Anatomical Planes, Directions, Movements, Positions, and Levels of Organization

Anatomical Planes

  • Sagittal plane
    • Divides the body into right and left halves.
    • Sagittal comes from Latin, meaning arrow; the sagittal plane is described as an arrow passing through the body to separate right and left aspects.
  • Coronal plane (also called the frontal plane)
    • Divides the body into front and back portions.
    • Passes through the coronal suture (also called the crowning suture) in the middle of the skull, dividing the skull into a front part and a back part.
    • This gives rise to the terms coronal plane and coronal suture.
  • Transverse plane (also known as the horizontal plane)
    • Trans means across; horizon runs from right to left.
    • Divides the body into an upper and a lower portion.
  • Practical note
    • These planes can be used with reference to the entire body or to any aspect of the body.
    • Example: planes of the heart (demonstrating reference planes within an organ).
  • Medial (median) plane
    • Medial aspect refers to toward the middle.
    • The medial aspect of the entire body is toward the midline.

Anatomical Body Directions

  • 1. Lateral

    • Latin: Lat; means the side.

  • 2. Central portion

    • Central means the center of something.
    • The belly button is the center or central aspect of the human body in its entirety.
    • The fingers are usually lateral to the body's midline.

  • 3. Posterior

    • Means lies behind or after.
    • In the anatomical position, dorsal can mean the same as posterior.

  • 4. Anterior; Ventral

    • Anterior refers to the foremost part of the body.
    • Ventral is sometimes used to refer to the anterior aspect of the human body in a normal anatomical position.
    • If not referring to the human anatomical position and using anterior, posterior, ventral, and dorsal, they would refer to different aspects of the body.
    • For clarity, these terms can be better understood with reference to an animal (e.g., a dog):
    • Anterior would be the dog’s head,
    • Posterior the tail,
    • Dorsal the upper back,
    • Ventral the belly.

  • 5. Superior

    • Means above.
    • Supra also means above; hyper can occasionally be used to refer to above.

  • 6. Inferior

    • Means below.
    • Infra and hypo also mean below.

  • 7. Cranial

    • Pertains to the skull.

  • 8. Caudal

    • Pertains to the tail.

  • 9. Proximal

    • Means closest to, or the first segment of a finger or toe.
    1. Distal
    • Means the last segment, or the part that's furthest away.
    1. Cephalic
    • Pertains to the head.
    1. Plantar
    • Pertains to the sole of the foot (e.g., plantar warts).
    1. Palmar
    • Pertains to the palm of the hand.

  • Note on movement terminology

    • The terms above are easy to use for describing a non-moving body.
    • Describing movement requires specific movement terms, discussed in the next section.

Anatomical Movement Terms

  • Flexion
    • The process of bending.
  • Extension
    • The process of stretching outward.
  • Pronation
    • Turning something downward; the body or hand in a downward position.
  • Supination
    • Turning something upward; the body or hand with the palm facing up.
    • Example: cupping the hand to catch water or hold snacks reflects a supinated hand with the palm facing upward.
  • Supine position
    • Lying on the back; the body is face up.
  • Prone position
    • Lying on the stomach; the body is face down.
    • Arms may be positioned at angles to the body as shown in typical demonstrations.
  • Recovery position
    • Used to minimize movement until normal body functions can be restored.
  • Anatomical position
    • The standard reference position: the body is erect, with hands turned forward and palms facing outward.
  • Supine position (reiterated)
    • The term can apply to any body part in an upward position.
  • Prone position (reiterated)
    • A patient is placed face down; arms may be at angles to the body as described.

Body Positions

  • Dorsal recumbent position
    • The patient is on their back with knees bent up and usually in stirrups.
    • This is a birthing position and is used for female pelvic exams and other procedures (e.g., vasectomies).
  • Dorsal sacral position / Lithotomy position
    • The patient is flat on their back with the knees drawn up much higher toward the chest area.
  • Knee-chest (Genupectoral) position
    • The patient is on their knees with the chest facing down.
  • Sims position
    • The patient is on their left side with the right knee drawn up and the left arm along the back, chest leaned forward.
  • Fowler's position
    • The head is raised up to a modified sitting position in bed.
  • Trendelenburg position
    • The patient lies flat on their back with the head lower than the feet.
  • Apostatinous position
    • Not an anatomical position or a position used for an exam or recovery.
    • It is described as being adopted by a patient with nervous system complications (e.g., meningitis, encephalitis, cerebral palsy) where the patient arches their back upwards with the back of the head pressed against the bed surface.

Levels of Organization

  • All life can be organized into different levels of structural organization.
  • These levels start from the smallest and most simplistic life forms or parts and progress in size and complexity with each level.
  • Each level feeds into the next, progressively increasing in size and complexity.
  • In the human body, the levels are:
    • Cells
    • Tissues (multiple cells forming tissues)
    • Organs (tissues forming organs)
    • Organ systems (organs forming organ systems)
    • Body or organism (integration of organ systems)