Plexus: Cervical
Entrapment Sites: ? Muscles: Swallowing Muscles |
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Segmental Branches
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Plexus: Cervical
Entrapment Sites: ? Muscles: Levator Scapula, Middle Scalenes, Anterior neck muscles |
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Axillary Nerve
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Plexus: Brachial Plexus (Posterior Cord)
Entrapment Sites: Quadrangular Space (area between triceps, humerus, teres major, teres minor) Muscles: Deltoid, Teres minor |
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Radial Nerve
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Plexus: Brachial Plexus (Posterior Cord)
Entrapment Sites: Saturday Night Palsey (compression against humerus), gap btwn teres major and triceps long head, over styloid process of radius Muscles: STAB (supinator, triceps, anconeous, brachioradialis), all wrist/hand extensors |
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Musculotaneous
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Plexus: Brachial
Entrapment Sites: Coracobrachialis Muscles: BBC (biceps brachii, brachialis, coracobrachialis) |
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Median (Carpenter's Nerve)
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Plexus: Brachial
Entrapment Sites:Pronator teres and carpal tunnel Muscles: Pronator teres, quadratus, flexor carpi radialis, palmaris longus, flexor digitorum superficialis, flexor pollicus longus, thenar eminence. MOST anterior forearm and lateral two lumbricals. |
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Ulnar (Musician's Nerve)
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Plexus: Brachial
Entrapment Sites: Cubital Tunnel in flexor carpi ulnaris entrapment Muscles: Flexor carpi ulnaris, flexor digitorum profundus, hypothenar eminence, medial two lumbricals and interossei |
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Other Nerves of the Brachial Plexus
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Long Thoracic
Thoracodorsal Lateral and Medical Pectoral Suprascapular |
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Divergent Circuits
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Most common in the sensory division where one impulse travels to different areas.
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Convergent Circuits
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Most common in the motor division where multiple impulses converge on one PNS neuron.
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Sensory Pathways
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Spinothalamic (anterior and lateral)
Spinocerebellar (anterior and posterior) Medial Lemniscus (posterior column) |
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Medial Lemniscus ... higher level functioning ... not all animals possess this pathway
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1st order neuron ... receptor-PGH-medulla (SYNAPSE)
2nd order neuron ... medulla-medial lemniscus-OPPOSITE side thalamus 3rd order neuron ... thalamus to cerebral cortex |
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Spinothalamic (Anterior or Lateral Pathways)
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1st order neuron ... receptor to PGH
2nd order neuron ... PGH-opposite side track via commisures-thalamus 3rd order neuron ... thalamus to cerebral cortex |
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Spinocerebellar (Anterior or Posterior Pathways) ... coordination of movement
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1st order neuron ... receptor to PGH
2nd order neuron ... PGH to cerebellum |
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Somatic Motor Pathways
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Pyramidal/Corticospinal Pathway
Extrapyramidal Pathway |
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Final Common Pathway
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The pyramidal and extrapyramidal tracts share the lower motor neuron and this is call the final common pathway.
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Pyramidal/Corticospinal Tract
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cerebral cortex-AGH (upper motor neuron or CNS motor neuron)
AGH-ventral root-spinal nerve-effector (lower motor neuron) |
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Extrapyramidal Tract
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brain (except cerebral cortex)-AGH (upper motor neuron or CNS motor neuron)
AGH-ventral root-spinal nerve-effector (lower motor neuron) |
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Autonomic Motor Pathways
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Autonomic motor neurons of the CNS to LGH OR nuclei of a cranial nerve.
LGH or nuclei to to autonomic ganglion. (preganglionic neurons) Autonomic ganglion to effector organ (post ganglionic neurons) |
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True or False ... Pyramidal tracts are mostly excitatory and extrapyramidal tracts are mostly inhibitory.
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True
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Endoneurium
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Protective sheath of an axon.
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Perineurium
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Protective sheath of a fascicle.
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Epineurium
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Protective sheath of a nerve.
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What are the five components of a reflex arc?
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1. Receptor
2. Sensory Neuron 3. Integration Center 4. Motor Neuron 5. Effector |
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Describe the path of a Stretch Reflex.
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1. Stimulus ... stretch and speed of the stretch
2. Receptor ... Muscle Spindle Organ 3. Sensory Neuron ... Unipolar 1st Order 4. Integration Center ... 1st Order Neuron synapses directly with Motor Neuron 5. Motor Neuron ... Carries impulse to effector. 6. Effector ... Muscle Contracts |
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Describe the path of a Golgi Tendon Reflex.
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1. Stimulus ... Tension in the muscle from contracting
2. Receptor ... Golgi Tendon Organ at musculotendinous junction 3. Sensory Neuron ... 1st Order Neuron 4. Integration Center ... 1st order neuron synapses with an interneuron that INHIBITS the motor neuron 5. Motor Neuron ... is inhibited so it stops firing and contracting the muscle 6. Effector ... muscle that was contracting "gives up" under too much of a load |
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Describe the path of a Flexor/Withdraw Reflex.
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1. Stimulus ... pain
2. Receptor ... nociceptor ... free nerve endings that sense pain 3. Sensory Neuron ... unipolar 1st order neuron 4. Integration Center ... interneurons travel is short tracts 5. Motor Neurons ... sends signals out to flexor muscles 6. Effector ... flexor muscles withdraw limb from source of pain |
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Describe the path of a Crossed Extensor Reflex.
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1. Stimulus ... pain
2. Receptor ... nociceptor ... free nerve endings 3. Sensory Neuron ... 1st order unipolar neuron 4. Integration Center ... interneurons travel is short tracts cross gray commisures 5. Motor Neurons ... send signals to flexors on one side and extensors on the other side 6. Effectors ... flexor muscles on side of pain; extensor muscles on opposite side |
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What is a relfex?
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Fast, survival oriented, predictable, unlearned, involuntary repsonse.
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What is a spinal reflex?
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Connections and processing occur in the spinal cord.
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What is a monosynaptic reflex?
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There is only one synapse in the reflex arc ... no interneurons are involved.
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What is a polysynaptic reflex?
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There is more than one synapse in the reflex are ... interneuron involvement.
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What is a monosegemental reflex?
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The receptor and effector are located in the same cord segment ... usually small repsonses.
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What is a poly (inter)segmental reflex?
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Interneurons spread the response to adjacent segements via short tracts ... usually larger responses.
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What is a somatic reflex?
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The effector is skeletal muscle.
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What is an autonomic (visceral) reflex?
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The effector is cardiac, smooth muscle or a gland.
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What is a viscero-somatic reflex?
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The stimulus is in the viscera and the effector is in the soma.
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What is a somato-visceral reflex?
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The stimulus is in the soma and the effector is in the viscera.
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What is an ipsilateral reflex?
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The receptor and effector are on the same side of the body.
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What is a contralateral reflex?
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The receptor is on one side and the effectors are on both sides.
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Descriptive categories of the Stretch Reflex.
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Monosynaptic
Monosegmental Ipsilateral Excitatory |
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Descriptive categories of the Golgi Tendon Reflex.
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Polysynaptic
Monosegmental Ipsilateral Inhibitory |
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Descriptive categories of the Flexor/Withdraw Reflex.
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Polysynaptic
Polysegmental Ipsilateral Excitatory |
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Descriptive categories of the Crossed Extensor Reflex.
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Polynaptic
Polysegmental Contralateral Excitatory |
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What is reciprocal innervation?
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A phenomenon that occurs outside of the reflex arc that helps the response to occur smoothly. Example ... in order to facilitate the agonist, the antagonist will relax.
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Name common types of reflexes.
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Baro (presso) Reflexes ... Blood Pressure
Osmo Reflexes ... Osmolarity Chemo Reflexes ... Chemicals Proprio Reflexes ... Body Position Nociceptive Reflexes ... Pain |
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How does a passive stretch activate the Stretch Reflex AND the Golgi Tendon Reflex?
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Initially, the MSO is active to cause contraction against the passive stretch. Over about 10 seconds of stretching, the MSO "resets" and relaxes. The GTOs then kick in because they sense tension on the tendons and cause further relaxation of the muscle ... all facilitating stretch.
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How does Tapotement increase tonicity?
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Tapotement stimulates the muscle spindle and therefore the Muscle Spindle Organ causing contraction ... increasing tonicity.
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Where does the medulla begin?
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It is an extension of the spinal cord so begins at the base of the brain.
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Name three vital reflex centers in the medulla.
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1. Medullary Rhythmicity Center
2. Cardiac Center ... a. Cardiac Inhibiting Center; b. Cardiac Accelerating Center 4. Vasomotor Center |
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What other, less vital, reflex centers also exist in the medulla?
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Nuclei that control swallowing, coughing, gagging, vomiting, sneezing, yawning, salivating and balance/equilibrium (known as Vestibular Nuclei)
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Name the major descending tracts which cross on the anterior surface of the medulla.
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Corticospinal (Pyramidal) Tracts
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What is another term for the crossing of tracts?
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Decussation
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What is the significance of the crossing of these tracts from the functional point of view?
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Right side of the brain controls the left side of the body and vice versa.
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What type of movement is activated by impulses through the pyramidal tracts?
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Precise, voluntary movements most of which are extremities muscles.
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Where do the pyramidal tracts arise and where do they terminate?
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They originate in cerebral cortex and terminate at the Anterior Gray Horn of the spinal cord.
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What is meant by an extrapyramidal tract? Give an example.
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A motor tracts that originates anywhere else in the brain BUT the cerebral cortex and controls involuntary skeletal muscle. Examples are tone, posture, balance, etc.
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Locate the pons relative to other parts of the brain.
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The pons is the middle aspect of the brainstem.
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What does the word pons mean and why is it called that?
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Pons means "bridge" and it is used because it ...
1. connects the two halves of the cerebellum 2. connects the medulla and the midbrain |
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What lies just posterior to the pons?
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Cerebellum
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What are the pneumotaxic center and the apneustic center?
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Pneumotaxic Center ... inhibits inhalation so that exhalation occurs.
Apneustic Center ... stimulates inhalation so that inhalation occurs. |
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Is the pons composed mostly of white matter or gray matter?
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Mostly white matter ... tracts.
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What and where is the corpora quadrigemina?
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It means the "body of four twins" ... located in the midbrain. Reflex center for head/neck movements in response to visual and auditory stimuli. Origin of Tectospinal (Extrapyramidal) Tracts.
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What and where is the red nucleus?
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Origin of Rubrospinal (Extrapyramidal) Tract. Located in the midbrain and carries motor impulses that control muscle tone. More iron so more red.
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What and where is the substantia nigra?
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Located in the midbrain ... cell bodies that synapse in the basal ganglia of the cerebrum and release dopamine. The dopamine helps to smooth out muscles and decrease muscle tone.
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Locate the hypothalamus and thalamus in the diencephalon.
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The diencephalon is superior to the midbrain. Within the diencephalon ... the thalamus is superior and the hypothalamus is inferior.
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Name the major functions of the thalamus.
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Giant relay center for ALL senses. Also motor tracts for somatic responses to emotional stimuli. Nuclei for Cranial Nerve II.
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Which sense does not pass through the thalamus?
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Olfactory
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Where are impulses relayed from the thalamus?
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Most sensory/ascending tracts synapse in the thalamus except smell. Motor tracts carry impulses for somatic effects of emotional states to the effectors.
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What gland (and system) is intimately related to the hypothalamus?
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Pituitary gland and the endrocrine system.
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Which efferent system is also largely controlled by the hypothalamus?
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Autonomic Nervous System
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Sensory impulses come into the hypothalamus for where?
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The viscera.
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What is the significance of drive centers?
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They regulate life sustaining and homeostatic function so that we do not have to consciously pay attention to them.
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What is the name of the emotional brain?
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The limbic system.
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What other parts are included in the limbic system besides the diencephalon?
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Limbic System ... groups of nuclei in the lower cerebrum and diencephalon.
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Explain how sensory information is interpreted in the limbic system.
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Sensory input enters the Limbic System and evokes an emotional response. The emotions cause motor responses ... both autonomic and somatic motor responses.
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How is the Limbic System related to memory?
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If an event touches us emotionally we are more likely to remember it.
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What is the reticular formation?
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Groups of interconnected nuclei that are spread out in the Diencephalon and Brain Stem. They help control stereotypical and repeated movements so they can occur without conscious thought.
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What is the Reticular Activating System?
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Filters sensory information going to the cerebral cortex. Maintains consciousness and awakens us from sleep.
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What and where is the cerebral cortex?
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The most superficial layer of the cerebrum. Main area of conscious awareness and organized into functional areas ... motor, sensory and association.
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How thick is the cerebral cortex?
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6 layers of cell bodies.
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What color is the cerebral cortex and what does that represent? What color is the remainder of the cerebrum?
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(look up on internet)
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Name the group of nuclei located deep in the cerebrum?
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Basal Ganglia or Cerebral Nuclei
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What is their main function?
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Control large automatic movements of skeletal muscles like arm swing when walking. They also help regulate muscle tone and initiate movement. Surrounds diencephalon. Early learned patterned movements ... creeping, crawling, running, cycling.
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What type of tracts originate in the basal ganglia (cerebral nuclei)?
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Extrapyramidal Tracts
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What pathology is associated with the basal ganglia and the substantia nigra?
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Parkinson's Disease
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What is a fissure?
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Deep indentation in the cerebral cortex
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What is a sulcus?
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Shallow indentation in the cerebral cortex
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What is a gyrus?
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Raised part between a sulcus
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How is the cerebral cortex divided and organized?
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Hemisphere ... divides right and left.
Lobes ... divisions within each hemisphere. |
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What does the longitudinal fissure divide?
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It divides the cerebrum into right and left hemispheres.
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Name the five lobes of each hemisphere.
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1. frontal
2. parietal 3. temporal 4. occipital 5. insular |
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What white matter interconnects the hemispheres of the cerebral cortex?
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Commisural Tracts ... connects the hemispheres in a horizontal plane. One examples is the Corpus Callosum.
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Name the sulcus that separates the frontal and parietal lobes.
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Central Sulcus
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What are the three types of tracts that which run within the cerebrum?
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1. Commisural Tracts ... connects right and left hemispheres. Horizontal Plane.
2. Projection Tracts ... connects the cerebrum with other parts of the CNS. Vertical Plane. 3. Association Tracts ... connects gyri of the SAME hemisphere. Travels front to back. |
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What and where is the primary motor area and the premotor area of the cerebral cortex?
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The primary motor area of the cerebral cortex is in the PRE-CENTRAL GYRUS of the FRONTAL LOBE.
The premotor area (motor association) of the cerebral cortex in just anterior to the primary motor area on the FRONTAL LOBE. |
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What type of tracts originate in the primary motor and premotor areas of the cerebral cortex? Impulses for what types of movements originate here?
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The pyramidal tracts originate here.
Impulses for voluntary movements originate here. |
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Where do these tracts terminate (pyramidal tracts)?
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They originate in the cerebral cortex (premotor area) and travel to the AGH of the spinal cord. Lower motor neurons carry the impulse to the effector muscle.
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Which cerebral hemisphere controls motor activity on the left side of the body?
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Right side.
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How is the primary motor area of the cerebrum organized?
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It is organized in a homunculus which is a "map" that lies on the cortex upside down and disproportionately.
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What does it imply if a large area of motor cortex is assigned to a small portion of the body?
What does this imply about motor units to that part of the body? |
Areas of the body that are controlled by a large portion of the motor cortex are capable of PRECISE COORDINATED movements.
It implies that more motor units are required to perform precise coordinated movements. |
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Where is the general sensory (somesthetic) area of the cortex?
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On the post central gyrus of the PARIETAL LOBES.
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Which sensations are interpreted in the general sensory area of the cortex?
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Allows us to determine shape and texture of an object without looking. Makes two point discriminations and senses body position. Stores memories of past sensory experiences.
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Which areas of the body receive disproportionate representation in the general sensory area of the cortex?
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The head and hands have more representation which implies that they have more receptors than other areas of the body and are, thus, more sensitive.
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Name the primary areas of vision, audition, olfaction and gustation.
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Primary Visual Area ... Occipital Lobe ... color, shape and contrast
Primary Auditory Area ... Temporal Lobe ... pitch, volume and rhythm Primary Gustatory Area ... Parietal Lobe ... bitter, sweet, sour, salty Olfactory Area ... Temporal AND Frontal Lobe ... smell. Connected to the limbic system also. |
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What occurs in the surrounding association areas of vision, audition, olfaction and gustation?
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Visual Association Area ... gives meaning to what we see as well as emotional connections.
Auditory Association Area ... interprets and understands sound. WERNIKES AREA ... gives meaning to sounds/words. Olfaction is closely linked to taste and does not have its own association area. Gustatory Association Area ... interprets taste and is closely linked to olfaction. |
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How are the cerebral hemispheres asymmetrical ... what function is localized on one side?
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Sensory ... Wernikes Area is a small part of the auditory association area that is ONLY IN THE LEFT HEMISPHERE.
Motor ... Broca's Area ... Motor Speech Area ... LEFT SIDE OF FRONTAL LOBE ONLY. |
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How are tracts named? How can the names indicate if they are ascending or descending?
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Tracts are named for origin and end point. Tracts beginning with the prefix Spino- are ascending (sensory) tracts. Those ending with spinal are descending (motor) tracts.
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How do pyramidal and extrapyramidal tracts affect lower motor neurons?
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They either inhibit or excite lower motor neurons. Pyramidal neurons control voluntary skeletal muscle and extrapyramidal are involuntary skeletal muscle movements.
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What are upper and lower motor neurons?
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Upper motor neurons begin in the brain and end in the AGH of the spinal cord.
Lower motor neurons begin the AGH to the spinal nerve to the effector. |
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What is the final common pathway and why is it called that?
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The final common pathway are the motor impulses from the pyramidal AND extrapyramidal tracts. It called that because the tracts share lower motor neurons ... hence COMMON Final Pathway.
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Describe a typical sensory pathway from receptor to cortex.
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Stimulus - receptor - 1st order neuron (receptor to PGH) - 2nd order neuron (PGH to thalamus) - 3rd order neuron (thalamus to cerebral cortex)
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