Final answer:
A nerve plexus is the network of spinal nerve axons that form peripheral nerves to the neck, limbs, and pelvis. The main plexuses are cervical, brachial, lumbar, and sacral, with prominent nerves like the radial, ulnar, median, and sciatic originating from these plexuses.
Step-by-step explanation:
The network of spinal nerve axons from which peripheral nerves are projected to the neck, limbs, and pelvis is known as a nerve plexus. These plexuses are specifically cervical plexus, brachial plexus, lumbar plexus, and sacral plexus. They are important for sensory and motor functions, reorganizing the axons from spinal nerves to innervate various body regions. The brachial plexus, for instance, gives rise to several nerves that control the arms, such as the radial nerve, ulnar nerve, and median nerve. The sacral plexus is notable for the sciatic nerve, which is vital for leg function and can be associated with sciatica.