Hand and Wrist: What to Know

Medically Reviewed by Jabeen Begum, MD on October 04, 2022
4 min read

Your hand and wrist are some of the most important structures in your body, allowing you to physically interact with your surroundings. Unfortunately, they are also prone to injuries and other conditions ranging from fractures to tendonitis. 

You can prevent some of these conditions by understanding the anatomy of the hands and wrists and keeping them healthy. Here’s what you need to know.

The hand and wrist are complex structures located at the end of your arms that allow you to interact precisely with your physical surroundings. There are a total of 27 hand and wrist bones — 19 in the hand and eight in the wrist. Together, they let you perform various complex and precise activities, such as writing and grabbing objects.

Interesting hand and wrist facts:

  • Only about 10% of people in the world are left-handed. Left-handedness means that they are more precise with the left hand and tend to use it for complex motions such as sewing. Although handedness is mostly determined by the brain’s structure, many societies have tried to “cure” those with left-handed tendencies.
  • Between both your hands and wrists, you have approximately 54 bones. Surprisingly, this makes up for more than 20% of the bones in your body.

The complex structure of the hands allows a wide range of movements that can occur together or separately. Experts consider that the hand to have two main movements: the power grip and the precision grip. The first is more suitable for heavy objects that require more strength and less subtlety. Meanwhile, a precise grip is used on small, light objects such as a pen.

The individual movements of the hand consist of contracting, extending, and bending the fingers, moving them horizontally, and closing and opening the palm. The thumb has some more independence of movement, though, as it is capable of greater forward and backward movement.

The wrist lets you flex and extend your hands, along with some small range of sideways motion. However, this range of movements isn’t as extensive or complex as the ones that the fingers are capable of.

While hand and wrist anatomy is complex, it can be broken down into the following sections:

Carpus (wrist bones). The wrist joint begins at the end of two of your forearm bones: the radius and the ulna. There, two rows of four bones each form the rest of the wrist — these bones are separated from the ulna by a cartilage disk.

Metacarpus. The metacarpus comes after the rows of carpus bones and consists of five long bones that run from the wrist to your fingers. The one corresponding to the thumb is particularly flexible thanks to an extra structure called the basal joint. 

Fingers. The fingers are made up of three bones with the exception of the thumb, which only has two. Each of these bones, called phalanges, is connected by three joints that enable flexibility and bending.

Muscles. The hand and wrist muscles that allow finger contractions are found between the individual metacarpal bones. Two such groups of muscles are dedicated to moving the thumb and little finger. However, most hand and wrist movements start in the forearm and not in the hands themselves.

Ligaments and tendons. The hand and wrist ligaments and tendons connect most bones and muscles individually. They provide structure and stability to the bones while also granting the flexibility needed for complex and precise movements. 

Hand and wrist injuries are most common among athletes — however, they can affect everyone, even if no trauma is involved. While pain is the most obvious sign, the following symptoms may also appear after an injury:

  • Swelling
  • Bruising
  • Numbness that affects the impacted area or the fingers
  • Weakness when applying pressure
  • Restricted mobility

Some injuries such as fractures may even be visible to the untrained eye. If you find that a bone or a muscle is visibly out of place, or you find yourself in a lot of pain, make sure to check with your medical provider as soon as possible.

Because they are complex structures, the hand and wrist are often subject to many problems ranging from fractures to arthritis. Here are some of the conditions that can affect the hand and wrist tendons, ligaments, muscles, and bones:

Arthritis. Arthritis is a condition that causes joint inflammation in one or more areas of the hand and wrist. Osteoarthritis is the most common form of arthritis, usually affecting older people or athletes who have sustained an injury.

Carpal tunnel syndrome. Carpal tunnel refers to the compression of one of the primary nerves that go through the wrist. Usually, this causes trouble gripping objects, pain, general numbness, and swelling of the fingers.

Tendonitis. Tendonitis is the inflammation of one or more tendons in the hand and wrist. This irritation causes symptoms such as swelling, pain, and discomfort. Surgery may be required in severe cases where the irritation leads to a tendon rupture.

Fractures and sprains. Sprains and fractures are some of the most common injuries that affect the hand and wrist. Sprains refer to excessive stretching that leads to ligaments being overstrained. Fractures involve the actual cracking or breaking of one of the bones.

The hand and wrist are constantly exposed to overworking and trauma. However, there are some things you can do to improve your overall hand and wrist health. This will not only help to prevent related conditions but also strengthen your grip.