Lecture 17 - Skeletal System and bone Flashcards
What bone marrow is active in producing red blood cells?
red bone marrow
Understand the gross anatomy of bone, bone composition, and the specific gross anatomy of long bones
a. Bone – consists of compact bone sandwiching spongy bone
b. Bone composition
i. Bone is a form of connective tissue
ii. 35% organic components (collagen)
iii. 65% inorganic hydroxyapatites (mineral salts)
iv. Strong and resilient: minerals resist compression, collagen resists tension.
c. Gross anatomy of a long bone
i. Diaphysis – forms the long axis of the bone
ii. Epiphysis – proximal and distal ends
iii. Metaphysis – regions between epiphysis and diaphysis
iv. Articular cartilage – hyaline cartilage covering the joint surface
v. Periosteum – outer fibrous covering, double-layed membrane
vi. Marrow (medullary) cavity – hollow space within diaphysis; contains yellow (fat) marrow + blood vessels
vii. Endosteum – thin membrane, lines medullary cavity, internal bone surfaces, trabeculae, lines canals of compact bone
Classify bones by their shapes into long bones, short bones, flat bones, and irregular bones
a. Long bones
i. Longer than they are wide
ii. Bear a lot of weight (e.g. femur, humerus)
b. Short bones
i. Similar width and length (cube shaped)
ii. Stability and support with little movement (e.g. carpal bones of wrist)
iii. Sesamoid bones (‘sesame shaped’) special type that forms in a tendon
c. Flat bones
i. Thin, flattened, usually a bit curved
ii. Protect vital organs, provide surfaces for large muscle attachment (e.g. sternum, skull bones)
d. Irregular bones
i. Don’t fit into other categories, complicated shapes (e.g. vertebrae)
Summarise the functional properties of trabecular and cancellous bone
a. Trabecular (spongy bone)
i. Looks poorly organised, but trabeculae aligned to assist with weight bearing
ii. Lines of compressive stress + lines of tensile stress
iii. Filled with red or yellow bone marrow (also medullary cavity)
b. Cancellous (compact)
i. Dense bone, forms outer shell of all bone, surrounds spongy bone
ii. Hollow pillars of bone matrix containing nerves and blood vessels
Understand the neurovascular supply of bones
a. Periosteal arteries supply periosteum and outer compact bone, enter through many small canals
b. Large nutrient artery enters via nutrient foramen at centre of diaphysis
c. Ends of long bone supplied by epiphyseal and metaphyseal arteries
osteoblasts
i. Bone-building cells
ii. Synthesise and secrete collagen fibres, organic components to build extracellular matrix of bone
iii. Initiate calcification
osteoclasts
i. Break down bone ECM (bone reabsorption)
ii. Releases lysosomal enzymes + acids to digest protein and mineral components of ECM
Describe the processes of intramembranous and endochondral ossification
a. Intramembranous ossification
i. Development of ossification centre: osteoblasts secrete organic ECM
ii. Calcification: calcium and other mineral salts are deposited, and ECM calcifies (hardens)
iii. Formation of trabeculae: ECM develops into trabeculae that fuse to form spongy bone
iv. Development of the periosteum: mesenchyme at the periphery of the bone develops int the periosteum
b. Endochondral ossification
i. From cartilage derived from mesenchyme
ii. Cartilage models of bone form from mesenchyme during fetal period, bone replaces cartilage
Understand the process of bone remodelling
a. Bone is very active tissue
b. Every week we recycle 5-7% of our bone mass
c. Spongy bone is replaced every 3-4 years
d. Compact bone id replaced every 10 years
Be familiar with the anatomical terminology of bone markings and apply this terminology to specific bony landmarks
a. Sites of muscle and ligament attachment
i. Tuberosity, crest, trochanter, lien, tubercle, epicondyle, spine, process
b. Projections that help to form joints
i. Head, facet, condyle, ramus
c. Depressions and openings for passage of nerves and vessels
i. Groove, fissure, foramen, notch, meatus, sinus, fossa
describe the factors that affect bone growth and remodelling over a lifetime
a. response to mechanical stress
b. weight bearing exercise
c. vitamins and minerals
d. hormones
