Level of Body Organization
The Eleven Systems of The Human Body
ANATOMICAL TERMINOLOGY
Anatomical Terms
Anatomical Position and Directional Terms
• Standard Anatomical Position
– Body erects, feet slightly apart, palms facing forward with thumbs pointing away from body
• Directional terms describe one body structure in relation to another body structure
– Direction is always based on standard anatomical position
– Right and left refer to the body being viewed, not right and left of observer
Regional Terms
• Two major divisions of body
– Axial (Head, neck, and trunk)
– Appendicular (Limbs (legs and arms))
• Regional terms designate specific areas within body divisions
Body Planes and Sections
• Body planes
– Surfaces along which body or structures may be cut for anatomical study
– Three most common planes:
• Sagittal plane
• Frontal (coronal) plane
• Transverse (horizontal) plane
• Sections
– Cuts or sections made along a body plane
• Named after plane, so a sagittal cut results in a sagittal section
• Sagittal plane
– Divides body vertically into right and left parts
– Produces a sagittal section if cut along this plane
- Midsagittal (median) plane
• Cut was made perfectly on midline
– Parasagittal plane
• Cut was off-centered, not on midline
• Frontal (coronal) plane
– Divides body vertically into anterior and posterior parts (front and back)
– Produces a frontal or coronal section
• Transverse (horizontal) plane
– Divides body horizontally (90° to vertical plane) into superior and inferior parts (top and bottom)
– Produces a cross section
• Oblique section
– Result of cuts at angle other than 90° to vertical plane
Body Cavities and Membranes
• Body contains internal cavities that are closed to environment
• Cavities provide different degrees of protection to organs within them
• Two sets of cavities:
– Dorsal body cavity
– Ventral body cavity
Dorsal Body Cavity
• Protects fragile nervous system
• Two subdivisions
– Cranial cavity
• Encases brain
– Vertebral cavity
• Encases spinal cord
Ventral Body Cavity
•
Houses the internal organs (collectively called viscera)
• Two subdivisions, which are separated by the diaphragm:
– Thoracic cavity
– Abdominopelvic cavity
• Thoracic cavity
– Two pleural cavities
• Each cavity surrounds one lung
– Mediastinum
• Contains pericardial cavity
• Surrounds other thoracic organs, such as esophagus, trachea, etc.
– Pericardial cavity
• Encloses heart
• Abdominopelvic cavity
– Abdominal cavity
• Contains stomach, intestines, spleen, and liver
– Pelvic cavity
• Contains urinary bladder, reproductive organs, and rectum
Clinical – Homeostatic Imbalance 1.1
Whereas the pelvic bones provide limited protection to the pelvic cavity, the walls of abdominal cavity
are formed by muscle only, so organs in this area are most vulnerable to trauma.
Ventral Body Cavity (cont.)
• Membranes in ventral body cavity
– Serosa (also called serous membrane)
• Thin, double-layered membranes that cover surfaces in ventral body cavity
– Parietal serosa lines internal body cavity walls
– Visceral serosa covers internal organs (viscera)
• Double layers are separated by slit-like cavity filled with serous fluid
• Fluid secreted by both layers of membrane
• Named for specific cavity and organs that they are associated with
– Pericardium
• Heart
– Pleurae
• Lungs
– Peritoneum
• Abdominopelvic cavity
Clinical – Homeostatic Imbalance 1.2
• Serous membranes can become inflamed because of infection or other causes
• Normally smooth layers can become rough and even can stick together, resulting in excruciating pain
• Examples: pleurisy and peritonitis
Abdominopelvic quadrants and regions
– Quadrants are divisions used primarily by medical personnel
• Abdominopelvic region is sectioned into quarters:
– Right upper quadrant (RUQ)
– Left upper quadrant (LUQ)
– Right lower quadrant (RLQ)
– Left lower quadrant (LLQ)
– Nine divisions called regions, resembling a tic-tactoe grid, are used primarily by anatomists
• Right hypochondriac region
• Umbilical region
• Epigastric region
• Right Iliac (inguinal) region
• Left hypochondriac region
• Hypogastric region
• Right lumbar region
• Left iliac (inguinal) region
Other Body Cavities:
• In addition to the two main body cavities, the body has several smaller cavities that are exposed to
environment
– Oral and digestive cavities
– Nasal cavity
– Orbital cavities
– Middle ear cavities
• Not exposed to environment
– Synovial cavities: joint cavities
Anatomical Terms of Movement
Flexion is a movement that decreases the angle between body parts.
Extension is a movement that increases the angle between body parts.
Abduction is a motion that pulls a structure away from the midline of the body or limb.
Adduction is a motion that pulls a structure towards the midline of the body or limb.
Medial rotation is rotation towards the center of the body.
Lateral rotation is rotation away from the center of the body.
Elevation is movement in a superior direction.
Depression is movement in an inferior direction.
Circumduction is a circular movement.
Special motions of the hands and feet
Dorsiflexion is flexion of the foot at the ankle.
Plantarflexion is extension of the foot at the ankle.
Pronation is rotation of the forearm so that in the anatomical position the palm is facing posteriorly.
Supination is rotation of the forearm so that in the anatomical position the palm is facing anteriorly.
Eversion is a movement that tilt the sole of the foot away from the midline of the body.
Inversion is a movement that tilt the sole of the foot towards the midline of the body.
Opposition is a movement that brings two opposing digits together.