The Teres minor muscle is on of the rotator cuff muscles. It originates on the lateral border of the scapula, and inserts on the inferior facet of the greater tubercle of the humerus. This muscle assists with external rotation of the humerus as well as shoulder stability. This muscle is often damaged with a shoulder injury. Trigger points will refer into the posterior deltoid and down the back of the arm.
The sternalis muscle is a little known muscle located at the sternum. This muscle seems to be vestigial in that it doesn’t have a known function. In originates on the superior portion of the sternum and the upper part of the pectoralis muscle. It’s insertion is the cartilage of ribs 3-7, or sometimes the sheath of the rectus abdominis, or the lower part of pectoralis major. Even though this muscle doesn’t seem to have a purpose anymore it can still harbour trigger points. These points will cause pain to be felt intensely deep in the sternum, with spillover pain radiating down the inside of the arm.
A very common muscle to become overloaded and damaged, and thus develop trigger points, is the pectoralis major muscle. This is the muscle that makes up the chest. It’s main functions are adduction and internal rotation at the shoulder. Poor rounded shoulder posture is a common cause of pec tightness and trigger points. trigger points in this muscle will produce pain felt into the front of the shoulder, the chest, and down the medial arm. If these symptoms occur in the left pec it can mimick heart pain. In women, these points can be a cause of breast pain and nipple hypersensitivity.
The subscapularis muscle is one of the rotator cuff muscles. It is located on the inside of the scapula, and can be difficult to access. This muscle functions to internally rotate the arm as well as to adduct the shoulder. It is also a stabilizer of the shoulder joint. When this muscle is overloaded or injured trigger points can form. These points will refer pain into the back of the shoulder and down the inside of the arm to the wrist. Trigger points in the subscapularis are often associated with a frozen shoulder.
The triceps muscle is the main extensor of the elbow. It is the muscle in the back part of the arm and travels from the shoulder to the elbow. Trigger points in this muscle will cause pain when trying to straighten the elbow. Tricep trigger points refer pain into both the inside and outside of the elbow and are thus a common cause of both tennis and golfers elbow.
The biceps brachii is the most well-known of the arm due to its prominence. It is the muscle we think of when we imagine someone with ‘big arms.’ Its chief role is elbow flexion, and, while it is not the only elbow flexor, its role makes it prone to
overload problems which can lead to trigger points. When trigger points form they will produce pain felt in the elbow arm and up into the front of the shoulder. Shoulder pain is usually felt as superficial as opposed to deep in the joint.