Hand and Finger Bones
The technical names for hand bones and finger bones are the metacarpals and phalanges.
The metacarpals of the fingers make up the bone structure of most of the hand.
They are all similar in shape and have joints in the wrist on one end, and the finger at the other end.
The index and middle finger metacarpals have very little motion, while the metacarpals of the ring and little finger move much more.
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.
The proximal phalanx is the largest of the three bones in each finger; it has joints with the metacarpal and with the middle phalanx.
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.
The middle phalanx has joints with the proximal phalanx and with the distal phalanx of the finger.
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.
On the tip of the phalanx is a bulbous tuft of bone that helps give the finger its rounded appearance.
The distal phalanx is also important for supporting the fingernail.
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.
This is largely due to the unusual shape of the base of the metacarpal and the trapezium.
The head of the metacarpal has a large joint surface next to the thumb proximal phalanx.
The thumb sesamoids are two small round bones at about the level of the thumb metacarpophalangeal joint.
These bones, as with all sesamoid bones, lie within tendons.
The flexor pollicis brevis tendon and the adductor pollicis attach to the thumb sesamoids.
Sesamoid bones help change the line of pull for their tendons which can help increase the force of tendon pull across the joint.
Thumb Proximal Phalanx
The thumb proximal phalanx is a short and stout bone between the metacarpal and distal phalanx.
There is no middle phalanx in the thumb.
Thumb Distal Phalanx
The thumb distal phalanx is a short bone with a rounded tuft at the end that makes a joint with the proximal phalanx.
The bulbous tuft at the end of the bone gives the thumb its rounded end.
This bone supports the thumb nail.
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