The upper limbs

Information

For anatomists, the upper limb consists of the arm (the upper arm), the forearm (the lower arm), and the hand. The arm consists of a single bone, the humerus. The forearm consists of two bones, the ulna and radius. And the hand consists of 27 bones, which are grouped into the phalanges, metacarpals, and carpals.

Fig 7-8. The bones of the left upper limb.

 

The major processes and markings of the humerus, ulna, and radius bones are shown in Figures 7-9, 7-10, and 7-11, respectively.

The bones of the hands are divided into three groups. The carpals articulate with the ulna and radius bones of the forearm and are named after the carpus, or wrist. There are 8 carpal bones and each has its own name. In Figure 7-12 they are numbered so that 1-trapezium, 2-trapezoid, 3-capitate, 4-hamate, 5-pisiform, 6-triquetrum, 7-lunate, 8- scaphoid.

Figure 7-9. The left humerus and its various processes and markings.

 

Figure 7-10. The left ulna (in brown) and its major markings and processes.

 

Figure 7-11. The left radius (in brown) and its major markings and processes.

 

The metacarpals are five individual bones that are wrapped in muscle and collective tissue to create a single solid mass that serves as the palm of the hand. They are numbered I – V, starting with the metacarpal under the thumb and moving sequentially to the little finger. Metacarpals are individually named according to the hand they come from and their number. So the metacarpal under the little finger in Figure 7-12 is name left metacarpal V.

There are 14 bones that make up the fingers. All are called phalanges (singular is phalanx). Each finger is made up of three phalanges, labelled the proximal, middle and distal phalanges as you move farther out from the metacarpals. Each thumb only has two phalanges, labelled proximal and distal. The phalanges are numbered I through V, like the metacarpals. Each phalanx then is named according to which hand it comes from, which number it is, and whether it is proximal, middle, or distal. So the second phalanx on the pointing finger in Figure 7-12 is the left medial phalanx II.

Figure 7-12. The bones of the left hand.

Lab 7 Exercises 7-3

  1. Using one of the full skeletons in the room, fill out the tables below with three or four steps to determine whether each individual upper limb bone comes from the anatomical left or anatomical right.
  1. You can describe any features on that bone and which direction it has to face to allow you to determine whether that particular bone came from anatomical left or anatomical right.
  1. You don’t have to use anatomical jargon if you don’t want. Use terms which will make sense to you when you read it again. Use as many steps as you need, not necessarily four.

 

 

Humerus – Anatomical left from anatomical right.
1.
2.
3.
4.

 

 

Ulna – Anatomical left from anatomical right.
1.
2.
3.
4.

 

Radius – Anatomical left from anatomical right.
1.
2.
3.
4.