Summary
Use it or lose it
Period 5, 2023-2024
,Case 1
Skeleton
Central and axial skeleton is the core framework of the body,
containing the skull, vertebral column, ribs, and sternum. These
bones form the central axis of the body and provide structural
support and protection
Peripheral skeleton comprises the bones of the limbs as well as
the shoulders and pelvic girdles. These bones connect to the axial
skeleton and facilitate movement and mobility
The functions of the skeleton are:
- Protection
o Skeleton as a protective shield for delicate internal organs
- Support
o Bones provide a framework that supports the body and cradles its soft organs
- Mineral and growth factor storage
, o Bones are a reservoir for minerals, with calcium and phosphate as the most important.
The stored minerals are released into the bloodstream in ionic form as needed for
distribution to all body parts. Deposits and withdrawals of minerals to and from the bone
happen almost continuously.
o Mineralized bone matrix stores important growth factors
- Triglyceride (fat) storage
o Storage in the bone cavities
- Erythrocyte production (hematopoiesis)
o Within certain bones (especially flat bones like sternum, ribs, pelvis, and skull) the red
bone marrow produces red blood cells (erythrocytes), white blood cells (leukocytes),
and platelets (thrombocytes) through hematopoiesis
- Hormone production
o Bones produce osteocalcin, a hormone that not only helps regulate bone formation, but
also protects against obesity, glucose intolerance, and diabetes
Bones
The important big bones, or groups of bones are
- Skull; contains the cranium and facial bones → protects the brain
- Vertebral column (spine); provides support and protects spinal cord
- Rib cage; protects the thoracic organs as heart and lungs
- Scapula (shoulder); are for the arm movement
- Arms; contain humerus, radius and ulna, carpals, metacarpals and phalanges
- Hips; containing ilium, pubis, and ischium
- Legs; contain femur, patella, tibia and fibula, tarsals, metatarsals and phalanges
Types
- Long bones
o E.g. tubular bones of the limbs
o Components:
▪ Epiphysis: are the ends of the bone, are made
from spongy (cancellous) bone tissue, which is
porous and contains red bone marrow for
erythrocyte production
• Proximal: closest to the body’s midline
• Distal: furthest from the body’s midline
▪ Diaphysis: the shaft of long bone, between the
epiphyses. Contains mainly compact bone
tissue which is dense and provides strength
• Contains medullary cavity, a hollow
space containing yellow bone marrow,
which primarily consists of adipose cells
and functions as energy storage, then it
is called the yellow marrow cavity.
▪ Epiphyseal line: known as the growth plate,
between the epiphysis and diaphysis of a longer
bone
• In the childhood, the line is the site of
active bone growth (chondrocytes
continuously divide and contribute to
growth)
• After ossification, the line doesn’t
contribute to bone growth
, ▪ Periosteum is the fibrous membrane (double-membrane) that covers the outer
surface of the bone, except the joint. It contains blood vessels, nerves, and
lymphatic vessels. They pass through the shaft to enter the marrow cavity via
nutrient foramina, these perforating fibers are important in bone growth, repair,
and remodeling, as it delivers nutrient from the blood
▪ Endosteum is a thin layer of connective tissue that lines the inner surface of
bones, including compact and spongy bone. It contains osteoblasts and
osteoclasts
▪ Cortical bone is the dense (outer) layer of the bone that provides strength
▪ Articular cartilage covers the surface of the bones within the joints, it acts as a
smooth, low-friction surface that allows bones to glide over each other with
minimal resistance, during movement.
• Lacks blood vessels and nerves
• Damage leads to pain due to higher friction of the bone (osteoarthritis)
▪ Apophysis is the bony outgrowth or point that serve as a point of attachment for
muscles, ligaments, or tendons. Typically located near the ends of bones or at
the junctions where bones meet
- Short bones
o Are short, kind of cube-shaped
o E.g. carpal and tarsal bones
- Flat bones
o Thin and flat bones, are crucial for protecting vital organs
o E.g. scapula (shoulder blade), ilium (part of hipbone), and bones of the calvaria (skull
cap)
- Irregular bones
o Complex shapes
o E.g. vertebrae anomalous, supernumerary bones not consistently present, as in the skull
base
- Pneumatic bones
o Containing air-filled spaces, contributing to respiratory function and voice resonance, as
facial skeleton and paranasal sinuses
o E.g. the patella
- Sesamoid bones
o Bones incorporated in tendons
o E.g. the patella
- Accessory bones
o Anomalous, supernumerary bones, which are not present in every individual, may be a
result of failure to fusion
o As in the calvaria and foot (generally result from the failure of fusion of certain adjacent
ossification centers)
Laminar bone refers to the organized arrangement of bone tissue in layers or sheets, also lamellae. These
form rings around central channels called the Haversian canals in compact bone tissue.
The external layer is compact bone, and internal to this is spongy bone ( a honeycomb of small needle-
like trabeculae)
Tubular systems, known as Haversian systems or osteons, are structural units found in compact bone
tissue. Each tubular system consists of concentric lamellae arranged around a central Haversian canal.
These canals contain blood vessels, lymphatic vessels, and nerves, providing nutrients and
oxygen to bone cells and facilitating waste removal.
Use it or lose it
Period 5, 2023-2024
,Case 1
Skeleton
Central and axial skeleton is the core framework of the body,
containing the skull, vertebral column, ribs, and sternum. These
bones form the central axis of the body and provide structural
support and protection
Peripheral skeleton comprises the bones of the limbs as well as
the shoulders and pelvic girdles. These bones connect to the axial
skeleton and facilitate movement and mobility
The functions of the skeleton are:
- Protection
o Skeleton as a protective shield for delicate internal organs
- Support
o Bones provide a framework that supports the body and cradles its soft organs
- Mineral and growth factor storage
, o Bones are a reservoir for minerals, with calcium and phosphate as the most important.
The stored minerals are released into the bloodstream in ionic form as needed for
distribution to all body parts. Deposits and withdrawals of minerals to and from the bone
happen almost continuously.
o Mineralized bone matrix stores important growth factors
- Triglyceride (fat) storage
o Storage in the bone cavities
- Erythrocyte production (hematopoiesis)
o Within certain bones (especially flat bones like sternum, ribs, pelvis, and skull) the red
bone marrow produces red blood cells (erythrocytes), white blood cells (leukocytes),
and platelets (thrombocytes) through hematopoiesis
- Hormone production
o Bones produce osteocalcin, a hormone that not only helps regulate bone formation, but
also protects against obesity, glucose intolerance, and diabetes
Bones
The important big bones, or groups of bones are
- Skull; contains the cranium and facial bones → protects the brain
- Vertebral column (spine); provides support and protects spinal cord
- Rib cage; protects the thoracic organs as heart and lungs
- Scapula (shoulder); are for the arm movement
- Arms; contain humerus, radius and ulna, carpals, metacarpals and phalanges
- Hips; containing ilium, pubis, and ischium
- Legs; contain femur, patella, tibia and fibula, tarsals, metatarsals and phalanges
Types
- Long bones
o E.g. tubular bones of the limbs
o Components:
▪ Epiphysis: are the ends of the bone, are made
from spongy (cancellous) bone tissue, which is
porous and contains red bone marrow for
erythrocyte production
• Proximal: closest to the body’s midline
• Distal: furthest from the body’s midline
▪ Diaphysis: the shaft of long bone, between the
epiphyses. Contains mainly compact bone
tissue which is dense and provides strength
• Contains medullary cavity, a hollow
space containing yellow bone marrow,
which primarily consists of adipose cells
and functions as energy storage, then it
is called the yellow marrow cavity.
▪ Epiphyseal line: known as the growth plate,
between the epiphysis and diaphysis of a longer
bone
• In the childhood, the line is the site of
active bone growth (chondrocytes
continuously divide and contribute to
growth)
• After ossification, the line doesn’t
contribute to bone growth
, ▪ Periosteum is the fibrous membrane (double-membrane) that covers the outer
surface of the bone, except the joint. It contains blood vessels, nerves, and
lymphatic vessels. They pass through the shaft to enter the marrow cavity via
nutrient foramina, these perforating fibers are important in bone growth, repair,
and remodeling, as it delivers nutrient from the blood
▪ Endosteum is a thin layer of connective tissue that lines the inner surface of
bones, including compact and spongy bone. It contains osteoblasts and
osteoclasts
▪ Cortical bone is the dense (outer) layer of the bone that provides strength
▪ Articular cartilage covers the surface of the bones within the joints, it acts as a
smooth, low-friction surface that allows bones to glide over each other with
minimal resistance, during movement.
• Lacks blood vessels and nerves
• Damage leads to pain due to higher friction of the bone (osteoarthritis)
▪ Apophysis is the bony outgrowth or point that serve as a point of attachment for
muscles, ligaments, or tendons. Typically located near the ends of bones or at
the junctions where bones meet
- Short bones
o Are short, kind of cube-shaped
o E.g. carpal and tarsal bones
- Flat bones
o Thin and flat bones, are crucial for protecting vital organs
o E.g. scapula (shoulder blade), ilium (part of hipbone), and bones of the calvaria (skull
cap)
- Irregular bones
o Complex shapes
o E.g. vertebrae anomalous, supernumerary bones not consistently present, as in the skull
base
- Pneumatic bones
o Containing air-filled spaces, contributing to respiratory function and voice resonance, as
facial skeleton and paranasal sinuses
o E.g. the patella
- Sesamoid bones
o Bones incorporated in tendons
o E.g. the patella
- Accessory bones
o Anomalous, supernumerary bones, which are not present in every individual, may be a
result of failure to fusion
o As in the calvaria and foot (generally result from the failure of fusion of certain adjacent
ossification centers)
Laminar bone refers to the organized arrangement of bone tissue in layers or sheets, also lamellae. These
form rings around central channels called the Haversian canals in compact bone tissue.
The external layer is compact bone, and internal to this is spongy bone ( a honeycomb of small needle-
like trabeculae)
Tubular systems, known as Haversian systems or osteons, are structural units found in compact bone
tissue. Each tubular system consists of concentric lamellae arranged around a central Haversian canal.
These canals contain blood vessels, lymphatic vessels, and nerves, providing nutrients and
oxygen to bone cells and facilitating waste removal.
