Supraspinatus

By, Sean Light CSCS

SLStrength.com

Continuing with the rotator cuff, today we look at the supraspinatus. Because it’s a member of the four muscle rotator cuff club, this means that it plays a big role in shoulder stability. It is the superior most muscle of the RC. It also contributes, along with the deltoid, in abducting the arm, which is just raising your arm out to the side. The first twenty degrees of abduction is when the suprasinatus is most involved.

Origin: Supraspinous Fossa of the Scapula which is just superior to the scapular spine.

Insertion: Greater Tubercle of Humerus

SOURCE: Hosford DPT, Darryl, “Shoulder Girdle Musculature,” http://www.PTCentral.com/muscles

Subscapularis

By, Sean Light CSCS

SLStrength.com

The subscapularis is the only muscle of the four rotator cuff muscles on the anterior side of the scapula. Along with basic stabilization of the glenohumeral joint, it also has a large role in internally rotating the arm.

For more information on general movements of the shoulder, read my article on the BIOMECHANICS OF BASEBALL PITCHING.

The subscapularis originates on the subscapular fossa, which is a small cavity on the anterior lateral portion of the scapula.

Contracting towards the origin is the point of insertion at the lesser tubercle of the humerus located just inferior to the humeral head.

It’s important to understand that the muscles of the rotator cuff will insert on the top of the humerus and pull the humerus medially thus stabilizing the shoulder.

SOURCE: Hosford DPT, Darryl, “Shoulder Girdle Musculature,” http://www.PTCentral.com/muscles

Shoulder Sulcus Sign

By, Sean Light CSCS

SLStrength.com

Shoulder sulcus is a sign of laxity in your shoulder. This video explains how to test for a shoulder sulcus sign.

If the sulcus sign is positive, meaning the the glenohumeral joint (shoulder joint) is indeed loose, you will be able to see an indentation form on their shoulder when performing this test.

From an injury standpoint, this laxity will certainly put you at greater risk of injury. This sulcus sign could be a result of previous injury or gradual wear and tear but it is important to tighten up the ligaments to decrease the laxity. The shoulder already has enough trouble stabalizing with a shallow fossa (socket) and large range of motion.

From a baseball standpoint, increased shoulder laxity can improve your throwing velocity but at the cost of higher injury risk. You can’t throw if you are not on the field so it is more important to tighten up that joint for a more efficient and less dangerous range of motion.

If your shoulder is demonstrating a positive sulcus sign there are some exercises you can do to help. Simple internal (keep your elbow tight to your body) and external rotation exercises, flexion exercises (pushups, front raises), rows, lat pull-downs and scapular mobility exercises.

For a reminder on basic shoulder movement patters, check out my article on the Biomechanics of Baseball Pitching.

SOURCES:

Sawyer PT, Chris, “Rehab of the Unstable Shoulder,” http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CEwQFjAA&url=http%3A%2F%2Fwww.childrensmercy.org%2FContent%2FuploadedFiles%2FDepartments%2FGraduate_Medical_Education%2FCME%2FRehabilitation%2520of%2520the%2520Unstable%2520Shoulder.pptx&ei=lBb3T4KGKcnc0QGlhOX4Bg&usg=AFQjCNG7Szx801P5CS2vNPjbP7-5vL2u6g&sig2=bMJSuLEGBc9zFB3uB2UEmg

“All About Shoulder Dislocation,” http://www.ori.org.au/bonejoint/shoulder/diagnosis.htm

“Sulcus Sign,” http://videos.rehabstudents.com/sulcus-sign/

Preventing Injury with Yoga

By, Sean Light CSCS

SLStrength.com

Pick up a dumbbell, start with your arms fully extended and attempt a bicep curl. Now, instead of starting with your arms extended, start the arm at a ninety degree angle. The curl is certainly easier when starting with the modified start position. This is because at the end of any given range of motion, the muscle is at its weakest.

In order for a muscle to contract, myofilaments called actin and myosin must connect using cross-bridges within the part of the muscle called the sarcomere. When the muscle is fully contracted, the actin and myosin are too close together to get a maximal amount of connections. Conversely, at the end range of motion, the myofilaments are too far apart to achieve maximal connections. Thus, somewhere in between end range of motion and full contraction is the range for the most cross-bridge connections.

One of the most common ranges for injury to occur is at the end range of motion. In order to better prevent athletes from finding themselves on the disabled list, it’s important to increase strength and the end range of motion.

Traditional weight lifting, assuming proper form is used, strengthens throughout an entire range of motion. Isometric exercises pinpoint one area of the range of motion to strengthen.

Isometric exercises are holds. The athlete locks into one position and holds the position for a given amount of time. Examples are pushup holds, wall sits and pull up holds.

If the strength and conditioning coach properly selects the isometric exercises, he or she can increase the athlete’s strength at the end range of motion and decrease the athlete’s risk of injury at that particular range.

Yoga revolves around “poses,” or positions held for a given period of time. Sound familiar? These poses are isometric exercises. Instituting yoga poses into strength and conditioning program is a great way to help athletes avoid the disabled list.

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