Posted on 30 Aug 2012 16:22
The biceps brachii is a two-headed muscle located on the front of the arm, and makes up the largest part of its bulk. The name biceps is derived from the Greek word bi, meaning "two" and the Latin caput, meaning "head." The name brachii is a form of the Latin and Greek words brachialis and brachion, which describe something that pertains to the arm. Thus, biceps brachii means "two headed muscle of the arm." These two heads, one shorter than the other, arise from two separate origins which, although they partially combine into one large muscle, retain somewhat their separate features, both inserting together at the elbow.1
The short head originates on the coracoid process of the scapula and the upper lip of the glenoid fossa. The long head orginates on the supraglenoid tubercle of the scapula and the posterior portion of the glenoid labrum. Both heads insert onto the tuberosity of the radius and the bicipital apaneurosis, itself inserting into the deep fascia of the ulnar aspect of the forearm.1,3The biceps brachii should be thought of as a three-joint muscle, as it not only crosses the glenohumeral and elbow joints, but also the radioulnar.4
Although the most well-known function of the biceps is as a strong elbow flexor, it is also a strong supinator of the forearm, a weak flexor of the shoulder joint, and a shoulder stabilizer (long head), assisting in maintaining the humeral head in the glenoid cavity. Also, since the short head has its origin on the coracoid process, it can also assist with adduction, as well as flexion, of the humerus.
The biceps is most effective in elbow flexion when the forearm is supinated (palm facing up). It is joined in this role primarily by the brachialis, and brachioradialis, but also the coracobrachialis, and flexor pronators. For supination, it is most effective when the elbow is flexed. As the forearm pronates (palms facing away) the biceps becomes less effective due to the rotation of the radius making its pull less advantages.1,3
Barbell or dumbbell curling, pullups, lat pulldowns and any climbing movements all work the biceps brachii. During the curling movement, the origin is fixed, so that the muscle moves the forearm toward the humerus. During the pullup, the insertion is fixed, so that the muscle moves the humerus toward the forearm. The biceps is an important stabilizer while carrying any heavy object at waist level, such as a suitcase, and without it, the shoulder would be pulled apart.
Avoid carrying objects in this position with
biceps trigger points. Turn palm inward instead.
It is also active in the throwing action, both as an elbow flexor during late cocking and a forearm decelerator during follow-through. As well, it is thought to be an important stabilizer during throwing motions. During shoulder abduction in the scapular plane, the long head of the biceps may act as a stabilizer, although its precise role as a stabilizer is a subject of controversy.2,4
Biceps Brachii Origin, Insertion, and Actions
- Short head: Apex of coracoid process of the scapula in the conjoined tendon of the coracobrachialis and the upper lip of the glenoid fossa.
- Long head: Supraglenoid tubercle of the scapula and posterior portion of the glenoid labrum, above the superior lip of the glenoid fossa.
Actions: Elbow flexion with stronger action during supination, assisting abduction of the shoulder when the arm is externally rotated, weak shoulder flexion when the arm is internally rotated, supination of the forearm when the elbow is not fully extended. The long head provides stabilization of the shoulder, keeping the head of the humerus in the glenoid fossa when a heavy weight is carried at the waist.4,3
image by robswatski via flickr
Biceps Brachii Trigger Points Causes and Symptoms
Various daily lifting activities can overload the biceps brachii muscle, leading to trigger points. These include lifting heavy objects with the palm up, and weight lifting or other exercises that utilize the biceps. Repeated supination under load, such as turning a screwdriver, can also aggravate the muscle. Violin playing may cause a strain, due to the biceps of the arm supporting the instrument needed to be continuously contracted, usually the left. The biceps can also be overloaded during hard tennis serves or throwing activities. Over-exertion from shoveling snow may also aggravate the muscle.
Trigger points in the biceps may also start because of pain referred from TrP's in the infraspinatus or subclavius muscles. The TrP's themselves tend to occur in the middle portion of the muscle and pain is projected primarily upwards.
The chief pain symptom of biceps brachii trigger points is pain or aching in the front of the shoulder, which is superficial and not deep to joint itself. The tenderness in these areas may be mistaken for bicipital tendinitis or subdeltoid bursitis. Additional pain may be felt in the crook of the elbow.
Sometimes pain may skip to the suprascapular region. There does not tend to be pain referred to the biceps muscle itself.5
Biceps Brachii Trigger Points and Referred Pain Patterns
Biceps Trigger Points Self Treatment
Focus massage on the area of trigger points in the mid portion of the muscle, which can be found in either head. Use the knuckles or thumb of the opposite hand and rake deeply. A knobble massage tool may also be used. See the Trigger Point Therapy Workbook for information on other muscles that cause pain in these areas. Secondary trigger points may develop in the brachialis and supinator muscles as well as the triceps. Later, the anterior deltoid, supraspinatus, and upper trapezius muscles may develop TrP's.
During periods of active biceps brachii trigger points, remember to carry heavy objects with the hand pronated to take some of the stress off the muscle, and avoid prolonged heavy carrying and other aggravating activities.5
Self Stretch of the Biceps Brachii using Doorway
After you have successfully treated the biceps trigger points, use a passive stretch on a daily basis. To stretch the biceps, the arm must be extended behind the back and the thumb facing down. Stand in a doorway and reach your hand up to your side and grab onto the doorjamb with your thumb facing the floor. Lean forward slightly and slowly rotate your body away from the doorjamb so that a stretch is felt in the biceps muscle. Stretch the muscle gently and slowly, without jerking for a few seconds, then relax for a few moments before repeating the stretch for a total of six repetitions.5
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This page created 30 Aug 2012 16:22
Last updated 23 Feb 2015 19:33