The image for this learn node is from Dr. Emad Eskandar’s Harvard-MIT Health Sciences and Technology Neuroscience course handout (Motor Systems I). Page 2, With the image the handout explains:
We will begin our discussion from the bottom up starting with the physiology of the muscles and the spinal cord. An important concept to grasp is that of the motor unit. The following points should be kept in mind.
- A whole muscle is made up of many muscle fibers
- A muscle fiber is a single mutlinucleated cell
- Each muscle fiber is innervated by only one alpha motor neuron
- Each alpha motor neuron innervates numerous muscle fibers within a muscle
- A single neuron and all the muscle fibers it innervates are a motor unit
- The motor unit is the smallest division that the system can control individually
You can connect the muscle concepts above to another superb academic source by going to the Tufts Dental School course: Histology: Study of Cells, Tissues and Organs. Lecture 9: Muscle, on page 5 of the PDF summarizes the sequence of events of a muscle contraction. This Tufts muscle lecture can flex the most curious young mind � one that wants move past the medium learning fare.
To drop by and look over the shoulders of some scientists learning about muscle motor neurons from the transparent spinal cord of the zebrafish, click into The Journal of Neuroscience, where the articles are freely open online for the benefit of scientists, students and teachers.
For a look at the same information in non-academic, non-medical terms: How Muscles Work at HowStuffWorks.com.
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