Complete list of bone markings

Condyle

Condyles are rounded knobs that form articulations with other bones. They often provide structural support to the articular surface, helping to absorb the force exerted at the joint. The lateral condyle of femur is one example, which is easily palpable at the knee.

Epicondyle

Epicondyle is a bony area on or above a condyle. It serves mainly as an area for a muscle or ligament attachment. Example: medial epicondyle of humerus.

Process

A process is a bulging bony outgrowth of a larger bone. An example is the mastoid process, which is easily palpable from behind the ear, and to which many head muscles are attached.

Protuberance

Protuberances, similar to processes, are swelling, bulging or protruding parts of bone. The external occipital protuberance is one example. Jutting out from the midline of the external surface, it is palpable from the back of the head.

Tubercle vs tuberosity

Tubercles and tuberosities are subtly different structures which are often confused.

A tubercle is a small rounded prominence, often a site of tendon or ligament attachment e.g. adductor tubercle of femur. A tuberosity is larger, found in varying shapes and often rough in texture.

The ulnar tuberosity is one example. Both tubercles and tuberosities are often found close to sites of tendon or ligament attachment.

Trochanter

This landmark is present only in the femur and it refers to a very large, blunt, irregularly shaped process of the femur that serves as an attachment point for muscles and ligaments. On the femur there is a greater trochanter and a less prominent lesser trochanter.

Spine

The spine (or spinous process) is a sharp, slender projection of the bone which is useful for attachment of muscles or ligaments. Example: spine of sphenoid bone.

Linea (line)

The term linea refers to a subtle, long, and narrow impression which distinguishes itself in elevation, color or texture from surrounding tissues. The linea aspera of femur is one example. Found on the posterior surface, it consists of medial and lateral lips diverging at its superior and inferior ends.

Facet

The facet is a flat smooth area of the bone which serves as an articular surface. Example: acromial facet of clavicle.

Crests and ridges

Crests can be described as prominent, raised edges of a bone. They are of medium thickness and often found at sites where connective tissue connects muscle and bone. The iliac crest is one example. Found inferior to the quadratus lumborum, for which it serves as the origin point, it is palpable along its entire length, and is thicker at the extremities than the center.

Ridges are linear elevations, margins or borders. The lateral supracondylar ridge of humerus is one example, where we notice a slight projection compared to the surrounding bone.

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Foramen and fissure

Foramina (sing: foramen) are holes or openings in a bone, usually through which nerves and blood vessels pass. The jugular foramen is one example through which the inferior petrosal sinus, sigmoid sinus, glossopharyngeal, vagus and accessory nerves pass.

Fissures are open slits, grooves or depressions in a bone, often housing nerves and blood vessels. An example is the inferior orbital fissure. Separating the floor from the lateral wall, it gives passage to structures like the zygomatic nerve and orbital branches of the pterygopalatine ganglion.

Meatus

A meatus is a short, tube-like channel extending into the bone. It can provide passage and protection to nerves and vessels. An example is the external acoustic meatus, also known as the ear canal, which connects the middle and outer ear.

Fossa and fovea

A fossa is a depression in the bone surface which is often broad and shallow. It may support brain structures, or receive another articulating bone. The temporal fossa is one example. It is one of the largest landmarks on the skull, serving as an origin site for the temporal muscle.

Fovea refers to a pit or depression - similar to a fossa, but generally much smaller. An example is the fovea capitis, found in the center of the head of the femur.

Notch and sulcus

Notches (or incisures) can be defined as indentations at the edge of a structure, like a cleft. The scapular notch, which forms a deep, distinctive depression along the superolateral border of the scapula, is one example.

A sulcus is a furrow or fissure usually specific to the surface of the brain, but also in bones and other organs. When referring to bones, sulci are very often referred to as grooves. Grooves often trace the length of nerves or vessels, providing space to prevent compression from surrounding muscles or external forces. An example is the groove for the transverse sinus.

Sinus

A sinus is a cavity or hollow space. The paranasal sinuses, a group of four paired, bilateral sinuses in the nasal cavity, are a notable example.