Lesson 11: Biceps Brachii, Brachialis, Triceps Brachii, Brachioradialis and Coracobrachialis

This course describes the location, actions, and functions of the arm muscles, including the biceps brachii, brachialis, triceps brachii, brachioradialis, and coracobrachialis. These muscles contribute to motion of the shoulder joint (glenohumeral joint), elbow joint (humeroulnar joint), and the radioulnar joint.

Examples include:

• Muscles in the anterior compartment of the upper arm with attachment to the scapula (shoulder blade) may contribute to shoulder flexion (coracobrachialis and biceps brachii), and anterior compartment muscles attaching to the radius and ulna contribute to elbow flexion (biceps brachii, brachialis and brachioradialis).
• The posterior compartment muscles of the upper arm with attachment to the scapula (shoulder blade) contribute to shoulder extension (long head of the triceps), and posterior compartment muscles with attachment to the olecranon process contribute to elbow extension (triceps brachii).
• Interestingly, two anterior compartment muscles of the upper limb contribute to radioulnar supination (biceps brachii and brachioradialis); however, the posterior compartment muscles of the upper limb (triceps brachii) cannot contribute to supination or pronation. Note, none of these muscles have an influence on the wrist.

Knowing these facts may help build strong arms by avoiding wasted time performing less effective arm exercises. For example, changing hand position does not affect which head of the triceps brachii is emphasized because the triceps brachii cannot contribute to supination or pronation and does not cross the wrist.

Sports medicine professionals (personal trainers, fitness instructors, physical therapists, massage therapists, chiropractors, occupational therapists, athletic trainers, etc.) must be aware of these muscles for detailed analysis of human movement, and the development of sophisticated exercise programs and therapeutic (rehabilitation) interventions. Further, this course is essential knowledge for future courses discussing detailed anatomy like neural innervations (e.g. the musculocutaneous nerve, radial nerve, etc.), synergistic function with other muscles of the shoulder, elbow, and scapula (e.g. long head of the triceps as a shoulder extensor), role in injury (e.g. elbow ligament injuries, elbow ligament pain, hypertonic muscle fibers, shoulder impingement syndrome, biceps tendon tear or rupture – you don’t always need surgery), and sports performance (e.g. best arm exercises for bodybuilders and strength athletes with the goal of increasing muscle strength or muscle growth).

For more advanced anatomy check out our integrated functional anatomy courses:

• Coracobrachialis

Caption: The biceps brachii muscle (long head and short head)