Human Body Orientation - Chapter 1

Chapter 1 - Orientation of the Human Body

• Anatomy: Study of the structure of the human body
• Gross anatomy: Visible with the naked eye (e.g., dissections)
• Microscopic anatomy: Structures seen only with a microscope (e.g., histology)
• Surface anatomy: Visible structures on the surface of the body

Hierarchy of Structural Organization

• Chemical level: Atoms forming molecules (e.g., 90% of the human body is composed of C, H, O, N).
• Cellular level: Cells and their subunits. 50-100 trillion cells, constantly forming and dying.
• Tissue level: Groups of similar cells working together (epithelial, connective, muscle, nervous).
• Organ level: Discrete structures with defined borders, containing more than one tissue type; examples include bones, blood vessels.
• Organ system level: Organs working together for a common function (e.g., digestive system).
• Organismal level: The whole functioning body.

Anatomical Terminology

• Anatomical position: Standing upright, feet together, palms forward, thumbs pointed away from the body.
• Directional terms: Used to describe locations relative to the anatomical position (e.g., superior/cranial, inferior/caudal, anterior/ventral, posterior/dorsal). These are often used in relation to the body's reference frame.
• Superior: Toward the head.
• Inferior: Away from the head.
• Anterior/Ventral: Towards the front of the body.
• Posterior/Dorsal: Towards the back of the body.

Body Regions

• Axial region: Head, neck, and torso.
  • Cephalic (head): Nasal (nose), Oral (mouth), Cervical (neck).
  • Thorax (chest): Axillary (armpit), and chest.
  • Abdominal: Umbilical (navel area), rest of abdomen, vertebral (around spine), back/dorsal, gluteal (butt).
• Appendicular region: Limbs (upper and lower).
  • Upper limb: Acromial (shoulder), Brachial (arm), Antebrachial (forearm), Carpal (wrist), Pollex (thumb), Digital (fingers, toes), Palmar (hand), Coxal (hip), Femoral (thigh), Popliteal (back of knee), Crural (leg), Hallux (big toe).
  • Lower limb: Same terms as above but for the lower body

Body Planes and Sections

• Coronal/frontal plane: Divides the body into front and back.
• Sagittal plane: Divides the body into left and right halves.
  • Median/midsagittal: Divides the body into equal halves.
• Transverse plane: Divides the body into top and bottom portions (cross-section).
• Oblique plane: Divides the body along an angle other than those listed above.

Body Cavities

• Dorsal body cavity: Posterior cavity, protects nervous system.

  • Cranial cavity: Contains the brain.
  • Vertebral cavity: Contains the spinal cord.

• Ventral body cavity: Anterior cavity, contains organs of the internal systems.

  • Thoracic cavity: Contains the heart and lungs.
  • Superior mediastinum: Upper region of the thoracic cavity.
  • Pleural cavities: Contain the lungs. Pericardial cavity contains the heart.
  • Abdominal cavity: Contains organs of digestion; separated from the thoracic cavity by the diaphragm.
  • Pelvic cavity: Contains bladder, reproductive organs, and rectum.

• Abdominopelvic cavity: Abdominal and pelvic cavities together (sometimes used interchangably).

• Membranes: Lining these body cavities are often serous membranes with a parietal (outer) and visceral (inner layer). They reduce friction.

Abdominal Regions

• Using 4 quadrants or 9 regions: Right and left upper/lower quadrants, and regions like hypochondriac, umbilical, iliac.
• Retroperitoneal organs: Organs are outside the peritoneal cavity but close to the abdominal wall like the kidneys.

This quiz covers the foundational concepts of human body orientation, including the various levels of structural organization such as chemical, cellular, tissue, organ, organ system, and organismal levels. It also explores the different branches of anatomy, like gross and microscopic anatomy, along with essential anatomical terminology.