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Bones of the Arm and Hand: Anatomy and Functions

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  • 0:06 Guns and Arms
  • 0:29 The Phalanges
  • 0:51 The Metacarpal Bones
  • 1:52 The Radius, Ulna and Humerus
  • 3:24 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov
The humerus isn't all that funny; it plays an important role in your body. Likewise, the radius, ulna, carpals, metacarpals and phalanges are all important components of your arm, wrist and fingers.

Guns and Arms

Bodybuilders love to work on building their biceps and triceps. While they may be devoting quite a bit of time to showing off those 'guns,' they use their entire arm and hand in the process of trying to improve their physique. Let's go over the critical skeletal aspects involved in their desire to curl the heaviest dumbbell in the gym.

The Phalanges

A diagram of the bones found in the hand
Hand Bones

When the weightlifter reaches out to grab hold of a 100lb dumbbell, he extends his fingers outward. The bones of each finger and toe are known as the phalanges (or phalanx when singular). There are three phalanges in each finger and each toe, except for the thumb and big toe, which only have two phalanges.

The Metacarpal Bones

The bones connecting to the proximal phalanx, or the phalanx closest to the palm of the weightlifter's hand, are called the metacarpal bones. These are the five bones of the hand located in between the finger and carpal bones.

The carpal bones are the eight bones that form the wrist. A cool fact is that the root 'carp-' in carpal bones means to 'gather' or pluck something away from somewhere else, which is what our wrists do! Knowing all of that, it shouldn't come as a surprise to you that the scientific name for the bony part of our wrist is known as carpus (or carpi when plural).

In fact, I'm almost positive you've heard of something called the carpal tunnel syndrome, which is when a nerve running through a tunnel partially formed by the carpal bones becomes compressed, leading to pain and numbness in the wrist area. Now you know where the 'carpal' in 'carpal tunnel syndrome' came from!

The Radius, Ulna and Humerus

The humerus is found in the upper part of the arm.
Humerus Bones

Well, our weightlifter thankfully doesn't have this painful condition. After using the phalanges of his fingers to grasp the dumbbells, the metacarpals of the hand to palm the weight and the carpal bones of the wrist to gather the weight off of the floor, the weightlifter then needs to use his arm and forearm to start doing bicep curls in order to gain muscle mass.

Each of his two forearms has two bones. One of these bones is known as the radius, which is a bone that articulates with the carpal bones, humerus and ulna. The radius runs parallel to another bone in the forearm call the ulna, which is a bone that articulates with the radius and humerus.

As I just mentioned, both the radius and ulna articulate with the humerus, which is a long bone in the arm that connects to the shoulder and the forearm. The humerus, radius and ulna combine to make up the elbow joint, which, like the knee joint, is a type of hinge joint because motion is permitted only in one plane, or axis, as opposed to ball and socket joints that allow rotation, or multi-plane motion (like your shoulder and hip joints).

The ulnar nerve is what you actually bump when you hit your funny bone.
Ulnar Funny Bone

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