Final answer:
The sensory dermatomes of the nipples and the umbilicus are located at the levels of T4 and T10, corresponding to the innervation by the T4 and T10 spinal nerves.
Step-by-step explanation:
The sensory dermatomes of the nipples and the umbilicus are typically located at the levels of T4 and T10, respectively. Dermatomes are areas of skin that are mainly innervated by a single spinal nerve root. They are essential in the neurological examination to assess the level of spinal cord or nerve root damage. The T4 spinal nerve innervates the skin around the level of the nipples, which corresponds to the location of the sensory dermatome for this area. Similarly, the T10 spinal nerve is related to the dermatome level of the skin around the umbilicus.