Final answer:
The superficial intrinsic back muscles include the splenius muscles that are responsible for neck and head movements, while the intercostal muscles aid in the breathing process.
Step-by-step explanation:
The superficial intrinsic back muscles are important for maintaining posture and controlling movements of the vertebral column. These muscles lie deep to the skin but superficial to the spinal column, and they are intrinsic because they are contained entirely within the back. The surface anatomy of the back reveals several groups of muscles that move the back, neck, and scapulae. The intrinsic muscles are divided into three layers: superficial, intermediate, and deep. The superficial layer includes the splenius muscles, which extend from the mid-back up to the base of the skull, acting to extend or hyperextend the neck and head.
Apart from these, other muscles such as the intercostal muscles located between the ribs are critical for the breathing process. The superficial external intercostal muscles aid in inspiration by raising the rib cage and expanding it. The internal intercostal muscles promote expiration by drawing the ribs together and constricting the rib cage. Additionally, the innermost intercostal muscles serve as synergists to the action of the internal intercostals. The muscular system of this region is essential for various functions including posture, movement, and respiration.
The superficial intrinsic back muscles, such as the splenius muscles, are crucial for neck and head movements. The intercostal muscles aid in breathing by allowing for the expansion and constriction of the rib cage during inspiration and expiration respectively.