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• Anatomy is the science that studies the form and structure of all organisms.
• Physiology studies the integrated functions of the body and all its parts including biophysical and biochemical processes.

Branches of Anatomy

• Gross or Macroscopic Anatomy studies structures visible without a microscope.
• Comparative Anatomy studies animal structures, emphasizing characteristics that aid classification.
• Embryology studies developmental anatomy from conception to birth.
• Microscopic Anatomy or Histology studies tissues and cells using a microscope.
• Ultrastructural cytology deals with portions of the cells and tissues (organelles and structures) as visualized with the aid of the electron microscope.

Nomenclature for Systemic Anatomy

• Osteology is the study of the skeletal system, whose chief structures are bones.
• Arthrology studies the articular system, whose chief structures are joints.
• Myology studies the muscular system, whose chief structures are muscles.
• Splanchnology studies the digestive and respiratory systems, whose chief structures are the stomach, intestines, lungs & airways,
• Urology studies the urinary system, whose chief structure is kidney & urinary bladder
• Endocrinology studies the endocrine system, whose chief structures are ductless glands.
• Neurology studies the nervous system, whose chief structure is brain, spinal cord and nerve
• Cardiology studies the circulatory system, whose chief structure is the heart and blood vessels
• Esthesiology studies the sensory system, whose chief structures are the eye and ears

Anatomical Terms

• Cranial means toward the head.
• Caudal means toward the tail.
• Rostral refers to features of the head towards the nose.
• Median plane is an imaginary plane passing through the body, dividing it into equal right and left halves.
• Sagittal (midsagittal) plane is any plane parallel to the median plane.
• Transverse plane is at right angles to the median plane, dividing the body into cranial and caudal segments.
• Horizontal plane is at right angles to both the median and transverse planes, dividing the body into dorsal and ventral segments.
• Medial indicates close or toward the median plane.
• Lateral means away from the median plane.
• Dorsal is toward or beyond the backbone/vertebral column.
• Ventral is away from the vertebral column or toward the midabdominal wall.
• Proximal refers to being relatively close to a given part.
• Distal describes being relatively far to a given part and is usually used in reference to portions of an extremity.

Osteology

• Osteology studies the bones that make up the skeleton or framework of the body.
• Bones support the body.
• Bones provide leverage for locomotion.
• Bones protect soft tissues within the body.
• Bones act as a storage organ for calcium and phosphorus.

Compact Bone

• A dense or cortical bone.
• It is made up of a hard layer that constitutes the exterior of most bones.
• Forms almost the entire shaft of long bones.

Cancellous Bone

• It's also known as spongy bone.
• Composed of spicules arranged to form a porous network.
• Space usually filled with red bone marrow.

Medullary Cavity

• Contains marrow.
• Space surrounded by the cortex of long bones.
• Contains yellow bone marrow.

Bone Structure

Key components include:

• Epiphysis: Either end of a long bone.
• Diaphysis: Cylindrical shaft of long bone between two epiphyses.
• Metaphysis: Mature bone adjacent to the epiphysis.
• Epiphyseal cartilage or disk: Layer of hyaline cartilage in the metaphysis of an immature bone, the area in which a bone can lengthen.
• Articular cartilage: Thin layer of cartilage that covers the articular (joint) surface of a bone.
• Periosteum: A fibrous membrane that covers the surface of a bone, except where articular cartilage is located

Osteon

• a.k.a. Haversian System
• Is the fundamental functional unit of compact bone.
• Osteons are roughly cylindrical structures that are several millimeters long and around 0.2 mm in diameter.
• Each osteon consists of concentric layers, or lamellae, of compact bone tissue that surround a central canal, the Haversian canal.
• The Haversian canal contains the bone's blood supplies and nerve fibers.

Endosteum

• Fibrous membrane that lines the marrow cavity and osteonal canal of the bone.

Classification of Bones

Classification of bones according to gross appearance:

• Long bones consist of a relatively cylindrical shaft and two extremities; levers and aid in support, locomotion, and prehension.
• Short bones are generally cuboid or approximately equal in all dimensions; absorb concussion and example include carpus & tarsus.
• Flat bones are relatively thin; protect vital organs, and provide an area for muscle attachment; examples include scapula, ribs, pelvic bone, bones of skull, etc.
• Irregular bones are unpaired bones on the median plane; protection, support and muscular attachment; example consist of bones of the vertebrae and some of the unpaired bones of the skull
• Sesamoid bones resemble a sesame seed; reduce friction, increase leverage or change direction of pull.
• Pneumatic bones contain air spaces/sinuses that communicate with the atmosphere; the frontal as well as maxillary bones are an example.

Division of Bones

• Axial skeleton runs from the head to the tip of the tail, forming the axis of the animal.
• Appendicular skeleton consists of the appendages.
• Splanchnic skeleton- Bones which lie within soft tissue and not attached to the main skeleton.

Axial Skeleton

• The axial skeleton includes the:
  • Skull
  • Vertebral Column
• Skull contains the:
  • Cranium
  • Facial Component
• The vertebral column includes:
  • Cervical vertebrae
  • Thoracic vertebrae
  • Lumbar vertebrae
  • Sacral vertebrae

Skull

• Bones of the head.
• Protect the brain
• Support and provide attachment for the muscles of mastication, swallowing, vocalization, and facial expression.
• Support many of the sense organs.
• Provides a bony channel through which inspired air can enter the body.
• Cranium is a box shaped structure that houses the brain and is attached to the two nasal chambers.
• Facial bones of the face.

Vertebral Column

• Made up of median irregular bone called vertebrae.
• It protects the spinal cord.
• Supports the body with a stiff but flexible rode.
• Provides attachment for the rib cage and muscles, which protects the internal organs.
• Includes the cervical, thoracic, lumbar, sacral Coccygeal vertebrae

Cervical Vertebrae

• Bones of the neck region.
• Have well developed articular processes to accommodate the large range of motion of the neck.
• Atlas is the first cervical vertebrae.
• Axis is the second cervical vertebra.

Thoracic Vertebrae

• Bone of the chest region.
• Characterized by well-developed spinous processes and articular facet for the ribs.

Lumbar Vertebrae

• Bones of the loin region.
• Hav large flattened transverse processes that project laterally.

Sacral Vertebrae

• Bones of the pelvis region.
• Fused to form a single-wedge bone which articulates with:
  • The last lumbar vertebra cranially
  • With the first caudal vertebra caudally
  • With the wings of the ilia craniolaterally

Vertebral Formula of Common Domestic Animals and Human

Sternum and Ribs

• Sternum forms the ventral of the bony thorax and gives attachment to the costal cartilage of the ribs as well as providing a bony origin for the pectoral muscles.
• Parts of the sternum includes the:
  • Manubrium is the cranial extremity of the sternum.
  • Body is the middle portion of the sternum.
  • Xiphoid process is the caudal cavity of the sternum.
• Consists of individual bones called sternebrae that tend to fuse as age advances.
• Number of sternebrae (excluding the manubrium and xiphoid from the count), varies with species.
• Ribs, forms the lateral wall of the bony thorax.
• Function in forming the thoracic cavity, protect soft tissues within the thoracic cavity, & enable respiration to take place.
• True or Sternal ribs, are ribs that articulate with the sternum.
• False or Asternal ribs, ribs that touch the costal cartilage of the rib in front.
• Floating ribs, are ribs that short and the ventral end is free.

Number Of Ribs Of Common Domestic Animals

Bones of Axial Skeleton

Appendicular Skeleton

• They made up of the bones of the limb including:
  • Pectoral or thoracic limb
  • Pelvic limb

Pectoral/Thoracic Limb

• Can be divided into:
  • Shoulder
  • Upper arm
  • Forearm
• The pectoral girdle has no bony attachment between the limb and trunk The connection is made entirely by muscles running from the scapula and humerus to the head, neck, and thorax.
• Clavicle is a thin spicule of unconnected bone lying within the muscle running between the forelimb and the head and neck.
• Scapula: includes a large triangular flat bone applied to the wall of the thorax between ribs 1 and 4
• Forelimb includes: the humerus, radius and ulna, carpus, metacarpal as well as digits
• Humerus is the largest bone in the forelimb.
• Radius and ulna are bones of antebrachium (forearm)
• Radius is the larger bone of the two.
  • It enters into the elbow joint proximally and the carpus distally
  • The most medial of the two bones forming the lower limb
  • The main weight-bearer
• Ulna forms the lower forelimb with the radius being larger and longer.
• Carpus is a complex region that includes two rows of small bones corresponds to the human wrist and is frequently, although erroneously called the knee by horseman.
• Metacarpal is boned distal to the carpus

Pelvic Limb

• Divisions includes the:
  • Hip
  • Thigh
  • Leg
  • Pes
• Pelvic girdle consists of two halves, each formed from three flat bones.
  • Ilium: its vertical and forms the cartilaginous sacroiliac joint with the sacrum as well as it is largest and most dorsal of the pelvic bone and
• Irregularly triangular with the acetabulum apex/its base projecting craniodorsal
• Ischium: projects backward and ventral from the acetabulum forming much of the floor of the pelvic cavity and has a large roughened caudal prominence – the tuber ischiadicum - pin bone in cattle
• Pubis: the smallest of the tree pelvic bone forms the cranial part of the floor of the pelvic cavity.

Pelvic Girdle (Female vs Male)

• FEMUR is long bone which forms the skeleton of the thigh.
• FIBULA is a finer bone that that forms lower hind limb, smaller and lies of lateral side of leg.
• TIBIA the lager of the two bones of lower limb and lies on medial to Fibula.
• TARSUS also calls hock it's like the of carpus or thoracic limbs composed of multiple small bones; it corresponds to human ankle.

Appendicular Skeleton: Thoracic Limb vs Pelvic Limb