1
Q
The diameter of peripheral nerve fibres
A
0.3 - 22 um
2
Q
What cells form the cytoplasmic tube around the nerve?
A
Schwann Cells
3
Q
where are motor units cell bodies found?
A
anterior grey horn (grey matter)
(inside spinal cord)
4
Q
where are sensory units cell bodies found?
A
posterior root ganglia
(outside spinal cord)
5
Q
spinal nerves exit the vertebral column via which foramen?
A
intervertebral foramen
6
Q
what is the spinal nerve formed from?
A
ventral and dorsal roots
7
Q
What does the endoneurium surround?
A
axons of nerve fibres
8
Q
what does the perineurium surround?
A
fascicles - nerve bundles
9
Q
what does epineurium surround?
A
the entire nerve
10
Q
fascicles are bundles of nerves
a. true
b. false
A
a. true
11
Q
Nerves are covered by endoneurium
a. true
b. false
A
Epineurium
(endoneurium covers the individual axons, perineurium the fascicle’s)
12
Q
Aa are the fastest nerve fibres
a. true
b. false
A
A. true
60-100 metres/sec
13
Q
What is the function of Aa fibres
A
found in large motor axons
detect
muscle stretch and tension
14
Q
Aa - afferent fibres detect?
A
muscle stretch and tension
60-100metres/sec
15
Q
AB nerve fibres detect?
A
touch , pressure, vibration, joint position
30-60 metres/sec (second fastest)
16
Q
Where are Ay (alpha gamma fibres found)?
A
efferent motor axons
17
Q
Ay (alpha gamma) fibres conduct impulses at what speed?
A
15-30 metres/second
(Aa , Ab, Ay, Ad, B, C)
18
Q
What do C nerve fibres detect?
A
dull pain, burning , temperature
19
Q
Which fibres detect sharp pain?
A
Alpha delta
sharp pain, light touch and temperature
10-15 m/s
20
Q
Which nerve becomes compressed in carpal tunnel syndrome
A
median nerve of wrist
21
Q
when a spinal nerve is compressed by an intervertebral disc- it describes?
A
sciatica
22
Q
what is damaged in mortons neuroma?
A
Digital nerve in 2nd or 3rd web space of forefoot
23
Q
where is cortical bone found?
A
epiphysis - thin shell
diaphysis - thicker shaft of long bones
24
Q
Cortical bone has a high young’s modulus
a. true
b. false
A
a. true
means - it is not easily bent or stretched under force
25
80% of the adult skeleton is cortical bone
a. true
b. false
a. true
26
Trabecular bone is better for shock absorption
a. true
b. false
a. true
more biologically active and greater turnover rate
27
Trabecular bone has a higher water content than compact bone
a. true
b. false
a. true
but lower calcium content
28
What are osteoblasts that have been trapped in the osteoid called?
osteocytes
osteoblasts lay down osteoid during the formation phase of bone remodelling and transform into osteocytes embedded in mineralised bone matrix
29
osteoblast activity exceeds osteoclast activity in osteoporosis
a. true
b. false
b. false
osteoclast > osteoblast
thin bones/reduced bone mineral density
bone resorption > bone formation
30
risk factors for osteoporosis (thin bones)
- smoking
- female
- aging
- low bodyweight/bmi
- corticosteroids
- low VitD (can't absorb calcium)
31
Mesenchymal stem cells and haematopoietic stem cells are found in red bone marrow
a. true
b. false
a. true
32
Satellite cells are precursors to muscle tissue
a. true
b. false
a. true
can be stimulated to proliferate and differentiate into skeletal muscle cells
33
At which stage of bone remodelling are osteoblasts active in laying down new bone?
Formation stage
34
C5 dermatome is responsible for shoulder abduction
a. true
b. false
a. true
35
What movement is C5 dermatome responsible for?
shoulder abduction
36
Which movement is affected if C6 dermatome is damaged?
Elbow flexion/wrist extension
37
Which movement is affected if C6 dermatome is damaged?
Elbow flexion/wrist extension
38
Paget's disease of the bone is associated with which of the following findings on blood tests?
ALP?
calcium?
phosphate?
will be high or low??normal
ALP alkaline phosphatase - high
Calcium - normal
Phosphate - normal
39
the adult skeleton is 80% cortical bone and 20% compact bone
a. true
b. false
a. true
40
A 63-year-old woman attends her GP to get the results of her recent DEXA scan. The GP explains that she received a score of –2.4. Which of the following is her diagnosis?
osteopenia (-1 to -2.5)
reduction in bone density but not as severe as osteoporosis
41
DEXA score indicating osteopenia
-1 to -2.5
42
What does DEXA scan record?
x-rays of hip/spine to assess density of bones
43
Where do osteocytes reside in mature bones?
lacunae
44
actions of calcitonin
1. decreases calcium reabsopriton in kidney
2. INCREASES phosphate excretion (Rather than increasing)
^^promotes diuresis
3/ reduces calcium and phosphate release from bone (reduce activites of osteoclasts
45
actions of calcitonin
1. decreases calcium reabsopriton in kidney
2. INCREASES phosphate excretion (Rather than increasing)
^^promotes diuresis
3/ reduces calcium and phosphate release from bone (reduce activites of osteoclasts
46
After injury, bone tissue will first replicate and grow, later remodelling according to the forces acting on it. A teenager fell off his bike 2 weeks ago, fracturing his distal radius, and wants to know when his wrist will have healed and be strong enough for him to risk doing some sports again.
What type of bone will most likely first form at the site of the fracture?
woven, trabecular
47
What is the osteoid primarily composed of?
type 1 collagen fibrils (90%) of osteoid
ground substance
48
hormone replacement therapy is antiabsorptive
a. true
b. false
a. true
low level estrogens and progestins can be used after menopause
49
what DEXA score indicates osteoporosis
minus 2.5
- 2.5
50
Treatment of osteoporosis
- prevent falls
- HRT
- Vitamin D and calcium
- Oral bisphosphonates
50
When serum calcium levels are high, what happens to serum phosphate?
inversely related!!!!
when calcium rises - phosphate decreases!!! as phosphate binds to the free calcium - decreasing phosphate levels
50
Risk factors for osteoporosis
female sex,
increasing age
smoking
corticosteroids
low BMI/bodyweight
Vitamin D deficiency
50
kyphosis is associated with osteoporosis - what part of the spine is affected?
excessive forward curvature of the thoracic region
humpback appearance
50
osteoporosis is caused by?
osteoclast activity > osteoblast
decreased bone density
increased fractures in low trauma
50
Which cells do osteocytes originate from?
mesenchymal stem cells (e.g. of adult stem cells)
through osteoblasts differentiation
50
Which of the following calcium-binding proteins regulates the calcium-dependent contraction in most SMOOTH MUSCLES
calmodulin (smooth muscles)
- protein which forms a complex with Myosin light chain kinase (MLC)
- MLC phosphorylates myosin light chains, allows cross bridge cycling/contraction to occur
51
Which protein regulates calcium dependent contraction in skeletal and cardiac muscles?
troponin
(the binding of troponin to calcium removes tropomyosin from the myosin binding sites on Actin
52
cortical bone has a high young's modulus
a. true
b. false
a. true
can resist changes in length when under compression
resists compression
53
trabecular bone features
- shock absorber
- high turnover rate
- found in metaphysis
- high surface area to volume ratio (more porous and therefore higher surface area)
54
why are osteoclasts important?
prevent bones from getting to big, heavy and brittle
55
What do osteoclasts bind to in order to stimulate bone resorption?
bone matrix via integrin receptors
when integrin receptors on the osteoclast bind to bone matrix, osteoclasts become polarised and stimulate bone resorption
56
What is the most prevalent disorder of bone remodelling?
osteoporosis
57
Which disease is associated with premature death and dysfunction of osteocytes?
osteoporosis
ultimately leads to necrosis via damage associated molecular patterns (DAMPS)
58
What is the correct ratio of inorganic and organic material in adult bone?
65% inorganic
35% organic
59
DKA is likely to present with
metabolic acidosis
raised anion gap
60
what type of bone is the patella
seasmoid bone
61
the medial collateral ligament is attached to the medial meniscus
a. true
b. false
a. true
but the lateral meniscus is not attached to the lateral collateral ligament -> more mobile
62
attachments of the lateral collateral ligament
tip of fibula
and lateral femoral epicondyle
63
functions of the synovium>
lubrication of cartilage
nutrients to chondrocytes within joints
maintain intact tissue surface
control of synovial fluid volume (hyaluronan, lubricin)
64
Branching cells and intercalated disks are histological features of which cell type(s)?
cardiac muscle
65
In adult bone, 65% is inorganic material (hydroxyapatite) and 35% is made up of organic material (e.g. collagen).
a. true
b. false
a. true
66
osteoblasts produce hydroxyapatite
a. true
b. false
a. true
67
What is the primary role of the organic component of the bone extracellular matrix (ECM)?
mechanical support to bone cells - type 1 collagen (organic ECM)
flexibility and tensile strenght
68
black people have higher vitamin D requirements
a. true
b. false
a. true
melanin lowers the skins ability to make vitamin D in response to sun exposure
69
3 types of joints
1. fibrous
2. cartilaginous
3. synovial
70
3 types of fibrous joints
1. interosseus membranes (syndesmoses)
2. periodontal ligaments (gomphoses)
3. cranial sutures
71
2 types of cartilaginous joints
1. primary - (hyaline cartilage only)- synchondrosis
2. secondary - symphysis (hyaline and fibrous cartilage)
72
which part of a joint produces synovial fluid
synovial membrane
73
what type of cartilage is articular cartilage
hyaline
74
hyaluronic acid is a GAG (glycosaminoglycan)
a. true
b. false
a. true
molecule found in cartilage
polar - attracts water to the joint- water is incompressible
75
lubricin is a glycoprotein found in cartilage
a. true
b. false
a. true
lubrication of joint
76
aggrecan is a proteoglycan found in cartilage
a. true
b. false
a. true
binds to hyaluronic acid (GAG)
77
what cells are found on the articular surface of articular cartilage (superficial layer)?
- chondroblasts (small/flat)
- they produce lubricin (glycoprotein that lubricates joints)
- they produce collagen fibres
78
what cells are found on the transitional layer of articular cartilage?
- chondrocytes (mature cells)
- produce proteoglycans (aggrecan) which attract water
79
what type of collagen fibres are found in cartilage?
collagen type 2
they change in content and orientation from superficial to deep layers of cartilage
resistance under compression/shearing forces
80
where is the thickness of articular cartilage greatest?
patella 5-6 mm
(patella is pressed against the femur when the knee is flexed)
81
when the knee is flexed there is increased force on the patella
a. true
b. false
a. true
82
How does cartilage get the majority of its blood supply?
diffusion!
(nutrients deliver and waste is taken away)
83
what is the synovium?
the tissue making up the synovial membrane
- produces synovial fluid
- supply's nutrients and removes waste from the periphery AFTER diffusion process
84
outline the layers from superficial to deep of synovial joint
1. fibrous capsule
2. capillary network to synovial membrane
3. no epithelia lining
4. synoviocytes and synovial fluid
5. cartilage
85
there is no epithelial lining between the capillary's and synovial fluid
a. true
b. false
a. true
direct exchange of nutrients
86
function of type A synoviocytes
they look like macrophages
1. remove debris
2. contribute to synovial fluid production
87
function of type B synoviocytes
MAIN producer of synovial fluid
fibroblast like
88
What molecules does synovial fluid contain?
1. GAGs - hyaluronic acid
2. lubricin (glycoprotein)
3. Fluid - from blood plasma
89
where does the fluid component of synovial fluid come from?
blood plasma
90
name 4 mechanisms of lubrication
1. Fluid film - surfaces kept apart by fluid
2. Weeping - volume of fluid is increased (squeezed out of cartilage due to increased pressure)
3. Boundary - bio-lubricants (lipids, hyaluronic acid, lubricin, surface molecules are in direct contact with each other)
4. Bursae and fat pads
91
What are bursae
fluid filled sacs which reduced friction around joints/prevent damage
92
The upper trunk of the brachial plexus is formed by which nerve roots?
C5 and C6
93
The middle trunk of the brachial plexus is formed by which nerve roots?
C7 on its own
94
The lower trunk of the brachial plexus is formed by which nerve roots?
C8 and T1
95
The lateral cord of the brachial plexus consists of?
Anterior divisions of the
1. upper trunk
2. middle trunk
96
The medial cord of the brachial plexus consists of?
Anterior division of the
1. lower trunk
97
The posterior cord of the brachial plexus consist of?
Posterior divisions of the
1. upper
2. middle
3. lower
trunks
98
Which cord does the axillary nerve arise from
posterior cord
99
which two nerves does the posterior cord give off?
axillary C5-C6
radial C5-C8
100
which nerves does the lateral cord give off?
musculocutaneous
median nerve
101
which nerve does the medial cord give off?
ulnar nerve
102
what anatomical vessel are the cords of the brachial plexus described in relation to?
the axillary artery
103
which enzyme recycles hypoxanthine into purines
HGPRT !!!
104
how are purines entered into the body
diet
breakdown of DNA/RNA
105
how are purines expelled from the body
75% by kidneys
35% GI tract
106
which type of collagen fibres are in ligaments?
type 1
produced by fibroblasts
107
How are ligaments different to tendons
join bone to bone
less collagen
less organisation of collagen
more proteoglycans and water (more compliant)
rounder fibroblasts
108
how are tendons different to ligaments
increased collagen
increased organisation of collagen
reduced proteoglycans and water
flat fibroblasts
muscle to bone
109
how do ligaments heal
1. haematoma/haemorrhage - the blood clots and is gradually reabsorbed and replaced by heavy cellular infiltrate
2. Replaced by cellular infiltrate - proliferative phase (disorganised connective tissue) and production of scar tissue
3. remodelling - matrix becomes more ligament like but still different in composition , architecture and function
110
how do tendons insert into bone
sharpeys fibres
(longitudinal arrangement of cells - tenocytes) and collagen type 1 fibres
111
outline the structure of tendons
collagen fibril bundles - endotenon
fascicles - paratenon
tendon - epitenon
112
how do tendons receive blood?
Vinculum (fine network of blood vessels in the paratenon)
113
What is the vincula tendinea?
Slender tendinous bands that connect flexor tendons to the phalanges in the hand
Carries the blood supply to the flexor digitorum superficalis/profundus
114
the sheaths of tendons have synovial lining and fluid
a. true
b. false
a. true
allows gliding and lubrication and nutrition
115
function of tendons
provide propulsion - PULL on bones
flexible and strong under tension
like to MOVE - if immobile for a long time (H20 content reduces, GAGs, and strenght)
116
how do long bones develop?
1. hyaline cartilage
2. primary ossification centre
3. secondary centres at each end
4. medullary cavity
5. epiphyseal plates
117
where is cortical bone found?
diaphysis region
resists bending and torsion
less biologically active
slow growing
118
where is cancellous bone found? spongey bone
metaphysis region
resists and absorbs under compression
shock absorption
biologically active
118
shorthand for fracture
#
119
what is stage 1 of regeneration of fractures?
1/ inflammation -> haematoma and fibrin clot, angiogenesis, mesenchymal and osteoprogenitor cells are transformed from medullary canal into osteoblasts
2/soft callous (pain + swelling subside - bony fragments united by cartilage or fibrous tissue) - stability to fracture
3/ hard callous - cartilage is converted to woven bone
4/ remodelling -> lamellar bone
120
outline how neurons are organised
axons - endoneurium
fasciles - perinerium
nerve - epineurium
121
nerve fibres responsible for dull, aching pain, burning and temperature?
C fibres
122
nerve fibres which detect sharp pain
Ad fibres
123
What is neuropraxia?
The is injured but completely intact!! (bruised/stretched)
There is damage to microcirculation
Direct trauma
Conduction blocked for a short time
Localised ischaemia and demyelination
124
what is Wallen's degeneration
nerve fibre disappears distal to the site of injury
starts 2-3 weeks after injury
125
axonal growth rate
1-3mm /day
recovery of nerve injuries is slow
126
dysesthesia
disordered sensation
e.g. numbness, pins and needles (paraesthesia)
127
what is tinnels signs?
tap the end of the growing nerve -> parathesis (abnormal sensation) felt as far distally as the regeneration has progressed
128
features of
