Sesamoid bones are small ossified nodes embedded in the tendons to provide extra leverage and reduce pressure on the underlying tissue. Many exist around the palm at the bases of the digits; the exact number varies between different people. The articulation of the human hand is more complex and delicate than that of comparable organs in any other animal. Without this extra articulation, we would not be able to operate a wide variety of tools and devices, nor achieve the wide variety of possible hand gestures.
While hand and wrist injuries are very common, some athletes never seek treatment. Unfortunately, delaying the diagnosis and treatment may result in long-term problems or even a permanent disability. Here is a list of some of the most common injuries athletes experience. Wrist The wrist joint is the complex joint formed between the distal ends furthest from the body of the Radius and Ulna two forearm bones and the carpal bones. Bones and Articulation The Ulna is the larger of the two forearm bones, although it tapers at the wrist end, to become narrower than the Radius at this point.
Altogether there are 8 carpal bone which are arranged in two rows, proximal and distal Lunate Triquetrum Pisiform Capitate Trapezium Trapezoid Hamate Scaphoid The scaphoid bone crosses both rows as it is the largest carpal bone.
Share this page. Hand and Finger Bones The technical names for hand bones and finger bones are the metacarpals and phalanges. Finger Metacarpals The metacarpals of the fingers make up the bone structure of most of the hand. Proximal Phalanges The proximal phalanx of the fingers is the proximal, or first bone, in the fingers when counting from the hand to the tip of the finger. There are three phalanges in each finger. Middle Phalanges The middle phalanx of the finger is the middle or second of the three bones in each finger when counting from the hand to the tip of the finger.
Distal Phalanges The distal phalanx of the finger is the distal or third of the three bones in each finger when counting from the hand to the tip of the finger. The distal phalanx has a joint just with the middle phalanx. The distal phalanx is also important for supporting the fingernail.
Thumb Metacarpal The thumb metacarpal is similar in shape to the metacarpals of the fingers, but it is thicker. The thumb metacarpal has significantly more motion than the other metacarpals. It makes a joint with the trapezium that allows much of the thumb motion.
This joint allows the thumb to move in a way that allows pinching. It then becomes a tendon, crosses the wrist, and attaches at the pisiform bone at the base of the palm. This large muscle is built for power, bending and deviating the wrist away from the thumb.
Arising from the outside of the elbow is the brachioradialis BR. The BR inserts into the end of the radius bone, just below the wrist joint the distal radius , in line with the thumb. The forearm is in neutral position when the thumb is up, small finger towards the ground. In this position, the BR is a pure flexor of the elbow. If the palm is facing towards the ground, the BR can twist the forearm until the thumb is in the up position again neutral. When the palm is facing up, the BR twists the forearm back to the neutral position.
The flexor carpi radialis arises adjacent to the pronator teres an elbow muscle , crosses the elbow and wrist, and attaches to the base of the second hand bone. Its primary role is to bend the wrist, and it can help to move the wrist towards the thumb. At the wrist, the FCR tendon passes through a tunnel and is prone to tendonitis or even rupturing.
Fortunately, we can live without the function of the FCR; therefore it is a commonly used tendon for reconstruction or as a tendon transfer. Next to the FCR arises the palmaris longus muscle.
This muscle, with a long tendon, travels down the forearm to the center of the wrist and palm, where it attaches to the palmar aponeurosis a fibrous tissue layer between the thenar and hypothenar muscles.
It functions as a flexor of the wrist, and like the FCR is expendable. When present, it is frequently used as a source for tendon graft, where it is removed and used to rebuild a ligament or more important tendon. It is also a commonly used tendon transfer. The main action of this muscle is to straighten the thumb at its middle joint. The extensor pollicis longus attaches at the thumb and acts primarily to straighten the tip of the thumb.
Tendonitis of the EPL is unusual, however it is prone to rupture in its compartment. Most typically, this originates from non-displaced wrist fractures breaks or inflammatory arthritis. The extensor carpi radialis brevis arises just above the elbow. It crosses both the elbow and wrist joints before inserting onto the third hand bone. Its main function is to straighten the wrist and stabilize the wrist during power grasp. This is known as intersection syndrome. The ECRB is also often partially responsible for pain on the outside of the elbow, also known as tennis elbow or lateral epicondylitis.
When the origin of the ECRB is damaged from overuse, aging, or injury, the pain of tennis elbow occurs. Fortunately, this condition is usually self-limiting.
The extensor carpi radialis longus arises just above the ECRB muscle on the outside of the elbow and attaches to the 2nd hand bone. Along with the ECRB, its primary function is to straighten and stabilize the wrist.
It also pulls the wrist into radial deviation. This is the first part of the motion required to throw a dart, as the wrist cocks back.
The last 6th of the dorsal compartments houses the extensor carpi ulnaris tendon. Arising from the lateral epicondyle, an elbow bone, it attaches to the 5th hand bone after passing over the ulna bone. Its primary function is to straighten and stabilize the wrist, and it also provides the ability to move the wrist away from the thumb. When the subsheath ruptures, the ECU tendon will snap around the ulna in certain wrist positions causing pain.
The extensor digitorum communis provides the ability to straighten the index, middle, ring, and small fingers. It separates into four separate tendons.
The extensor indicis proprius attaches to the extensor expansion over the MCP joint of the index finger at the knuckle. It provides us the ability to independently straighten the index finger, as it has no juncture connecting it to other extensor tendons.
Supination of the forearm is the act of twisting the forearm into the palm up position. The supinator is located just below the elbow. The supinator provides about one half the power of the biceps muscle for supination. The supinator is also important as a location where the radial nerve can be entrapped. The radial nerve divides just prior to the supinator with the branch supplying muscles travelling through the supinator muscle between its two heads. The nerve can be pinched either at the entrance or exit point of the muscle, causing forearm pain or weakness of finger and thumb muscles.
The pronator quadratus muscle is found in the forearm just below the wrist. It has two heads, arising from the ulna and inserting onto the radius. With the pronator teres, the pronator quadratus allows us to twist our forearm into the palm-down position pronation.
The pronator quadratus is the main pronator of the forearm, especially as the elbow becomes more flexed, weakening the contribution of the pronator teres. This muscle attaches to the radius in the mid-forearm and acts to twist the forearm into the palm down position known as pronation.
It can also cause irritation or compression of the median nerve, which passes between the two heads of the muscle. Hypothenar The hypothenar muscle group is formed by three muscles: the abductor digiti minimi, the flexor digiti minimi, and the opponens digiti minimi. Thenar The thenar muscle group is found at the base of the thumb, forming the muscle bulk on the thumb side of the hand. Lumbricals 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.
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