Where the radius bone meets the wrist are two rows of small round bones—four in each row—known as carpal bones:. Together, the eight carpal bones are called the carpus.
The distal carpals form five joints with the hand bones. The hand bones are called metacarpal bones. Metacarpals are long bones that connect the distal carpals to the fingers and thumb.
There are several sets of joints in and around the wrist. These joints vary in type and have different motions. Most wrist fractures are the result of a break in the radius bone at the radiocarpal joint—known as a distal radius fracture.
The scaphoid is the second-most commonly fractured wrist bone. This action involves bending the wrist backward and toward the thumb, and then forward and toward the little finger. Common everyday activities that involve this motion are hammering a nail, throwing a ball, drinking from a glass, pouring from a jug, and closing the lid of a jar. On average, the wrist bends at an angle of 30 to 35 degrees backward during extension and 5 to 10 degrees forward during flexion in everyday wrist movements.
The wrist also contains several soft tissues, such as ligaments, tendons, nerves, and blood vessels. It is a complex formation of joints that connects to the ulna and radius of the forearm as well as the five metacarpal bones of the phalanges. Sometimes, physicians may have to surgically intervene in this complex structure with minimally invasive options such as wrist arthroscopy. The wrist serves as a transfer of force from the arm to the hand.
Without the wrist, our hands would neither be flexible nor strong. These details are made possible through the convergence of bones, joints, tendons, ligaments, nerves, and blood vessels. The eight bones that make up carpus are each called the trapezium, trapezoid, capitate, hamate, pisiform, triquetrum, lunate, and the scaphoid.
The unique cluster of small bones in different shapes and sizes is what gives the wrist its strength and flexibility. If your hand were made up of 3 or 4 larger bones, your hand and wrist would not work the same. The two long bones in the forearm running from the elbow to the wrist are your ulna and your radius. You may notice in reference to the picture that the ulna does not directly form a joint with the wrist bones, whereas the radius does.
The end of the ulna bone, closest to the littlest finger, is covered by a piece of cartilage that acts as a cushion between the wrist and the forearm bones. The radius bone, closest to the thumb, meets with the lunate and the scaphoid bones directly, which are considered part of the proximal carpals.
The row of carpal bones closest to the forearm is known as proximal carpals while the row of carpal bones closer to the fingers are known as distal carpals. The distal carpals meet with the hand bones, or the the metacarpal bones, and form five joints that make up our fingers. Metacarpals are the long bones connected to the distal carpals, which forms the fingers and thumb. Constant use and movement of these bones may cause issues such as arthritis or even carpal tunnel syndrome.
According to our fellowship trained hand and wrist surgeon, Dr. While there are a few joints inside the wrist, and these joints vary in the type and each support separate motions. Wrist fractures commonly occur on the joint surfaces. The radiocarpal joint is the largest and main joint in the wrist that is also known as a condyloid joint , which allows combined motions in multiple planes.
The distal radioulnar joint is located between the radius and the ulna and is one of two joints between the forearm bones. Flexor carpi ulnaris: This is the other tendon that bends the wrist. It attaches to the pisiform, another wrist bone, and to the 5th hand bone. For those who do have it, it can vary in size.
It is, however, a tendon you can live without because it has very little function in the hand and wrist. This tendon is often used to repair other tendons since it serves such a small purpose. Extensor carpi radialis brevis: This is one of 3 tendons along with the next two on this list that work together to bend back the wrist.
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