Lab 2 navigation
On the whiteboard, draw a cross section of the spinal cord and spinal nerves.
You can omit the vertebra in your drawing if you like. Label the following in your drawing:
■Dorsal and ventral horns of gray
■Dorsal and ventral roots
■Dorsal root ganglion
■Spinal nerve
■Dorsal and ventral rami
Questions
- Which part carries ONLY sensory nerve fibers?
- Which part carries ONLY motor nerve fibers?
- Which parts are mixed (carry BOTH motor and sensory fibers)?
- What does the dorsal root ganglion contain?
Now, sketch motor and sensory pathways in your spinal nerve drawing.
■Trace a motor neuron from the spinal cord (ventral horn of gray) to innervate a muscle on the anterior side of the body (e.g., intercostal muscle).
■This is a single neuron efferent pathway involving a multipolar neuron. Where is the cell body of the neuron located? Which root does the motor axon traverse—ventral or dorsal? Which ramus of the spinal nerve does the motor axon traverse—ventral or dorsal?
■Trace a sensory neuron that transmits a stimulus—from the anterior side of the body—to the spinal cord.
■This is a single neuron afferent pathway involving a pseudo-unipolar (sensory) neuron. Where is the cell body of the neuron located? Which ramus of the spinal nerve does the peripheral process of the neuron traverse—ventral or dorsal? Which root does the central process of the neuron traverse to enter the spinal cord—ventral or dorsal? The sensory neuron synapses on an interneuron within the spinal cord. Where does this occur?
■Trace a motor neuron from the spinal cord (ventral horn of gray) to innervate a muscle on the posterior side of the body (e.g., erector spinae muscle).
■This is a single neuron efferent pathway involving a multipolar neuron. Where is the cell body of the neuron located? Which root does the motor axon traverse—ventral or dorsal? Which ramus of the spinal nerve does the motor axon traverse—ventral or dorsal?
■Trace a sensory neuron that transmits a stimulus—from the posterior side of the body—to the spinal cord.
■This is a single neuron afferent pathway involving a pseudo-unipolar (sensory) neuron. Where is the cell body of the neuron located? Which ramus of the spinal nerve does the peripheral process of the neuron traverse—ventral or dorsal? Which root does the central process of the neuron traverse to enter the spinal cord—ventral or dorsal? The sensory neuron synapses on an interneuron after it has entered the spinal cord. Where does this occur?