Introduction to Anatomy: Positions & Terms

Introduction to Anatomy

• Anatomy is the study of the structure of the body.
• In Greek, anatomy means "to cut."
• In Latin, anatomy means "to dissect."
• Anatomy is studied at different levels:
  • Macroscopic or gross anatomy, which examines large structures.
  • Microscopic anatomy or histology, which examines small structures.
  • Radiological anatomy, which uses imaging techniques.

Anatomical Position

• Anatomical position is a standard reference position.
• It's used for accurate description of body parts.
• The body is standing upright, feet flat on the floor, and facing forward.
• Arms are at the sides, with palms facing forward.

Other Body Positions

• Supine: lying face up
• Prone: lying face down
• Right lateral: lying on the right side
• Left lateral: lying on the left side

Anatomical Terms of Position

• Superior: toward the head
• Inferior: away from the head
• 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: closer to the point of attachment
• Distal: farther from the point of attachment
• Superficial: closer to the surface
• Deep: farther from the surface

Anatomical Planes

• Midsagittal plane: divides the body into right and left halves.
• Paramedian plane: parallel to the midsagittal plane.
• Frontal (coronal) plane: divides the body into anterior (front) and posterior (back) portions.
• Transverse plane: divides the body into superior (upper) and inferior (lower) portions.

Coverings of the Body

• The body's coverings include skin and fascia.

The Skin

• The skin is the largest organ of the body.
• It protects the underlying tissues.
• It defends against microorganisms.
• It regulates body temperature.
• It helps in vitamin D production.
• Skin absorbs certain substances.
• Skin has sensory nerve endings for external environment awareness.

Skin Structure

• Epidermis: The superficial layer of skin.
  • Composed of several layers of cells.
  • Contains keratin, a water-insoluble protein.
  • Is devoid of blood vessels.
• Dermis: The deep connective layer of skin.
  • Contains blood vessels, nerves, hair follicles, and glands.
• Hypodermis (superficial fascia): Layer below the dermis.

Thickness of the Epidermis

• Usually thin, except on palms and soles of feet.
• Extra thickness provides protection against friction.

Appendages of the Skin

• Hairs: Cover most of the body, except palms, soles, and lips. Moved by arrector pili muscles.
• Sebaceous Glands: Located within the dermis, secretes sebum (lubricant) for hair and skin.
• Sweat Glands: Tubular glands throughout the body; except red lips and nail beds; secretes sweat.
• Nails: Flat horny plates on the dorsal surface of the distal phalanges of fingers and toes. Composed of a root, body, nail fold, and bed.

Clinical Applications

• Pathogenic organisms can enter skin through nail folds, hair follicles, and sebaceous glands.
• Infection between nail and nail fold is called paronychia.

The Fascia

• Connective tissue lining the skin, supporting muscles, and separating them from bones.
• Superficial Fascia: Close to the skin; contains fat, blood vessels, nerves, and muscles; helps regulate body temperature.
• Deep Fascia: Dense layer between the superficial fascia and deeper structures. Supports and separates muscle groups. Can form retinaculae or aponeuroses around joints. Surrounds blood vessels and nerves, creates sheaths (carotid sheath).

Learn the basics of anatomy, including body positions like supine and prone, anatomical position, and directional terms such as superior and inferior. Understand macroscopic, microscopic, and radiological anatomy. Perfect for students of biology and medicine.