Issue link: https://www.massageandbodyworkdigital.com/i/943527
ANTERIOR SCALENE—CONTRALATERAL ROTATOR OR IPSILATERAL ROTATOR? The anterior scalene attaches from the transverse processes of the cervical spine (C3–C6) to the first rib—near the border of the rib with its costal cartilage (Images 4A–4C). There is a lot of controversy as to whether the anterior scalene is a contralateral or ipsilateral rotator of the cervical spine; some textbooks state that it contralaterally rotates and some state that it ipsilaterally rotates. So, is it a contralateral rotator, an ipsilateral rotator, or not a rotator at all? Of course, once again, the answer is yes, yes, and yes. Let's examine this question by looking at the rotation capability of the right anterior scalene. Beginning with the fundamental concept that when a muscle concentrically contracts, it shortens and brings its attachments closer together, we can see that from anatomic position, as seen in Image 4A, when the right anterior scalene contracts, it will bring its transverse process attachments toward the right first rib attachment, which would result in rotating the cervical spine to the left, as seen in Image 4B. So, the right anterior scalene is a left rotator. In other words, from anatomic position, the anterior scalene is a contralateral rotator. However, looking at Image 4B, we see that the right anterior scalene rotates the cervical spine to the left, but it is important to realize that it can only rotate the cervical spine to the left approximately 45 degrees, which is the position in which its attachments are closest to each other. If, instead, the neck were to first be in a position of left rotation beyond 45 degrees, as seen in Image 4C, the right anterior scalene would actually rotate its cervical spine attachment to the right, approximating the attachments toward each other as seen in Image 4B. So, from a position of left rotation that is greater than 45 degrees, the right anterior scalene is a right rotator (in other words, an ipsilateral rotator). And what if the cervical spine were first in a position of 45 degrees of rotation toward the opposite side of the body, as seen in Image 4B? Then, the anterior scalene would have no rotation capability at all. RUBBER-BAND BUDDIES There is a simple way for two students or therapists to work together to figure out a muscle's action(s). Working in a pair as "rubber-band buddies," one is the client and the other is the therapist. A colorful rubber band is placed over the client's body to represent the muscle in question, holding each end of the rubber band on the body to represent the two attachments of the muscle. Then, while the client holds one end of the rubber band fixed, the therapist moves the other end toward the fixed end, directly along the line of the rubber band. The movement of the body part is the action(s) (or motion pattern) of the muscle. Then, change which end is fixed and reverse the process, and you will have the reverse action of that action of the muscle. (Note: given that a rubber band is elastic, be careful when performing this exercise near the face, because if one end is accidentally let go, the rubber band could hit the client in the face. When working near the face, perhaps a colorful shoelace would be preferable.) For a video demonstration of this technique, visit https://learnmuscles.com/mb. Anterolateral view of the right anterior scalene. 4A: From anatomic position, the anterior scalene is a contralateral rotator to a position that is approximately 45 degrees of contralateral rotation. 4B: Position of 45 degrees of contralateral (left) rotation. 4C: From a fully contralaterally rotated position, the anterior scalene is an ipsilateral rotator to a position that is approximately 45 degrees of contralateral rotation. Illustration by Giovanni Rimasti. Permission Joseph E. Muscolino. 4A 4B 4C