Anatomical Positions and Movements

Anatomical Positions and Movements

• Anatomical position is a universal standard for describing body parts and their relative locations
• Anatomical position: standing upright, feet parallel, arms at the sides, palms facing forward, and thumbs pointing away from the body
• Directional terms describe the position of one body part relative to another
  • Superior (cranial): closer to the head
  • Inferior (caudal): closer to the feet
  • Anterior (ventral): towards the front
  • Posterior (dorsal): towards the back
  • Medial: closer to the midline of the body
  • Lateral: farther from the midline of the body
  • Proximal: closer to the point of attachment
  • Distal: farther from the point of attachment
  • Superficial: closer to the surface of the body
  • Deep: closer to the core of the body
• Unilateral describes one side of the body
• Bilateral describes both sides of the body
• Ipsilateral describes structures on the same side of the body
• Contralateral describes structures on opposite sides of the body

Anatomical Planes

• Planes are imaginary surfaces used to section the body for description
• Sagittal plane: divides the body into right and left portions
  • Midsagittal (median) plane: divides the body into equal left and right halves
  • Parasagittal plane: divides the body into unequal left and right portions
• Frontal (coronal) plane: divides the body into front and back portions
• Transverse (horizontal, axial) plane: divides the body into upper and lower portions

Anatomical Axes

• Axes are imaginary lines that pass perpendicularly through a plane at joints
• Horizontal (transverse) axis: passes through the body from side to side
• Anteroposterior (sagittal) axis: passes through the body from front to back
• Longitudinal (vertical) axis: passes through the body from top to bottom

Types of Joints

• Joints are the sites where two or more bones meet
• Joints are classified by the tissue connecting the articulating bones

  • Fibrous: immovable

    • Sutures: skull bones
    • Syndesmoses: inferior tibiofibular joint
    • Gomphoses: teeth in sockets

  • Cartilaginous: slightly movable

    • Primary (synchondroses): temporary, hyaline cartilage
      • Examples: sternocostal joints
    • Secondary (symphyses): permanent, fibrocartilage
      • Examples: intervertebral discs, symphysis pubis

  • Synovial: freely movable

    • Plane: flat surfaces, gliding movements (e.g., between carpals)
    • Hinge: cylindrical projection fits into a trough, flexion and extension only (e.g., elbow, interphalangeal)
    • Pivot: rounded end protrudes into a sleeve of bone or ligament, rotation only (e.g., between axis and dens of atlas, proximal radioulnar)
    • Condyloid: oval surface fits into a complementary depression, permits angular motions (e.g., radiocarpal, metacarpophalangeal)
    • Saddle: each surface has both concave and convex surfaces, allows greater movement (e.g., carpometacarpal of thumb)
    • Ball-and-socket: spherical or hemispherical head of one bone fits into a cuplike socket of another, permits most freely moving synovial joints (e.g., shoulder, hip)
• Gliding movements: one flat bone surface glides over another

Movements at Joints

• Flexion: bending a joint and decreasing the angle between two bones

• Extension: straightening a joint and increasing the angle between two bones

• Hyperextension: bending a part of the body beyond its anatomical position

• Abduction: moving a body part away from the midline

• Adduction: moving a body part toward the midline

• Pronation: turning the forearm medially, so the palm faces downward

• Supination: turning the forearm laterally, so the palm faces upward

• Elevation: raising a body part

• Depression: lowering a body part

• Protraction: moving a body part forward

• Retraction: moving a body part backward

• Rotation: turning a body part around its long axis

• Circumduction: moving a body part in a circular motion

• Lateral flexion: side-bending left or right

• Inversion: turning the sole of the foot inward

• Eversion: turning the sole of the foot outward

• Dorsiflexion: movement at the ankle joint bringing the foot towards the shin

• Plantarflexion: movement at ankle joint pointing the foot downward

• Radial deviation: movement of the wrist toward the radius or lateral side

• Ulnar deviation: movement of the wrist toward the ulna or medial side

• Movements of fingers: abduction, adduction, flexion, extension

• Movements of thumb: flexion, extension, abduction, adduction, opposition, repositioning