Markings on bones, explained with one real example each

What the markings on a bone tell you

The surface of a bone records what happens around it. The OpenStax chapter on bone structure explains that surface features vary with the function and location of each bone, and it groups them into three classes. An articulation is where two bone surfaces come together, and the two surfaces tend to fit each other, one rounded and the other cupped. A projection rises above the surface and gives attachment to tendons and ligaments; its size and shape reflect the forces pulling on it. A hole is an opening or groove that lets blood vessels and nerves enter the bone, and its size reflects what passes through it.

So the class already tells you what a marking did, even before you know its name.

A list of markings on bones, grouped by type

The list follows the OpenStax table and adds two projections you will meet on the femur and the humerus. Learn each term with its example, since the example is what you point at in a practical.

Articulations

• Head: a prominent rounded surface, such as the head of the femur.
• Facet: a flat surface, such as the costal facets where the ribs meet the thoracic vertebrae.
• Condyle: a rounded surface, such as the occipital condyles that rest on the atlas.

Projections

• Protuberance: a part that protrudes, such as the chin or the external occipital protuberance.
• Process: a prominent feature, such as the transverse process of a vertebra or the mastoid process of the temporal bone.
• Spine: a sharp process, such as the ischial spine.
• Tubercle: a small, rounded process, such as the greater tubercle of the humerus.
• Tuberosity: a rough surface, such as the deltoid tuberosity.
• Line: a slight, elongated ridge, such as the temporal lines of the parietal bones.
• Crest: a ridge, such as the iliac crest.
• Trochanter: a projection at the upper end of the femur; the greater trochanter is the large one on the lateral side where the neck meets the shaft, and the lesser trochanter lies medially below the neck.
• Epicondyle: a projection on or beside a condyle, such as the medial and lateral epicondyles of the humerus.

Holes and depressions

• Fossa: an elongated basin, such as the mandibular fossa, which, with the articular eminence, forms the socket of the jaw joint.
• Fovea: a small pit, such as the fovea capitis on the head of the femur.
• Sulcus: a groove, such as the intertubercular groove of the humerus, which holds the tendon of the long head of the biceps.
• Canal: a passage in bone, such as the hypoglossal canal of the occipital bone.
• Fissure: a slit through bone, such as the superior orbital fissure of the sphenoid.
• Foramen: a hole through bone, such as the foramen magnum of the occipital bone.
• Meatus: an opening into a canal, such as the external acoustic meatus.
• Sinus: an air-filled space in bone, such as the sphenoid sinuses.

That makes 20 terms. Check your syllabus for extras such as notch or ramus, and learn them the same way.

Tuberosity vs tubercle

Both words name a projection and differ by a few letters, which is why they get mixed up. OpenStax separates them by shape: a tubercle is a small, rounded process, while a tuberosity is a rough surface. In practice, a tubercle looks like a knob, and a tuberosity looks like a roughened patch or a broad bump where a large tendon or ligament attaches.

The humerus is the best bone to practice on, because it carries both. Its greater and lesser tubercles, at the upper end next to the head, anchor the rotator cuff muscles, and its deltoid tuberosity, on the lateral side of the shaft, receives the deltoid. Open the humerus page of our Bone Atlas and find all three before you move on.

Other tuberosities follow the same pattern: the radial tuberosity receives the biceps tendon, the tibial tuberosity the patellar ligament, and the calcaneal tuberosity the Achilles tendon. Tubercles stay small, like the conoid tubercle of the clavicle or the tubercle of a rib, which forms a joint with the transverse process of its vertebra.

Condyle vs epicondyle

A condyle is part of a joint. OpenStax lists it among the articulations as a rounded surface, and each classic example sits against another bone: the occipital condyles rest on the atlas, the two condyles at the lower end of the femur form the upper surface of the knee, and the condyles of the tibia receive them.

An epicondyle does not form the joint. The prefix epi- means on or upon, and an epicondyle is a projection on or beside the condyle region where muscles anchor. On the humerus, the medial and lateral epicondyles are landmarks you can feel at the elbow, and they are where the flexor and extensor muscles take their origin. The medial one is also the funny bone spot: hitting it presses the ulnar nerve against the bone.

A quick test settles most cases. If the surface is smooth and meets another bone, it is a condyle. If it is a bump beside that surface, where muscles pull, it is an epicondyle.

Fossa vs foramen, and other look-alike pairs

Several terms describe a hollow, so ask whether the opening goes through the bone. A fossa and a fovea do not; a foramen and a fissure do. A canal is a passage, and a meatus is the opening into one.

Read the table across first. Then cover the middle column and explain each pair aloud, using the example to prove your answer.

How to memorize markings on bones

A flat list of 20 terms is hard to hold, so build it in layers:

1. Learn the three classes first, so every new term has a place: joint surface, projection or hole.
2. Learn the look-alike pairs together, with the table above, rather than one term at a time.
3. Tie each term to one example you can touch. Several are easy to find on yourself: the epicondyles of the humerus at the elbow, the tibial tuberosity below the knee, the iliac crest, which is the upper rim of the hip bone, and the external occipital protuberance at the back of the skull.
4. Use the names. Articulus is Latin for joint, which is where the articulations get their name, and epi- means upon.
5. Test yourself on bones, not on words: point at a marking on a bone or a photo, name it, then name its class.

For the last step, the human anatomy lab manual by Rosanna Hartline defines each marking with lab examples, from the fovea capitis of the femur to the optic canal, which is the format you need for drilling. When you revise from photos of real bones, Osteo+ can name the bone first, so you know which landmarks to look for.

Reading the markings on a real bone

In a practical, markings are how you prove which bone you hold and which way it faces. Take the femur. Its head carries the fovea capitis. The greater trochanter is the large projection on the lateral side where the neck meets the shaft, and the lesser trochanter sits medially below the neck. The linea aspera runs as a vertical ridge down the back of the shaft, and the two condyles form the lower end. Find those markings and you know which end is up, which side is medial and which face is posterior.

From there, deciding whether you hold a left or a right femur takes one more step, which our guide on how to tell if a bone is left or right walks through. The femur page of the atlas lists these landmarks along with the muscles attached to them, from the gluteus medius on the greater trochanter to the gastrocnemius on the condyles.

Before the practical

Write the 20 terms from memory once, grouped by class, then check them against the list. The next day, redo only the ones you missed, with a bone or a photo in front of you. A term you can point to on a bone is the version of it you will need on exam day.

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