Bones Flashcards
What are the functions of bones (4)
- Weight bearing/support
- Protection
- Mineral store
- Blood formation (red bone marrow)
5 Types of Bone + example
- Flat bone - skull bones
- Long bone - femur
- Short bone - carpal (wrist)
- Irregular bone - vertebra
- Sesamoid bone - patella
Function of sesamoid bones
releave tension within muscles and tendons, protecting them from wear and tear
2 types of bone
- Compact/cortical bone
- Spongy/cancellous/trabecular bone
Basic anatomy of bones
Blood vessels, medullary cavity, bone marrow, membranes (periosteum, endosteum) - see sheet
Explain the structure of compact bone
Osteons/haversian systems - compact bone organised in circular structures, with Cental Hacersian canals and horizontal perforating/Volkmann’s canals. Also with osteocytes (bone cells like ants) and concentric rings of mone matrix (lamallae) around haverian canal. - see sheet
What are canaliculi
small canals where osteons are connected
Describe the structure of spogny bone
- less dense than compact bone
- Poreous with a network of lamellated trabeculae filled with bone marrow
- Orientation of trabeculae (struts) reflects main directions of mechanical forces
What is the growth plate called/made from
Epiphyseal plate - made from hyaline cartilage
What is bone in general composed of?
Is a CT so:
* Cells - osteoclasts, osteoblasts, osteocytes
* ECM - 45% Minerals (hydroxypatite crystals = complex from of calcium phosphate), 35% collagen type 1, 20% water
How do the minerals in bone afffect it?
Makes it stiff and able to support structures, with a high strength under compression
How does collagen in bone affect it?
Gives it some flexibility, reducing the risk of fracture. Has high strength under tension
Explain red bone marrow
Forms all the Blood cells with the exeption of lymphocytes (produced in the marrow and reach maturation in lymphoid organs)
Explain yellow bone marrow
Primarily a storehouse for fats but can be converted to RBM under certain conditions (e.g. severe blood loss/fever)
Where is a balance found in bones
Between bone removal and formation (turnover/remoddling)
Constant process in adults and children and occurs in healthy bone
Briefly describe general principle of bone remoddelling
Bone —> osteoclasts break down old bone —> osteoblasts build new bone —> new bone
What are osteoclasts
Large multinucleated cells derived from haematopoietic stem cells (like macrophages)
Where are osteoclasts found and what is their function
- Found: bone surface
- Function: resorb bone matrix (ruffled boarder releases acid to dissolve bone M) - bone resorbing cells
Whate are osteoblasts?
Immature bone cells created from osteopregenitor cells in periosteum and endisteum
What is the function of osteoblasts
Produce bone matrix (unmineralised matrix = osteoid) and initiate calcification (turn into proper bone)
What do osteoblasts finally do?
Become osteocytes once surrounded by matrix (burry themselves alive)
What are osteocytes
Mature bone cells
Where are osteocytes found
Inside lacunae (holes) in bone matrix - cells lie in canaliculi (connects lacunae to each other, allowing communication between cells)
Function of osteocytes
Unsure - may maintain bone matrix and sense mechanical forces
What is the structure of the ECM like in bones
Minerals, protein (collagen) and water:
- modified type 1 collagen fibres which are strongly cross linked and with large gaps within fibres (gaps give space for hydroxyapatite crystals)
What is the collagen fibre orientation of the ECM linked to
Mechanical forces
What are 3 common disorders of bone remodelling and how can they present
Probs not examanible
- Osteoporosis: resorption>formation - fractures common
- Pagent’s disease: ^resorption/formation - loss of hearing?
- Osteopetrosis: dec resorption - short stature
What can affect bone mass
Ageing, genes, environment (e.g. smoking), gender
What do osteoblasts secrete?
A matrix material called osteoid, a gelatinous substance made up of collagen (a fibrous P), mucopolysaccharide (organic glue)
Ossification
Process of bone formation
Most common type of bone growth often in long bones
Endochondral ossification
What is the lesser common type of bone growth and where does it occur?
Intramembranous ossification - flat bones of skull, mandible, maxilla, also long bones
How are most bones formed in terms of bone growth
By a combination of both types
Explain endochrondral ossification
- Bone forms as cartilage model first
- Blood vessels invade cartilage
- Cartilage replaced with bone
- Cartilage remains in epiphysial growth plate
- growth plate eventually ossifies
So where does endochondral ossification occur
epiphyseal(/metaphysial?) growth plates
Summarise endochondral (long bone) ossification in 4 words
Bones form within cartilage
How does intramembranous (flat bone) ossification work
Mesenchymal cells develop into osteoprogenitor cells that mature into osteoblasts (found in periosteum and endosteum) that start depositing bone. Residual mesenchymal cells develop blood vessels and bone marrow. This bone formation also occurs in adult bones
What does each type of ossification give ries to (in terms of types of bone growth)
Endochndral ossification - interstitial growth
Inramembranous ossification - appositional growth
Where does the epiphysial plate lie
between epiphyses and metaphyses - growth of long bones occurs here
Appendicular skeleton
Upper and lower limbs which inc shoulder and hip girdle
Axial skeleton
Bones on long axid of body - skull, spine, ribcage and sacrum
What are limb girdles
Limb girdles surround and support the proximal ends of the limb bones and provide a point of attachment for the appendicular skeleton to the axial skeleton.
Epiphysis
rounded end of a long bone, at its joint with adjacent bone(s).
Diaphysis
shaft of long bone
What lies between epipysis and diaphysis
Metaphysis - wide portion of long bone and includes epiphyseal growth plate
Difference between condyle and epicondyle
- Condyles more round-shaped than epicondyles
- Condyle is smooth and large, whereas epicondyle is rough and small
- Condyle articulates with a bone, but epicondyle provides a surface for muscle and ligament attachment
Where does intersititial bone growth occur
(endochondral ossification)
periosteum
Think wrong: ans is epithelial growth plate
What does bone form the supporting tissue for
Haemopoiesis - production of blood cells and platelets (in bone marrow)
What does bone continously undergo
A continous process of renewal
What are osteocytes derived from
Differentiation of osteoblasts
What are osteoclasts derived from
the haemopoietic lineage
What are osteoblasts derived from
The mesenchymal lineage
key regions - see other anatomy flashcards for more
Cranial
Thorax
Abdomen
(Pelvis)
Upper Extremities (limbs)
Lower Extremities (limbs)
What are girdles
wo more or less complete bony rings at the anterior and posterior ends of the vertebrate trunk supporting the arms and legs respectively
2 girdles
- Shoulder girdle
- Pelvic girdle
what makes up the shoulder girdle
The shoulder girdle is composed of the clavicle and the scapula, which articulates with the proximal humerus of the upper limb.
what makes up the pelvic girdle
The pelvic girdle, as I said above, is made up of three fused bones: the ischium, the ilium, and the pubis. The pubis forms the anterior part of the pelvic girdle. It is a flattened, irregular-shaped bone that articulates with the pubic symphysis, a cartilaginous joint.
What is a condyle
large prominence in a bone, which often provides structural support to the overlying hyaline cartilage. It bears the brunt of the force exerted from the joint.
What does it mean for a condyle (e.g. bottom of femur) to be lateral/medial
- Lateral = on outside
- Medial = on inside
What is a epicondyle
a protuberance above or on the condyle of a long bone, especially either of the two at the elbow end of the humerus.
Difference between condyle and epicondyle
Condyle is the smooth surface area at the end of a bone that forms part of a joint. The epicondyle is a rounded protuberance at the end of a bone, serving as a place of attachment for ligaments, tendons, and muscles.
what are condyles lined with
hyaline cartilage
