WEEK ELEVEN - BONE TISSUE, SKELETAL SYSTEM AND JOINTS, MUSCLES Flashcards
List & describe 5 functions of the skeleton [spmbe]
1.support
framework for body shape
2.protection
hard tissue protects organs it surrounds eg vertebral column for spine
3.movement
muscle attach to bones = bones move body
4.blood cell production
RBW WBC platelets made in bone marrow
5.electrolyte balance
skeleton stores calcium and phosphate ions - released when needed
Describe the 4 different bone shapes with examples for each
long - levers for muscles to pull on eg femur
short - limited motion - glide across each other
flat - provide for thin/roughly parallel surfaces eg parietal and frontal bones, scapula, sternum
irregular - complex bones with short/flat/rigid surfaces eg facial bones
Describe the general structure for long and flat bones
long [shaft =diaphysis, and enlarged bone ends]
shaft - compact bone surrounds central hollow medullary cavity
- enlarged ends = thin outer layer of compact bone surrounding spongy bone
periosteum - thick CT membrane lines OUTER bone surface
endosteum - thin CT lines INNER bone surface + canals inside bone
flat - external+internal surface = compact bone
middle layer = spongy [diploe]
- has bone marrow between trabeculae
List & describe the cell types and the matrix of bone tissue [1p-4c]
- osteoprogenitor
stem cells found in membranous endosteum and periosteum [differentiate into osteoblasts] - osteoblasts
bone building cells - secrete bone matrix - osteocytes
= osteoblasts that have become surrounded the bone matrix they secreted
- communicate with other osteocytes via canaliculi [tentacle projections] to monitor/maintain bone matrix - osteoclasts
large, multi nucleated cell that dissolves and resorbed bones by secreting acids and proteolytic enzymes
= they released stored minerals in bones
bone matrix [1/3 organic + 2/3 inorganic]
organic = collagen + proteoglycans
inorganic = 85% hydroxyapatite [calcium phosphate crystal] + 10% calcium carbonate/other minerals
= combination of inorganic/organic –> provides strength and resilience
[minerals = strength] lack = floppy and too flexible –> osteomalacia
[collagen= flexibility] lack = bones too brittle –> osteogenesis imperfecta
Describe the histology of compact and spongy bone
compact - closely packed osteons
osteon = central canal [osteonic canal] surrounded by concentric rings [lamellae of matrix]
between matrix = osteocytes found in lacunae spaces
spongy - formed by bone plates [trabeculae]
trabeculae spaces filled with reticular CT = red bone marrow] = site of blood cell production
- lack osteons + central canal but osteocytes are supplied by blood
List & describe the two methods of bone formation
intramembranous ossification [in skull and clavicle bones]
- mesenchymal stem cells aggregate and replicate –> begin differentiating into osteoblasts
- osteoblasts release uncalcified osteoid tissue which is then ossified by calcium phosphate
- further differentiates into osteocytes
- osteocytes compact together = osteon = forms compact bone surrounding spongy bone + periosteum on top
endochondral [forms rest of skeleton]
- perforation of hyaline cartilage delivers osteogenic cells –> differentiate into osteoblasts - secrete osteoid
- secreted osteoid encases diaphysis [shaft] in bone collar
- vascular invasion of boney collar = osteoblasts+osteoclasts shape marrow cavity
- killing and replacement of chondrocyte cartilage cells with bone cells [osteocytes+calcified osteoids]
- In the adult, cartilage remains only as articular cartilage at the joint surfaces
Explain how mature bone continues to grow and also explain Wolff’s law
interstitial growth - increase in length
- by chondrocytes at epiphyseal plates
- growth continues until 1st ossification centre joints with 2nd = epiphyseal line
appositional growth - increase in width throughout life
1. cartilage osteoblasts beneath periosteum lay down bone = form ridges
2. blood vessel lies in groove between ridges = groove becomes tunnel when ridges meet
3. periosteum of groove becomes endosteum of tunnel
4. osteoblasts lay down bone = forms concentric lamellae
5. more concentric lamellae = new osteons
wolff’s law of bone = architecture of bone determined by mechanical stresses place on it = bones will adapt
Discuss how the body maintains calcium homeostasis
calcitriol + parathyroid hormone [PTH] = INCREASES blood calcium levels
- PTH increases osteoclast activity, decreasing osteoblast activity ++ promotes kidney calcium resorption
- calcitriol increases calcium absorption from gut, bone and kidneys
calcitonin = DECREASES blood calcium levels
- reduced osteoclast activity and increase osteoblast activity
List and identify the bones of the axial and appendicular skeletons
axial [central axis]
- skull bones
- vertebral column/sacrum
- ribs/sternum
appendicular [limb bones + pelvic/pectoral girdles
Explain how the structural features of the skull reflect its function
- skull = very thick post. and ant. = protection of brain
- rigid/non-moveable sutures between bones = protection
- one movable bone [mabdible] and joint [temporo-mandibular joint] = mastication and speech
- sinuses = lightens skull + adds resonance to voice
- outer+inner layer of compact bone sandwich sponngy bone = fracture may leave inner layer of compact bone undamaged
Explain how the structural features of the vertebral column (VC) reflect its function
- 33 individual bony vertebrae = movement + protection at same time
- Intervertebral discs = shock absorption and increased ROM
- cervical, thoracic, lumbar, and sacral curvatures = BW distribution over base of support = walking efficiency + shock absorption
- vertebral neural arch enclosing spinal cord - spinal cord protection
Explain how the structural features of the thoracic cage reflects its function
12 pairs of ribs and sternum = Protection of lungs/heart
- attachment points for breathing muscles [intercostals], limb muscles [pectoralis major and minor] and torso muscles [abdominals]
Sternoclavicular joint = Attachment pectoral girdle [clavicle+scapula]
attachment of costal cartilages to sternum = allows rhythmical expansion of rib cage = draws air into lungs
Discuss the similarities & differences between the pelvic & pectoral girdle
similarities
- provide articulation with limbs via ball/socked joint
- large area for muscle attachment sites
- fibrocartilaginous rim [glenoid fossa - humerus// acetabulum-femus] = deepens sockets
differences
- pectoral girdle = 2 bones [clavicle+scapula]
- pelvic girdle = 3 bones [ilium + ischium + pubis]
- pelvic girdle (hip joint) = deeper sockets compared to pectoral girdle (shoulder joint) = shallow socket = implications for shoulder dislocation
- pelvic girdle - attached to vertebral column = movement of spine [does not happen with pectoral girdle
Discuss similarities and differences between the upper and lower limb bones
similarities
- single bone in upper segment eg humerus and femur
- two bones in lower segment eg arm= radius/ulna, leg= tibia/fibula
- both hand+feet = similar number of bones = 5 metatarsal/metacarpals
- hinge at knee and elbow
differences
- patella at knee joint [reduces friction of quadriceps tendon] , but not at elbow
- greater ROM in forearm bones [radius/ulna] over tibia/fiba for hand range of motion
- larger limbs bones in leg for weight bearing purposes
List & describe the structure of the 3 types of fibrous joint types with examples for each
- sutures
immovable fibrous joints that bind skull bones together, short collagen fibres - gomphoses
attachment of a tooth to its socket.
- help in place by fibrous periodontal ligament
- some movement while chewing
- intermediate length collagen fibres - syndesmoses
- MOST MOVEABLE fibrous joints
- two bones bound by ligament only interosseous membrane
- eg tibia-fibula and radius-ulna
List & describe the structure of the 2 types of cartilaginous joint types with examples for each
primary cartilaginous joints
- bones joined by hyaline cartilage
- epiphyseal plate in children binds to epiphysis and diaphysis [not present in adults]
- eg 1st rib attachment to sternum
secondary cartilaginous joints [only slight movements possible]
- bones joined by fibrocartilage
- pubic symphysis and intervertebral joints
List & describe the anatomical components of a typical synovial joint
when two bones separated by joint cavity [space with synovial fluid] , most are freely moveablw
components
1. fibrous capsule - encloses joint cavity/continuous with periosteum
- synovial membrane - thin membrane lining inside of joint capsule - secretes synovial fluid
- synovial fluid- nourishes cartilage
- articular cartilage - hyaline cartilage covering joint surfaces
- joint cavity - cavity around two bones surrounded by joint capsule and filled with synovial fluid
Discuss factors that affect a joint’s range of motion
- shape of articular surfaces = determines deg. freedom at joint eg monoaxial, biaxial, multiaxial joint
- type of joint eg fibrous, cartilaginous, synovial
- strength and tautness of tendon/ligament/capsules = stretching = increasing ROM
- structural limitations –> ball and joint sockets = large ROM, hinge joints –> one plane of movement
State the 6 classes of synovial joint types with examples for each
- ball and socket joint eg humeroscapula joint
- pivot joint ed radioulna [radius-ulna]
- saddle joint eg trapeziometacarpal [trapezium of wrist to metacarpal bone
- hinge joint eg humeroulna
- gliding joint eg intercarpal [carpal bones]
- condyloid joint eg metacarpophalangeal
Exemplify correct anatomical terminology for all synovial joint movements
flexion - at elbow, knee, hip, shoulder, head
Flexion = ANTERIOR movement from hip joint/above
Flexion = POSTERIOR movement from knee joint/below
abduction/adduction+circumduction - shoulder and hip
elevation/depression/protraction/retraction/medial + lateral rotation - at shoulder girdle
ankle joint - dorsiflexion [toes towards body] , plantarflexion [toes away from body]
sole inversion = medial rotation [inside of foot up]
sole eversion = lateral rotation [outside of foot up]
Describe the varied functions of muscles [mpcoh]
movement
- of joints by attachment to skeleton
- of food in oral cavity, stomach, intestines
- of uterine/faeces
posture
- stabilisiation of joints
communication
- speech, writing
openings and passageways
- anus, pupils, stomach intestines, urethra, blood vessels
heat production
- muscle contraction + shivering = heat
List & describe the connective tissue coverings of a muscle
epimysium
- blends into CT between muscles
- covers WHOLE muscle belly
perimysium
- slightly thicker CT layer
- surrounds muscle fascicle [bundle of cells]
endomysium
- thin sleeve of loose CT - surrounds muscle fibre
List & describe the various shapes of skeletal muscles with examples for each and relate to function
fusiform [thick middle, tapered ends ]
eg biceps brachii
great degree of shortening = quick and wide ROM
parallel [parallel fasicles]
eg abdominis
long muscle length = increased ROM [skeletal muscle shortens to 30% of resting length
convergent [broad at origin - tapers to narrow insertion]
eg latissmus dorsi, pectoralis major, deltoids
covers broad surface + different actions to be produced by same muscle due to different fibre directions within mass
pennate [different types]
eg unipennate = extensor digitorum on forearm, bipennate = rectus femoris, multipennate= deltoid, circumpennate = tibialis anterior
- unipennate = fibres insert on one side of tendon
- bipennate = fibres insert on tendon on opposite sides
[like feather]
- multipennate = similar to bipennate but multiple
‘feathers’ side by side
circular [rings around body openings like mouth, eyes]
eg iris, anal sphincter
Explain the terms origin, insertion, belly and action of a muscle
origin - attachment to stationary end of bone [usually proximal]
insertion - attachment to mobile end of bone [usually distal]
belly - thicker, middle region of muscle
action - joint muscle crosses + produced movement eg biceps brachii = elbow joint flexor// triceps brachii = elbow joint extensor
Explain the different functional roles of muscles (e.g. prime mover, agonists, synergist, antagonist & fixator) using elbow joint flexion as an example
prime mover- muscles that play MAJOR role in movement eg brachialis
agonist - general term for muscles that produce desired joint movement
eg biceps brachii, pronator teres, brachioradialis
synergist - helps prime mover perform movement [either by assisting movement directly or neutralising antagonists]
eg brachialis
antagonist - action opposite to agonist
eg triceps brachii
fixator - stabilises a bone/body part, located more at proximal joints
eg muscle holding scapula in place eg rhomboids
