MSK physio Flashcards
1
Q
What cranial nerves form the brachial plexus?
A
C5-C8 and T1
2
Q
What are the four major branches of the brachial plexus from proximal to distal?
A
Roots
Trunks (named for anatomical position)
Divisions
Cords/Terminal nerves (named for what they supply)
All come off the cervical spine. Know and understand innervations of the nerves of the upper limb. Common in sports injuries for this to be complicated.
3
Q
What are the terminal nerves of the brachial plexus?
A
Axillary, Musculocutaneous, Median, Ulnar, Radial
4
Q
Where is the axillary nerve located?
A
Close to the surgical neck of the humerus; susceptible to damage with fractures. Provides motor functions to the deltoid and teres minor muscle, and sensory innervation to the same area.
5
Q
What does the musculocutaneous nerve supply?
A
Supplies the lateral cutaneous nerves of the arm and is responsible for movement of the anterior arm and sensory innervation.
6
Q
What is the function of the median nerve?
A
Does not innervate anything in the upper arm; serves the muscles on the anterior forearm and sensory to the tips of the fingers. Important in carpal tunnel syndrome.
7
Q
What does the ulnar nerve innervate?
A
Serves the ‘funny bone’, supplies the muscles of the anterior forearm and most intrinsic muscles of the hands, and provides sensory innervation.
8
Q
What is the function of the radial nerve?
A
Major nerve of the posterior forearm with some motor function.
9
Q
What condition is caused by damage to the radial nerve?
A
Wrist drop
10
Q
Describe the lumbar plexus.
A
Arises from L1 to L4; innervates anterior thigh (hip and knee flexors) and medial thigh (adductors). Aids in hip flexion and knee flexion.
11
Q
What are the major nerves of the lumbar plexus?
A
Femoral nerve and obturator nerve.
12
Q
What does the femoral nerve innervate?
A
Innervates quadriceps and skin of anterior thigh and medial surface of leg.
13
Q
What does the obturator nerve do?
A
Passes through obturator foramen to innervate adductor muscles of medial thigh.
14
Q
Describe the sacral plexus.
A
Arises from L4 to S4; serves the gluteal muscles and posterior thigh muscles (i.e. hamstrings).
15
Q
What nerve is the major contributor to the sacral plexus?
A
Sciatic
16
Q
What are all the major spinal nerve plexuses
A
17
Q
Describe the sciatic nerve
A
Innervates hamstring muscles, adductor magnus, and most muscles in leg and foot. Composed of two nerves: tibial and common fibular.
18
Q
How do bones grow?
A
The epiphyseal plate thins and then is replaced by bone. The epiphyseal plate closure occurs when epiphysis and diaphysis fuse.
19
Q
When do growth plates fuse?
A
Women: 18 years. Men: 21 years.
20
Q
How does appositional growth occur?
A
Growth of the bone diameter in response to increased weight and added stress.
21
Q
How does growth hormone affect bone growth?
A
Stimulates growth at the epiphyseal plate in infancy and childhood.
22
Q
How does thyroid hormone affect bone growth?
A
Modulates and ensures the proper amount of growth hormone and therefore bone growth.
23
Q
How does testosterone and estrogen affect bone growth?
A
Promotes adolescent growth spurts and ends the growth of bones by inducing epiphyseal plate closure (at the end of adolescence).
24
Q
How does an excess or deficit in growth hormones affect the skeletal system?
A
They may cause abnormal skeletal growth.
25
How does bone remodeling work?
Done by osteoclasts and osteoblasts
- Repairs micro-damage (everyday stress of disrupting our bones)
- Adapts in response to mechanical stress
- Regulates calcium and phosphate
- Bone mass and structural integrity
Regulated by PTH, calcitonin, Vitamin D, and sex hormones
26
What would calcitonin do?
Would stimulate osteoclasts to pick up calcium and put that in and build up bone.
27
What is the negative feedback mechanism of hormonal bone control?
Low calcium levels stimulate PTH from the thyroid gland.
28
What is the timeline of the skeletal system?
Tiny humans have 275 bones (due to fusion) and adults have 206. Women and their estrogen impact bone remodeling. Post-menopausal women tend to get osteoporosis and are at increased risk of fractures and lots of pain.
29
What is the pathophysiology of how a Vitamin D deficiency occurs?
Occurs a lot in the wintertime. Needs a lot of coordination between multiple body systems. We mostly give Vitamin D3 clinically.
30
What population do Vitamin D deficiencies affect?
Location, time of year. African Americans are more likely to have lower vitamin D levels due to skin pigmentation reducing vitamin D production. Diffuse body pains should clue you in.
31
What are the bony landmarks of the spine?
Vertebral body, vertebral arch, spinous process, transverse processes, superior and inferior articular processes, vertebral foramen.
32
What are the functions of the vertebral body?
Most anterior weight-bearing portion. Separated by vertebral discs.
33
What are the functions of the vertebral arch?
Formed by the pedicles and laminae (form the C-shaped arch).
34
What are the spinous processes?
Most posterior projection.
35
What is the superior and inferior articular processes?
Form what are called facet joints that help to attach adjacent vertebrae.
36
What are the transverse processes?
Lateral projections, where a lot of muscles and ligaments attach to.
37
What are the vertebral foramen?
Hole in the middle, where the spinal cord and the nerves are housed.
38
What are the intervertebral discs?
Herniated discs are formed by two structures: Nucleus pulposus and Annulus fibrosis.
39
What is the nucleus pulposus?
The inner portion that herniates and pushes on the spinal cord.
40
What is the annulus fibrosis?
Outside is a capsule that protects the nucleus and acts as a cushion for the spine.
41
What are the long ligaments of the vertebral column?
Anterior and posterior longitudinal ligaments. Prevent hyperextension and hyperflexion.
42
What are the short ligaments of the vertebral column?
Ligaments in between that connect the vertebrae above and below. Think about when you are doing a lumbar puncture, we poke through these and should hear a pop.
Ligamentum flavum
Interspinous ligament
Supraspinous ligament
43
What is the ligamentum flavum?
Connects the lamina of adjacent vertebrae.
44
What is the interspinous ligament?
In between our spinous process of adjacent vertebrae.
45
What is the supraspinous ligament?
Runs a bit longitudinally from the cervical vertebrae and all the way down, but connects adjacent vertebrae too.
46
Define the appendicular skeleton.
Bones of the upper and lower limbs and girdles attaching limbs to the axial skeleton.
47
How do the bones work to support the body?
For body and soft tissue organs.
48
How do the bones work to protect the body?
Brain, spinal cord, and vital organs.
49
How do the bones work to move the body?
Levers for muscle action.
50
How do the bones work for mineral and growth factor storage in the body?
Calcium and phosphorus, and growth factors reservoir.
51
How do the bones work to transport blood to the body?
Blood cell formation.
52
How do the bones work for hematopoiesis in the body?
Occurs in red marrow cavities of certain bones.
53
How do the bones work in triglyceride (fat) storage in the body?
use as an energy source.
54
How do the bones work with the endocrine system in the body?
Hormone production.
55
How do the bones work with osteocalcin in the body?
Secreted by bones helps to regulate insulin secretion, glucose levels, and metabolism.
56
Define the long bones.
Longer than they are wide; limb bones.
57
What is an example of a long bone?
Humerus.
58
Define the irregular bones.
Complicated shapes.
59
What is an example of an irregular bone?
Vertebrae and hip bones.
60
Define the flat bones.
Thin, flat, and slightly curved.
61
What is an example of a flat bone?
Sternum, scapulae, ribs, most skull bones.
62
Define the short bones.
Cube-shaped bones (in wrist and ankle).
63
What is an example of a short bone?
The talus.
64
Define the sesamoid bones.
Bones from within tendons. They vary in size and number in different individuals.
65
What is an example of a sesamoid bone?
Patella.
66
What is compact bone?
Looks smooth and solid.
67
What is spongey bone?
Has a mesh of bony spines called trabeculae (honey-comb-like). The open spaces in the trabeculae is where we have bone marrow. Primarily in long bones.
68
What two bone types make up the bone marrow?
Compact and spongey. No defined bone marrow cavity, but just flows in between the trabeculae.
69
What are the structures of a typical long bone?
Diaphysis, Epiphyses, Epiphyseal plate
70
What is the diaphysis?
Shaft, more spongey bone
71
What is the epiphyses?
The end of the long bones, containing a bit more compact bone. there are 2
72
What is the epiphyseal plate?
Metaphysis, aka the growth plate
73
What are the two membranes of the bones?
Periosteum (Fibrous layer
Osteogenic layer and nutrient formation) and Endosteum
74
Describe the periosteum
White external membrane that serves as an anchoring point of ligaments and tendons. The fibrous layer attaches the periosteum to the bone. The osteogenic layer helps to make osteocytes, nutrients, and supports bone growth.
75
Describe the endosteum
Contains osteogenic cells to support the inner layer of the periosteum and provide nutrients
76
What are the functions of osteogenic cells?
Precursor stem cells to osteoblasts or bone-lining cells
77
What are the important bone cells and when do they work?
These cells are ALWAYS working: Osteogenic cells, osteoblasts, osteocytes, bone-lining cells, osteoclasts
78
What are the functions of osteoblasts?
Bone-forming cells (osteoblasts Build Bone)
79
What are the functions of osteocytes?
Mature bone cells and stimulate bone remodeling
80
What are the functions of bone-lining cells?
Flat cells on the surface of the bone to help maintain bony matrix
81
What are the functions of osteoclasts?
Bone breakdown (osteoClasts Chomp bone)
82
How does osteogenesis occur?
Ossification
83
What is the process of endochondral (cartilage) ossification?
At about 8 weeks in utero, bone tissue starts to replace fibrous membranes and hyaline cartilage of the fetal skeleton. Bone growth occurs until middle adulthood.
84
Define the axial skeleton
The long axis of the body: Skull, vertebral column, rib cage
85
Identify the fascicle and muscle fiber
Cross section of the biceps brachii.
There are many different structures that make up the muscles
86
What are the components of thick (myosin) filaments?
Heavy chains
Light chains with cross-bridges to exert force
The chains have binding sites on the head of the myosin. The myosin will bind to the actin (actin binding site) and kind of crawl along the actin during muscular contraction to apply force. ATP will be used by binding to myosin as well to aid in the action of contraction.
87
What causes the muscle to contract?
The actin and myosin
88
Skeletal muscle is made up of smaller units called what?
Sarcomeres
89
Why are muscle fibers striated?
Due to the presence of **smaller functional units called sarcomeres**.
90
What are the different types of muscle in the body?
Smooth, cardiac, and skeletal.
91
What does a muscle fiber (single muscle cell) contain?
Myofibrils, which contain **sarcomeres (the smallest functional contractile unit)** made up of actin (thin filament) and myosin (thick filament).
92
What are the components of thin (actin) filaments?
Troponin (pink) + tropomyosin (blue)
Work to regulate muscle contraction
Prevent contraction from happening when it doesn’t need to
**Troponin will push tropomyosin out of the way to allow actin to bind to myosin and allows for the cross bridging (Confirmational change)**
93
What is the sarcolemma?
It is the plasma membrane that connects to the transverse (T) tubules and then to the sarcoplasmic recticulum (Ca2+)
94
What is the function of the sarcolemma in the activation of muscle contraction?
Action potentials form neurons are fired along the plasma membrane aka the sarcolemma, the neuron will fire and stimulate the sarcolemma to depolarize which will then be spread throughout the transverse tubules (which is continuous with the sarcoplasmic recticulum). Once the stimulation reaches the **sarcoplasmic recticulum**, calcium is realised to stimulate muscle contraction by moving troponin out of the way.
95
What is the main function of the sarcoplasmic recticulum?
**To store calcium for muscle contraction**.
96
Define the term muscle contraction
Muscle contraction does not always mean shortening in MSK physiology but refers to the activation of those myosin-actin cross-bridges.
97
When we hold a dumbbell steady, with a bent elbow, what are the muscles doing?
They are contracting, but NOT shortening
98
What are the motor units of the muscles?
Motor neurons + skeletal muscle fibers.
Occurs synchonisely
99
What does a single muscle stimulation look like electrically?
Our muscle fiber action potential shows depolarization and repolarization
Muscle contraction is shown in orange. We see the latent period at the beginning where the cross bridges are starting to be prepared, period of shifting from excitation to contraction. After the action potential there is a refractory period. Cardiac muscle cannot control tetany, but it can happen in muscle fibers and it is called summation
100
What is the refractory period for muscle contraction?
This is the process of summation. We see stimulus after stimulus and see the twitch leading to a brief contraction and full relaxation. Once we get to more frequent stimuli and more frequent twitches, we can how our contraction looks and how that tension increases. Multiple contractions and stimuli will causes what is called fused tetanus
101
What is summation?
Occurs when a second stimulus comes before we were able to achieve full relaxation and that cycle continues resulting in greater tension. The more calcium, the more cross bridging and muscle contraction we have. This tension will build and causes what is called unfused tetanus. This is an osalaitng, where there is some recovery but the calcium
102
What is fused tetanus?
Repeated stimulation back to back
High frequney relaxation has no relaxation time, because of sustained stimuli and fused tetanus.
103
What electrolyte abnormality leads to tetany?
hypocalcemia
104
Fused tetanus is not always a bad thing. When might it be beneficial?
Posture, lifting
Although in people with low clacium, who have muscle spasms, who have motor neuron diseases, spastiicty, abnormal firing would stimulate tetnay
105
Is muscle fiber activiation aerobic or ananaerobic?
Aerobic. Muscles rely on a steady supply of ATP. The three major pathways to do this.
106
What is the byporduct of ATP?
ADP + P
107
What are the 3 ways a muscle fiber can form ATP?
1. Phosphorylation of ADP by **creatinine phosphate (good for short burst of high energy for exercise, but is not sustainable for very long)**
2. Oxidative phosphorylation of ADP in the mitochondria (this mechanism is mostly turned on during long distance running and endurance activities)
3. Phosphorylation of ADP by the glycotic pathway in the cystol (conversion of glucose into ATP and **lactic acid is the byproduct and gives the burn during really intense exercise)**
108
What are the the two things that ATP is needed for in muscle control?
division of actin and myosin
pumping of calcium back into the sarcoplasmic recticulum
109
What is peripheral muscle fatigue determined by?
Many body dependent factors
**ATP reduction is thought to be the cause of impaired muscle function**, even if there is neural stimulation.
110
What is central muscle fatigue?
Cerebral cortex fails to send excitatory signals to motor neurons. No signals = no contraction.** In athletes they somethings feel like they have “hit a wall” and cannot continue.**
111
What is hypertrophy?
Increased amounts of contractile activity, such as regular exercise, can produce an increase in the size, hypertrophy, of muscle fibers as well as changes in their capacity for ATP production and the subtype of myosin they express
112
What is atrophy?
“Use it or lose it” muscles that are not used will atrophy.
113
What are the 2 types of atrophy?
Disuse atrophy (like an arm in a cast, immobilization)
Denervation atrophy (nerve damage= loss of function)
114
Where are Upper Motor Neurons (UMNs)?
In the CNS they transmit signals from the brain to the spinal cord or brain stem to synapse with lower motor neurons.
115
What is the function of UMNs?
They initiate and coordinate voluntary movements. **Damage can lead to spasticity, *hyperreflexia*, weakness, changes in muscle tone, *stroke*, cerebral palsy, MS**
116
Where are Lower Motor Neurons (LMNs)?
In the PNS, directly innervate muscles and produce movement
117
What is the function of LMNs?
Play a crucial role in generation of movement and muscle tone.
118
Damage to the LMNs can cause what?
**Damage can cause muscle weakness, *atrophy*, *hyporeflexia,* muscle twitches, spinal musculature atrophy, sclerosis, muscular dystrophy, will primarily impact these neurons.**
119
What is the neuromuscular junction?
Motor neuron cell bodies (spinal cord and brainstem) → axon → axon terminal
120
What is the motor end plate?
Aka the neuromuscular junction. Region of the muscle fiber plasma membrane that lies directly under the terminal portion of the axon. Acetylcholine (ACh).
At the end of the motor neuron, we have a small vesicles right in those vesicles of the motor neuron contain neurotransmitter Ach. You can see that once we have the release of acetylcholine into binding on the circle, and we have propagation of the action potential into the into the muscle to cause contraction.
121
What is the process of muscle depolarization?
Motor neuron receives stimulation of action potential that moves down the axon and reaches the axon terminal
Action potential stimulates the opening of voltage gated Ca2+ channels allowing Ca to flow into the neuron
Ca2+ entry causes the release of ACh vesicles into the synaptic cleft
ACh binds to nicotinic receptors on motor end plate of muscle causing the opening of Na and K ion channels
The entrance of Na+ into the muscle cell (and K outward) causing depolarization and generation of an action potential in the muscle fiber which is propagated through the sarcolemma, T-tubules, and sarcoplasmic reticulum* (6-8)
9. ACh is degraded by acetylcholinesterase to prevent
122
How can we described the depolarization of muscle fibers?
The motor neuron itself receives an action potential moves it downward to the terminal (or the button) portion of the neuron, and from that we have calcium channels open and calcium flows into the neuron cell. Calcium stimulates the release of the binding of these vesicles here to release into the synapse. Then it will go to the sarcoplasmic membrane and bind to receptors specifically nicotinic receptors on this causes of sodium and potassium ion channels. The generation of depolarization in the muscle fiber spread to the sarcoplasmic reticulum. Calcium is being released by reticulum and causes contraction.
123
Why is the breakdown of acetylcholine in the synapse so important?
Acetylcholine is broken down by Acetylcholinesterase, because the more Ach that gets bound is the more muscle contraction we have. We don’t always want to be contracting out muscle because that could be problematic. so you know it and receptors are actually really good targets for drugs such as suing rocky vecuronium. These are called neuromuscular blocking agents so paralytics. For example when we paralyze people because we don’t have to use as much anesthetic.
124
What is the indication for paralytics in settings like the ICU?
People still move when they’re unconscious for example, and when people are placed on ventilators, we need to paralyze them to control their their breathing
125
How are Ach receptors good targets for pharmacologic therapies especially in the setting of surgery?
Good targets for rocuronium, succinylcholine, vecoronium. These are called neuromuscular blocking agents (paralytics). For example when we paralyze people because we don’t have to use as much anesthetic.
126
What infectious disease works on the motor neuron synapse?
Botulisim. Botulism causes paralysis which causes tetany and is a type of food poisoning. It prevents the release of acetylcholine on the vesicles within the neuron so that prevent the release of Ach and therefore cause paralysis. Botox has this same mechanism.
127
How does the neuromuscular signal travel from the sarcolemma trhough to the muscles?
Sarcolemma (plasma membrane) → transverse (T) tubules → sarcoplasmic recticulum (Ca 2+) → Ca2+ binds to troponin to activate the sliding filament mechanism to pull the tropomyosin to allow for cross bridgine of actin and myosin.
128
How is muscle relaxantation stimulated?
calcium ATPase will pump calcium back into the sarcoplasmic reticulum by active transport, so where we have the reverse process to get rid of all calcium from binding and so that calcium can be recycled back into the reticulum
129
Where does more overlap of the actin and myosin occur?
130
What is the difference between isotonic contraction and isometric contraction?
**Isometric contraction** occurs when a muscle develops tension but does not shorten or lengthen, like when carrying a bag, meaning supporting a load in a CONSTANT position. Muscle is contracting but NOT shortening
**Isotonic contraction** occurs when a muscle changes lengthen while the load on the muscle remains constant so like in weight training.
131
What are the two types of isotonic contraction?
**Concentric contraction**- muscles curling up and contracting and shortening. tension exceeds the load.
**Eccentric contraction**- muscle lengthens but is still generating force so when we are lowering the weight back down. the load exceeds the tension
132
What is the load?
Muscle exerted by an object
133
What are the opposing forces of muscle contraction?
Our contraction vs what we are contracting against
134
What is muscle tension?
The force that is exerted on a muscle
