Function Biceps

the biceps works across 3 joints. important of these functions supinate forearm , flex elbow. in more detail, actions are, joint:

proximal radioulnar joint (upper forearm) – contrary popular belief, biceps brachii not powerful flexor of forearm, role belongs deeper brachialis muscle. biceps brachii functions powerful supinator of forearm (turns palm upwards). action, aided supinator muscle, requires elbow @ least partially flexed. if elbow, or humeroulnar joint, extended, supination carried out supinator muscle. biceps particularly powerful supinator of forearm due distal attachment of muscle @ radial tuberosity, on opposite side of bone supinator muscle. when flexed, biceps pulls radius neutral supinated position in concert supinator muscle.
elbow (humeroulnar joint) – biceps brachii functions important flexor of forearm, particularly when forearm supinated. functionally, action performed when lifting object, such bag of groceries or when performing biceps curl. when forearm in pronation (the palm faces ground), brachialis, brachioradialis, , supinator function flex forearm, minimal contribution biceps brachii. important note regardless of forearm position, (supinated, pronated, or neutral,) force exerted biceps brachii remains same; however, brachioradialis has greater change in exertion depending on position biceps during concentric contractions. is, biceps can exert force, , forearm position changes, other muscles must compensate.
shoulder (glenohumeral joint) (shoulder) – several weaker functions occur @ glenohumeral, or shoulder, joint. biceps brachii weakly assists in forward flexion of shoulder joint (bringing arm forward , upwards). may contribute abduction (bringing arm out side) when arm externally (or laterally) rotated. short head of biceps brachii assists horizontal adduction (bringing arm across body) when arm internally (or medially) rotated. finally, short head of biceps brachii, due attachment scapula (or shoulder blade), assists stabilization of shoulder joint when heavy weight carried in arm. tendon of long head of biceps assists in holding head of humerus in glenoid cavity.




^ biceps brachii . exrx.net. retrieved 16 january 2017. 
^ simons david g.; travell janet g.; simons lois s. (1999). 30: biceps brachii muscle . in eric johnson. travell & simons myofascial pain , dysfunction (2nd ed.). baltimore, maryland: williams , wilkins. pp. 648–659. isbn 0-683-08363-5. 
^ saladin, kenneth (2015). anatomy , physiology: unity of form , function. mcgraw-hill education, 2 penn plaza, new york, ny 10121: mcgraw-hill education. pp. 346–347. isbn 978-0-07-340371-7. 
^ cite error: named reference bogart2007 invoked never defined (see page).
^ kleiber, tim; kunz, leo; disselhorst-klug, catherine (2015-01-01). muscular coordination of biceps brachii , brachioradialis in elbow flexion respect hand position . integrative physiology. 6: 215. doi:10.3389/fphys.2015.00215. pmc 4526813 . pmid 26300781. 
^ saladin, kenneth (2015). anatomy , physiology: unity of form , function. mcgraw-hill education, 2 penn plaza, new york ny 10121: mcgraw-hill education. p. 295. isbn 978-0-07-340371-7.