Human Anatomy - Kotsan I. Ya. 2009

General overview of the muscles responsible for movements of individual body parts
Movements of the vertebral column

THE Vertebral Column, along with the entire torso, neck, and HEAD, can perform the following movements:

— extension and flexion (backward and forward bending of the torso);

— lateral movements (bending to the right and left);

— rotation (twisting) to the right and left;

— circular motion.

Extension of the vertebral column. The Muscles that extend the vertebral column include those that cross the frontal (transverse) axis of rotation and are located posterior to it on the back of the torso and neck:

1) trapezius muscles;

2) serratus posterior muscles (superior and inferior);

3) splenius Muscles of the Head and Neck;

4) erector spinae Introduction/39.html">Muscles and their components: iliocostalis, longissimus, and spinalis muscles;

5) transversospinales muscles: semispinalis, multifidus, and rotatores;

6) short back muscles.

Flexion of the vertebral column. The Muscles responsible for flexing the torso, neck, and head include those whose resultant forces lie anterior to the frontal axes passing through the centers of the intervertebral discs and anterior to the frontal axis of the atlanto-occipital joint. These include the anterior Neck Muscles, Abdominal muscles, and iliopsoas muscles. The most important among them are:

1) sternocleidomastoid muscles;

2) scalene muscles;

3) longus capitis and longus colli muscles;

4) rectus abdominis muscles;

5) oblique abdominal muscles (internal and external);

6) iliopsoas muscles.

The latter participate in the flexion of the vertebral column only when the lower extremities are fixed.

Lateral flexion of the vertebral column. Lateral bending of the vertebral column occurs According to the parallelogram of forces rule during the simultaneous contraction of the flexor and extensor muscles on one side. They are assisted, working from the corresponding side, by:

1) levator scapulae Muscle (when the scapula is fixed);

2) quadratus lumborum muscle;

3) intercostal muscles;

4) intertransversarii muscles.

Rotation of the spinal column around the vertical axis, or twisting,

is primarily performed by the following muscles when acting unilaterally:

1) the upper portion of the trapezius muscle, which has a small rotational component directed in the opposite direction;

2) the scalene muscles, together with the contralateral levator scapulae muscle, form a force couple that rotates the head and neck;

3) the external oblique muscle of the abdomen, together with the contralateral internal oblique muscle of the abdomen;

4) the transversospinales muscles;

5) the iliopsoas muscle (with a fixed Femur).

Circumduction of the spinal column occurs through the sequential engagement of all trunk muscle groups responsible for flexion, extension, lateral bending, and rotation.