Bones, Joints, and Synovial Fluid

Skeletal function

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

Bones Labeled

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)

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

a specialized type of connective tissue that covers the ends of bones in joints; reduces friction and absorbs shock in joints

Cancellous Bone

a porous bone tissue that houses red marrow for blood cell production and provides lightweight support

Epiphyseal Plate

Enables bone growth in length

Marrow Cavity

Cavity that stores fat (yellow marrow) or produces blood cells (red marrow)

Periosteum

a dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints that supports bone growth, repair, and nutrient supply

Compact Bone

dense, hard outer layer of bones that provides strength and structural support

Epiphysis

the end part of a long bone that forms joints and contains spongy bone with marrow

Diaphysis

The shaft of the bone, providing leverage and strength

Haversian Canal (Central Canal)

minute tubes which form a network in bone; contains blood vessels, nerves, and lymphatic vessels to supply nutrients and oxygen to bone cells

Lamellae

Concentric rings of calcified matrix inside the bone that provide bone strength

Lacunae

Small spaces between
lamellae that house osteocytes (bone
cells)

Canaliculi

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

Volkmann’s Canals

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

Osteoblasts

Build bone by producing and mineralizing bone matrix

Osteocytes

Mature bone cells; 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.

Cartilage Model

Bone
starts as hyaline cartilage

Primary Ossification

Bone replaces cartilage in
the diaphysis

Secondary Ossification

Bone forms in the
epiphyses after birth

Epiphyseal Plate Growth

Cartilage grows and is
replaced by bone in distinct
zones

Epiphyseal Plate Closure

The thin layer of cartilage near the ends of long bones ossifies into the epiphyseal line, stopping growth in adulthood

Bone remodeling

Osteoclasts reshape the bone, restoring strength and structure; a continuous process of renewal: 1) Activation (Osteoclasts are recruited), 2) Reabsorption (Osteoclasts break down the old bone), 3) Reversal (Osteoclasts die and osteoblasts arrive), 4) Formation (Osteoblasts build new bone); ARRF

Hematoma Formation

Blood clot forms at the fracture site to stabilize and bring repair cells

Fibrocartilaginous Callus Formation

Soft callus of collagen and cartilage bridges the fracture

Bony Callus Formation

Osteoblasts replace soft callus with spongy bone

Joints Labeled