Introduction to Anatomy

• Anatomy is the study of the body's structure and the relationships among its parts.
• Branches of anatomy include gross anatomy, microscopic anatomy (histology), developmental anatomy (embryology), and radiographic anatomy.

Gross Anatomy

• Gross anatomy, or macroscopic anatomy, studies body structures visible to the naked eye.
• Systemic anatomy studies the body by systems like skeletal, muscular, nervous, and cardiovascular systems.
• Regional anatomy studies the body by regions (e.g., head, neck, thorax, abdomen).
• Surface anatomy studies external body features to understand internal structures.

Microscopic Anatomy (Histology)

• Microscopic anatomy studies structures at the microscopic level.
• Histology is the study of tissues, which are groups of cells performing specific functions.
• Cytology studies cells, including their structure, function, and life cycle.

Developmental Anatomy (Embryology)

• Studies changes from conception to birth.
• Embryology focuses specifically on embryo development.

Radiographic Anatomy

• Radiographic anatomy studies body structures using imaging techniques like X-rays, CT scans, and MRIs.

Anatomical Position

• Anatomical position is a standardized reference point for describing body part locations consistently.
• Characterized by: body erect, feet slightly apart, palms facing forward, and thumbs pointing away from the body.

Anatomical Terminology

• Provides precise language for describing body structures and their relationships.

Directional Terms

• 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.
• 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 of a body part or the point of attachment of a limb to the body trunk.
• Distal: Farther from the origin of a body part or the point of attachment of a limb to the body trunk.
• Superficial (external): Toward or at the body surface.
• Deep (internal): Away from the body surface.

Regional Terms

• Axial Region: Includes the head (cephalic), neck (cervical), trunk (thoracic, abdominal, pelvic, and back).
• Appendicular Region: Includes the upper limb (shoulder, arm, forearm, wrist, and hand) and lower limb (thigh, leg, ankle, and foot).

Planes of the Body

• Sagittal Plane: Divides the body into right and left parts.
  • Midsagittal (median) plane: Divides the body into equal right and left halves.
  • Parasagittal plane: Offset from the midline.
• Frontal (coronal) plane: Divides the body into anterior and posterior parts.
• Transverse (horizontal) plane: Divides the body into superior and inferior parts.

Body Cavities

• Dorsal Body Cavity:
  • Cranial cavity: Contains the brain.
  • Vertebral (spinal) cavity: Contains the spinal cord.
• Ventral Body Cavity:
  • Thoracic cavity: Contains the heart and lungs.
    • Pleural cavities: Each surrounds a lung.
    • Mediastinum: Contains the heart, esophagus, and trachea.
  • Abdominopelvic cavity: Contains abdominal and pelvic organs.
    • Abdominal cavity: Contains, stomach, intestines, liver, and other organs.
    • Pelvic cavity: Contains the bladder, reproductive organs, and rectum.

Skeletal System

• Provides support, protection, movement, mineral storage, and blood cell formation.

Types of Bones

• Long bones: Longer than they are wide (e.g., femur, humerus).
• Short bones: Cube-shaped (e.g., carpals, tarsals).
• Flat bones: Thin, flattened, and usually curved (e.g., skull bones, ribs).
• Irregular bones: Complex shapes (e.g., vertebrae, hip bones).
• Sesamoid bones: Embedded in tendons (e.g., patella).

Bone Structure

• Compact bone: Dense outer layer.
• Spongy bone: Inner layer with trabeculae.
• Periosteum: Outer covering.
• Endosteum: Inner lining.

Joints (Articulations)

• Fibrous joints: Immovable or slightly movable (e.g., sutures of the skull).
• Cartilaginous joints: Slightly movable (e.g., intervertebral discs).
• Synovial joints: Freely movable (e.g., knee, shoulder).

Muscular System

• Enables movement, maintains posture, and generates heat.

Types of Muscle Tissue

• Skeletal muscle: Voluntary, striated.
• Smooth muscle: Involuntary, non-striated.
• Cardiac muscle: Involuntary, striated.

Muscle Function

• Movement: Muscles contract to produce movement.
• Posture: Muscles maintain body posture.
• Heat Production: Muscle contraction generates heat.

Muscle Actions

• Flexion: Decreasing the angle between two bones.
• Extension: Increasing the angle between two bones.
• Abduction: Movement away from the midline.
• Adduction: Movement toward the midline.
• Rotation: Turning a bone around its longitudinal axis.
• Circumduction: Moving a limb in a circular motion.

Nervous System

• Controls and coordinates bodily functions.

Central Nervous System (CNS)

• Brain: Control center.
• Spinal cord: Connects the brain to the peripheral nervous system.

Peripheral Nervous System (PNS)

• Cranial nerves: Emerge from the brain.
• Spinal nerves: Emerge from the spinal cord.
• Divisions of the PNS:
  • Sensory (afferent) division: Transmits impulses from sensory receptors to the CNS.
  • Motor (efferent) division: Transmits impulses from the CNS to effectors (muscles and glands).
    • Somatic nervous system: Voluntary control of skeletal muscles.
    • Autonomic nervous system: Involuntary control of smooth muscle, cardiac muscle, and glands.
      • Sympathetic division: "Fight or flight" response.
      • Parasympathetic division: "Rest and digest" response.
• Neurons transmit electrical signals.
• Neuroglia support and protect neurons.

Endocrine System

• Regulates body activities through hormones.
• Key endocrine glands:
  • Pituitary gland
  • Thyroid gland
  • Parathyroid glands
  • Adrenal glands
  • Pancreas
  • Ovaries (in females)
  • Testes (in males)
• Hormones travel through the bloodstream.

Cardiovascular System

• Transports blood, delivering oxygen, nutrients, and hormones, while removing waste products.
• Components:
  • Heart: Pumps blood.
  • Blood vessels: Arteries, veins, and capillaries.
  • Blood: Transports substances.
• Circulation:
  • Pulmonary circulation: Blood flow between the heart and lungs.
  • Systemic circulation: Blood flow between the heart and the rest of the body.

Lymphatic System

• Returns fluids to the bloodstream and plays a role in immunity.
• Components:
  • Lymph vessels
  • Lymph nodes
  • Lymphatic organs (spleen, thymus, tonsils)
• Functions:
  • Fluid recovery
  • Immunity
  • Lipid absorption

Respiratory System

• Enables gas exchange.
• Components:
  • Nose
  • Pharynx
  • Larynx
  • Trachea
  • Bronchi
  • Lungs
• Process:
  • Inspiration (inhalation)
  • Expiration (exhalation)

Digestive System

• Breaks down food, absorbs nutrients, and eliminates waste.
• Components:
  • Oral cavity
  • Esophagus
  • Stomach
  • Small intestine
  • Large intestine
  • Liver
  • Pancreas
  • Gallbladder
• Processes:
  • Ingestion
  • Digestion
  • Absorption
  • Elimination

Urinary System

• Eliminates waste, regulates blood volume and pressure, and controls electrolyte and acid-base balance.
• Components:
  • Kidneys
  • Ureters
  • Urinary bladder
  • Urethra
• Functions:
  • Filtration
  • Reabsorption
  • Secretion

Reproductive System

• Enables reproduction.

Male Reproductive System

- Testes
- Ducts
- Accessory glands
- Penis

Female Reproductive System

- Ovaries
- Uterine tubes
- Uterus
- Vagina
- Mammary glands

Integumentary System

• Protects the body, regulates temperature, and provides sensory information.
• Components:
  • Skin
  • Hair
  • Nails
  • Glands
• Functions:
  • Protection
  • Temperature regulation
  • Sensation
  • Vitamin D synthesis

Anatomy is the study of body structures and their relationships. It includes gross anatomy, which examines macroscopic structures through systemic, regional, and surface approaches. Microscopic anatomy, or histology, studies tissues and cells at a microscopic level.