Overview of Anatomy and Its Branches

Study Notes

Anatomy is the branch of science that deals with the form and structure of tissues and organs in the body. The word "Anatomy" originates from Greek and means "cutting a part".
Gross (or macroscopic) anatomy studies large structures.
Microscopic anatomy (or Histology) investigates finer details of structure and minute organisms.
Developmental anatomy (or Embryology) examines changes organisms undergo throughout development, usually focusing on early phases when tissues and organs form.
Ontogeny is the term for the full development of an individual.
Phylogeny is the historical development of a species, relating the anatomy of an individual to its ancestors.
Comparative anatomy describes and compares the structure of animals, forming the basis for animal classification and elucidating the significance of many structural facts. It provides general laws of form and structure (morphology) or philosophical anatomy.
Special anatomy describes the structure of a particular type or species (e.g., anthropotomy, hippotomy).
Veterinary anatomy is the branch that examines the structures of domesticated animals, often using the horse as a primary study subject.

The body is viewed as a collection of systems with similar origins and structures, associated in function.
Divisions of systematic anatomy include:
- Osteology: studies bones and cartilages for support and protection.
- Arthrology: studies joints for movement and connecting bones.
- Myology: studies muscles and their accessory structures for movement.
- Splanchnology, including:
  - Digestive system
  - Respiratory system
  - Urogenital system (including urinary and genital organs).
- Angiology: studies the circulatory system (heart, arteries, veins, lymphatics).
- Neurology: studies the nervous system for control and coordination.
- Esthesiology (Sense Organs): studies the eye and ear.
- Common Integument: studies the skin and its functions in protection.

It methodically determines the positions of body parts and structures, assuming a quadruped in its normal standing posture.
Topographic terms are used to indicate positions and directions.

Median plane: divides the body into right and left halves (similarly in extremities).
Sagittal planes: run parallel to the median plane.
Paramedian planes are near the median plane.
Transverse planes (or horizontal): perpendicular to the long axis.
Frontal (coronal): perpendicular to the median and transverse planes.
Medial: near the median plane.
Lateral: further from the median plane.
Cranial (anterior): toward the head.
Caudal (posterior): toward the tail.
Rostral: near the head (often in the head region).
Ventral: toward the belly.
Dorsal: opposite of ventral.
Superficial, deep (profundus): relative distance from the surface.
Proximal: closer to the body axis.
Distal: further from the body axis.
Cranial (in limbs): above; caudal (below).
Plantar (in hind limbs): below; dorsal (above).

Osteology: the study of bones.
The skeleton is a framework of hard structures (bones, cartilages) supporting and protecting soft tissues.
Classification of the skeleton:
- Endoskeleton: embedded within soft tissues (mostly mesodermal origin, except in primitive axial skeleton).
- Exoskeleton: external structure (e.g., shells, scales, hairs).
Bones are classified as long, flat, short, and irregular based on shape.

Compact (cortical) and spongy (cancellous) substance are found in a long bone's structure.
The bone marrow fills the spongy bone and medullary cavity, sometimes being categorized as red (blood-forming) or yellow (fatty).
The periosteum is a membrane covering the bone (except cartilage-covered areas), with an outer fibrous layer and an inner cellular layer.
The endosteum is a thin membrane lining the marrow cavity.
Blood vessels and nerves supply the bone, passing through Haversian canals.
Bone is composed of organic (mostly collagen) and inorganic (mostly calcium and phosphorus) materials with varying proportions. Bone tissues contain bone cells, bone matrix, collagen fibers, and various minerals giving toughness and elasticity along with rigidity and hardness.