The Skeletal System Flashcards
How many bones are there in the appendicular skeleton?
126 bones
Osteology
= the study of the bone
What does collagen enable bones to do?
- Enable bone to resist being stretched or torn apart (tensile strength).
- Prevents bones being hard and brittle.
Osteoprogenitor cells
these are stem cells derived from mesenchyme (connective tissue found in the embryo) they have the ability to become osteoblasts
What does the appendicular skeleton include?
- Upper limbs
- Lower limbs
What does the axial skeleton include?
- Head (cephalic)
- Neck (cervical)
- Chest and trunk (thoracic)
- Lumbar and pelvis
Osteoblasts
secretes collagen and other organic components to form bones (builders)
Osteocytes
mature bone cells that maintain the daily activities of the bone
Osteoclasts
cells found on the surface of bones and they destroy or resorb bone tissue (demolition crew)
What can spongy bone also be known as (2)?
- Cancellous
- Trabecular bone
What is spongy bone responsible for?
the flexibility and weight distribution shifts that can withstand multidirectional forces
Describe the structure of spongy bone.
It is light, porous, and is made up of small, needle-like pieces of bone arranged like a honeycomb.
What is compact bone also known as?
cortical bone
Where is compact bone found?
forms outer layer of most bones (found in shafts of femur, tibia and fibula).
Describe compact bone.
It is dense, hard, and heavy tissue which makes up most of the bone’s weight.
What is the purpose of compact bone?
It provides strength and protection, insulation, movement frameworks and ideal for resisting compressive forces.
What are compact bones made up of?
units called osteons or Haversian systems.
What are (7) functions of bones?
- Support
- Shape
- Protection
- Movement
- Mineral storage (calcium, phosphate and fat storage)
- Blood cell production in bone marrow
- Storage of energy (as bone marrow stores lipids, which can be used as an energy reserve)
What is intramembranous ossification?
where bone forms on or within loose, fibrous connective tissue membranes without first going through a cartilage stage
What is endochondral ossification?
where bones form in hyaline cartilage which has been produced by chondroblasts
What are some clinical features of fractures?
- pain
- deformity
- oedema
- muscle spasm
- abnormal movement
- crepitus
- loss of function
- hypovolaemic shock
- limitation of joint movement
- muscle atrophy
What are the 4 steps to fracture healing?
- Haematoma formation and inflammation
- Fibrocartilaginous callus formation (woven bone/spongy bone formation)
- Bony callus formation/Consolidation (lamella bone formation - solid union of fracture)
- Bone remodelling
How do we know when a fracture is healed?
- Absence of pain on weight-bearing, lifting or movement
- No tenderness on palpation at the fracture site
- Blurring or disappearance of the # line on x-ray
- Full or near full functional ability
How long does cancellous (spongy) bone take to heal?
approx. 3-12 weeks
How long does is take compact bone to heal?
approx. 12-18 weeks
What is bone growth in length called?
interstitial growth
What is bone growth in diameter called?
appositional growth
What is bone growth primarily controlled by?
hormones
Describe the steps involved in intramembranous ossification
- Clusters of osteoblasts form a centre of ossification that secretes the organic extracellular matrix.
- The extracellular matrix hardens by deposition of the calcium and mineral salts.
- Bony matrices fuse to form trabeculae.
- Periosteum develops on the bone’s periphery.
- Spongy bone is replaced with compact bone on the bone’s surface.
What is a zone of hypertrophic cartilage?
a column-like layer of maturing chondrocytes.
What is a zone of calcified cartilage?
a region of dead chondrocytes.
What is a zone of proliferating cartilage?
a layer of actively dividing chondrocytes.
What is a zone of resting cartilage?
a layer of small, scattered chondrocytes anchoring the epiphyseal (growth) late to the bone.