How do hands move

Carpal bones. The 8 bones that create the wrist. The 2 rows of carpal bones are connected to 2 bones of the arm--the ulna bone and the radius bone. Numerous muscles, ligaments, tendons, and sheaths can be found within the hand.

It joins the proximal and middle phalanx on the palm side of the joint and prevents backwards bending of the PIP joint hyperextension. Intrinsic muscles are small muscles that originate in the wrist and hand. They are responsible for fine motor movement of the fingers during activities such as writing or playing the piano. Extrinsic muscles originate in the forearm or elbow and control the movement of the wrist and hand.

These muscles are responsible for gross hand movements. They position the wrist and hand while the fingers perform fine motor movements. Each finger has six muscles controlling its movement: three extrinsic and three intrinsic muscles.

The index and little finger each have an extra extrinsic extensor. Tendons are soft tissues that connect muscles to bones. When muscles contract, tendons pull the bones causing the finger to move. The extrinsic muscles attach to finger bones through long tendons that extend from the forearm through the wrist.

Tendons located on the palm side help in bending the fingers and are called flexor tendons, while tendons on top of the hand help in straightening the fingers, and are called extensor tendons. Nerves of the hand carry electrical signals from the brain to the muscles in the forearm and hand, enabling movement. They also carry the senses of touch, pain and temperature back from the hands to the brain. The three main nerves of the hand and wrist are the ulnar nerve, radial nerve and median nerve.

All three nerves originate at the shoulder and travel down the arm to the hand. Hands are made up of more bones and moving parts than most other areas of the body. They do a large number of tasks.

Hands do everything from very delicate movements to feats of strength. Was this helpful? Yes No Tell us more. Check all that apply. Wrong topic—not what I was looking for. It was hard to understand. It is comprised of three muscles: the abductor pollicis brevis, the flexor pollicis brevis, and the opponens pollicis.

The abductor pollicis brevis pulls the thumb away from the index finger, and the flexor pollicis brevis bends the thumb toward the small finger. The opponens pollicis performs one of the most important functions of the human hand: the ability to bring the thumb away from the fingers so that we can grasp objects. This fundamental function of the human hand is lost in severe carpal tunnel syndrome when the median nerve is damaged.

The main role of the lumbrical muscles is to allow the fingers to straighten, although they can also help bend the MCP joints, which are at the knuckle. The name of this muscle is derived from the Greek word for earthworm. It helps fill the first webspace between the thumb and index finger and weakens with severe cubital tunnel syndrome or other lesions of the ulnar nerve. The abductor pollicis longus passes through the 1st dorsal compartment of the wrist. The biceps is named for its two heads — short and long.

The biceps is the main supinator of the forearm which helps us rotate the palm up and down , and helps the brachialis and brachioradialis in bending the elbow. The biceps is prone to injury, particularly the tendon of the long head and the distal tendon which inserts into the radius. Fortunately, after the initial pain goes away, there is little loss of strength due to the continued attachment of the short head.

The brachialis is a large, deep muscle in the front of the arm. It lies beneath the biceps muscle and attaches onto the coronoid process of the ulna, just below the elbow joint. The brachialis is a strong flexor of the elbow allowing it to bend. The three-headed triceps muscle is the only muscle in the back of the arm. The triceps provides the important action of straightening our elbow, allowing us to push up out of a chair and throw a ball.

It also stabilizes the elbow when you are forcefully supinating think turning a screwdriver , otherwise the bending action of the biceps would be unopposed, and our elbows would bend with every twist. The three heads form a joined tendon that attaches to a prominence on the outside of humerus bone deltoid tuberosity.

Each head can work independently, as well as together. When the arm is at the side, the front anterior head of the muscle moves the arm forward. The middle head moves the arm sideways, away from the body, and the back posterior head moves the arm backwards. The deltoid is active in most shoulder motions, helping to stabilize the shoulder during carrying, lifting, and even walking.

The infraspinatous also arises from the back of the scapula, but from the area below the scapular spine. Because of its position more behind the shoulder joint, it works to primarily externally rotate the arm, as when cocking the arm back to throw, or to put your hand behind your head.

It is also frequently involved in rotator cuff tears, most commonly when the supraspinatous is also torn, creating a large tear and greater loss of function. The supraspinatous is one of the four rotator cuff muscles. The rotator cuff is the group of tendons of the subscapularis, supraspinatous, infraspinatous, and teres minor which attach around the head of the humerus encircling it like a cuff.

The supraspinatous arises from the upper part of the back surface of the shoulder blade scapula above the scapular spine. It attaches to the greater tuberosity of the humerus, forming the upper border of the rotator cuff. It works to bring the arm away from the body, and to stabilize the head of the humerus into the socket of the shoulder glenoid.

Degeneration and tearing of the supraspinatous is a common cause of shoulder pain , and it is the most common rotator cuff muscle to tear from its attachment. The teres major arises from the tip at the bottom of the shoulder blade, below the teres minor. It crosses the back of the shoulder and attaches to the upper humeral shaft, below the head. Like the teres minor, it helps bring the arm into the body, but unlike the teres minor, it is an internal not external rotator of the arm.

Fortunately, the teres major is very rarely injured, but it remains an important muscle to keep strengthened for proper shoulder function. The teres minor sits just below the infraspinatous in the back of the shoulder. It originates from the outer edge of the shoulder blade, then travels up to the lowest portion of the greater tuberosity. Like the infraspinatous, its primary action is to externally rotate the shoulder, but due to its lower position, it also helps pull the arm into the body.

The subscapularis is the only rotator cuff muscle in the front of the shoulder. It arises from the front surface of the shoulder blade, and attaches to the lessor tuberosity of the humerus.