Accessory bone

Accessory bone

An accessory bone is a bone that is not normally present in the human body but can occur as a variant in some individuals. These bones are often found in the foot, wrist, and other areas of the body. They are usually asymptomatic but can sometimes cause pain or discomfort, especially if they interfere with normal joint function.

Types of Accessory Bones

Foot

The foot is a common location for accessory bones. Some of the notable accessory bones in the foot include:

• Os trigonum: This is an accessory bone that can be found behind the talus bone in the ankle. It is present in a small percentage of the population and can sometimes cause pain, especially in athletes.

• Os tibiale externum: Also known as the accessory navicular bone, this bone is located near the navicular bone in the foot. It can cause a condition known as accessory navicular syndrome, which may require treatment if symptomatic.

• Sesamoid bones: These are small bones embedded within tendons. In the foot, they are commonly found beneath the first metatarsophalangeal joint.

Wrist

Accessory bones in the wrist are less common but can include:

• Accessory bones of the wrist: These can vary in number and location, sometimes causing confusion in diagnosis if not recognized as normal variants.

Other Locations

Accessory bones can also be found in other parts of the body, such as:

• Fabella: A small sesamoid bone located in the tendon of the gastrocnemius muscle behind the knee.

Clinical Significance

While accessory bones are often asymptomatic, they can sometimes lead to clinical issues. For example, the presence of an accessory bone can alter the biomechanics of a joint, leading to pain or discomfort. In some cases, surgical intervention may be necessary to alleviate symptoms.

Related pages

• Sesamoid bone
• Human anatomy
• Skeletal system
• Orthopedics

Gallery

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  Fabella

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  Accessory bones of the wrist

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  Sesamoid bones of the fingers

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  Accessory bones of the ankle

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  Accessory and sesamoid bones of the foot - dorsoplantar projection

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  Accessory and sesamoid bones of the foot - lateral projection

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  Os tibiale externum

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  Os trigonum - Os talonaviculare

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  Os trigonum 1

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  Os trigonum 2

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  Os trigonum 3