A single human hand contains 27 joints. These joints connect 27 bones across three regions: the wrist, the palm, and the fingers. That number includes the small joints between the wrist bones, the knuckle joints, and every joint along each finger and the thumb.
Where the 27 Joints Are Located
The joints of the hand fall into distinct groups based on which bones they connect. Starting from the wrist and moving toward the fingertips, here’s how they break down.
The wrist region contains eight small bones called carpal bones, arranged in two rows of four. These bones form multiple gliding joints where their surfaces slide against each other, allowing the wrist its subtle side-to-side and front-to-back adjustments. The joints between the two rows of carpal bones and between individual bones within each row account for a significant portion of the hand’s total joint count.
Moving into the palm, five metacarpal bones fan out from the wrist toward each finger. The base of each metacarpal connects to the wrist bones at a carpometacarpal (CMC) joint, giving you five more joints. At the other end, each metacarpal meets a finger bone at a knuckle joint, known as a metacarpophalangeal (MCP) joint. That’s another five.
The fingers contain 14 small bones called phalanges. Each of the four fingers has three phalanges separated by two joints: one closer to the knuckle (the PIP joint) and one near the fingertip (the DIP joint). That gives the four fingers eight interphalangeal joints total. The thumb has only two phalanges and a single interphalangeal joint, bringing the finger joint total to nine.
Why the Thumb Is Different
The thumb stands apart from the other fingers in both structure and movement. It has one fewer bone and one fewer joint than the other digits, with just two phalanges instead of three. But what it lacks in finger joints, it makes up for at its base.
The first CMC joint, where the thumb’s metacarpal meets the trapezium bone in the wrist, is a saddle joint. Its two interlocking concave surfaces let the thumb move in ways no other finger can: forward and back, side to side, and in the circular motion that lets you touch your thumb to each fingertip. This opposition movement is what makes the human hand so effective at gripping and manipulating objects. The axes of motion at the thumb’s base are rotated 90 degrees compared to those of the other fingers, which is why the thumb naturally rests at a right angle to the palm.
Types of Joints in the Hand
Not all hand joints work the same way. The hand uses several different joint designs, each suited to the type of movement needed at that location.
- Hinge joints: The interphalangeal joints (PIP and DIP) work like door hinges, bending and straightening in one plane only. DIP joints at the fingertips flex to about 80 degrees, while PIP joints in the middle of the finger reach about 100 degrees.
- Condyloid joints: The knuckle (MCP) joints allow bending and straightening plus a limited ability to spread the fingers apart and bring them together. They flex to roughly 90 degrees and can hyperextend up to 45 degrees in some people.
- Saddle joint: The thumb’s CMC joint is the textbook example of a saddle joint in the human body, allowing the widest range of motion of any joint in the hand.
- Gliding joints: The intercarpal joints between the small wrist bones allow subtle sliding movements that contribute to overall wrist flexibility.
Sesamoid Bones and Extra Articulations
Beyond the standard 27 joints, most hands contain small seed-shaped bones called sesamoid bones embedded within tendons near certain joints. These bones reduce friction and help redirect the pull of tendons during gripping and pinching. They form their own tiny articulations with the bones beneath them, though these aren’t typically included in the standard joint count.
A meta-analysis covering over 15,000 hands found that nearly every hand (99.85%) has sesamoid bones at the thumb’s knuckle joint. About half of people also have them at the fifth finger’s knuckle joint and at the thumb’s interphalangeal joint. Around 39% of people have one at the index finger’s knuckle joint. Fewer than 1 in 1,000 hands have no sesamoid bones at all. So while the textbook answer is 27 joints, the functional reality for most people includes a few additional small articulations.
What Holds These Joints Together
With 27 joints packed into such a compact space, the hand relies on over 100 ligaments and tendons to keep everything stable and moving properly. Each knuckle joint and each interphalangeal joint is reinforced by collateral ligaments on either side, preventing the fingers from bending sideways. A thick plate of tissue on the palm side of each finger joint acts as a check against hyperextension. The 34 muscles controlling the hand are split between intrinsic muscles (small muscles within the hand itself) and extrinsic muscles (larger muscles in the forearm whose tendons thread through the wrist to pull on the fingers). This combination of so many joints, stabilizing ligaments, and layered muscle control is what gives the hand its extraordinary blend of strength and precision.