There are 31 pairs of spinal nerves grouped by region of the vertebral column. The cervical nerves are the most superior and there are eight pairs of them. The first cervical nerves arise superior to the first cervical vertebra. The thoracic nerves arise as twelve pairs. They lead to nerves that innervate the muscles between the ribs and associated skin. There are five pairs of lumbar nerves and five pairs of sacral nerves. The last pair of spinal nerves is the coccygeal nerves.
A plexus is a web-like arrangement of nerves that is near the spinal cord and gives rise to the terminal nerves. The most superior plexus is the cervical plexus which arises from the first five cervical spinal nerves. The brachial plexus receives input from the fifth through eighth cervical nerves and the first pair of thoracic nerves. The lumbar plexus arises from the first four pairs of lumbar nerves and the sacral plexus is associated with the last two pairs of lumbar nerves and the first four pairs of sacral nerves. Sometimes the lumbar and sacral plexuses are grouped together as the lumbosacral plexus. Use one color to color in the short segments of the spinal nerves and label the plexuses. Color each plexus a different color.
Answer Key: a. Cervical plexus, b. Brachial plexus, c. Lumbar plexus, d. Sacral plexus, e. Cervical nerves, f. Thoracic nerves, g. Lumbar nerves, h. Sacral nerves, i. Coccygeal nerves
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.