Chapter 7. Axial Skeleton

7.2 Bone Markings

Bone Markings

Learning Objectives

By the end of this section, you will be able to:

  • Define and list examples of bone markings

 

The surface features of bones vary considerably, depending on the function and location in the body. Table 2 describes the bone markings, which are illustrated in (Figure 7.21). 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.

Bone Markings (Table 2)
Marking Description Example
Articulations Where two bones meet Knee joint
Head Prominent rounded surface Head of femur
Facet Flat surface Vertebrae
Condyle Rounded surface Occipital condyles
Projections Raised markings Spinous process of the vertebrae
Protuberance Protruding Chin
Process Prominence feature Transverse process of vertebra
Spine Sharp process Ischial spine
Tubercle Small, rounded process Tubercle of humerus
Tuberosity Rough surface Deltoid tuberosity
Line Slight, elongated ridge Temporal lines of the parietal bones
Crest Ridge Iliac crest
Holes Holes and depressions Foramen (holes through which blood vessels can pass through)
Fossa Elongated basin Mandibular fossa
Fovea Small pit Fovea capitis on the head of the femur
Sulcus Groove Sigmoid sulcus of the temporal bones
Canal Passage in bone Auditory canal
Fissure Slit through bone Auricular fissure
Foramen Hole through bone Foramen magnum in the occipital bone
Meatus Opening into canal External auditory meatus
Sinus Air-filled space in bone Nasal sinus
This illustration contains three diagrams. The left diagram is titled examples of processes formed where tendons or ligaments attach. The image shows an anterior view of the femur and an anterior view of the humerus. For the femur, the distal epiphysis contains a smaller lateral bulge and a larger medial bulge. These are examples of condyles. The inner halves of the two condyles as well as the groove between them compose a facet. An oval-shaped ridge on the medial surface of the distal metaphysis is an example of a tubercle. On the proximal epiphysis of the femur, the large knob that attaches to the hip socket is an example of a head. The tip of the head contains a small depression, an example of a fovea called the fovea capitis. On the humerus, the distal epiphysis contains a central depression that is an example of a fossa. Two condyles are located on the right and left sides of the fossa. The diaphysis of the humerus contains a small ridge running up the shaft that is an example of a tuberosity. The proximal epiphysis of the humerus contains a lateral and a medial bulge that are both examples of tubercles. Finally, a narrow groove runs from the center of the proximal metaphysis in between the medial and lateral condyles. This is an example of a sulcus. The middle image is entitled elevations or depressions. It shows an anterior view of the hip bones. The hip bones are shaped like two wings that join at the bottom. The crest along the upper edge of each hip bones, at the tip of each “wing” is an example of an elevation. A depression on the inner surface of both hip bones just under the crest is called out as a fossa. The right image is entitled examples of openings and shows an anterior view of the skull. The bone underlying the chin is an example of a protuberance while two small holes above each eye socket are examples of foramen. Five green sinuses surround the nose cavity are colored green. These are sinuses because they are hollowed out cavities within the skull bones. A small channel leads into the corner of each eye where the tear ducts occur. These two channels are both examples of a canal. Finally, the bones that form the posterior wall of the eye socket have a small crack running diagonally away from the nose. These are examples of fissures.

Figure 7.21 – Bone Features: The surface features of bones depend on their function, location, attachment of ligaments and tendons, or the penetration of blood vessels and nerves.