Motions of the Elbow Joint

As a free-moving synovial joint, the elbow glides and pivots easily in its encased socket. The humerus of the upper arm and the ulna and radius of the forearm articulate to create the elbow joint. These bones form three pivot joints encased in one united capsule. Allowing shortened and lengthened arm movements, the elbow permits rotation of the forearm. The elbow participates in intricate hand motions and increases power to the upper body.

Extension and Flexion

• Straightening and bending the forearm, the elbow joint moves in synovial fluid within the capsule. The elbow is an extension of the shoulder joint. It allows smooth, controlled motion. The elbow joins the wrist and shoulder joints to allow complex movements of the shoulder girdle down to the fingertips, according to Dr. Huei-Ming Chai of National Taiwan University. Using the elbow to direct the wrist and hand to pick an apple, this complex motion involves extending or reaching for the fruit. It also requires bending or flexing the elbow and wrist to pick up the apple and put it in a basket. This basic act utilizes the triceps, biceps, forearm, wrist and hand muscles.

Supination and Pronation

• Rotating the forearm outward and upward is supination, while rotating the forearm inward and downward is pronation. These rotating actions allow the shoulder girdle, the upper and lower arms, and the wrist and hands free and smooth movements, as noted by Dr. John McNulty of Loyola University. Motions completed with precise control allow you to hold and eat a bowl of soup, play sports, type on a computer, drink a beer with friends, or detail a miniature painted figurine. Fluid motions permit immediate suspension and stability of muscles and joints. This balance is so precise that a person can stumble down a few stairs while holding a hot cup of coffee and not spill a single drop.

Supinated Flexion

• Shaking hands requires flexion of the elbow as well as supination and flexion of the hand and wrist.

  The gliding and pivoting elbow joint gathers its strength and balance from ligaments, tendons, muscles and bone articulation that work in unison, according to creators of MedCharts Anatomy, Gest & Schlesinge. Developed for use at The University of Michigan Medical School in collaboration with Dr. Pat Tank, these MedCharts show the upper arm bent at the elbow joint and the forearm, wrist and hand rolled outward and upward in flexed supination. Shaking hands, playing tennis, volleying a ball, gently lifting a baby, or boosting an object above the head might be impossible tasks without the benefit of flexion and supination.

Pronated Flexion

• Since the shoulder, elbow and wrist provide support to the entire shoulder girdle, the elbow can lift weights in excess of a person's own body weight. Muscles that attach to these joints work in synergy and resistance to each other and create a perfect fulcrum, as noted by Dr. Jill Owen of Eastern Illinois University. This pronated flexion allows the forearm to roll inward and downward and the elbow to bend and straighten. These fluid motions allow a person to dribble a basketball, type on a computer, and loosen the clasp of a snagged piece of jewelry without damaging it.