Human Anatomy Introduction and Orientation

Human Anatomy Introduction and Orientation

• Definition of Anatomy: The study of an organism's structure and the relationship among its parts. It originated as "cutting up," using dissection to learn about the body's structure. The Greek and Latin roots are "ana" (up or through/between) and "tome" (a cutting).

Fields of Anatomy

• Gross (Macroscopic) Anatomy: Examines the general structures of the body visible to the naked eye.
• Microscopic Anatomy: Studies structures that require magnification, including:
  • Histology: Examines tissues.
  • Cytology: Studies the internal structure of cells.
• Developmental Anatomy (Embryology): Traces structural changes occurring throughout life, focusing on changes from conception to birth.
• Systemic Anatomy: Studies the organ systems, groups of organs working together
• Regional Anatomy: Studies all structures in a specific region (e.g., head and neck) simultaneously.
• Pathological Anatomy: Studies structural changes caused by diseases.
• Radiographic Anatomy: Studies internal structures using X-rays or specialized scanning procedures.
• Topographical Anatomy: Studies anatomy by identifying underlying structures via their visible contours on the surface.

Levels of Structural Organization

• Chemical level: Atoms combine to form molecules
• Cellular level: Cells are made of molecules
• Tissue level: Tissues consist of similar cell types
• Organ level: Organs are made up of different types of tissues
• Organ system level: Organ systems consist of different organs working together
• Organismal level: Human organisms are made up of many organ systems

Anatomical Position

• Body is erect.
• Upper limbs hang at the sides.
• Palms face forward.
• Fingers extended.
• Feet flat on the floor.
• Face directed forward (straight ahead).

Other Anatomical Positions

• Prone: Body lying horizontally, face down.
• Supine: Body lying horizontally, face up.
• Lateral Recumbent: Body lying on its side.
• Fowler's: Body lying on its back, head and torso elevated.
• Trendelenburg: Body lying on its back, head and torso tilted downward.

Directional Terms

• Anterior (Ventral): Toward the front of the body.
• Posterior (Dorsal): Toward the back of the body.
• Superior (Cranial): Toward the head or upper part of a structure.
• Inferior (Caudal): Away from the head or toward the lower part of a structure..
• Medial: Toward the midline of the body.
• Lateral: Away from the midline of the body.
• Proximal: Closer to the origin of a body part or the point of attachment of a limb.
• Distal: Farther from the origin of a body part or the point of attachment of a limb.
• Superficial: Toward or on the surface of the body.
• Deep: Away from the surface of the body.
• Internal: Inside a structure.
• External: Outside a structure.
• Parietal: Relating to the walls of body cavities.
• Visceral: Relating to the organs within body cavities.

Body Planes and Sections

• Body or its organs can be cut along imaginary planes to produce different sections.
• Sagittal plane (Median line): Divides the body into left and right portions.
• Frontal (Coronal plane): Divides the body into anterior and posterior portions.
• Transverse plane: Divides the body into superior and inferior portions

Body Cavities

• Cranial Cavity: Houses the brain.
• Spinal Cavity: Contains the spinal cord and meninges, extending from the foramen magnum to the sacrum.
• Thoracic Cavity: Contains respiratory, cardiovascular, digestive, urinary and reproductive systems. Separated from the abdominal cavity by the diaphragm. Contains these sub-cavities:
• Mediastinum(heart)
• Pleural cavity(lungs)
• Pericardial cavity
• Abdominopelvic Cavity: Large cavity below diaphragm.
• Subdivided into:
• Abdominal Cavity (stomach, intestines, liver, etc.)
• Pelvic Cavity (bladder, reproductive organs, etc.)
• Sub-regions can be denoted by quadrants or regions (see image of abdominal pelvic cavity on Figure 27)
• Other smaller cavities: oral, nasal, orbital, middle ear and joint cavities.

Membranes (Serous Membranes)

• Pericardium: Lines the pericardial cavity and covers the heart.
• Pleura: Lines the walls of the thoracic cavity and covers the lungs.
• Peritoneum: Lines the abdominopelvic cavity and covers the organs within that cavity.