Written and illustrated by Lee Jarvis. Editing and proofreading by Lauren White.
The book Principles of Osteopathy by Dain Loren Tasker, DO was originally published in 1903. Although this was not the only Osteopathic publication of this time, what is worthy of noting is that it has an extensive number of photographs of manual Osteopathic applications. In some cases, the subjects in these photographs literally had anatomy illustrations drawn directly on them in ink. It is for this reason that we endeavour to further illustrate Tasker’s work of which we hope that he would have approved of our efforts. In this series we not only intend to reveal the mechanics of the technical applications relative to the patient, but just as importantly we hope to show how the operator generates leverage safely and effectively.
Relaxation of the Latissimus Dorsi: Principles of Osteopathy, page 405.
The Latissimus Dorsi (“Lats” for short) originate at the Iliac Crest, Spinous Process of L5-T7, Thoracolumbar Fascia, Lowest 3-4 Ribs, and the Inferior Angle of the Scapula. The Lats insert into the Intertubercular Groove of the Humerus.
In this image/explanation by Tasker they are attempting to lengthen the Lat muscle for the purpose of relaxation. The publication of this book predates the term “Myofascial Release” and so it is instead explained as relaxation through lengthening from superficial to deep.
The practitioner’s down-table hand (or left hand in this image) applies enough pressure to “anchor” the Ilium and resist it from being pulled upward along with the same side arm.
The practitioner’s up-table hand (or right hand in this image) puts the patient’s arm into a fully abducted and shoulder-flexed position. This works to fully lengthen the Lat by separating the superior and inferior attachment points of the muscle.
If we note that there is also enough external rotation of the arm/shoulder to lengthen the Lat just that much more as it wraps to the front of the humerus in its insertion, then we can conclude that the attachment points become even further apart.
Though not explicitly stated in the description, we can assume that there is a small amount of traction being generated by the practitioner. This traction generated would be very small but it still furthers the lengthening of the Lat. In the case of the practitioner, note that they are holding their up-table arm directly onto their body while this maneuver is performed. This allows the weight of the patient to be borne more by the trunk and lower body of the practitioner and therefore with less muscular effort. The down table arm is straight and “locked” in that position. This is essential for when the practitioner pushes into the patient’s ilium with their arm (protracts the Scapula). The practitioner will then twist their body around a vertical axis as the picture indicates, which adds to the downward pressure into the ilium as well as an upward pull on the arm.
This method employed by the practitioner emphasizes the Lat lengthening using the force of their body, not the muscular power of their arms. The avoidance of muscular efforts in exchange for effort generated by body weight of the practitioner is always important as muscular effort is not as easily sustainable over the course of a day as compared to leverage generated by body weight.
In addition to relaxing the Lats, Tasker states that this position can also be used to lift (side bend) the attached Thoracic and Lumbar Vertebrae with the 4 lower ribs.
As always, the effectiveness of this method depends on the knowledge, skill, and willingness to practice of the practitioner.