How to label a whole human skeleton, from the skull down to the toes, in one fixed order

1. What a labeled human skeleton has to show

A worksheet and a practical station ask for the same thing: the right name on the right bone. The adult skeleton has 206 bones, and the OpenStax chapter on the divisions of the skeleton splits them into 80 axial bones and 126 appendicular bones.

The axial skeleton is the vertical center of the body: the bones of the head and neck plus those of the chest and back. The appendicular skeleton holds the upper and lower limbs plus the bones that attach each limb to that center. The split gives you the order of work, because the limbs attach to the girdles and the girdles attach to the axial bones. If you still hesitate over where a bone belongs, the axial vs appendicular guide sorts any bone with four questions.

Check one thing before you write a name: which way the figure faces. In anatomical position the radius lies lateral to the ulna and the tibia lies medial to the fibula, so the direction of the figure decides which name goes on which line.

2. Label the bones of the skeleton in a fixed order

Work in six passes and do not jump between them. On a fixed route a blank line shows up as a gap in one region, and the last column below tells you how many names each pass should produce.

The six totals add up to 206, and the first three add up to the 80 axial bones. The full count of the 206, region by region explains where each number comes from.

When a diagram gives a single line to a group such as the carpals or the ribs, write the group name and move on. Save the individual names for the lines that point at a single bone.

3. Start with the skull, the hyoid and the ear ossicles

The skull has 22 bones. The osteology appendix of Explorations divides it into the mandible and the cranium, then splits the cranium into the braincase and the facial skeleton. Label in that order:

• Braincase (neurocranium), 8 bones. The frontal, occipital, sphenoid and ethmoid are single bones. The parietal and temporal come in pairs.
• Face, 13 bones. The maxilla, nasal, zygomatic, palatine, lacrimal and inferior nasal concha come in pairs. The vomer is single.
• Mandible, 1 bone. The lower jaw, with its horizontal body and its vertical ramus.

Sutures make useful signposts when the lines crowd together. The coronal suture lies between the frontal and parietal bones, the sagittal suture between the two parietals and the lambdoid suture between the parietals and the occipital. On a side view, the squamous suture marks the lower edge of the parietal, where the temporal begins.

The sphenoid and ethmoid need the most care, because both sit deep in the center of the skull. Both reach the walls of the orbit, along with the frontal, zygomatic, maxilla, lacrimal and palatine, so a line ending inside the eye socket points at one of these seven.

Then add the seven bones associated with the head that sit outside the 22. The hyoid is the U-shaped bone in the neck, below the mandible, and it meets no other bone. The malleus, incus and stapes lie inside the temporal bone, three on each side, hidden from a whole-body view.

4. Move down the spine and around the rib cage

The vertebral column gives 26 bones. Read it from the top: 7 cervical vertebrae (C1 to C7), 12 thoracic (T1 to T12) and 5 lumbar (L1 to L5), then the sacrum, made from five fused vertebrae, and the coccyx, made from three or four. The first two cervical vertebrae have names of their own, the atlas (C1) and the axis (C2).

You may see a higher figure for the spine. The adult column holds 32 or 33 vertebrae if every fused segment is counted, and 26 bones once the sacrum and coccyx are each taken as one. For a bone count, use 26.

The thoracic cage adds the sternum and 24 ribs, which makes 25. Label the sternum from top to bottom: manubrium, body, xiphoid process. For the ribs, the question is how each one reaches the sternum:

• True ribs, 1 to 7. Each joins the sternum through its own costal cartilage.
• False ribs, 8 to 10. Each joins through the cartilage of the rib above.
• Floating ribs, the last two. They do not reach the sternum. Some figures call ribs 8 to 12 false and treat ribs 11 and 12 as a floating subgroup.

The 12 thoracic vertebrae form the back of the cage, but they are already in the total for the spine. Count them once, in pass two.

5. Which skeleton bones do you label on the girdles?

Pass four is the shortest, with six bones, three on each side. Each girdle anchors a limb to the axial skeleton.

• Clavicle. The S-shaped strut between the scapula and the sternum.
• Scapula. A large flat bone. Lines on it may point at the acromion, the coracoid process, the spine of the scapula or the glenoid cavity, where the head of the humerus fits.
• Hip bone. Also written os coxa. Its three parts, the ilium, ischium and pubis, fuse at the acetabulum, the socket of the hip joint.

Two traps sit here. The ilium, ischium and pubis can each get their own line, yet together they count as one bone per side. The sacrum joins both hip bones at the back and some courses teach it with the pelvic girdle, while the count of 206 keeps it in the vertebral column, so it stays in pass two.

6. Finish with the upper and lower limbs

Each limb has 30 bones, and the two follow the same plan from the shoulder or hip out to the digits. Seeing them side by side makes the names easier to place:

• One bone. The humerus in the arm, the femur in the thigh.
• Two bones side by side. The radius and ulna in the forearm, the tibia and fibula in the leg.
• A cluster of small bones. Eight carpals in the wrist, seven tarsals in the ankle.
• A set of five. The metacarpals in the palm, the metatarsals in the foot.
• The digits. Fourteen phalanges in each hand or foot, three per digit, except the thumb and the big toe, which have no middle phalanx.

The lower limb has one small bone fewer, and the patella makes up the difference, so both limbs reach 30.

When a diagram asks for individual carpals, go from lateral to medial, thumb side first. The proximal row runs scaphoid, lunate, triquetrum, pisiform, and the distal row runs trapezium, trapezoid, capitate, hamate. In the ankle, start at the top with the talus, go down to the calcaneus, the heel and the largest tarsal, then forward to the navicular on the medial side, the medial, intermediate and lateral cuneiforms, and the cuboid on the lateral side.

7. The bones in the body whose names get swapped

Some names sit so close together that a correct answer lands on the wrong line. Check these pairs once the passes are done:

Check the line on the kneecap as well. The patella rests against the front of the lower femur and does not meet the tibia.

If your worksheet accepts common names, collarbone stands for clavicle, shoulder blade for scapula, breastbone for sternum, kneecap for patella and tailbone for coccyx.

Before your next diagram

Take a blank figure, cover the first table and write the six passes from memory, then add up your totals. When you are ready for timed stations, the three-week plan for an anatomy practical shows how to build the drill. Osteo+ can name a bone from a photo, which gives you a quick check on the ones you keep getting wrong.

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