Theme 1 Anatomy - Skeletal system Flashcards
what are the two parts of the skeletal system?
axial and appendicular
what is the axial skeleton?
skull, vertebrae, sternum and hyoid bone
what is the appendicular skeleton?
limb bones, pectoral bones and pelvic girdle
name four functions of the skeleton
protection of organs, movement, production of red blood cells, metabolic reservoir for calcium and mineral salts,
what germ layer does the skeletal system arise from and at what week?
from mesoderm from week 4 onwards
which bones ossify last and at what age is this?
clavicle, humerus, femur at 20-30 years and carpals at 18 years
which type of mesoderm forms the appendicular skeleton?
lateral plate mesoderm
what are the two types of ossification?
intramembranous and endochondral
what is intramembranous ossification and where does it occur?
direct mineralisation of connective tissue and occurs in the skull, mandible and clavicle
what produces the radial pattern of bone in the skull?
direct mineralisation where the capillary networks are - bone grows outward from the primary ossification centre
what happens to the connective tissue that does not become bone in intramembranous ossification?
is penetrated by blood cells and undifferentiated mesenchyme and gives rise to bone marrow
how much remodelling is there in intramembranous ossification (skull)?
not very much - a little to increase the thickness of the skull
what type of ossification starts with a cartilage template which is replaced by bone in an ordered fashion?
endochondral ossification
where does primary ossification occur?
the bone collar on the diaphysis
where does secondary ossification occur and what does it make?
the epiphysis and makes spongey bone
how do bones grow in length during development?
cartilage cells are stacked on top of each other at the growth plate and bone is laid down behind them
what structure can look like a fracture on X ray in children?
the epiphyseal growth plate
does cartilage become bone or is it replaced by bone?
hyaline cartilage acts as a template and is replaced by bone
what processes allows bone to grow both radially as well as in length and which hormone controls this?
partial reabsorption by parathyroid hormone
what structure is abolished when bone becomes mature from immature?
the epiphyseal plate
what three dietary elements regulate bone development and maintenance?
calcium, phosphorus and vitamins
what is the function of vitamin D and what does deficiency cause?
it is essential for calcium absorption and deficiency causes rickets due to lack of calcium
what three hormones control bone growth and where are they produced?
parathyroid hormone produced in the parathyroid glands, calcitonin produced by the thyroid gland and growth hormone produced by the pituitary gland
what is the function of parathyroid hormone?
increases absorption of bone and therefore increases the amount of calcium circulating in the blood
what does too much parathyroid hormone lead to?
osteopenia - edges of the bone being eaten away
what does calcitonin do?
works in opposition to PTH and reduces amount of calcium circulating in the blood
what does too much or too little growth hormone cause?
too little before puberty causes dwarfish, too much after puberty causes acromegaly (elongation of mandible and maxilla)
how does cartilage get its nutrients?
from diffusion as its avascular
what are the two types of bone?
compact (outside) and spongey (in the middle)
what is the thin membrane covering bone?
periosteum or perichondrium if connective tissue
what is the role of the periosteum
helps get blood vessels into the bone through the nutrient foramen
what are the four cell types that make up bone?
osteoprogenitor cells, osteoblasts, osteocytes and osteoclasts
what is the role of osteoprogenitor cells?
can turn into any form of cell
what is the role of osteoblasts?
building cells - lay down organic matrix around them and trap themselves
what is the role of osteocytes?
trapped osteoblasts become osteocytes - maintain the organic matrix and sit in their own lacunae
what is the role of osteoclasts?
eat and destroy bone under the influence of parathyroid hormone
what is the name of the concentric later of inorganic matrix laid down by osteoblasts in compact bone?
lamella
which way does the Haversian canal run and what is its role?
runs vertically and transports blood and nerve supply to bone
what are canaliculi?
radiate out of lacunae and help with nutrient transport to the osteocyte
what is another name for spongey bone
cancellous bone
what are spaces in spongey bone filled with?
bone marrow therefore are highly vascularised
give two examples of flat bones
scapula and skull
give three examples of irregular bones and how can they be described?
vertebrae and sacrum - developed over time for a specific function
give an example of a sesamoid bone and how can it be characterised?
patella - completely surrounded by tendons
why does the mastoid process have a bump on it?
flat at birth then pressure from the sternocleidomastoid bone makes it produce a bump in order to strengthen
what are the three types of joints?
synovial, fibrous and cartilaginous
what is a synovial joint and where is it found?
has a joint capsule and a synovial cavity to allow movement - knee joint
what is a fibrous joint and where is its found?
connected by collagen and doesn’t allow movement - sutures of skull
what is a cartilaginous joint and where is it found?
connected by cartilage - some but not much movement - intervertebral disks
what do the menisci in the knee joint do?
shock absorb and stabilise the knee
what two things stables the knee?
menisci and ligaments (ACL and PCL)
