In this anatomy lesson, I’m going to cover the types of bones found in the human skeleton. As you’ve probably noticed, bones have different shapes, so anatomists have classified them into different categories.
We have four major categories: long bones, short bones, flat bones, irregular bones. We also have two minor categories of bones: sesamoid bones and sutural bones.
List of Long Bones
First, I’ll talk about the long bones, which is the most common type of bone. These bones can vary in length (short or long), but the key characteristic is that they are longer than they are wide. These bones are going to have a shaft made primarily of compact bone, and two bulky ends, which often contain spongy bone.
There are 90 long bones in the adult skeleton, consisting mostly of the bones of the upper and lower extremities, as well as the clavicle bones:
Upper Extremity/Pectoral Girdle:
- 2 Clavicles
- 2 Humerus bones
- 2 Radius bones
- 2 Ulna bones
- 10 Metacarpals
- 28 Phalanges of the Hand
Lower Extremity:
- 28 Phalanges of the Foot
- 2 Femur bones
- 2 Tibia bones
- 2 Fibula bones
- 10 Metatarsals
List of Short Bones
Short bones have approximately the same length and width, which gives them a cube-like appearance. They consist mostly of spongy bone that is covered by a thin layer of compact bone.
There are 28 short bones in the adult skeleton, consisting of the tarsals and most of the carpals:
Carpal Bones:
- 2 Scaphoid
- 2 Trapezium
- 2 Trapezoid
- 2 Lunate
- 2 Triquetral
- 2 Capitate
- 2 Hamate
Tarsal Bones:
- 2 Talus
- 2 Calcaneus
- 2 Navicular
- 2 Cuboid
- 2 Lateral Cuneiform
- 2 Intermediate Cuneiform
- 2 Medial Cuneiform
List of Sesamoid Bones
Sesamoid bones are a special subcategory of short bones that are embedded in tendons. The word sesamoid sounds kind of like sesame seed, and that’s because these seed-shaped bones get their name from a Greek word that means “resembling a sesame seed.” There are 4 sesamoid bones in the adult skeleton:
- 2 Patella bones (knee cap bones)
- 2 Pisiform bones (carpal bones)
Additional sesamoid bones can sometimes form on the tarsal, metatarsal, or incus bones, but this can vary per individual.
List of Flat Bones
Flat bones provide protection to vital organs. As the name suggests, they are mostly flat and curved, having a thin plate-like formation. They contain a layer of spongy bone covered by a thin layer of compact bone. Some flat bones contain irregular structures. For example, the scapula bone is a flat bone, but it contains a spine, acromion, and coracoid process that make it appear somewhat irregular.
There are 36 flat bones in the adult skeleton, including some skull bones, as well as the sternum and ribs:
Flat Skull Bones:
- 1 Frontal bone
- 2 Parietal bones
- 1 Occipital bone
- 2 Nasal bones
- 2 Lacrimal bones
- 1 Vomer bone
Flat Pectoral Girdle Bones:
- 2 Scapula bones
Flat Thorax Bones:
- 1 Sternum
- 24 Ribs
Sutural Bones
While we’re talking about the flat bones of the skull, it’s a good time to mention another minor category of bones, called sutural bones (or wormian bones). These independent bones are found within the cranial sutures in some, not all, individuals. They don’t actually serve a functional purpose, but they can be a marker for some diseases.
List of Irregular Bones
Irregular bones come in various funky shapes and sizes, and they don’t fit any of the other bone categories. These bones also consist of a layer of spongy bone, covered by a thin layer of compact bone.
There are 48 irregular bones in the adult skeleton, including the hip bones, vertebrae, hyoid bone, and some skull bones.
- 26 Vertebrae (7 cervical, 12 thoracic, 5 lumbar, 1 sacrum, and 1 coccyx)
- 2 Hip bones
- 1 Hyoid bone
Irregular Skull Bones:
- 2 Temporal bones
- 1 Sphenoid bone
- 1 Ethmoid bone
- 2 Zygomatic bones
- 2 Maxilla bone
- 1 Mandible
- 2 Palatine bones
- 2 Inferior nasal concha
Irregular Auditory Ossicles (Ear Bones)
- 2 Malleus bones (ear)
- 2 Incus bones (ear)
- 2 Stapes (ear)
Quick note: some anatomists (or sources) will disagree over the exact classification of bones, so always reference your textbook. Nevertheless, this should give you a general idea of how the bones are commonly classified.
Free Quiz and More Anatomy Videos
Take a free bone types anatomy quiz to test your knowledge. In addition, you might want to watch our anatomy and physiology lectures on YouTube, or check our anatomy and physiology notes.