Muscle Monday: Lats (LATISSIMUS DORSI)
The latissimus dorsi or lat is a big and strong muscle of the back that climbers love to use. Best worked out with the overhand pull-up, the lats help pull your arms back and down to your side. It is the only muscle connecting your arm to your spine!
The latissimus dorsi has a broad attachment from the back of your pelvis, lower back and ribs, and mid spine all the way up to the top of your humerus bone (upper arm). Along with bringing your arm back and down to the side, it also helps rotate your arm in towards the center of your body (if you have your arm down at your side and you turn your arm inwards to have your watch face against your hip). Its actions are dependent on the fixation of the arm or pelvis. For example, if your arm stays still, the lats can lift the pelvis. Conversely if your pelvis stays still, the lats move your arms, such as when doing lat pull downs at the gym.
The latissimus dorsi is easy to see in most people as it is a superficial muscle that sits just below your skin and defines the lower half of your back. Having problems with this muscle can mean a big decrease in daily functions and lead to overuse issues of other muscles. For instance, a climber’s arms will quickly fatigue if they do not appropriately engage their lats when climbing. When you look at the pure size of the muscles that help with climbing (lats, biceps, triceps, shoulder muscles, etc.) you can see how quickly these smaller muscles might fatigue if they are doing the majority of the work, when really the powerful latissimus dorsi should be doing the bulk of the heavy work.
Another issue we see often with the lats is tightness or trigger points in the muscle which can limit the range of motion the shoulder joint can perform – especially for reaching overhead. This can really pose an issue for people who do overhead lifting or repetitive reaching activities. The reason for this is due to the attachment of the latissimus dorsi on the humerus bone. The joint where your humerus (ball) sits into your shoulder blade (socket) is called the glenohumeral joint (G-H joint). The G-H joint is all about a delicate balance of stability and mobility. The lats work with the rotator cuff muscles as well as other muscles of the shoulder to help maintain the delicate balance of muscles controlling the G-H joint. Because of their involvement with shoulder motion, having weakness or tightness of the lats can make using your arm a real challenge. Pain and loss of function would be just the beginning of issues you would notice, eventually that skewed balance would damage other parts of the rotator cuff and shoulder.
What type of person do we typically see having problems with this muscle?
· Rock climbers
· Bodybuilders/ weight-lifters
· People performing pull-ups
Over-use or improper body mechanics can agitate or damage and/or impair the latissimus dorsi. Issues experienced with the lats could include but are not limited to spasms, knots, paralysis, tightness, weakness, atrophy and pain.
How will you know the best way to fix your latissimus dorsi issue?
To identify the true cause of your latissimus issue, you really need a full assessment of all of the muscles of your upper extremity and trunk and someone to analyze your movement patterns. At Nashville Physical Therapy we have specialists who can perform a Total Body Wellness Assessment and/or Movement Analysis in which we can identify any weak muscles, tight muscles, joint restrictions and movement pattern issues and then provide the specific exercises needed to address the true cause of your pain.
Other facts about the latissimus dorsi:
· It is supplied by the thoracodorsal nerve from the spinal level C6-8. It is the only muscle innervated by this nerve.
· The latissimus dorsi also helps with breathing by assisting you in forcing a breath out and breathing in deeply. This is due to its attachment to the ribs.
· A well-developed latissimus dorsi can create the aesthetic of a wider back. A lot of professional bodybuilders will have the “cobra head” look when they lift their arms up and flex.
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