7.6: Bone Markings

Bone Markings

Bone markings are very important since they allow for identification of bones and bony pieces, enable joints to form, enable bones to slide past each other, enable bones to lock in place, and provide places for muscle and connective tissues to attach and provide structural support. Bone markings also provide stabilization, protection and a pathway to nerves, vessels, and other structures.

The surface features of bones vary considerably, depending on the function and location in the body. There are three general classes of bone markings: (1) articulations, (2) projections, and (3) holes. As the name implies, an articulation is where two bone surfaces come together (articulus = “joint”). These surfaces tend to conform to one another, such as one being rounded and the other cupped, to facilitate the function of the articulation. A projection is an area of a bone that projects above the surface of the bone. These are the attachment points for tendons and ligaments. In general, their size and shape is an indication of the forces exerted through the attachment to the bone. A hole is an opening or groove in the bone that allows blood vessels and nerves to enter the bone. As with the other markings, their size and shape reflect the size of the vessels and nerves that penetrate the bone at these points.

Common bone markings include the following:

Type of Bone Marking	Description of Bone Marking Type
angle	Sharp bony angulations which may serve as bony or soft tissue attachments. Examples: superior, inferior, and acromial angles of the scapula; superior, inferior, lateral angles of the occipital bone; angle of the mandible
body	Usually refers to the largest most prominent segment of bone. Examples: diaphysis or shaft of long bones like the femur and humerus; body of the mandible
canal	Passageway through a bone. Example: optic canal
condyle	Refers to a large rounded prominence which often provides structural support to the overlying hyaline cartilage. Examples: femoral lateral and medial condyles; tibial lateral and medial condyles; occipital condyles articulate with atlas (C1)
crest	A raised or prominent part of the edge of a bone. Crests are often the sites where connective tissue attaches muscle to bone. An example is the iliac crest is found on the ilium. Example: median sacral crest
epicondyle	A prominence that sits atop of a condyle. The epicondyle attaches muscle and connective tissue to bone, providing support to this musculoskeletal system. Examples: femoral medial and lateral epicondyles; humeral medial and lateral epicondyles
facet	A smooth, flat surface where two bones meet to forms a joint. Example: articular facets of the vertebrae for flexion and extension of the spine
fissure	An open slit in or between bones. It usually houses nerves and blood vessels. Examples: superior and inferior orbital fissures
foramen (pl. foramina)	A hole in a bone through which nerves and blood vessels pass. Examples: foramen magnum; supraorbital foramen; infraorbital foramen; mental foramen
fossa (pl. fossae)	A shallow depression in a bone surface. Examples: trochlear fossa; posterior, middle, and anterior cranial fossae
fovea (pl. foveae)	Shallow pit that allow the attachment of a ligament. Example: fovea capitis of the femur
groove	A long shallow depression on the bone surface that usually allows a blood vessel or nerve to travel along the length of the bone. Example: radial groove
head	A rounded end of a bone, it is a prominent extension of bone that forms part of a joint. Example: the head of the radius; the head of the femur
line	Ridge along a bone that allows a muscle to attach to the bone. Example: arcuate line (of the ilium)
margin	The edge of any flat bone. Example: edge of the temporal bone articulating with the occipital bone is the occipital margin of the temporal bone
meatus (pl. meatuses)	A tube-like channel that extends within the bone, which may provide passage and protection to nerves, vessels, and sound. Examples: external acoustic meatus; internal auditory meatus
neck	The segment between the head and the shaft of a bone. Example: anatomical neck of the humerus
notch	A depression in a bone which often, provides stabilization to an adjacent articulating bone. Examples: trochlear notch on the ulna; radial notch of the ulna; suprasternal notch; mandibular notch
process (pl. processes)	Bony projection, allow for muscle attachment. Examples: spinous process, acromial process, radial styloid process
protuberance	A bump or outgrowth on a bone. Example: external occipital protuberance
ramus (pl. rami)	The curved part of a bone that gives structural support to the rest of the bone. Example: ramus of the mandible
sinus	A cavity within a bone. Example: sphenoidal sinus
sulcus	Same as groove. Example: intertubercle sulcus of the humerus
trochanter	A large prominence on the side of the bone. Some of the largest muscle groups and most dense connective tissues attach to the trochanter. Examples: greater and lesser trochanters of the femur
tubercle	A small, rounded prominence where connective tissues attach. Examples: greater and lesser tubercle of the humerus
tuberosity	A moderate prominence where muscles and connective tissues attach. Its function is similar to that of a trochanter. Examples: tibial tuberosity; deltoid tuberosity; ischial tuberosity

Attributions

• "Anatomy and Physiology" by J. Gordon Betts et al., OpenStax is licensed under CC BY 4.0
• "Anatomy and Physiology I Lab" by Victoria Vidal is licensed under CC BY 4.0