The Central Axis of the Human Anatomy

Question 1 

Why are most neck and trunk muscles bilateral? 

The neck and trunk represent the central axis of the human anatomy. They are all attached to the body at the axis to enable coordinated movement of the body and neck. Given that the muscles are all on both sides of the body axis, the arrangement is known as bilateral to help in equal body movement coordination. The neck and trunk muscles are found on both sides of the axis and assist in rotating the head insides, left and right side. Thus they are known as bilateral muscles. It means that body movement originating from the muscles of the trunk and neck are both balanced between the left and right midsection of the body. 

Question 2 

What are two structural differences between the cervical vertebrae and the lumbar vertebrae, and how can these structural differences be explained by the different roles played by the cervical spine and the lumbar spine (i.e., the critical functions of each spine section? 

Short transverse processes characterize lumbar vertebrae in addition to a large size due to the considerable weight they carry. Their inferior processes face forward while the superior processes face backward. However, cervical vertebrae are small in size and take the least amount of body weight. The inferior and superior articular processes face downward or upward, respectively, and are flat. They are also structurally different as they have a Y-shaped spinous process. 

Question 3 

How does the orientation of the lines of the muscle fibers differ between rectus abdominis and the external obliques, and how are these muscles fiber orientations related to the trunk movement they produce? 

Lines of the muscle fibers in rectus abdominis run vertically on both sides of a human abdomen in the anterior wall. On the other hand, lines of the muscle fiber in external oblique originate from the outer surface of the fleshy muscles within the lower six ribs shaft. In rectus abdominis, the lines are visible and create the muscle bellies commonly called the six or four pack in a human’s abdomen. Despite their difference in location, the muscles help in coordinated locomotion’s that are critical for the sliding movement between muscle fibers. During trunk movement, the muscles side and bend the trunk. At the same time, they enable spinal stability for the abdominal muscles that include the internal oblique, transversus abdominis, and external oblique. Rectus abdominis assist in twisting, stabilizing, and bending the torso. The trunk movements produced help in achieving the functions of the external obliques. 

Question 4 

What is the role of transverse abdominis during most skills? 

Also known as TVA, the transverse abdominis is founded beneath the rectus abdominis running horizontally along the human abdomen and its function is required during the use or application of a limp. The transverse abdominis is involved in significant functions of the body that include rotating and bending the body to different sides. Each time the body is engaged in any skill or activity such as throwing, defecating, exhalation, or coughing, the abdominis compresses the abdomen. It thus aligns the body muscles to its proper tone assisting with back pain. At the same time, it helps in compression and exhalation of the inner organs. During such times, its primary function is to stabilize, activate, and musculature the pelvic region and lower region of the body before any movement occurs. It is the natural “weight belt” of the body. 

Question 5 

Review Activity 4 from lab 5. For tasks 5,6 and 7 (holding backpack, arm overhead, backpack over the shoulder? Were there more considerable changes in spinal curvature evident in the vertical spine, or the thoracic spine, of the lumbar spine? 

Through the tasks that involved backpack, overhead, holding back, over the shoulder, considerable changes were evident in the spinal curvature as the cervical spine, thoracic spine and lumbar spine all tried to align with the body changes. More significant differences are observed on the vertical spine and lumbar spine, firstly due to its elongated length in addition to bearing the enormous weight or movement. Despite being at a position to bear heavy weights, the two spine regions curve to help absorb the most weight and protect the inner areas of the spine from injury. Overheads lead to small changes on the lumbar extensions. Overhead weights also bring forth significant changes on the cervical spine but minimal changes on thoracic spine.