Bony Markings

At the end of each long bone is a wider area known as the epiphysis. This is filled with spongy

bone and red marrow. Each epiphysis meets the diaphysis at the metaphysis, which is a

narrower area that consists of the epiphyseal plate, which is the growth plate of the bone.

When the person stops growing, the epiphyseal plate becomes ossified and defined as the

epiphyseal line.

There is a membranous lining called the endosteum inside the bone in the medullary cavity.

This is where bone repair, remodeling, and bone growth occur. The outer membrane of bone is

called the periosteum, which contains the blood vessels, lymph vessels, and nerves that supply

the compact bone. Tendons and ligaments attach to bones at the periosteum. It covers the

entirety of bone except where the epiphyses for joints; this is where the articular cartilage

covers bone instead.

Flat bones are slightly different from long bones. They have two layers of compact bone that

sandwiches a spongy layer called the diploe. The inner layer can protect the internal structure,

such as the brain in the cranial bones, even if the outer layer gets fractured.

BONY MARKINGS

There are many different markings on bone, of which there are three types:

• Articulations—also referred to as joints, where two bones meet to facilitate movement.

• Projections—these will stick out of a bone and is often where tendons and ligaments

attach.

• Holes—this is a groove or opening in the bone where nerves and blood vessels enter the

bone.

Types of articulations include the following:

• Head—such as the head of the femur, in which there is a prominent rounded surface at

one end

• Facet—this is a flat end of the bone, such as the facet joint of a vertebral bone

• Condyle—this is a rounded projection, such as the occipital condyles

Types of projections include the following:

• Protuberance—a protruding projection, such as the chin

• Process—a prominence that sticks out of the bone, such as the transverse process of a

vertebra

• Spine—this is a sharp process, such as the ischial spine or the spine of the scapulae

• Tubercle—this is a small, rounded process, such as the tibial tubercle (a tendon insertion

spot)

• Tuberosity—a rough projection, such as the deltoid tuberosity (a tendon insertion spot)

• Line—this is a ridge that is slightly elongated and elevated (such as the temporal lines of

the parietal bones)

• Crest—this is a ridge of bone, such as the iliac crest

There are several kinds of holes in bones, including the following:

• Fossa—an elongated basin in a bone, such as the mandibular fossa

• Fovea—a small pit in the bone, such as the fovea capitis (on the femur head)

• Sulcus—this is a groove in the bone, such as the sigmoid sulcus in the temporal bone

• Canal—a passage within the bone, such as the auditory canal

• Fissure—this is a slit through the bone, such as the auricular fissure

• Foramen—this is a hole through the bone, such as the foramen magnum in the skull

• Meatus—this is an opening into a canal including the external auditory meatus

• Sinus—an air-filled space within the bone, such as the ethmoid sinus