Exam 2: Bone Markings

2 types of markings

1) Projections that are sites of muscle and ligament attachments 2) Projections that help to form joints 3) Depressions and openings

head

Bony expansion carried on a narrow neck. A rounded, prominent extension of bone that forms part of a joint. It is separated from the shaft of the bone by the neck. The head is usually covered in hyaline cartilage inside of a synovial capsule, as it is the main articulating surface with the adjacent bone, together forming a "ball-and-socket" joint.

meatus

Canal-like passageway. A tube-like channel that extends within the bone, which may provide passage and protection to nerves, vessels, and even sound. Examples include external acoustic meatus and internal auditory meatus.

sinus

Cavity within a bone, filled with air and lined with mucous membrane. A cavity within any organ or tissue. Examples include paranasal sinuses and dural venous sinuses.

tuberosity

Large rounded projection; may be roughened. A moderate prominence where muscles and connective tissues attach. Its function is similar to that of a trochanter. Examples include the tibial tuberosity, deltoid tuberosity, and ischial tuberosity.

margin

The edge of any flat bone. It can be used to accurately define a bone's borders. For example, the edge of the temporal bone articulating with the occipital bone is called the occipital margin of the temporal bone. And vice versa, the edge of the occipital bone articulating with the temporal bone is called the temporal margin of the occipital bone.

line

Narrow ridge of bone; less prominent than a crest that attaches muscle and connective tissue to bone. Ex. Intertrochanteric line (between trochanters of the femur)

crest

Narrow ridge of bone; usually prominent. A raised or prominent part of the edge of a bone. Crests are often the sites where connective tissue attaches muscle to bone. The iliac crest is found on the ilium.

fissure

Narrow, slit-like opening. An open slit in a bone that usually houses nerves and blood vessels. Examples include superior and inferior orbital fissure.

epicondyle

Raised area on or above a condyle. A prominence that sits atop of a condyle. The epicondyle attaches muscle and connective tissue to bone, providing support to this musculoskeletal system. Examples include the femoral medial and lateral epicondyles, and humeral medial and lateral epicondyles.

diaphysis

Refers to the main part or the shaft of a long bone. Long bones including the femur, humerus, and tibia all have a shaft.

foramen

Round or oval opening through a bone. A hole through which nerves and blood vessels pass. Examples include supraorbital foramen, infraorbital foramen, and mental foramen on the cranium.

condyle

Rounded articular projection. Refers to a large prominence which often provides structural support to the overlying hyaline cartilage. It bares the brunt of the force exerted from the joint. Examples include the knee joint (hinge joint), formed by the femoral lateral and medial condyles, and the tibial lateral and medial condyles. Additionally, the occiput has an occipital condyle which articulates with atlas(C1) and accounts for approximately 25 degrees of cervical flexion and extension.

fossa

Shallow, basinlike depression in a bone, often serving as an articular surface. A shallow depression in the bone surface. Here it may receive another articulating bone, or act to support brain structures. Examples include trochlear fossa, posterior, middle, and anterior cranial fossa.

angles

Sharp bony angulations which may serve as bony or soft tissue attachments but often are used for precise anatomical description. Examples include the superior, inferior, and acromial angles of the scapula and the superior, inferior, lateral angles of the occiput.

spine (spinous process)

Sharp, slender, often pointed projection that attaches muscle and connective tissue to bone. A raised, sharp elevation of bone where muscles and connective tissue attach. It is different than a normal process in that a spinous process is more pronounced. Ex. Spinous process of vertebra.

tubercle

Small rounded projection or process. A small, rounded prominence where connective tissues attach. Examples include the greater and lesser tubercle of the humerus.

facet

Smooth, nearly flat articular surface. A smooth, flat surface that forms a joint with another flat bone or another facet, together forming a gliding joint. Examples can be seen in the facet joints of the vertebrae, which allow for flexion and extension of the spine.

epiphysis

The articulating segment of a bone, usually at the proximal and distal poles of the bone. It usually has a larger diameter than the shaft (diaphysis). The epiphysis is critical for the growth of bone because it sits adjacent to the physeal line, also known as the growth plate.

neck

The segment between the head and the shaft of a bone. It is often demarcated from the head by the presence of the physeal line in pediatric patients and the physeal scar (physeal line remnant) in adults. It is often separated into the surgical neck and anatomical neck. The anatomical neck, which may represent the old epiphyseal plate, is often demarcated by its attachment to capsular ligaments. The surgical neck is often more distal and is demarcated by the site on the neck that is most commonly fractured. For example, in the humerus, the anatomical neck runs obliquely from the greater tuberosity to just inferior to the humeral head. The surgical neck runs horizontally and a few centimeters distal to the humeral tuberosities.

trochanter

Very large, blunt, irregularly shaped process (only on the femur). A large prominence on the side of the bone. Some of the largest muscle groups and most dense connective tissues attach to the trochanter. The most notable examples are the greater and lesser trochanters of the femur.

process

any bony prominence

groove

Furrow. A furrow in the bone surface which runs along the length of a vessel or nerve, providing space to avoid compression by adjacent muscle or external forces. Examples include a radial groove and the groove for the transverse sinus.

notch

Indentation at the edge of a structure. A depression in a bone which often, but not always, provides stabilization to an adjacent articulating bone. The articulating bone will slide into and out of the notch, guiding the range of motion of the joint. Examples include the trochlear notch on the ulna, radial notch of the ulna, suprasternal notch, and the mandibular notch.

ramus

Armlike bar of bone. The curved part of a bone that gives structural support to the rest of the bone. Examples include the superior/inferior pubic ramus and ramus of the mandible.