General Anatomy Lecture 1: Introduction to Human Anatomy

Introduction to Human Anatomy

• Anatomy is the science that deals with the structures of all parts of the body, their function, relation, microscopical organization, and process by which they developed.
• The word "anatomy" comes from the Greek words "ana" meaning "up" and "tome" meaning "cut" or "dissect".

Branches of Anatomy

• Gross Anatomy (Macroscopic Anatomy): studies structures visible to the naked eye, such as external and internal bodily organs.
• Microscopical Anatomy (Histology): studies small structures that can only be seen with a microscope.
• Neuroanatomy: studies the central and peripheral nervous system, both grossly and microscopically.
• Pathological Anatomy: deals with morphologic changes in tissues, both grossly and microscopically.
• Radiological Anatomy: studies body structures using radiography and other imaging methods, such as ultrasound, CT scans, and MRI.

Levels of Organization of the Human Body

• Atom: the basic and fundamental unit of matter.
• Molecule and Macromolecule: formed by chemical bonds between two or more atoms.
• Organelle: a group of molecules.
• Cell: formed by a group of organelles.
• Tissue: a combination of different types of cells that perform specialized functions.
• Organ: a structure composed of two or more tissue types.
• Organ System: a group of organs that work together to perform major functions.
• Organism: the highest level of organization, a living subject with a cellular structure that can perform all physiologic functions necessary for life.

Body Regions

• The entire human body is divided into regions, including:
  • Head and neck
  • Chest
  • Abdomen and pelvis
  • Upper extremities
  • Lower extremities
• Each main region is divided into several smaller regions.

Body Cavities

• A body cavity is a space or compartment that accommodates organs and contains fluid.
• There are two major body cavities:
  • Dorsal body cavities:
    • Cranial cavity contains the brain
    • Vertebral cavity contains the spinal cord
  • Ventral body cavity:
    • Thoracic cavity contains pericardial and pleural cavities
    • Abdominal cavity contains esophagus, stomach, large intestine, small intestine, liver, spleen, pancreas, and kidneys
    • Pelvic cavity contains urinary bladder and ureter

Anatomical Position

• The standard anatomical position of the human body is standing upright and facing forward with the legs parallel to each other.
• The upper limbs hang at either side, and the palms face forward.

Anatomical Planes

• The anatomical planes are imaginary planes used to describe the location of structures in human anatomy.
• There are four anatomical planes:
  • Sagittal plane: a vertical plane that passes through the body longitudinally, dividing it into a left and right section.
  • Median (mid sagittal) plane: a vertical plane that passes down the midline of the body, separating it into equal halves.
  • Coronal plane: a vertical plane that passes through the body longitudinally, dividing it into a front (anterior) and back (posterior) section.
  • Transverse plane (cross section): a horizontal plane that divides the body into an upper (superior) and lower (inferior) section.

Descriptive Terms of Position

• Anterior (ventral): toward the front
• Posterior (dorsal): toward the back
• Medial: toward the midline of the body
• Lateral: away from the midline of the body
• Proximal: near the origin of the structure
• Distal: away from the origin of the structure
• External: toward the surface (superficial)
• Internal: away from the surface (deep)
• Superior: up toward the head
• Inferior: down toward the foot
• Central: at the midline
• Peripheral: away from the midline

Descriptive Terms of Movement

• Flexion: bend the joint
• Extension: make the joint straight
• Abduction: move the structure away from the midline
• Adduction: move the structure toward the midline
• Pronation: move the palm of the hand upward
• Supination: move the palm of the hand downward
• Inversion: move the sole of the foot toward the midline
• Eversion: move the sole of the foot away from the midline
• Dorsiflexion: stand on the heel
• Plantar flexion: stand on the toes
• Depression: move the part downward
• Elevation: move the part upward

Body Tissues

• Tissue is a group of cells that have similar structure and function together as a unit.
• There are four main types of body tissues:
  • Epithelial tissues: form the covering of all body surfaces, line body cavities, and are the major tissue in glands.
  • Connective tissues: bind structures together, form a framework and support for organs, store fat, transport substances, protect against disease, and help repair tissue damage.
  • Muscle tissue: composed of cells that have the special ability to shorten or contract in order to produce movement of body parts.
  • Nervous tissue: responsible for coordinating and controlling all body activities.

Body Membranes

• Body membranes are thin sheets of tissue that cover the body, line body cavities, and cover organs within the cavities.
• There are two main categories of body membranes:
  • Epithelial tissue membranes: include mucous, serous, and cutaneous membranes.
  • Connective tissue membranes: include synovial membranes and meninges.