The Human Body: Anatomical Regions, Directions, and Body Cavities

The Human Body: Anatomical Regions, Directions, and Body CavitiesOverview of AnatomyAnatomy the study of the structure of body parts and their relationships to one anotherGross or macroscopicMicroscopicDevelopmentalGross AnatomyRegional all structures in one part of the body (such as the abdomen or leg)Systemic gross anatomy of the body studied by systemSurface study of internal structures as they relate to the overlying skinMicroscopic AnatomyCytology study of the cell

Histology study of tissuesDevelopmental AnatomyTraces structural changes throughout life

Embryology study of developmental changes of the body before birthSpecialized Branches of AnatomyPathological anatomy study of structural changes caused by disease

Radiographic anatomy study of internal structures visualized by X ray

Molecular biology study of anatomical structures at a sub-cellular level

Chemical levelAtoms combine to form molecules1234Cellular levelCells are made up of moleculesTissue levelTissues consist of similar types of cells5Organ system levelOrgan systems consist of different organs that work together closelyOrgan levelOrgans are made up of different types of tissues6Organismal levelThe human organism is made up of many organ systemsAtomsMoleculesSmooth muscle cellSmooth muscle tissueConnective tissueSmooth muscle tissueEpithelial tissueBlood vessel (organ)HeartBlood vesselsCardiovascular systemLevels of Structural OrganizationFigure 1.1Levels of Structural OrganizationChemical atoms combined to form moleculesCellular cells are made of moleculesTissue consists of similar types of cellsOrgan made up of different types of tissuesOrgan system consists of different organs that work closely togetherOrganismal made up of the organ systemsHomeostasisHomeostasis is the ability to maintain a relatively stable internal environment in an ever-changing outside worldThe internal environment of the body is in a dynamic state of equilibriumChemical, thermal, and neural factors interact to maintain homeostasisAnatomical PositionBody erect Feet slightly apartPalms facing forward Thumbs point away from bodyFigure 1.7a

Directional TermsSuperior and inferior toward and away from the head, respectivelyAnterior and posterior toward the front and back of the bodyMedial, lateral, and intermediate toward the midline, away from the midline, and between a more medial and lateral structureDirectional TermsProximal and distal closer to and farther from the origin of the body

Superficial and deep toward and away from the body surfaceDirectional TermsTable 1.1

Directional TermsTable 1.1

Regional Terms: Anterior ViewAxial head, neck, and trunkAppendicular appendages or limbsSpecific regional terminology

Figure 1.7aRegional Terms: Posterior ViewFigure 1.7b

Body PlanesSagittal divides the body into right and left partsMidsagittal or medial sagittal plane that lies on the midlineFrontal or coronal divides the body into anterior and posterior partsTransverse or horizontal (cross section) divides the body into superior and inferior partsOblique section cuts made diagonallyBody Planes

Figure 1.8Anatomical VariabilityHumans vary slightly in both external and internal anatomyOver 90% of all anatomical structures match textbook descriptions, but:Nerves or blood vessels may be somewhat out of placeSmall muscles may be missing Extreme anatomical variations are seldom seenBody CavitiesFigure 1.9a

Body CavitiesDorsal cavity protects the nervous system, and is divided into two subdivisionsCranial cavity is within the skull and encases the brainVertebral cavity runs within the vertebral column and encases the spinal cordVentral cavity houses the internal organs (viscera), and is divided into two subdivisions: - Thoracic and Abdominopelvic cavitiesBody CavitiesFigure 1.9b

Body CavitiesThoracic cavity is subdivided into pleural cavities, the mediastinum, and the pericardial cavityPleural cavities each houses a lungMediastinum contains the pericardial cavity, and surrounds the remaining thoracic organsPericardial cavity encloses the heartBody CavitiesThe abdominopelvic cavity is separated from the superior thoracic cavity by the dome-shaped diaphragmIt is composed of two subdivisionsAbdominal cavity contains the stomach, intestines, spleen, liver, and other organsPelvic cavity lies within the pelvis and contains the bladder, reproductive organs, and rectumVentral Body Cavity MembranesParietal serosa lines internal body walls

Visceral serosa covers the internal organs

Serous fluid separates the serosae

Ventral Body Cavity Membranes

Figure 1.10aVentral Body Cavity MembranesFigure 1.10b

Other Body CavitiesOral and digestive mouth and cavities of the digestive organsNasal located within and posterior to the noseOrbital house the eyesMiddle ear contain bones (ossicles) that transmit sound vibrationsSynovial joint cavitiesAbdominopelvic RegionsUmbilicalEpigastricHypogastricRight and left iliac or inguinalRight and left lumbarRight and left hypochondriac

Figure 1.11aOrgans of the Abdominopelvic RegionsFigure 1.11b

Abdominopelvic QuadrantsRight upper (RUQ)Left upper (LUQ)Right lower (RLQ)Left lower (LLQ)

Figure 1.12