Musculoskeletal Flashcards
(196 cards)
1
Q
What are the 2 double meanings of bone?
A
Organ and tissue
2
Q
What are the 6 functions of the skeletal system?
A
Support, protection, movement, calcium and phosphorus storage, haemopoiesis, fat storage
3
Q
What percentage of the body’s calcium is found in bone?
A
90%
4
Q
Where is the majority of red bone marrow located?
A
Around the axial skeleton
5
Q
Where is the majority of yellow bone marrow located?
A
Around limbs/further from the centre of the body
6
Q
What is the main function of the axial skeleton?
A
Support, protection and haemopoiesis
7
Q
What is the main function of the appendicular skeleton?
A
Movement and fat storage
8
Q
What are the 3 regions of long bones?
A
Epiphysis, metaphysis and diaphysis
9
Q
How many axial bones are there?
A
80
9
Q
How many named bones are there in the body?
A
206
10
Q
How many appendicular bones are there?
A
126
11
Q
What are the layers of bone from outer to inner in the diaphysis?
A
Periosteum, compact bone, endosteum
12
Q
What are the layers of bone from outer to inner in the epiphysis?
A
Articular cartilage, compact bone, spongy bone
13
Q
What is the centre of bone called?
A
Medullary cavity
14
Q
What is spongy bone made of and what covers it?
A
Trabeculae, completely covered by endosteum
15
Q
What connects the periosteum to the compact bone?
A
Perforating/Sharpays fibers
16
Q
What 2 components make up ECM?
A
Fibres and ground substance
17
Q
What type of fibres are found in bone?
A
Collagen
18
Q
What do collagen fibres resist in bone?
A
Tension (stretching/pulling)
19
Q
What is the ground substance in bone made up of?
A
Hydroxyapatite
20
Q
What are the 4 cells that makeup bone in order from youngest to oldest?
A
Osteogenic cell, osteoblast, osteocyte, osteoclast
20
Q
What does the ground substance in bone resist?
A
Compression (squeezing/crushing)
21
Q
Where are osteogenic cells located?
A
On the surface of bone in the periosteum and endosteum, also found in central canals of compact bone
22
Q
What is the function of osteogenic cells?
A
Normally dormant but can divide and supply developing bone with osteoblasts
23
Where are osteoblasts located?
In the layer under the periosteum or endosteum - wherever new bone is being formed
24
What is the function of osteoblasts?
Synthesis, deposition and calcification of osteoid (the ECM)
25
What is calcification?
When the osteoid becomes infiltrated with bone salts (hydroxyapatite)
25
What is the osteoid, and what does it consist of?
The ECM of bone/precursor matrix mainly consists of collagen (70%), also proteoglycans, proteins and water
26
Where are osteocytes located?
Within lacunae
27
What is the function of osteocytes?
Bone tissue maintenance, repair, Ca2+ exchange
27
Where are osteoclasts located?
At sites where bone resorption is occurring
28
What is the function of osteoclasts?
Secrete acids and enzymes, dissolve the mineral and organic components of bone
29
What does the medullary cavity contain?
Bone marrow
30
What is the endosteum?
Thin, inner fibro cellular layer lining the medullary cavity and trabeculae
31
What does the periosteum contain?
Blood vessels and nerves
31
What is the periosteum?
Outer, fibro cellular sheath which surrounds bone
32
What is the diaphysis made of?
Periosteum, compact bone, endosteum and medullary cavity
33
What type of force are trabeculae arranged to resist?
Perpendicular force
34
What is the epiphysis made up of?
Articular cartilage, compact bone, spongy bone, endosteum
34
What are perforating/sharpays fibres made of?
Thick bundles of collagen
35
What are the 2 components of all connective tissue?
Cells and ECM
36
What is the organic component of bone connective tissue?
Fibres - collagen type 1
37
What is the inorganic component of bone connective tissue?
Ground substance - hydroxyapatite
38
What is the osteoid?
The organic ECM (collagen) of bone initially laid down by osteoblasts prior to calcification
38
Overall, what force does the ECM of bone resist?
Torsion
39
What percentage of the osteoid is collagen?
70%
40
What makes up the osteoid layer?
Collagen, proteoglycans, proteins and water
41
What is a lacunae?
Small space in bone containing osteocyte
42
What does the acid secreted by osteoclasts dissolve?
Mineral components of bone e.g. hydroxyapatite
43
What are canaliculi?
Small canals through which osteocytes communicate with neighbouring cells using their long cellular processes
44
How do osteocytes communicate with other cells?
Through cellular processes running thorugh canaliculi
45
In what order do osteoclasts dissolve bone (organic or inorganic first)?
Inorganic hydroxyapatite then collagen fibres
46
What do the enzymes secreted by osteoclasts dissolve?
Organic component of bone e.g. collagen
47
What is the name of the 'pit' formed under osteoclasts after the bone is dissolved?
Howships lacunae
48
What is the 'clear zone'?
Area/microbiome under osteoclast that ensures acid doesn't escape and helps to anchor the cell
49
How long do osteoclasts live for?
2-3 months
50
What is thicker - the endosteum or periosteum?
Periosteum
51
How does bone grow?
Via appositional growth
52
Describe the process of appositional growth
- Signal triggers osteogenic cells to divide, resulting in some of the daughter cells being pushed into the matrix and becoming osteoblasts
- Osteoblasts lay down osteoid and calcify it
- Some osteoblasts become trapped in lacunae, eventually forming osteoclasts
- When growth stops, osteoblasts convert back to osteogenic cells or die - peri/endosteum goes back into resting state
53
Describe the process of bone resorption.
- Monocyte precuser cells leave BV and start to fuse on bone surface forming syncytium/osteoclase
- Osteoclasts start dissolving bone
- Osteoclasts eventually die via apoptosis
- Blood vessels grow into newly formed space in bone
54
What is the other type of growth that occurs in the body that bone cannot undergo?
Interstitial growth
55
Why can bone not grow via interstitial growth?
Because it is required to resist deformation
56
What 2 processes make up 'bone remodelling'?
Appositional growth and bone resorption
57
How do long bones grow in length?
Endochondral ossification
58
Why can the epiphysis not undergo appositional growth?
Because it is covered in articulate cartilage
59
Describe endochondral ossification
- Chondrocytes in the hyaline cartilage in the epiphyseal plate divide (interstitial growth), growing the cartilage and pushing the epiphysis away from the metaphysis.
- Cartilage eventually dies, and osteoblasts place new bone as the ossification rate catches up to the cartilage growth rate
60
Where is the epiphyseal plate located?
Between the epiphysis and metaphysis - closes during puberty
61
What are the 2 types of bone?
Immature/woven & mature/lamellar
62
What are the 2 classes of mature bone?
Spongy (cancellous/trabecular) and Compact (cortical)
63
When is immature/woven bone seen?
Fetus - 3 years old and when a bone is quickly regrown e.g. broken arm
64
How does immature bone differ from mature bone?
Lower cell count, less dense, irregular collagen fibres
65
How is bone arranged in mature bone?
In sheets/layers called lamallae
66
What is the max width of an osteon or trabecula?
0.4mm
67
What is the max width of circumferential lamellae?
0.2mm
68
What are the 3 different organisations of lamellae in compact bone?
Circumferential, concentric and interstitial
69
Where are concentric lamellae found?
Osteons
70
Where are circumferential lamellae found?
Around the outer edge of the bone
71
What is the canal in which blood vessels run from the periosteum to central haversian canals?
Perforating/volkmanns canal
72
What are the 2 layers that make up the periosteum?
Outer fibrous layer and inner osteogenic layer
73
Where are interstitial lamellae found?
Between osteons
74
Describe the formation of a primary osteon
- Osteoblasts in active periosteum put down new bome forming ridges around blood vessels
- Ridges fuse (periosteum now endosteum)
- Osteoblasts build bone inwards towards the centre of the canal
- Bone continues to grow outwards as osteoblasts place circumferential lamellae
75
Describe the formation of a secondary osteon
- Osteoclasts form and gather in an area that needs remodelling
- Osteoclasts begin to bore through existing bone creating tunnel inside bone - cutting cone
- Osteoblasts move into newly formed tunnel and deposit osteoid/build concentric lamellae layers slowly filling tunnel in - closing cone. Some osteoblasts are trapped and become osteocytes
- Eventually tunnel is reduced to size of typical haversian canal and osteoblasts lining the tunnel either die or revert back to osteogenic cells making up resting endosteum
76
What are the percentages of compact bone and spongy bone in long bones?
90% compact, 10% spongy
77
What component of mature bone are osteoclasts often found on and why?
Trabeculae as spongy bone can grow 5x faster than compacts bone - good Ca2+ source
78
Where is spongy bone predominantly located in long bones?
Epiphysis
79
What is the main function of spongy bone?
Support stress from multiple directions
80
Where is compact bone predominantly located in long bones?
Diaphysis
81
What is the main function of compact bone?
Support and protection
82
What is the location of blood supply for spongy bone?
Blood vessels between trabeculae
83
What is the location of blood supply for compact bone?
Blood vessels running through volkmanns and haversion canals
84
Why are not all osteons primary?
There are not enough blood vessels for osteons to form around
85
What is the cement line?
Line between newly formed secondary osteon and old bone
86
What is the rate of bone resorption of the cutting cone?
1mm/20 days
87
Approximately what percentage of our skeleton do we replace every year?
10%
88
What is the unit of spongy bone?
Trabeculae
89
What is the direction of unit growth in spongy bone?
Outwards
90
What is the unit of compact bone?
Osteon
91
What is the direction of unit growth in compact bone?
Inwards
92
What percentage of connective tissue in bone is crystallised mineral salts?
50-60%
93
What do tendons connect?
Muscle to bone
94
What do ligaments connect?
Bone to bone
95
What are the 3 main functions of joints?
Movement
Force transmission
Growth
96
What is a joint?
Any point at which 2 or more bones interconnect
97
What are the 3 functional classifications of joints?
Synarthrosis, amphiarthrosis, diarthrosis
98
What are synarthrosis joints?
Immovable, highly stable, common in axial skeleton, for growth and force transmission
99
What are amphiarthrosis joints?
Slightly moveable, medium stability, common in axial skeleton, e.g. intervertebral disks, force transmission
100
What are diarthrosis joints?
Freely moveable, low stability, common in the appendicular skeleton
101
What percentage of diarthrosis joints are found in the appendicular skeleton?
80%
102
What functional class of joint are synovial joints?
Diarthrosis
103
What is the most common type of joint?
Synovial
104
What are the 4 common features of synovial joints?
Articular cartilage, articular capsule, joint cavity, synovial fluid
105
What is the thickness of articular cartilage?
1-7mm
106
What type of cartilage is articular cartilage?
Hyaline (specialised)
107
What percentage of articular cartilage is cells?
5%
107
What is the articular cartilage attached to?
Bone
108
What are the functions of articular cartilage?
Protect ends of bones, absorb shock, support heavy loads for extended time periods, provide smooth and frictionless surface when combined with synovial fluid
109
What cells are found in articular cartilage?
Chondrocytes
109
Describe the cells in articular cartilage
Chondrocytes which build, repair and maintain cartilage
Live in lacunae
Live by themselves or in nests (depending on zone)
Secrete ECM
110
What percentage of articular cartilage is ECM?
95%
111
What 3 components make up the ground substance of the ECM in articular cartilage?
Water (+soluble ions), GAGS and PGs
112
What fibre is present in the ECM of articular cartilage
Collagen - type 2
112
What makes up the fixed solid component of articular cartilage?
PGs and Collagen fibres
113
What percentage of the wet weight of articular cartilage is water?
75%
113
What percentage of the dry weight of articular cartilage is collagen?
75%
114
What percentage of the dry weight of articular cartilage is PGs?
25%
115
What provides the swelling and hydrating mechanism for the proper function of articular cartilage?
GAGs
116
What are 3 of the common GAGs found in articular cartilage?
Hyaluronic acid, chondroitin sulphate, keratin sulphate
117
What is the common PG found in articular cartilage?
Aggrecan
118
What are the 3 zones that make up the functional zone of articular cartilage?
Surface, middle and deep zones
119
What zone of articular cartilage has the lowest PG level?
Surface zone
120
What zone of articular cartilage has the highest PG level?
Deep zone
121
What are the infoldings of the synovial membrane called?
Vili
122
What is the junction between calcified cartilage and subchondral bone called?
Osteochondral junction
123
What are thicker sections of the fibrous capsule called?
Capsular ligaments
124
How are the chondrocytes in cartilage nourished?
By diffusion
125
Where is the nearest blood supply to the articular cartilage?
In the articular capsule
126
What is unloaded equilibrium?
When the swelling force = the tension force
127
What is loaded equilibrium?
When the cartilage stops shrinking after load has been placed on it
128
What is the fluid loss out of cartilage due to load known as?
Creep
129
What are the 2 layers of the synovial membrane?
Intima & subintima
129
What are the 2 layers of the articular capsule?
Outer fibrous layer and inner synovial membrane
130
What does the synovial membrane line?
All non-articular surfaces in joint cavity
131
What is the synovial membrane made of?
Loose connective tissue
132
What is the fibrous capsule made of?
Dense connective tissue (irregular & regular)
133
What cells make up the intima layer of the synovial membrane?
Synoviocytes
134
What do proprioceptors do?
Monitor stretch and help us know the positions of our joints
135
What do synoviocytes secrete?
Hyaluronic acid and lubricating proteins
136
What does synovial fluid consist of?
Ultrafiltrate of blood plasma, hyaluronic acid, lubricating proteins, free cells (mono, lymph, macro, synovio)
137
What are the functions of synovial fluid?
Shock absorption, joint lubrication, chondrocyte metabolism, joint maintenance
138
Which is the larger GAG: keratin sulphate or chondroitin sulphate?
Chondroitin (125 units)
138
What is the max volume of synovial fluid in the joint cavity?
2ml
138
What does the tide mark indicate?
The boundary between the deep zone and calcified cartilage
138
What is the outer fibrous layer of the articular capsule continuous with?
Periosteum of bone
139
What is the most vascular layer of the articular capsule?
Subintima of the synovial membrane
139
What percentage of body mass is skeletal muscle?
40-50%
140
What are the 5 main functions of muscle?
Movement, stability, communication, control of body passages and heat production
141
What is the junction between bone and tendon called?
Osteotendinous junction
142
What is the junction between muscle and tendon called?
Myotendinous junction
143
What are the layers of skeletal muscle in order from outer to inner?
Epimysium -> perimysium -> fascicle -> endomysium -> myocyte -> sarcolemma -> sarcoplasm -> myofibril
144
What does the epimysium surround?
The entire muscle
145
What does the perimysium surround?
Fascicles
146
What are the epimysium and perimysium both made of?
Dense irregular connective tissue
147
What is a fascicle?
Buncle of myocytes
148
What does the endomysium surround?
Myocytes
149
What surrounds myocytes?
Endomysium
150
What is endomysium made out of?
Loose, irregular CT
151
What contains the nerve and blood vessels supplying myocytes?
Endomysium
152
What does a myofibril contain?
Sarcomeres
152
What does a myocyte contain?
Sarcolemma, sarcoplasm, myofibrils
153
What is the thickness range of myocytes?
10um -> 100um
154
What does the sarcoplasm contain?
Mitochondria, myoglobin, glycogen
155
What are deeper walls of deep fascia called?
Investing fascia
156
What is deep fascia between 2 bones called?
Interosseous membrane
156
What is deep fascia between muscles called?
Intermuscular Septa
157
What is deep fascia made of?
Dense irregular and regular CT
158
What is the outermost layer of muscle?
Epimysium
159
What is hypertrophy?
Increase in muscle size due to increased number of individual myofibrils inside myocytes
160
What are anabolic steroids?
Synthesized variants of testosterone
160
What are 2 ways hypertrophy can occur?
Resistance training and anabolic steroids
161
What are some of the side effects of anabolic steroids?
Acne, hair loss/growth, liver failure, shrivelled testes, infertility, mood swings, increased risk of coronary artery disease
162
What is atrophy?
Decrease in muscle size due to reduction of myofibrils in myocytes
163
What causes atrophy?
Lack of stimulation of muscle by motor neurons
164
At what age does muscle loss become accelerated?
50
165
What percentage of muscle is lost by 80 years?
40%
166
At what age does normal muscle loss begin?
20
167
What is hypoplasia?
Myocyte loss
168
How are myocytes created?
Fusion of many myoblasts during fetal growth
168
Myocytes contain many nuclei so are a.......
Syncytium
169
How are satellite cells made?
Formed from unfused myoblasts
170
Where are satellite cells located?
Outside the sarcolemma but within the basement membrane of myocytes
171
What is the role of satellite cells?
Divide upon signal and fuse to form new myocytes to repair damage
172
What are the 4 functions of skeletal muscle CT?
Organisation/scaffolding
Medium for blood vessels and nerves
Prevent excessive stretching
Distribute forces generated by contraction
173
What protein helps to align sarcomeres between myofibrils?
Desmin
174
What is the role of desmin?
To align sarcomeres between adjacent myofibrils
175
How do the Z lines of the outermost myofibrils attach to the sarcolemma, basement membrane and enomysium?
Via protein complexes
176
What are the protein complexes in myocytes responsible for?
Attaching myocytes and surrounding connective tissue
Strengthing the sarcolemma
