Accessory bone

is present in 10% to 30% of individuals. An accessory bone or supernumerary bone is a bone that is not normally present in the body, but can be found as a variant in a significant number of people. It poses a risk of being misdiagnosed as bone fractures on radiography.

Wrist and hand

of the wrist, with most common accessory bones labeled.

Os ulnostyloideum

The os ulnostyloideum is an ulnar styloid process that is not fused to the rest of the ulna bone. On X-rays, an os ulnostyloideum is sometimes mistaken for an avulsion fracture of the styloid process. However, the distinction between these is extremely difficult. It is alleged that the os ulnostyloideum has a close relationship with or is synonymous with the os triquetrum secundarium.

Os centrale

The os carpi centrale (also briefly os centrale) is, where present, located on the dorsal side of the wrist between the scaphoid, the trapezoid and capitate, radially to the deep fossa of the capitate. The bone is present in almost every human embryo of 17–49 mm length, but then usually fuses with the ulnar side of the scaphoid. Sometimes it fuses with the capitate or the trapezoid. The literature also refers to an os centrale at the palm of the carpus, but this existence is questioned.…

is present in 10% to 30% of individuals. ]] An accessory bone or supernumerary bone is a bone that is not normally present in the body, but can be found as a variant in a significant number of people. It poses a risk of being misdiagnosed as bone fractures on radiography.

Wrist and hand

of the wrist, with most common accessory bones labeled. ]]

Foot

by dorsoplantar projection, with most common accessory and sesamoid bones of the foot. ]]

Neck

Nodules in the posterior margin of the nuchal ligament form bone tissue in approximately 11% of males and 3–5% in females after the third decade of life, and may then be regarded to be sesamoid bones.

Shoulder

An os acromiale forms when any of its four ossification centers fail to fuse. These four ossification centers are called (from tip to base) pre-acromion, meso-acromion, meta-acromion, and basi-acromion. In most cases, the first three fuse at 15–18 years, whereas the base part fuses to the scapular spine at 12 years. Such failure to fuse occurs in between 1% and 15% of cases. It rarely causes pain.

Vertebral column

An Oppenheimer ossicle is found in approximately 4% (range 1–7%) of individuals. It is associated with the facet joints of lumbar spines. It usually occurs as a single, unilateral ossicle at the inferior articular processes, but can also occur at the superior articular processes.

Knee

The fabella is present in 10% to 30% of individuals.

Text derived from https://en.wikipedia.org/w/index.php?oldid=1312817745 under CC BY-SA 4.0; modifications have been made.