L9 Principles of Skeletal System Flashcards
Axial
Skull, vertebrae, ribs, sternum and hyoid bone
Appendicular
Limb bones and bones of pectoral and pelvic girdle
Skeleton function
Protection, support, movement, RBC production and metabolic reservoir
How long does the bone development period last for?
week 8 and finishes at 20yo
What is bone derived from?
mesoderm -> paraxial and lateral plate mesoderm
Intramembranous ossification - what is it?
Direct mineralisation of CT (mesenchyme)
Cells divide and condense around capillary network
Starting point is called primary ossification centre
Grows radially -> fuse and replace CT
CT that remains is penetrated by blood cells and undifferentiated mesenchyme gives rise to bone marrow
Skull mandible and clavicle
Endochondral ossification - what is it?
Cartilaginous template from mesenchyme
Template replaced by bone - osteogenesis
Different ossification centres emerge (primary in diaphysis and secondary in epiphysis)
Initially a bone collar is produced and this is where primary centre develops
Epiphyseal plate (growth plate) exists between diaphysis and epiphysis
Ossification centres and plates in endochrondral ossification are…
primary in diaphysis and secondary in epiphysis
Epiphyseal plate (growth plate) exists between diaphysis and epiphysis
Bone growth - what is it?
Associated with partial reabsorption of previously laid down bone and new bone
Long bone gradually lengthen as ossification continues
Developing bone is penetrated by blood vessels at week 9
Maturity = epiphyseal plate abolished
Bone penetrated by…
blood vessels at week 9
Important vitamins and their roles include…
Vit A - bone remodelling
Vit C - CT
Vit D - Calcium absorption
Important hormones and their roles include…
Parathyroid hormone - hyperparathyroidism (calcitonin - thyroid)
Growth hormone - dwarfism and acromegaly
What is cartilage? [4]
CT
Forms skeleton where flexibility is needed
Avascular
Proportion of bone to cartilage changes as individual develops
What is bone? [4]
Hard form of CT
Provide ridged framework
Vascular
Compact (outside) and spongy
What are the coverings of cartilage/bone called?
CT surrounding bone is called periosteum
CT surrounding cartilage is perichondrium
No CT where articulation needed
Bone cell types include… [4]
Osteoprogenitor, Osteoblast, Osteocyte and Osteoclasts
Compact bone - what is it?
Covered by periosteum
Lamella (concentric layers of inorganic matrix) laid by osteoblasts
Lamella forms harversian canal in centre
Haversian canal contains vascular and nerve supply
Osteoblasts become trapped and turn into osteocytes
Each osteocyte occupies its own lacunae
Radiating from each lacunae are minute canals (canaliculi)
Nutrients travel in the canaliculi to the osteocyte
Spongy bone - what is it?
Also known as cancellous bone
Irregular lamellae
Has red bone marrow surrounding it
Highly vascular
What are the bone classifications?
Long (femur), Flat (skull), Irregular (vertebra), Short (carpals) and sesamoid (patella)
What is the number of bones in the body?
270 Bones at birth, 206 by adulthood.
Bones: skulls, spine, thorax, arm, pelvis and leg
Skull (29 including hyoid and inner ear)
Spine (26) –
Thorax- (25) Ribs- (24 in 12 pairs), sternum
Arm- (64) Scapula, Humerus, radius, carpals, metacarpals, phalanges
Pelvis- (2) made up of Ilium, ischium and pubis
Leg- (60) Femur, tibia, fibula, tarsals, metatarsals and phalanges
What is a synovial joint?
joint capsule and a synovial
cavity, they permit movement. Further classified
into six types: Plane e.g. Intercarpal, Hinge e.g.
knee, Saddle e.g. carpometacarpal, Condyloid e.g.
metacarpophalangeal, Ball and Socket e.g. hip, Pivot
e.g. radioulnar.
What is a fibrous joint?
connected by collagen, they do
not permit movement e.g. sutures of skull.
What is a cartilaginous joint?
connected by cartilage to
allow some movement e.g. growth plates,
