Thoracic and Lumbar Muscles of the Dog, aka The Backstrp

Full Title: Thoracic and Lumbar Muscles of the Dog, aka The Backstrap

Author: Mary Jo Nieson

Date of Publication: May 25, 2012


Research Paper Text:

The backstrap of a dog is found on the two sides of the spine. It encompasses the thirteen thoracic and seven lumbar vertebrae (T1 through L7.)

On a deer harvested by a hunter it is considered to be the most palatable cut, the tenderloin. This muscle group feels very thick, smooth and solid to touch. In fact the two sides of the backstrap look almost like the handles or ‘straps’ on a bag or a satchel. It basically hangs between the shoulder and the hip socket.

The vertebrae of the spine are held together by very thick supraspinous ligaments. Tendons attach to the periosteum ( collagenous membrane) of the bone. They are flattened here in comparison to other tendons in the body which are rounded. The similar collagen makeup allows the tendon fibers to blend with those of the periosteum. The intervertebral muscles are tiny and run from one vertebrae to the next along each side of the spinal column.

This central portion of the vertebra column acts a bridge offering support for the two sets of limbs on the dog; fore (anterior) and rear (posterior) legs. It also helps to protect the spine as well as providing an anchor for the strong muscle groups of the dog’s body.

The backstrap supports virtually every muscle in the body. The longissimus (intermediate) muscle is the longest of the backstrap, the iliocostal (lateral) and the transverospinal (medial) muscle systems are all part of the interwoven muscles that make this supportive and strong. The sublumbar muscles also affect movement allowing the trunk to be flexed or pulled tightly to the caudal.

The sympathetic nerves, part of the autonomic system are found here. They exit from the intervertebral spaces and enter a sympathetic chain of ganglia (nerve nucleus) and go on to the body from there.

Blood supply arrives to the backstrap from the oxygen rich aorta (before it divides into 2 femoral arteries serving the posterior limbs) and then returns to the heart by the caudal caval vein.

Normally the back muscles allow lateral movement or flexing of the body. One side contracts as the other side flexes. This is a unilateral contraction and flexion. Because these muscles tie to the hip, dogs with hip dysplasia and or arthritis can have a sore back. Counterpoint, if the back is sore the posterior limbs will also be weak or sore. The large abdominal oblique muscles also play a part in the lateral movement. Ribs #11 and/or 12, and 13 tie into the thoracic vertebrae. The external and internal abdominal obliques, transveroabdominus, rectus abdominus and intercostal muscles stablilize the rib cage and abdomen during movement of the dog and so also assist in back flexion. Therefore if the muscles in the thoracic area are injured or weak, breathing can also be painful as the ribs need to flex on air intake and outflow. Lateral contraction of the body will also help drain and create fluid movement as there are lymph nodes and lymph centers (lumbar and Iliosacral) in this same area of the back. As well there are lymph nodes near the lungs and along the diaphragm that would come into play with breathing and lateral movement by the dog.

If the body is restricted or weak along the muscle sides of the spine (backstrap) then all body functions in turn could well be affected. Lateral as well as forward movement of the dog would be impaired, reduced or impossible depending on the severity. Inhalation and exhalation could also be reduced, exacerbating the problem with lack of oxygen to the muscles and the rest of the body. An indication of problems in the back muscles might be shown by twitching of the muscles as well as tenderness along the back and rib cage muscles.

Fascia of the backstrap manipulated by massage is the spinotransveral f. and the thorocolumbar f. To sedate the backstrap It would be preferable to use light to light medium pressure, first of all one does not want to increase discomfort in the body with too much pressure. Techniques would begin with a muscle warm up by stroking away from the heart with effleurage for drainage. If the client is resisting touch due to discomfort the massage can also start with an ice cup massage to numb the nerve endings. Continuing on with muscle squeezing, shaking, rocking and a positional release with a light stretch of the posterior limbs would be indicated. Acupressure where knots are felt along the muscle will also be helpful, with of course light to medium touch. Finish with effleurage to drain the area again.

To stimulate this same group of muscles once again start with stroking, but towards the heart, with fast, vigorous touch up to heavy pressure. Follow with effleurage for drainage and move on to kneading, hacking, skin rolling, tapotement (raindrops), rocking, and stretching of posterior limbs.

Use whatever of these techniques the dog approves or is most comfortable with. These muscles are best worked on post exercise as they move much easier and accept more vigorous massage when warm. A warm pack (heated towel for ex.) can be used for this purpose if desired. This work can then soothe stiffness and prevent any trigger point formation. Once again finish with effleurage to drain the area.


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