Okay, you probably know that the human body has two arms. These are sometimes called your upper limbs. But, do you know the parts of your arm? What’s inside? Do you know how it connects to the rest of your body? Do you know how your arm moves to throw a ball or pick up a book? Read on to learn more about your arm and how it works.
In a more common use, the term “arm” refers to the whole upper limb, with the terms upper arm and lower arm describing the two parts. In this section we will use the more common definition of “arm” to mean the whole upper limb.
The arm consists of three large bones. The humerus bone is in the upper arm. One end connects with the scapula at the shoulder joint. The other end connects with the radius and ulna at the elbow joint. The radius and ulna bones are in the lower arm, connecting between the elbow joint and the wrist. One easy way to remember which bone is the radius and which is the ulna is that the radius connects to the thumb side of the wrist.
The upper limb consists of three movable joints. These are the shoulder, elbow and wrist. These joints allow you to raise your arm, rotated in circles and bend it. These joints allow movements such as throwing a ball, picking up a book, or waving good-bye.
Via – kidport