Chapter 1 Notes: Terminology, Positioning, and Imaging Principles

General, Systemic, and Skeletal Anatomy and Arthrology

  • Levels of Human Structural Organization:
    • Atoms
    • Molecule
    • Cell
    • Tissue
    • Organ
    • System
    • Organism (10 systems)

Skeletal System

  • Consists of 206 separate bones.
  • Osteology: Study of bones.
  • Arthrology: Study of joints.

Circulatory System

  • Distributes oxygen to cells.
  • Transports waste products from cells.
  • Includes cardiovascular and lymphatic organs.

Digestive System

  • Involves absorption and elimination processes.

Respiratory System

  • Supplies oxygen.
  • Eliminates carbon dioxide.

Urinary System

  • Regulates blood.
  • Eliminates waste products.

Reproductive System

  • Reproduces organism.
  • Male and female systems.

Nervous System

  • Regulates body activities.

Muscular System

  • Allows for movement.
  • Skeletal, visceral, and cardiac types.

Endocrine System

  • Ductless glands of the body.
  • Regulates body via hormones.

Integumentary System

  • Protects the body.
  • Eliminates waste through perspiration.

Axial and Appendicular Skeletons

  • Total Adult Skeleton: 206 separate bones.
  • Axial skeleton (80 bones):
    • Central axis of body.
    • Includes skull, vertebral column, ribs, and sternum.
  • Appendicular skeleton (126 bones):
    • Limbs.
    • Shoulder and pelvic girdles.

Classification of Bones

  • Long Bones:
    • Limbs.
    • Compact bone.
    • Spongy bone.
    • Periosteum.
  • Short and Flat Bones:
    • Carpal and tarsal bones.
    • Calvarium, sternum, ribs, and scapulae.
  • Irregular Bones:
    • Limbs.
    • Peculiar shapes (vertebrae, facial bones, and pelvic bones).

Bone Development

  • Primary center: Diaphysis (body).
  • Secondary centers: Metaphysis, Epiphyseal plate, Epiphyses.

Classification of Joints (Arthrology)

  • Structural:
    • Classified by tissue type.
    • Fibrous: held together by fibrous tissue.
    • Cartilaginous: held together by cartilage.
    • Synovial: synovial fluid in joint capsule.
  • Functional:
    • Classified by function.
    • Synarthrodial: immovable.
    • Amphiarthrodial: limited movement.
    • Diarthrodial: freely movable.

Fibrous Joints (3 Types)

  1. Syndesmosis:
    • Amphiarthrodial (slightly movable).
    • Example: Distal tibiofibular joint, Interosseous ligament.
  2. Suture:
    • Synarthrodial (immovable).
    • Example: Skull suture, Sutural ligament.
  3. Gomphosis:
    • Amphiarthrodial (only limited movement).
    • Example: Roots of teeth.

Cartilaginous Joints (2 Types)

  1. Symphyses:
    • Amphiarthrodial (slightly movable).
    • Example: Intervertebral joint (fibrocartilage), Symphysis pubis.
  2. Synchondroses:
    • Synarthrodial (immovable).
    • Example: Epiphyseal plates (cartilage).

Synovial Joints (7 Types)

  • Generally freely movable or diarthrodial.
  • Features:
    • Joint cavity (contains synovial fluid).
    • Accessory ligaments.
    • Fibrous capsule.
    • Hyaline articular cartilage.

Synovial Joints - Movement Types

  • Plane (gliding): Intermetacarpal, Intercarpal, Carpometacarpal
  • Ginglymus (hinge): Interphalangeal joints (fingers), Elbow joint
  • Trochoid (pivot): Proximal and distal radioulnar joints, C1-2 joint
  • Ellipsoid (condyloid): Wrist joint, Metacarpophalangeal joints (1st to 5th)
  • Sellar (saddle): 1st carpometacarpal joint (thumb)
  • Spheroidal (ball and socket): Hip joint, Shoulder joint
  • Bicondylar

Body Habitus

  • Sthenic
  • Hyposthenic
  • Hypersthenic
  • Asthenic
  • Bariatric Patient (Obesity)

Quiz Me 1

  • Which of the following joints is classified as trochoidal?
    • Wrist joint
    • Metacarpophalangeal
    • Distal radioulnar
    • Shoulder
  • Answer: C. Distal radioulnar

Quiz Me 2

  • Which of the following joints is classified as ellipsoidal?
    • Wrist
    • Interphalangeal
    • Ankle
    • Hip
  • Answer: B. Interphalangeal

Quiz Me 3

  • Which of the following joints is classified as bicondylar?
    • Metacarpophalangeal
    • First carpometacarpal joint
    • Proximal radioulnar joint
    • Knee
  • Answer: D. Knee

Positioning and Terminology

  • Radiography
  • Radiograph
  • Image Receptor (IR)
  • Central Ray (CR)
  • Radiographic procedure (examination)

Anatomic Position

  • Standard reference point for anatomical descriptions.

Body Planes

  • Sagittal (midsagittal or median) plane
  • Coronal (frontal or midcoronal) plane
  • Horizontal (axial) plane
  • Oblique plane

Body Planes

  • Transverse or Axial Sections (Cross-sections)
  • Oblique transverse plane or section of leg
  • Transverse (axial or cross-sectional) plane or section of arm

Planes of Skull

  • Base plane
  • Occlusal plane

Posterior vs. Anterior

  • Anterior surface (ventral)
  • Posterior surface (dorsal)
  • Dorsum (dorsum pedis)
  • Plantar surface of foot

Dorsal and Palmar Surfaces of Hand

  • Dorsal (posterior, dorsal manus)
  • Palmar (anterior)

Radiographic Projections

  • AP (Anteroposterior)
  • PA (Posteroanterior)

AP and PA Oblique Projections

Lateral Projections

  • Lateromedial
  • Mediolateral

General Body Positions

  • Include various recumbent (lying down) and erect (standing) positions.

Lithotomy Position

  • A specific recumbent position often used in gynecological and urological procedures.

Modified Sims' Position

  • A specific recumbent position where the patient lies on their side with one leg flexed.

Erect and Recumbent Lateral Positions

Oblique Positions

  • Described by the part of the body closest to the Image Receptor (IR).

Decubitus (Decub) Positions

  • Patient lying down, named by the surface they are lying on (e.g., lateral decubitus).

Dorsal and Ventral Decubitus Positions

Special Projection Terms

  • AP axial (semiaxial) projection. Example angle: 37^{\circ}
  • Axial (superoinferior) projection.

Tangential Projections

  • Skims a body part.

Relationship Terms

  • Medial vs. lateral
  • Proximal vs. distal

Caudad and Cephalad CR Angles

  • Caudad: Angling the CR towards the feet.
  • Cephalad: Angling the CR towards the head.

Relationship Terms

  • Superficial vs. deep

Movement Terms

  • Flexion vs. extension
  • Hyperextension vs. extension
  • Radial vs. ulnar deviation
  • Dorsiflexion vs. plantar flexion
  • Medial vs. lateral rotation
  • Abduction vs. adduction
  • Supination vs. pronation
  • Protraction vs. retraction
  • Elevation vs. depression
  • Circumduction movements
  • Rotation vs. Tilt

Terminology Review

  • Identify position/projection from images.

Terminology Review Questions

  1. A projection where the CR is parallel to or greater than a 10^{\circ} angle along the long axis of the body or part? Axial projection
  2. A projection that merely skims a body part? Tangential projection
  3. A projection in which the hand is pronated, then rotated laterally 45^{\circ}? Oblique projection
  4. A specific oblique position where the right anterior aspect of the body is closest to the IR? Recumbent RAO position
  5. A body position where the patient lies on the abdomen with the x-ray beam directed horizontally? Dorsal decubitus position
  6. A general body position where the head is lower than the feet? Trendelenburg position

Radiographic View

  • Not an accepted positioning term in the United States.
  • View describes body part as seen by IR or other recording medium.

Positioning Principles

  • Accuracy is key.

Positioning Accuracy

  • All pertinent anatomy demonstrated.
  • Multiple images aligned on IR.
  • Proper collimation.
  • No rotation.
  • Central ray (CR) centered.

Evaluation Criteria (Lateral Forearm)

  • Anatomy demonstrated: elbow and wrist joints included.
  • Position: no rotation at wrist and elbow joints.
  • Exposure: optimal exposure factors.
  • Image markers: “R” marker visible.

Essential IR Markers

  • Anatomic side markers (left/right).

Sample Procedure Markers

  • Examples: LEFT, RIGHT, COMPARISON, SUPINE, WT. BEARING, AFTER, ERECT, FLEXION, BEFORE, PRONE, EXTENSION, LATERAL, DECUB, STANDING, SCOUT, EXT. ROT, P. REDUCTION, PRELIM, INT.ROT, REPEAT EXAM

Positioning Rules and Principles

  • Minimum of two projections:
    • For anatomic structures superimposed.
    • Localization of lesions or foreign bodies.
    • Determination of alignment of fractures.
  • Minimum of three projections when joints are the prime interest area:
    • AP or PA
    • Lateral
    • Oblique

Long Bones Require Two Projections

Exceptions to Positioning Rules

  • Postreduction upper and lower limbs generally require only two projections to check fracture alignment.
  • Pelvis study requires only a single AP projection unless a hip injury is suspected.

Quiz Me 4

  • Hand: 3 projections
  • Forearm: 2 projections
  • Femur: 2 projections
  • Knee: 2 projections
  • Humerus: 2 projections

Palpation of Topographic Landmarks

  • Applying light, gentle pressure with the fingertips to locate positioning landmarks.
  • Inform the patient before the process begins.

Image Receptor (IR) Alignment

  • Portrait (lengthwise)
  • Landscape (crosswise)

Viewing Radiographic Images

  • Patient facing the viewer, patient’s right to the viewer’s left.
  • Lateral projections.
  • Decubitus projections.

Viewing Radiographic Images

  • Limbs: Anatomic position.
  • Hands and feet: Digits up.

Viewing Radiographic Images

  • AP chest (L appears right-side-up)
  • PA chest (L appears reversed)

Viewing Radiograph Images

  • Left lateral chest
  • Left lateral decubitus chest

Viewing CT and/or MR Images

  • Viewed as radiographs, patient’s right to viewer’s left.
  • Coronal, Sagittal, Transverse.