Final answer:
The spinal cord segments T7 - T12, L1 are responsible for sending signals to the muscles as part of the sensory-somatic nervous system. Motor neurons in the ventral horn of the spinal cord's gray matter innervate skeletal muscles, and the cerebral cortex is where high-level integration occurs when testing temperature.
Step-by-step explanation:
Spinal Cord Nerve Signals
The spinal cord segments at T7 - T12, L1 send signals to the muscles. Specifically, these segments are part of the sensory-somatic nervous system which handles transmitting information from the skin, muscles, and sensory organs to the central nervous system, and sending motor information to and from the peripheral nervous system and the muscles.
When considering the regions of the spinal cord involved in motor control of skeletal muscles, the ventral horn of the spinal cord's gray matter is where motor neurons that innervate skeletal muscles are located.
In terms of integration within the nervous system, when testing the temperature of a shower, the greatest level of integration takes place in the cerebral cortex.