Skeletal_System

Skeletal System

The framework of bones and other structures that support the body and protect internal organs.

Long bones

Bones that have a shaft with two knob-like ends, such as the femur and humerus.

Spongy bone

A type of bone tissue that has a porous, honeycomb-like structure and is found at the ends of long bones.

Compact bone

A dense and hard type of bone tissue that forms the outer layer of bones.

Intramembranous ossification

The process of bone formation where bone tissue develops directly from mesenchymal connective tissue.

Endochondral ossification

The process of bone formation where bone tissue replaces a cartilage model.

Ligaments

Structures that connect bones to other structures, providing stability and support.

Tendons

Structures that connect muscles to bones, allowing for movement.

Cartilages

Flexible connective tissues that provide cushioning and support between bones.

Support

One of the functions of the skeletal system, providing a structural framework for the body.

Protection

One of the functions of the skeletal system, protecting underlying organs such as the brain and heart.

Movement & anchorage of muscles

One of the functions of the skeletal system, allowing muscles to attach to bones and move them.

Mineral Homeostasis

The regulation of minerals, such as calcium and phosphorus, in the body by storing and releasing them as needed.

Haematopoiesis

The process of blood cell formation, which occurs in the red marrow of certain bones.

Energy reserve (triglycerides)

The storage of energy in the form of triglycerides in the yellow marrow of long bones.

Flat bones

Thin bones that provide extensive muscle attachment surfaces, such as the sternum and skull bones.

Irregular bones

Bones with varied and complex shapes, such as vertebrae and auditory ossicles.

Short bones

Cube-like bones that are roughly the same length and width, such as wrist and ankle bones.

Sesamoid bones

Bones that develop within a tendon in areas of tension, friction, or stress, such as the patella (kneecap).

Articular cartilage

A pad of hyaline cartilage that covers the ends of bones at joints, acting as a shock absorber and reducing friction.

Epiphysis

The expanded proximal and distal ends of a long bone, consisting mainly of spongy bone with red bone marrow.

Diaphysis

The shaft of a long bone, consisting of compact bone and containing a central medullary cavity filled with yellow marrow.

Endosteum

The single, inner lining of the medullary cavity, composed of dense irregular connective tissue.

Periosteum

The outer, fibrous, protective covering of the diaphysis, containing a rich supply of blood vessels, lymph vessels, and nerves.

Nutrient foramen

A canal that allows blood vessels to enter and leave the bone, providing nutrients to the bone tissue.

Osteogenic cells

Bone cells derived from mesenchyme that can undergo mitosis and become osteoblasts.

Osteoblasts

Bone cells that form the bone matrix by secreting collagen and cannot undergo mitosis.

Osteocytes

Mature bone cells derived from osteoblasts that maintain daily cellular activities, exchange nutrients and wastes with blood, and participate in bone repair.

Osteoclasts

Large cells found in the endosteum that are responsible for bone resorption, the breakdown of bone matrix.

Hydroxyapatite

The mineral salts, primarily calcium phosphate, that give bone hardness and rigidity.

Haversian System or Osteon

The structural unit of compact bone, consisting of concentric lamellae surrounding a central Haversian canal containing blood vessels and nerves.

Lacunae

Small spaces in bone tissue that contain osteocytes.

Trabeculae

Small needle-like pieces of bone that make up the lattice-like structure of spongy bone.

Canaliculi

Small channels within bone tissue that connect the lacunae of osteocytes and allow for the exchange of nutrients and wastes.

Volkmann's canals

Channels that connect the blood, lymph, and nerve supply of adjacent Haversian systems in compact bone.

Epiphyseal plate

A layer of hyaline cartilage located at the junction of the diaphysis and epiphysis of a long bone, allowing for growth in length.

Epiphyseal line

The remnant of the epiphyseal plate once bone growth is complete.

Bone Formation

The process of creating bone by replacing cartilage with minerals.

Osteogenesis/Ossification

Another term for bone formation.

Skeleton

The framework of bones in the body.

CT (Connective Tissue)

Tissue formed from mesenchyme and hyaline cartilage, which shapes the bones in an embryo.

Mesenchyme

The embryonic connective tissue from which bones are formed.

Hyaline Cartilage

A type of cartilage that serves as a model for bone formation.

Ossification Center

The area where bone formation begins.

Osteogenic Cells

Cells that have the potential to become osteoblasts, which are responsible for bone formation.

Osteoblasts

Cells that secrete the matrix of bone and eventually become surrounded by it.

Calcification

The process of depositing minerals in the matrix of bone, causing it to harden.

Osteocytes

Mature bone cells that reside in lacunae.

Lacunae

Small spaces in the bone matrix where osteocytes are located.

Blood Capillary

A small blood vessel that supplies nutrients to the developing bone.

Trabeculae

Small bone spicules that form a network in intramembranous ossification.

Periosteum

The outer layer of the bone that develops from mesenchyme and becomes a layer of compact bone.

Endochondral Ossification

The process of bone formation from a hyaline cartilage model.

Chondroblasts

Cells that secrete the cartilage model in endochondral ossification.

Chondrocytes

Mature cartilage cells that are responsible for the growth of the cartilage model.

Perichondrium

The connective tissue that surrounds the cartilage model.

Primary Ossification Center

The area where bone formation begins in endochondral ossification.

Medullary Cavity

The central cavity of a long bone that is formed during endochondral ossification.

Secondary Ossification Center

Additional areas of bone formation that develop in the epiphyses of long bones.

Articular Cartilage

Hyaline cartilage that covers the ends of bones in a joint.

Epiphyseal Plate

A layer of hyaline cartilage between the diaphysis and epiphysis of a growing bone.

Osteoclasts

Cells that break down bone tissue, allowing for bone remodeling and growth in thickness.

Axial Skeleton

The portion of the skeleton that includes the skull, vertebral column, and thoracic cage.

Appendicular Skeleton

The portion of the skeleton that includes the bones of the upper and lower limbs, as well as the pectoral and pelvic girdles.

Sutures

Areas where skull bones fuse together.

Foramina

Openings or holes in bones that allow blood vessels, nerves, and ligaments to pass through.

Depressions

Indentations or hollow areas in bones, often involved in joint formation.

Processes

Projections on bones that serve as attachment points for ligaments, tendons, and muscles.

Function

Encloses fluid-filled cranial cavity, cushions and supports the brain, attaches blood vessels, nerves, and membranes to the inner cranial surface, contains air-filled chambers (sinuses) that produce mucus, lighten the skull, and serve as resonating areas for sounds.

Cranium

The skull, which includes the frontal bone, parietal bones, and occipital bone.

Frontal bone

The bone that forms the forehead and the superior portion of the eye socket (orbit), and contains frontal sinuses.

Parietal bones

Paired bones located behind the frontal bone, forming the superior and lateral aspects of the cranium.

Occipital bone

The bone located at the posterior-inferior (base) of the cranium.

Frontal sinus

A sinus located in the frontal bone.

Ethmoid sinuses

Sinuses located in the ethmoid bone.

Maxillary sinus

A sinus located in the maxilla bone.

Temporal bone

The bone located inferior-lateral to the parietal bones, forming the temples and ears.

Nasal bone

The bone that forms the bridge of the nose.

Occipital condyles

Rounded processes on either side of the foramen magnum that articulate with the first vertebra (atlas).

Foramen magnum

A large hole in the occipital bone through which nerve fibers pass from the brain to the spinal cord.

Sagittal suture

The suture that connects the parietal bones along the midline of the skull.

Lambdoid suture

The suture that connects the parietal bones to the occipital bone.

Zygomatic arch

The arch formed by the temporal bone and the zygomatic bone (cheekbone).

Hyoid bone

A bone located in the neck between the lower jaw and the larynx, which supports the tongue.

Facial bones

The bones that shape the face, provide attachment for muscles that move the jaw and control facial expressions, and protect and support the entrance of the digestive and respiratory systems.

Maxillae

The bones that mostly form the upper jaw.

Mandible

The bone that forms the lower jaw and is movable.

Zygomatic bones

The bones that contribute to the cheek prominence.

Nasal bones

The bones that form the bridge of the nose.

Vomer

A bone that is part of the nasal septum.

Inferior nasal conchae

The bones that form the inferior portions of the lateral nasal wall.

Lacrimal bones

The bones located lateral and posterior to the nasal bones, forming the inner walls of the eye socket.

Palatine bones

The bones located in the posterior portion of the hard palate, and also contributing to the nasal cavity and orbits.

Vertebral column

The spine, consisting of irregular bones divided into five curvatures:cervical, thoracic, lumbar, sacrum, and coccyx.

Intervertebral disc

A protective pad of fibrocartilage between individual vertebrae, providing a slightly movable joint.

Body (centrum)

The large, solid anterior region of a vertebra.

Vertebral arch

The posterior region of a vertebra, consisting of pedicles, laminae, and processes.

Vertebral foramen

The opening through which the spinal cord passes in a vertebra.

Thorax

The chest, consisting of ribs, sternum, thoracic vertebrae, and costal cartilage.

Sternum

The breastbone, consisting of the manubrium, body, and xiphoid process.