Bones, Joints, and Synovial Fluid

Skeletal function

Structure, organ protection, locomotion, mineral storage, hematopoiesis, and adaptation

Axial skeleton

lies on the long axis (midline) of the body and includes the skull, vertebrae, and those bones attached to the vertebrae (ribs, ventral connections of the ribs, and sternum)

Bones of the axial skeleton

Skull (maxilla and mandible), vertebrae (cervical, thoracic, lumbar, sacrum, and caudal vertebrae), ribs, and sternum

Nucleus pulposus

acts as a gel-like shock absorber that distributes pressure within the intervertebral disc, while the anulus fibrosus provides structural support, containing the nucleus and resisting excessive movement

Appendicular skeleton

made up of the bones of the front (thoracic) and hind (pelvic) limbs and their respective pectoral girdle (shoulder) and pelvic girdle (pelvis)

Articular Cartilage

Reduces friction and absorbs shock in joints

Cancellous Bone

Houses red marrow for blood cell production and provides lightweight support

Epiphyseal Plate

Enables bone growth in length

Marrow Cavity

Stores fat (yellow marrow) or produces blood cells (red marrow)

Periosteum

Supports bone growth, repair, and nutrient supply

Compact Bone

Provides strength and structural support

Epiphysis

Forms joints and contains spongy bone with marrow

Diaphysis

The shaft of the bone, providing leverage and strength

Haversian Canal (Central Canal)

Contains blood vessels, nerves, and
lymphatic vessels to supply nutrients
and oxygen to bone cells

Lamellae

Concentric rings of calcified
matrix that provide bone strength

Lacunae

Small spaces between
lamellae that house osteocytes (bone
cells)

Canaliculi

Tiny channels connecting
lacunae, allowing osteocytes to
exchange nutrients and waste

Volkmann’s Canals

Perpendicular
canals that connect Haversian canals,
facilitating blood flow between osteons

Osteoblasts

Build bone by producing and mineralizing bone matrix

Osteocytes

Maintain bone structure and regulate nutrients.

Osteoclasts

Break down bone for remodeling and calcium release.

Osteoprogenitor Cells

Stem cells that differentiate into osteoblasts for bone growth and repair.