Anatomy: Structures and Systems

• Anatomy studies the structure of living organisms.
• Includes the study of cells, tissues, organs, and systems of the body.
• Foundational science for medicine and health professions.
• Provides a framework for understanding how the body works in health and disease.

Levels of Anatomical Study

• Gross Anatomy (Macroscopic Anatomy): Study of structures visible to the naked eye, without the aid of microscopy.
• Microscopic Anatomy (Histology): Study of structures at the microscopic level, using microscopes to examine tissues and cells.
• Developmental Anatomy (Embryology): Study of the development of the organism from fertilization to birth.
• Systemic Anatomy: Study of the body by systems, such as the skeletal, muscular, nervous, and cardiovascular systems.
• Regional Anatomy: Study of the body by regions, such as the head, neck, thorax, and abdomen.
• Surface Anatomy: Study of the external features of the body and their relationship to internal structures.
• Comparative Anatomy: Study of the anatomy of different species to understand evolutionary relationships.
• Clinical Anatomy: Application of anatomical knowledge to the diagnosis and treatment of disease.

Anatomical Position and Planes

• Anatomical Position: Standard reference position for describing the human body.
• Body is standing erect, facing forward, with arms at the sides and palms facing forward.
• Feet are parallel and flat on the floor.
• Importance: Provides a consistent frame of reference for anatomical descriptions and helps avoid confusion.
• Sagittal Plane: Vertical plane dividing the body into right and left parts.
• Midsagittal Plane (Median Plane): Sagittal plane lying exactly in the midline.
• Parasagittal Plane: Sagittal plane offset from the midline.
• Frontal Plane (Coronal Plane): Vertical plane dividing the body into anterior (ventral) and posterior (dorsal) parts.
• Transverse Plane (Horizontal Plane or Axial Plane): Horizontal plane dividing the body into superior (cranial) and inferior (caudal) parts.
• Oblique Plane: Any plane not sagittal, frontal, or transverse, passing through the body at an angle.

Anatomical Terms of Location and Direction

• Superior (Cranial or Cephalic): Toward the head or upper part of a structure.
• Inferior (Caudal): Away from the head or toward the lower part of a structure.
• Anterior (Ventral): Toward the front of the body.
• Posterior (Dorsal): Toward the back of the body.
• Medial: Toward the midline of the body.
• Lateral: Away from the midline of the body.
• Proximal: Closer to the origin or point of attachment of a limb to the trunk.
• Distal: Farther from the origin or point of attachment of a limb to the trunk.
• Superficial (External): Toward or on the surface of the body.
• Deep (Internal): Away from the surface of the body.
• Ipsilateral: On the same side of the body.
• Contralateral: On the opposite side of the body.

Anatomical Movements

• Terms describing the actions of muscles and joints.
• Flexion: Decreasing the angle between two body parts.
• Extension: Increasing the angle between two body parts.
• Abduction: Moving a limb away from the midline of the body.
• Adduction: Moving a limb toward the midline of the body.
• Rotation: Turning a bone around its longitudinal axis.
• Circumduction: Moving a limb in a circular motion.
• Pronation: Turning the palm of the hand posteriorly or inferiorly.
• Supination: Turning the palm of the hand anteriorly or superiorly.
• Dorsiflexion: Bending the foot upward at the ankle.
• Plantar Flexion: Bending the foot downward at the ankle.
• Inversion: Turning the sole of the foot medially.
• Eversion: Turning the sole of the foot laterally.
• Protraction: Moving a part of the body forward.
• Retraction: Moving a part of the body backward.
• Elevation: Raising a part of the body.
• Depression: Lowering a part of the body.

Body Cavities

• Spaces within the body that contain and protect internal organs.
• Dorsal Body Cavity: Located near the posterior (dorsal) surface of the body.
• Cranial Cavity: Contains the brain.
• Vertebral Canal: Contains the spinal cord.
• Ventral Body Cavity: Located near the anterior (ventral) surface of the body.
• Thoracic Cavity: Superior to the diaphragm; contains the heart and lungs.
• Pleural Cavities: Each surrounds a lung.
• Pericardial Cavity: Surrounds the heart.
• Mediastinum: Central part of the thoracic cavity; contains the heart, great vessels, trachea, esophagus, and thymus.
• Abdominopelvic Cavity: Inferior to the diaphragm; contains the abdominal and pelvic organs.
• Abdominal Cavity: Contains the stomach, intestines, liver, gallbladder, pancreas, spleen, and kidneys.
• Pelvic Cavity: Contains the urinary bladder, rectum, and reproductive organs.
• Serous Membranes: Thin, double-layered membranes lining the ventral body cavities and covering the organs within.
• Parietal Layer: Lines the cavity walls.
• Visceral Layer: Covers the organs.
• Serous Fluid: Lubricating fluid between the parietal and visceral layers reducing friction.

Skeletal System

• Bones, cartilage, ligaments, and joints.
• Provides support, protection, movement, mineral storage, and blood cell formation.
• Axial Skeleton: Skull, vertebral column, and rib cage.
• Appendicular Skeleton: Bones of the limbs and their girdles (pectoral and pelvic).
• Bone Types: Long, short, flat, irregular, and sesamoid.
• Bone Markings: Depressions, openings, and projections serving as attachment sites for muscles and ligaments, passageways for blood vessels and nerves, or articulating surfaces between bones.
• Joints (Articulations): Where two or more bones meet.
• Fibrous Joints: Immovable or slightly movable.
• Cartilaginous Joints: Slightly movable.
• Synovial Joints: Freely movable.

Muscular System

• Skeletal muscles, smooth muscles, and cardiac muscle.
• Responsible for movement, posture, heat production, and protection.
• Skeletal Muscles: Attached to bones and responsible for voluntary movement.
• Smooth Muscles: Found in the walls of internal organs and blood vessels; responsible for involuntary movement.
• Cardiac Muscle: Found in the heart; responsible for pumping blood.
• Muscle Actions: Flexion, extension, abduction, adduction, rotation, etc.
• Muscle Innervation: Nerves that supply muscles and control their function.

Nervous System

• Brain, spinal cord, nerves, and sensory receptors.
• Controls and coordinates bodily functions; responds to internal and external stimuli.
• Central Nervous System (CNS): Brain and spinal cord.
• Peripheral Nervous System (PNS): Nerves and sensory receptors outside the CNS.
• Neurons: Nerve cells that transmit electrical signals.
• Neuroglia: Supporting cells that protect and assist neurons.
• Sensory (Afferent) Neurons: Transmit impulses from sensory receptors to the CNS.
• Motor (Efferent) Neurons: Transmit impulses from the CNS to effectors (muscles or glands).

Endocrine System

• Glands that secrete hormones into the bloodstream.
• Regulates bodily functions through hormones.
• Major Endocrine Glands: Pituitary, thyroid, parathyroid, adrenal, pancreas, ovaries, and testes.
• Hormones: Chemical messengers traveling through the bloodstream to target cells.

Cardiovascular System

• Heart, blood vessels, and blood.
• Transports oxygen, nutrients, hormones, and waste products throughout the body.
• Heart: Pumps blood through the circulatory system.
• Blood Vessels: Arteries, veins, and capillaries.
• Arteries: Carry blood away from the heart.
• Veins: Carry blood toward the heart.
• Capillaries: Smallest blood vessels; site of exchange between blood and tissues.

Lymphatic System

• Lymph vessels, lymph nodes, and lymphoid organs.
• Returns fluids to the bloodstream; involved in immunity.
• Lymph: Fluid circulating through the lymphatic system.
• Lymph Nodes: Filter lymph and house immune cells.
• Lymphoid Organs: Spleen, thymus, tonsils, and lymphatic nodules.

Respiratory System

• Lungs and air passageways.
• Exchanges gases (oxygen and carbon dioxide) between the air and the blood.
• Upper Respiratory Tract: Nose, pharynx, and larynx.
• Lower Respiratory Tract: Trachea, bronchi, and lungs.
• Alveoli: Air sacs in the lungs where gas exchange occurs.

Digestive System

• Alimentary canal (mouth, esophagus, stomach, small intestine, and large intestine) and accessory organs (liver, gallbladder, and pancreas).
• Breaks down food, absorbs nutrients, and eliminates waste.
• Mouth: Where digestion begins.
• Esophagus: Carries food to the stomach.
• Stomach: Stores food and mixes it with gastric juices.
• Small Intestine: Where most nutrient absorption occurs.
• Large Intestine: Absorbs water and electrolytes; forms and eliminates feces.
• Liver: Produces bile.
• Gallbladder: Stores bile.
• Pancreas: Produces digestive enzymes and hormones.

Urinary System

• Kidneys, ureters, urinary bladder, and urethra.
• Filters blood, eliminates waste, and regulates blood volume and pressure.
• Kidneys: Filter blood and produce urine.
• Ureters: Carry urine from the kidneys to the urinary bladder.
• Urinary Bladder: Stores urine.
• Urethra: Carries urine from the urinary bladder to the outside of the body.

Reproductive System

• Male Reproductive System: Testes, duct system, accessory glands, and penis.
• Female Reproductive System: Ovaries, uterine tubes, uterus, vagina, and mammary glands.
• Produces gametes (sperm and oocytes) and hormones; involved in reproduction.
• Testes: Produce sperm and testosterone.
• Ovaries: Produce oocytes and estrogen/progesterone.
• Uterus: Site of implantation and fetal development.