Long Bone, Cancellous, Marrow

Bone Cells

• Osteoblasts:
  • Form the matrix of bone
  • The matrix hardens through a process called ossification
  • "Blast" means "to produce" or "building"
• Osteocytes:
  • Trapped osteoblasts in the bony matrix called lacunae
  • Contact with other osteocytes and their blood supply is through cellular channels called canaliculi
  • Can revert back to osteoblasts if needed (e.g., to form new bone after an injury)
• Osteoclasts:
  • Cells that eat away at bone
  • Used to re-model bone that is not needed
  • Enable the body to extract Calcium from bones for use in blood
  • "C" for "chewing" or "cleaning"

Bone Structure

• Two main types of Bone:
  • Cancellous Bone (Spongy Bone):
    • Light, spongey
    • Consists of a network of bony spicules called trabeculae
    • Found in the end of long bones and surrounding the medullary cavity
    • Spaces in between the trabeculae contain bone marrow for blood cell production and fat storage
  • Cortical or Compact Bone:
    • Heavy, dense, very strong
    • Makes up the shaft of long bones and the outside layer of all bones
    • Function: strength and protection, allows weight bearing without forces bending/damaging the bone

Compact Bone

• Made up of tiny, tightly compacted cylinders of bone called Haversian systems (or osteon)
• Consists of a multilayered cylinder composed of circular layers of ossified bone matrix arranged around a central Haversian canal
• The Haversian canal contains blood vessels, lymph vessels, and nerves that supply the osteocytes
• Osteocytes are located at the junctions between the layers of bone that make up each Haversian system

Functions of the Skeletal System

• Support:
  • For soft tissue (like scaffolding)
  • A strong frame that supports the body and gives it its shape
• Protection:
  • Strong bones protect delicate vital organs and tissues by surrounding them partially or completely
• Movement (leverage):
  • Bones act as levers for muscles
  • Bones are attachment sites for skeletal muscles (via tendons)
• Blood cell formation:
  • In the bone marrow of some bones
• Storage of minerals:
  • e.g. Calcium, phosphorous

Types of Bones

• Long Bones:
  • Most bones of the limbs
• Short Bones:
  • Like cubes/marshmallows (e.g., carpal and tarsal bones)
• Flat Bones:
  • Thin and flat (e.g., skull, scapulae, pelvic bones)
• Irregular Bones:
  • Miscellaneous (e.g., vertebrae)

Bone Function and Structure

• Bone is a strong, lightweight, and dynamic tissue that allows for bone marrow storage and is adapted to specific forces (trabeculae).
• There are two main types of bone: cancellous bone (light, spongey) and compact bone (heavy, dense).

Cancellous Bone

• Also known as "spongy bone".
• Light but very strong, with a network of bony spicules called trabeculae.
• Trabeculae are organized into a mesh-like network along regions of biomechanical stress to handle forces from muscles, gravity, and other bones.
• Spaces in between trabeculae contain bone marrow for blood cell production (haematopoiesis) and fat storage.
• Found in the end of long bones and surrounding the medullary cavity, surrounded by an outer layer of compact bone.

Compact Bone

• Also known as cortical bone.
• Heavy, dense, and very strong.
• Makes up the shaft of long bones and the outside layer of all bones.
• Function: strength, protection, and weight-bearing without forces bending or damaging the bone.
• Composed of Haversian systems (or osteon) that run lengthwise to the bone.
• Haversian canal contains blood vessels, lymph vessels, and nerves that supply the osteocytes.

Bone Cells

• Osteoblasts: cells that form the matrix of bone through ossification.
• Osteocytes: osteoblasts trapped in the bony matrix (lacunae), with contact with other osteocytes and their blood supply through canaliculi.
• Osteoclasts: cells that eat away at bone to re-model bone that is not needed, and enable the body to extract calcium from bones for use in blood.

Bone Membranes

• Periosteum: membrane covering the outer surfaces of bones (except the articular/joint surfaces), contains blood vessels and nerves that supply bones.
• Endosteum: membrane lining the hollow interior surface of bones (lines the medullary cavity and trabeculae), contains cells involved in bone growth, remodeling, and repair.

Long Bones

• Longer than they are wide.
• Most bones of the limbs.
• Composed of:
  • Epiphysis: light, cancellous bone covered by a thin layer of compact bone, containing bone marrow.
  • Diaphysis: main section of long bone, made of strong compact bone for weight-bearing.
  • Epiphyseal plates: plates of cartilage (growth plates) that are sites of bone growth, weak and susceptible to fractures in young animals.
  • Medullary cavities: contain red and yellow marrow, blood vessels, and nervous tissue.

The Skeletal System

• The skeletal system is a framework of bones that support and protect the soft tissues of the body.

Functions of the Skeletal System

• Support: provides a strong frame that supports the body and gives it its shape.
• Protection: protects delicate vital organs and tissues by surrounding them partially or completely.
• Movement (leverage): bones act as levers for muscles, allowing for movement.
• Blood cell formation: occurs in the bone marrow of some bones.
• Storage of minerals: bones act as a mineral bank, storing minerals like calcium and phosphorus.

Bone Cells

• Osteoblasts: cells that form the matrix of bone through ossification.
• Osteocytes: osteoblasts that are trapped in the bony matrix, contacting other osteocytes and their blood supply through cellular channels.
• Osteoclasts: cells that break down and resorb bone, allowing for bone remodeling and the extraction of calcium from bones.

Bone Structure

• Two main types of bone: cancellous (spongy) and compact (cortical) bone.
• Cancellous bone: light, spongey, and strong, with a network of bony spicules (trabeculae) and bone marrow.
• Compact bone: heavy, dense, and strong, made up of Haversian systems (osteons) and containing blood vessels, lymph vessels, and nerves.

Bone Types

• Long bones: most bones of the limbs, consisting of a diaphysis, epiphysis, and epiphyseal plates.
• Short bones: like cubes or marshmallows, e.g., carpal and tarsal bones.
• Flat bones: thin and flat, e.g., skull, scapulae, and pelvic bones.
• Irregular bones: miscellaneous, e.g., vertebrae, some skull bones, and sesamoid bones.

Long Bones

• Epiphysis: contains red marrow and epiphyseal plates, and is the line of growth of bone.
• Diaphysis: the main section of the long bone, made of strong compact bone for weight-bearing.
• Epiphyseal plates: sites of bone growth, weak and prone to fractures in young animals.
• Medullary cavities: contain red and yellow marrow.
• Red marrow: responsible for blood cell production, larger proportion in younger animals.
• Yellow marrow: responsible for fat storage, majority of bone marrow in adults.
• Periosteum: membrane covering the outer surfaces of bones, containing blood vessels, nerves, and cells for bone growth, remodeling, and repair.
• Endosteum: membrane lining the hollow interior surface of bones, involved in bone growth, remodeling, and repair.

The Skeletal System

• The skeletal system is a framework of bones that support and protect the soft tissues of the body.

Functions of the Skeletal System

• Support: provides a strong frame that supports the body and gives it its shape.
• Protection: protects delicate vital organs and tissues by surrounding them partially or completely.
• Movement (leverage): bones act as levers for muscles, allowing for movement.
• Blood cell formation: occurs in the bone marrow of some bones.
• Storage of minerals: bones act as a mineral bank, storing minerals like calcium and phosphorus.

Bone Cells

• Osteoblasts: cells that form the matrix of bone through ossification.
• Osteocytes: osteoblasts that are trapped in the bony matrix, contacting other osteocytes and their blood supply through cellular channels.
• Osteoclasts: cells that break down and resorb bone, allowing for bone remodeling and the extraction of calcium from bones.

Bone Structure

• Two main types of bone: cancellous (spongy) and compact (cortical) bone.
• Cancellous bone: light, spongey, and strong, with a network of bony spicules (trabeculae) and bone marrow.
• Compact bone: heavy, dense, and strong, made up of Haversian systems (osteons) and containing blood vessels, lymph vessels, and nerves.

Bone Types

• Long bones: most bones of the limbs, consisting of a diaphysis, epiphysis, and epiphyseal plates.
• Short bones: like cubes or marshmallows, e.g., carpal and tarsal bones.
• Flat bones: thin and flat, e.g., skull, scapulae, and pelvic bones.
• Irregular bones: miscellaneous, e.g., vertebrae, some skull bones, and sesamoid bones.

Long Bones

• Epiphysis: contains red marrow and epiphyseal plates, and is the line of growth of bone.
• Diaphysis: the main section of the long bone, made of strong compact bone for weight-bearing.
• Epiphyseal plates: sites of bone growth, weak and prone to fractures in young animals.
• Medullary cavities: contain red and yellow marrow.
• Red marrow: responsible for blood cell production, larger proportion in younger animals.
• Yellow marrow: responsible for fat storage, majority of bone marrow in adults.
• Periosteum: membrane covering the outer surfaces of bones, containing blood vessels, nerves, and cells for bone growth, remodeling, and repair.
• Endosteum: membrane lining the hollow interior surface of bones, involved in bone growth, remodeling, and repair.

The Skeletal System

• The skeletal system is a framework of bones that support and protect the soft tissues of the body.

Functions of the Skeletal System

• Support: provides a strong frame that supports the body and gives it its shape.
• Protection: protects delicate vital organs and tissues by surrounding them partially or completely.
• Movement (leverage): bones act as levers for muscles, allowing for movement.
• Blood cell formation: occurs in the bone marrow of some bones.
• Storage of minerals: bones act as a mineral bank, storing minerals like calcium and phosphorus.

Bone Cells

• Osteoblasts: cells that form the matrix of bone through ossification.
• Osteocytes: osteoblasts that are trapped in the bony matrix, contacting other osteocytes and their blood supply through cellular channels.
• Osteoclasts: cells that break down and resorb bone, allowing for bone remodeling and the extraction of calcium from bones.

Bone Structure

• Two main types of bone: cancellous (spongy) and compact (cortical) bone.
• Cancellous bone: light, spongey, and strong, with a network of bony spicules (trabeculae) and bone marrow.
• Compact bone: heavy, dense, and strong, made up of Haversian systems (osteons) and containing blood vessels, lymph vessels, and nerves.

Bone Types

• Long bones: most bones of the limbs, consisting of a diaphysis, epiphysis, and epiphyseal plates.
• Short bones: like cubes or marshmallows, e.g., carpal and tarsal bones.
• Flat bones: thin and flat, e.g., skull, scapulae, and pelvic bones.
• Irregular bones: miscellaneous, e.g., vertebrae, some skull bones, and sesamoid bones.

Long Bones

• Epiphysis: contains red marrow and epiphyseal plates, and is the line of growth of bone.
• Diaphysis: the main section of the long bone, made of strong compact bone for weight-bearing.
• Epiphyseal plates: sites of bone growth, weak and prone to fractures in young animals.
• Medullary cavities: contain red and yellow marrow.
• Red marrow: responsible for blood cell production, larger proportion in younger animals.
• Yellow marrow: responsible for fat storage, majority of bone marrow in adults.
• Periosteum: membrane covering the outer surfaces of bones, containing blood vessels, nerves, and cells for bone growth, remodeling, and repair.
• Endosteum: membrane lining the hollow interior surface of bones, involved in bone growth, remodeling, and repair.

Bone Function and Structure

• Bone is a strong, lightweight, and dynamic tissue that allows for bone marrow storage and is adapted to specific forces (trabeculae).
• There are two main types of bone: cancellous bone (light, spongey) and compact bone (heavy, dense).

Cancellous Bone

• Also known as "spongy bone".
• Light but very strong, with a network of bony spicules called trabeculae.
• Trabeculae are organized into a mesh-like network along regions of biomechanical stress to handle forces from muscles, gravity, and other bones.
• Spaces in between trabeculae contain bone marrow for blood cell production (haematopoiesis) and fat storage.
• Found in the end of long bones and surrounding the medullary cavity, surrounded by an outer layer of compact bone.

Compact Bone

• Also known as cortical bone.
• Heavy, dense, and very strong.
• Makes up the shaft of long bones and the outside layer of all bones.
• Function: strength, protection, and weight-bearing without forces bending or damaging the bone.
• Composed of Haversian systems (or osteon) that run lengthwise to the bone.
• Haversian canal contains blood vessels, lymph vessels, and nerves that supply the osteocytes.

Bone Cells

• Osteoblasts: cells that form the matrix of bone through ossification.
• Osteocytes: osteoblasts trapped in the bony matrix (lacunae), with contact with other osteocytes and their blood supply through canaliculi.
• Osteoclasts: cells that eat away at bone to re-model bone that is not needed, and enable the body to extract calcium from bones for use in blood.

Bone Membranes

• Periosteum: membrane covering the outer surfaces of bones (except the articular/joint surfaces), contains blood vessels and nerves that supply bones.
• Endosteum: membrane lining the hollow interior surface of bones (lines the medullary cavity and trabeculae), contains cells involved in bone growth, remodeling, and repair.

Long Bones

• Longer than they are wide.
• Most bones of the limbs.
• Composed of:
  • Epiphysis: light, cancellous bone covered by a thin layer of compact bone, containing bone marrow.
  • Diaphysis: main section of long bone, made of strong compact bone for weight-bearing.
  • Epiphyseal plates: plates of cartilage (growth plates) that are sites of bone growth, weak and susceptible to fractures in young animals.
  • Medullary cavities: contain red and yellow marrow, blood vessels, and nervous tissue.

The Skeletal System

• The skeletal system is a framework of bones that support and protect the soft tissues of the body.

Functions of the Skeletal System

• Support: Provides a strong frame that supports the body and gives it its shape, like scaffolding for soft tissue.
• Protection: Protects delicate vital organs and tissues by surrounding them partially or completely, e.g., the skull protects the brain, and the ribs protect the heart.
• Movement (Leverage): Bones act as levers for muscles, allowing joints to move.
• Blood Cell Formation: Takes place in the bone marrow of some bones.
• Storage of Minerals: Stores minerals like calcium and phosphorus, acting like a mineral bank.

Bone Cells

• Osteoblasts: Form the matrix of bone, which hardens through ossification, and are responsible for building bone.
• Osteocytes: Trapped osteoblasts in the bony matrix, connected to other osteocytes and blood supply through cellular channels called canaliculi.
• Osteoclasts: Cells that break down and resorb bone, allowing the body to extract calcium from bones for use in blood.

Bone Structure

• Cancellous Bone: Light, spongey, and strong, consisting of a network of bony spicules called trabeculae, found in the ends of long bones and surrounding the medullary cavity.
• Cortical or Compact Bone: Heavy, dense, and strong, making up the shaft of long bones and the outer layer of all bones, providing strength and protection.

Bone Membranes

• Periosteum: A membrane covering the outer surfaces of bones, containing blood vessels and nerves that supply bones, and cells involved in growing and repairing bone.
• Endosteum: A membrane lining the hollow interior surface of bones, containing cells involved in bone growth, remodelling, and repair.

Long Bones

• Epiphysis: The light, cancellous bone at the ends of long bones, covered by a thin layer of compact bone, containing bone marrow.
• Diaphysis: The main section of long bone, made of strong compact bone, providing weight-bearing support.
• Epiphyseal Plates: Plates of cartilage at the ends of long bones, where bone growth occurs, and which ossify in adults to become solid bone.
• Medullary Cavity: Contains red and yellow marrow, with blood vessels and nervous tissue.

Bone Function and Structure

• Bone is a strong, lightweight, and dynamic tissue that allows for bone marrow storage and is adapted to specific forces (trabeculae).
• There are two main types of bone: cancellous bone (light, spongey) and compact bone (heavy, dense).

Cancellous Bone

• Also known as "spongy bone".
• Light but very strong, with a network of bony spicules called trabeculae.
• Trabeculae are organized into a mesh-like network along regions of biomechanical stress to handle forces from muscles, gravity, and other bones.
• Spaces in between trabeculae contain bone marrow for blood cell production (haematopoiesis) and fat storage.
• Found in the end of long bones and surrounding the medullary cavity, surrounded by an outer layer of compact bone.

Compact Bone

• Also known as cortical bone.
• Heavy, dense, and very strong.
• Makes up the shaft of long bones and the outside layer of all bones.
• Function: strength, protection, and weight-bearing without forces bending or damaging the bone.
• Composed of Haversian systems (or osteon) that run lengthwise to the bone.
• Haversian canal contains blood vessels, lymph vessels, and nerves that supply the osteocytes.

Bone Cells

• Osteoblasts: cells that form the matrix of bone through ossification.
• Osteocytes: osteoblasts trapped in the bony matrix (lacunae), with contact with other osteocytes and their blood supply through canaliculi.
• Osteoclasts: cells that eat away at bone to re-model bone that is not needed, and enable the body to extract calcium from bones for use in blood.

Bone Membranes

• Periosteum: membrane covering the outer surfaces of bones (except the articular/joint surfaces), contains blood vessels and nerves that supply bones.
• Endosteum: membrane lining the hollow interior surface of bones (lines the medullary cavity and trabeculae), contains cells involved in bone growth, remodeling, and repair.

Long Bones

• Longer than they are wide.
• Most bones of the limbs.
• Composed of:
  • Epiphysis: light, cancellous bone covered by a thin layer of compact bone, containing bone marrow.
  • Diaphysis: main section of long bone, made of strong compact bone for weight-bearing.
  • Epiphyseal plates: plates of cartilage (growth plates) that are sites of bone growth, weak and susceptible to fractures in young animals.
  • Medullary cavities: contain red and yellow marrow, blood vessels, and nervous tissue.

The Skeletal System

• The skeletal system is a framework of bones that support and protect the soft tissues of the body.

Functions of the Skeletal System

• Support: provides a strong frame that supports the body and gives it its shape.
• Protection: protects delicate vital organs and tissues by surrounding them partially or completely.
• Movement (leverage): bones act as levers for muscles, allowing for movement.
• Blood cell formation: occurs in the bone marrow of some bones.
• Storage of minerals: bones act as a mineral bank, storing minerals like calcium and phosphorus.

Bone Cells

• Osteoblasts: cells that form the matrix of bone through ossification.
• Osteocytes: osteoblasts that are trapped in the bony matrix, contacting other osteocytes and their blood supply through cellular channels.
• Osteoclasts: cells that break down and resorb bone, allowing for bone remodeling and the extraction of calcium from bones.

Bone Structure

• Two main types of bone: cancellous (spongy) and compact (cortical) bone.
• Cancellous bone: light, spongey, and strong, with a network of bony spicules (trabeculae) and bone marrow.
• Compact bone: heavy, dense, and strong, made up of Haversian systems (osteons) and containing blood vessels, lymph vessels, and nerves.

Bone Types

• Long bones: most bones of the limbs, consisting of a diaphysis, epiphysis, and epiphyseal plates.
• Short bones: like cubes or marshmallows, e.g., carpal and tarsal bones.
• Flat bones: thin and flat, e.g., skull, scapulae, and pelvic bones.
• Irregular bones: miscellaneous, e.g., vertebrae, some skull bones, and sesamoid bones.

Long Bones

• Epiphysis: contains red marrow and epiphyseal plates, and is the line of growth of bone.
• Diaphysis: the main section of the long bone, made of strong compact bone for weight-bearing.
• Epiphyseal plates: sites of bone growth, weak and prone to fractures in young animals.
• Medullary cavities: contain red and yellow marrow.
• Red marrow: responsible for blood cell production, larger proportion in younger animals.
• Yellow marrow: responsible for fat storage, majority of bone marrow in adults.
• Periosteum: membrane covering the outer surfaces of bones, containing blood vessels, nerves, and cells for bone growth, remodeling, and repair.
• Endosteum: membrane lining the hollow interior surface of bones, involved in bone growth, remodeling, and repair.

The Skeletal System

• The skeletal system is a framework of bones that support and protect the soft tissues of the body.

Functions of the Skeletal System

• Support: provides a strong frame that supports the body and gives it its shape.
• Protection: protects delicate vital organs and tissues by surrounding them partially or completely.
• Movement (leverage): bones act as levers for muscles, allowing for movement.
• Blood cell formation: occurs in the bone marrow of some bones.
• Storage of minerals: bones act as a mineral bank, storing minerals like calcium and phosphorus.

Bone Cells

• Osteoblasts: cells that form the matrix of bone through ossification.
• Osteocytes: osteoblasts that are trapped in the bony matrix, contacting other osteocytes and their blood supply through cellular channels.
• Osteoclasts: cells that break down and resorb bone, allowing for bone remodeling and the extraction of calcium from bones.

Bone Structure

• Two main types of bone: cancellous (spongy) and compact (cortical) bone.
• Cancellous bone: light, spongey, and strong, with a network of bony spicules (trabeculae) and bone marrow.
• Compact bone: heavy, dense, and strong, made up of Haversian systems (osteons) and containing blood vessels, lymph vessels, and nerves.

Bone Types

• Long bones: most bones of the limbs, consisting of a diaphysis, epiphysis, and epiphyseal plates.
• Short bones: like cubes or marshmallows, e.g., carpal and tarsal bones.
• Flat bones: thin and flat, e.g., skull, scapulae, and pelvic bones.
• Irregular bones: miscellaneous, e.g., vertebrae, some skull bones, and sesamoid bones.

Long Bones

• Epiphysis: contains red marrow and epiphyseal plates, and is the line of growth of bone.
• Diaphysis: the main section of the long bone, made of strong compact bone for weight-bearing.
• Epiphyseal plates: sites of bone growth, weak and prone to fractures in young animals.
• Medullary cavities: contain red and yellow marrow.
• Red marrow: responsible for blood cell production, larger proportion in younger animals.
• Yellow marrow: responsible for fat storage, majority of bone marrow in adults.
• Periosteum: membrane covering the outer surfaces of bones, containing blood vessels, nerves, and cells for bone growth, remodeling, and repair.
• Endosteum: membrane lining the hollow interior surface of bones, involved in bone growth, remodeling, and repair.

The Skeletal System

• The skeletal system is a framework of bones that support and protect the soft tissues of the body.

Functions of the Skeletal System

• Support: Provides a strong frame that supports the body and gives it its shape, like scaffolding for soft tissue.
• Protection: Protects delicate vital organs and tissues by surrounding them partially or completely, e.g., the skull protects the brain, and the ribs protect the heart.
• Movement (Leverage): Bones act as levers for muscles, allowing joints to move.
• Blood Cell Formation: Takes place in the bone marrow of some bones.
• Storage of Minerals: Stores minerals like calcium and phosphorus, acting like a mineral bank.

Bone Cells

• Osteoblasts: Form the matrix of bone, which hardens through ossification, and are responsible for building bone.
• Osteocytes: Trapped osteoblasts in the bony matrix, connected to other osteocytes and blood supply through cellular channels called canaliculi.
• Osteoclasts: Cells that break down and resorb bone, allowing the body to extract calcium from bones for use in blood.

Bone Structure

• Cancellous Bone: Light, spongey, and strong, consisting of a network of bony spicules called trabeculae, found in the ends of long bones and surrounding the medullary cavity.
• Cortical or Compact Bone: Heavy, dense, and strong, making up the shaft of long bones and the outer layer of all bones, providing strength and protection.

Bone Membranes

• Periosteum: A membrane covering the outer surfaces of bones, containing blood vessels and nerves that supply bones, and cells involved in growing and repairing bone.
• Endosteum: A membrane lining the hollow interior surface of bones, containing cells involved in bone growth, remodelling, and repair.

Long Bones

• Epiphysis: The light, cancellous bone at the ends of long bones, covered by a thin layer of compact bone, containing bone marrow.
• Diaphysis: The main section of long bone, made of strong compact bone, providing weight-bearing support.
• Epiphyseal Plates: Plates of cartilage at the ends of long bones, where bone growth occurs, and which ossify in adults to become solid bone.
• Medullary Cavity: Contains red and yellow marrow, with blood vessels and nervous tissue.