The muscles in your neck.
these include the splenius capitis and splenius cervicus muscles. When acting bilaterally these muscles extend the head and neck. when they only act on one side the laterally flex and rotate the head and cervical spine the the same side as the muscle. the sternocleidomastoid is also responsible fro rotating the skull to the opposite side and lateral flexion of the cervical spine on the same side as the muscle. (these muscles are bilateral which means they are on both sides of your body , left and right)
scalene muscles
to make it tight
You can flex skeletal muscles voluntary. These are the muscles you can control and move consciously. Smooth muscles and cardiac muscles, which work involuntarily, cannot be consciously flexed.
Your hamstring muscles.
Hamstring
The sternocleidomastoid muscles are the ones that flex when the intercostals are flexed. This will also cause the scalene muscles to flex.
To flex your chest, you tighten the muscles that are in that area. This might include your arms or back as well, but you tighten the muscles in your chest and abs.
Abdominal muscles are trunk muscles that help to rotate and flex the spine. The abdominal muscles are composed of:Rectus abdominus: originates at the pelvis and inserts into the sternum as well as ribs 5-7. This muscle flexes the spine or assists in posteriorly (behind or in back of) tilting the pelvis.External obliques: one of the abdominal muscles responsible for rotation and flexion (position that is flexed relative to neutral or extension) of the spine. Developing external oblique strength is important for spinal stabilization against movement faults.Internal obliques: one of the abdominal muscles responsible for rotation and flexion of the spine. Developing internal oblique strength is important for spinal stabilization against movement faults.Transversus abdominus: an important spinal-stabilizing muscle
Muscles can contract and shorten
i done no
You flex your muscles to do this and these pull on the tendons which link the muscles to the bones.
The erector spinae muscles, transverse abdominis, and quadratus lumborum play important roles in stabilizing the spine. These muscles help maintain proper posture and support the spine during movements such as bending, lifting, and twisting. Strengthening these muscles can help prevent back pain and injury.