General Anatomy and Radiographic Positioning

Osteology

The study of bones.

Axial and appendicular skeleton

The two primary structural divisions of the skeleton.

Sesamoid bones

Small bones sometimes found in tendons near joints.

Long bones

Bones with a body and two articular ends, found exclusively in the appendicular skeleton.

Periosteum

A dense fibrous membrane covering bones.

Short bones

Cuboidal bones composed mainly of cancellous tissue, found in wrists and ankles.

Flat bones

Bones made of two plates of compact bone, such as the calvarium, sternum, ribs, and scapula.

Irregular bones

Bones with peculiar shapes, such as vertebrae, facial bones, and pelvic bones.

Ossification

The process of bone formation, beginning in embryonic development and continuing until adulthood.

Diaphysis

The primary center of ossification located at the body of a bone.

Epiphysis

The secondary center of ossification located at the ends of a bone.

Synarthrosis

A functional joint classification describing an immovable joint.

Amphiarthrosis

A functional joint classification describing a joint with limited movement.

Diarthrosis

A functional joint classification describing a freely moveable joint.

Synovial joint

A freely moveable joint featuring a fibrous capsule containing synovial fluid.

Plane (gliding) joint

A synovial joint with the least amount of movement, such as intercarpal joints.

Ginglymus (hinge) joint

A synovial joint permitting only flexion or extension, such as the elbow or knee.

Trochoid (pivot) joint

A synovial joint allowing rotation around a single axis, such as the radioulnar joint.

Ellipsoid (condyloid) joint

A joint allowing flexion, extension, adduction, and abduction, such as the wrist.

Sellar (saddle) joint

A joint named for its saddle appearance, found at the first carpometacarpal joint.

Sphenoid (ball and socket) joint

A joint with the highest freedom of motion, found in the hip and shoulder.

Sagittal (midsagittal) plane

A body plane that divides the body into left and right parts.

Coronal (midcoronal) plane

A body plane that divides the body into anterior and posterior parts.

Horizontal axial plane

A transverse plane dividing the body into superior and inferior parts.

Oblique plane

A longitudinal or transverse plane that is angled.

Anterior (ventral) surface

The front half of the body, top of feet, and palms of hands.

Posterior (dorsal) surface

The back half of the body, bottom of feet, and back of hands.

Plantar surface

The sole or posterior surface of the foot.

Dorsum pedis

The top or anterior surface of the foot.

Palmar surface

The palm of the hand.

Posteroanterior (PA) projection

X-ray beam enters the posterior surface and exits the anterior.

Anteroposterior (AP) projection

X-ray beam enters the anterior surface and exits the posterior.

Axial radiographic projection

Implies a central ray angulation greater than 10° along the long axis of the body.

Tangential projection

Skimming a body part to project it in profile.

Supine position

Lying on the back.

Prone position

Lying on the stomach.

Trendelenburg position

A recumbent position with the body tilted so the feet are above the head.

Fowler's position

A recumbent position with the head above the feet.

Sims position

A recumbent oblique position lying on the left anterior side with the top leg crossed.

Lithotomy

recumbent with knees and hips flexed

Lordotic

Patient is upright and leaning backwards into the IR