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4 Cards in this Set
- Front
- Back
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Describe the anatomy of a spinal nerve. |
There are 31 pairs of spinal nerves (in the PNS), both motor and sensory axons. Spinal nerves arise from numerous rootlets along the dorsal and ventral surfaces of the spinal cord. A ramus is a major branch of a spinal nerve. Each spinal nerve has a dorsal and ventral ramus. Additional rami are called the communicating rami. The dorsal rami innervate most of the deep muscles of the dorsal trunk responsible for moving the vertebral column. The ventral rami are distributed in two ways. In the thoracic region, the ventral rami form intercostal nerves (between ribs). The ventral rami of the remaining spinal nerves form 5 major plexuses. |
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What is the difference between ventral roots and dorsal roots in a spinal nerve? |
Spinal nerves arise from numerous rootlets along the dorsal and ventral surfaces of the spinal cord. * 6-8 of these rootlets combine to form a ventral root of the ventral (anterior) side of the spinal cord. The ventral roots contain the axons of MOTOR neurons and spinal nerves have both sensory and motor axons. * another 6-8 form a dorsal root on the dorsal (posterior) side of the spinal cord at each segment. The dorsal root contains axons of SENSORY neurons. Sensory neuron cell bodies are contained within the dorsal root ganglion (swelling). The ventral and dorsal roots extend laterally from the spinal cord, passing through the subarachnoid space, piercing the arachnid matter and dura matter, and joint one another to form a spinal nerve. |
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What is a plexus? |
Plexus (braid) is an intermingling of nerves. The ventral rami of different spinal nerves, called the roots, join with each other to form a plexus. (Median and periferal nerves) |
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Name the 5 major plexuses |
Cervical plexus- formed by the ventral rami of spinal nerves C1-4 Brachial plexus- C5-T1 (includes C8 nerve, even though there are only 7 cervical vertebrae) Lumbar plexus- L1-4 Sacral plexus- L4-S4 Coccygeal plexus- S5 and the coccygeal nerve (Co)
*neurons can travel through all different plexuses *1-4, 5-1, 1-4, 4-4 |
