Questions: A mixed nerve is one that contains both Multiple Choice cranial and spinal nerve fibers. sensory and motor neurons. unipolar and bipolar neurons. an endoneurium and an epineurium.

The answer is the second one (B): sensory and motor neurons.

Explanation for each option:

• Cranial and spinal nerve fibers: This option is incorrect because a mixed nerve does not specifically refer to the combination of cranial and spinal nerve fibers. Mixed nerves can be either cranial or spinal nerves that contain both sensory and motor fibers.
• Sensory and motor neurons: This option is correct. A mixed nerve contains both sensory (afferent) neurons, which carry signals to the central nervous system, and motor (efferent) neurons, which carry signals from the central nervous system to muscles and glands.
• Unipolar and bipolar neurons: This option is incorrect because the classification of mixed nerves is based on the function (sensory and motor) rather than the structural types of neurons (unipolar, bipolar, etc.).
• An endoneurium and an epineurium: This option is incorrect because these terms refer to the connective tissue layers surrounding nerve fibers and bundles, not to the functional composition of the nerve.

Summary: A mixed nerve is one that contains both sensory and motor neurons.