Intro to bone and soft tissue Flashcards
What does the Musculoskeletal System consist of ?
Bone-Joint
Muscle-Skeletal (give posture,movement)
Connective Tissue-Tendons(muscle to bone), Ligaments(bone to bone), Cartilage(structural support, protect tissues, Cartilage)
How many bones are their in the skeleton?
206
270 in children
What are the 3 planes?
CORONAL-front on view
SAGITAL(median)-side on view
TRANSVERSE(axial)-Looking from the feet upwards
What is the vocabulary to describe the direction of movement ?
Inferior(caudal)-bottom
Superior(rostral)-topp
Medial-towards the body
Lateral-away from the body
Anterior (ventral)-front
Posterior(dorsal)-back
What are the classifications of bones?
Flat bones (frontal bone)
Short bones(carpals)
Sesamoid bones(knee)
Sutured bones (skull sultures)
Irregular bones(vertebrae)
Long bone(femur)
What are the 5 main functions of the skeletal system?
Movement
Support
Protection of the vital organs
Storage of calcium
Haemopoesis
What are the 4 different bones cells?
Osteogenic cell-bone stem cell
Osteoblast:
- bone forming
- secretes OSTEOID-catalyse mineralisation of osteoid
Osteocyte:
- Mature bone
- formed when osteoblast becomes embedded in its secretions -sense mechanical strain to direct osteoclast and osteoblast activity
Osteoclast:
- Bone breaking
- dissolve and reabsorb bone by phagocytosis
- Derived from bone marrow
Where are bone cells found?
Osteocytes-embedded in bone matrix
Osteoclasts -bone surfaces and at sites of old injured or unneeded bone
Osteogenic cells-Deep Layers of Periosteum
Osteoblasts-growing portions of the bone, including periosteum and endosteum
What is the organisation of cortical/compact bone?
outer dense surface of bone
OSTEONS- have LAMELLAE which are concentric around a central HAVERSIAN CANAL
This canal contain blood vessels, nerves and lymphatics-which gives the bone cells food
LACUNAE-small spaces containing Osteocytes
VOLKMANS CANAL -transverse perforating canals
What is the structure and makeup of the bone matrix?
40% Organic compound-90% of this is type 1 COLLAGEN and 10% is ground substance(proteoglycans, glycoproteins, cytokine and growth factors)
60% is INORGANIC component- calcium hydroxyapatite or Osteocalcium phosphate
What are the different bone types?
Immature(WOVEN): -First bone produced -Laid down in a woven manner -relatively weak -mineralised and replaced by mature bone
Mature bone(LAMELLAR): -mineralised woven bone -LAMELLAR (layer) stucture-relatively strong
What 2 layers is the mature bone made up of?
CORTICAL: -compact -dense -suitable for weight bearing -outer layer
CANCELLOUS: -spongy-honeycomb strucure (TRABECULAE)-Not suitable for weight bearing -Inner structure
Why do we have cancellous bone?
Its to heavy if we were just made out of cortical bone
What is the structure of cancellous bone?
Has TRABECULAE- matrix of tissue that gives it a spongy appearence
What is Intramembranous Ossification?
Fibrous membranes->bone
Forms flat bones of the skull, clavicle and mandible
1-condensation of MESENCHYMAL CELLS/FIBROUS MEMBRANES which differentiate into osteoblasts=ossification centre forms
2-Secreted OSTEIOD traps osteoblasts which become osteocytes
3-Trabecular matrix and perisosteum form
4-compact bone develops superficial to cancellous bone. Crowded blood vessels condense into red bone marrow
What is endochondral ossification?
growing cartilage is replaced by bone to form the growing skeleton
Leads to the development of LONG BONES
Takes longer than intermembranous ossification
What are the 2 ways that bone form?
Intramembranous ossification
Endochondral Ossification
What are the steps of Endochondral ossification?
1-Bone collar formation
2-Cavitation
3-Periosteal bud invasion
4-Diaphysis elongation
5-Epiphyseal ossification
What is the primary and secondary ossificiation centre?
Primary-DIAPHYSIS
secondary-EPIPHYSIS
What is the epiphyseal plate?
- Growth plate at each end of a LONG bone
- ZONE OF ELONGATION of the long bone
- Contains HYALINE CARTILAGE
Describe interstitual growth?
This is lengthening of the long bones
1-Growth plate zones -change in Chondracytes(secrete matrix)
2-Reserve Zone- Matrix production
3-Proliferative zone-Mitosis of bone cells
4- Maturation and hypertrophy(lipids, glycogen and alkaline phosphate accumulate and matrix calcifies)
5- Calcified Matrix-cartilage has calcified and dies
6-Zone of Ossification-Primary and secondary spongiosa(cancallous bone)- dead cartilage replaced by bone
What is appositional growth?
deposition of bone beneath the periosteum to increase thickness
Describe Appostional growth?
1-ridges in the periosteum(connective tissue enveloping the bone) create a GROOVE for the periosteal blood vessel
2-Periosteal ridges fuse= endosteum-lines TUNNEL
3-Osteoblasts in the endosteum build new concentric lamellae inward toward center of tunnel forming a NEW OSTEON
4-Bone grows outwards as the osteoblasts in periosteum build new CIRCUMFERENTIAL LAMELLAE. Osteon formation repeats as new peristeol ridges fold over blood vessel
What is the role of bone in Calcium homeostasis?
Plasma calcium increase
this is detected by PARAFOLLICULAR cells in the thyroid gland which secrete CACITONIN
Calcitonin causes VITAMIN D to increase =OSTEOCLAST activity decrease =less bone broken down =less calcium released
Also CALCITONIN results in increased calcium secretion from the kidneys -less plasma calcium
What can high calcium levels sometimes be an indication of ?
Cancer
What is collagen structure?
- amino acids make up collagen
- 3 collagen polypeptides then arrange themselves into a triple helix rope like structure
- These molecules then build each other up into collagen fibrils
- These then rope together into collagen fibres which come together to form ligaments and tendons etc
What role does collagen play in connective tissue ?
Fibre component
What is a property of collagen ?
Non elastic behaviour
crimping of fibres
What is the most abundant protein in the human body?
Collagen
What are the types of collagen and where are they found in the human body?
Type 1-Dermis, tendons, ligaments and bone Type 2- Cartilage, vitreous body, nucleus pulposus Type 3 - Skin , vessel wall, reticular fibre of most tissues(lungs, liver, spleen)
What is tendon made of?
- made of collagen fibres(86%)
- Organised in parallel regular bundles to make it stiff and strong -Has a bit of elastin, gives a bit of spring to take stress away (2%)
- Proteoglycans (1-5%)
- inorganic components(0.2%) e.g copper, magnesium, and calcium
What is the function of the tendon?
-Transmit muscle forces
- Elastic energy storage/recoil
- PG resists compressive stresses
What is the function of ligaments?
-enable proprioception(ability to know if your joints are flexed or extended, where your joints are in space) -stabilise the joint
What are the features of ligaments?
- Have functional subunits that tighten or loosen depending on joint position
- is not densly innervated or vascularised
- contains some blood vessels and nerves in outer covering covering(epiligament)
- Contains proprioceptors
- transmit pain signals via type C fibres
What is the function of cartilage?
-SHOCK ABSORBER to reduce FRICTION
Where is cartilage?
- Covers and protects LONG BONES at joints
- structural component of ribs and IV discs
What are the 3 types of cartilage?
-Elastic -Hyaline (shiny surface on bone) -Fibrocartilage
What is a property of cartilage?
Avascular
In what disease is cartilage worn away?
OSTEOARTHRITIS
What are the 3 types of joints classified by structure?
Fibrous(synarthrosis)-In the skull, doesn’t move as this would dent the brain
Cartilaginous(Amphiarthrosis)-bit stiff and bit movement, in spine
Synovial(Diarthrosis)-move
Give examples of each type of joint structure?
Fibrous: -Sultures -Syndesmosis -Interoseous membrane
Cartilaginous: -Synchondroses -Symphyses
Synovial: -plane -Hinge -Condyloid -Pivot -Saddle -Ball and Socket
What does synovial fluid do?
- Shock absorber(due to hydrostatic pressure)
- nutrition of the joint
- reduces friction during movement
- lubricates the joint
What is the most common joint type?
Synovial joints
What is the most mobile joint?
Synovial joint
What is a key structural feature of a synovial joint?
JOINT CAPSULE:
ARTICULAR CAPSULE(outer)-keeps bones together structurally
SYNOVIAL CAVITY/membrane(inner)-contains synovial fluid
What is responsible for joint stability and how?
LIGAMENTS: -prevent excessive movement that could damage joint -more ligament and tighter ligaments=greater stability but less mobillity -less ligaments and laxer ligaments =greater mobility but less stability
What is the risk of having a joint with poor stability?
dislocation
What factors affect joint stability?
- Joint shape e.g hip vs shoulder
- Ligaments -Tendons -Cartilage
Compare hip vs shoulder stability?
Shoulder:
joint articulation-mismatch (shallow socket)
Joint Capsule-weak
Ligaments-lack strong ligaments
Muscles-rotator cuff dependent
Stability-unstable
Mobility-extremely mobile
Hip:
Complete fit-deep socket
Joint capsule-strong
Ligaments-strong networks of ligaments
Muscles-supported by muscles
Stability-stable
Mobility- less mobile
Why might gymnasts and dancers be more prone to ligamentous?
excessive ligament laxity and overuse=hypermobility=grater risk of injury
What features of the shoulder joint make it more prone to subluxation/dislocation than the hip joint
Shallow socket, weak joint capsule, lack of strong ligaments, greater mobility
