Final answer:
Dermatomes are topographic regions on the skin that relate to specific spinal nerves, while myotomes refer to the muscles innervated by these nerves. In the UE, dermatomes of cervical spinal nerves cover different regions of the arm, forearm, and hand, while myotomes innervate corresponding muscle groups.
Step-by-step explanation:
Dermatomes are topographic regions on the surface of the skin that correspond to different spinal nerves. These regions are defined based on the location of sensory endings in the skin, which are connected to specific spinal nerves. Myotomes, on the other hand, refer to the groups of muscles that are innervated by a specific spinal nerve. Just like dermatomes, myotomes are organized in a similar topographical manner.
For example, in the upper extremity (UE), the dermatomes of the cervical spinal nerves (C5-T1) cover different regions of the arm, forearm, and hand. Each dermatome corresponds to specific sensory innervation in these areas. Similarly, the myotomes of the UE are responsible for innervating different muscle groups in the arm, forearm, and hand.