PCOM DO (2025-) > MSK Week 2 > Flashcards

MSK Week 2 Flashcards

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1
Q

What is Physiology?

A

Study of functions of living things, focuses on how body functions across systems. Links basic sciences with medicine.

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2
Q

Define Homeostasis.

A

Maintenance of relatively stable internal fluid environment surrounding cells. Goal for normal bodily function.

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3
Q

What is Intracellular Fluid (ICF)?

A

Approximately 66% (2/3) of total body water, found within tissue cells.

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4
Q

What is Extracellular Fluid (ECF)?

A

Approximately 33% (1/3) of total body fluid, located outside tissue cells.

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5
Q

What does Interstitial Fluid (ISF) represent?

A

Makes up 75% of ECF, fluid in spaces between tissue cells.

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6
Q

List the components of the Homeostatic Control System.

A
  • Sensor * Control Center/Integrator * Effector
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7
Q

What is the function of a Sensor in homeostasis?

A

Detects variations from normal ‘set point’ in internal environment.

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8
Q

What is the role of the Control Center/Integrator?

A

Receives input from sensor, integrates with set point, sends instructions to effector.

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9
Q

Define the function of an Effector.

A

Carries out adjustments to restore controlled variable to normal.

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10
Q

What factors are maintained homeostatically?

A
  • Concentration of nutrients * O₂/CO₂ * Waste products * pH * Water/salt/electrolytes * Volume/pressure * Temperature
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11
Q

What is Intrinsic (Local) Control?

A

Built into an organ itself.

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12
Q

What is Extrinsic (Systemic) Control?

A

Initiated outside an organ, typically involving nervous and/or endocrine systems.

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13
Q

Define Negative Feedback.

A

Most common homeostatic control system, response opposes or counteracts the initial stimulus.

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14
Q

Give an example of Negative Feedback in blood glucose regulation.

A

High glucose triggers insulin release to lower levels; low glucose triggers glucagon to raise levels.

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15
Q

What is an example of Negative Feedback in arterial blood pressure regulation?

A

Baroreceptors sense BP changes, brain adjusts heart rate and blood vessel diameter.

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16
Q

Explain Negative Feedback related to body core temperature.

A

Nerve cells detect temperature, brain signals skeletal muscles to shiver or sweat.

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17
Q

Define Positive Feedback.

A

Rarer system, response reinforces initial stimulus, amplifying the effect.

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18
Q

What is an example of Positive Feedback in blood clotting?

A

Activated platelets release clotting factors, amplifying clot formation until vessel repaired.

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19
Q

Describe the Positive Feedback mechanism in childbirth.

A

Oxytocin causes contractions, cervical stretch causes more oxytocin release.

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20
Q

What is an example of Positive Feedback in nerve signals?

A

Initial Na⁺ influx causes more Na⁺ influx, propagating action potential.

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21
Q

Define Feedforward Control.

A

Mechanism to prevent problems before they occur.

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22
Q

Give an example of Feedforward Control in postural adjustments.

A

Adjusting posture before falling on an unstable surface.

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23
Q

What is an example of Feedforward Control in the GI system?

A

Salivation and stomach growling when smelling food.

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24
Q

Define Adaptive Control.

A

Type of delayed negative feedback allowing body to adjust responses over time.

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25
What does Allostasis refer to?
Process of achieving stability by adapting to chronic stressors.
26
Define Allostatic Load.
Physiological consequences or cumulative 'wear and tear' on body from chronic stress.
27
List examples of Allostatic Load.
* Abdominal body fat accumulation * Bone mineral loss * Chronic stress/fatigue * Atrophy of hippocampal nerve cells * Hypertension
28
How can one alleviate Allostatic Load?
Identify/remove underlying cause, increase social support, improve patient's quality of life.
29
Define Disease.
Failure of normal physiological function leading to negative symptoms.
30
What is the Aging Pitfall?
Inherently leads to homeostatic imbalance, increasing risk for illnesses.
31
Describe the Diabetes Pitfall.
Homeostatic imbalance in blood glucose regulation.
32
Clinical Application: What does uncontrolled hypertension in pregnancy indicate?
Disruption in the *negative feedback control system* regulating arterial blood pressure.
33
Clinical Application: What does labor induction with oxytocin exemplify?
Utilizing a *positive feedback control system* to amplify uterine contractions.
34
What are the two main divisions of the Nervous System?
CNS (Central Nervous System) and PNS (Peripheral Nervous System) ## Footnote CNS includes the brain and spinal cord, while PNS is outside the brain and spinal cord.
35
What is the third branch of the Autonomic Nervous System?
Enteric Nervous System ## Footnote It is covered with GI physiology.
36
What type of control does the Sympathetic Nervous System (SNS) exert?
Voluntary
37
What type of control does the Autonomic Nervous System (ANS) exert?
Involuntary
38
Describe the peripheral nerve anatomy of the SNS.
One motor neuron from spinal cord directly to skeletal muscle
39
Describe the peripheral nerve anatomy of the ANS.
Two neurons (pre-ganglionic & post-ganglionic) from spinal cord to smooth/cardiac muscle/glands, except adrenal medulla (one neuron)
40
What type of muscle is innervated by the SNS?
Skeletal muscle
41
What types of muscles or glands are innervated by the ANS?
Smooth muscle, cardiac muscle, glands
42
Are SNS axons myelinated?
Yes
43
Are ANS axons myelinated?
Pre-ganglionic are myelinated; Post-ganglionic are unmyelinated
44
What neurotransmitter is released by the SNS?
Acetylcholine (ACh)
45
What neurotransmitters are used in the ANS?
Acetylcholine (ACh), Norepinephrine (NE)
46
What type of receptors are found in the SNS?
Nicotinic (Nm)
47
What types of receptors are found in the ANS?
Muscarinic (M), Adrenergic ($\alpha, \beta$)
48
What are the main functions of the ANS?
Maintain homeostasis, manage stress responses, control visceral functions (all involuntarily)
49
What is the sympathetic nervous system often referred to as?
"Gas pedal," "fight or flight" system
50
What is the parasympathetic nervous system often referred to as?
"Break," "rest and digest" system
51
Where are the preganglionic cell bodies of the SANS located?
Thoracic and lumbar spinal cord
52
Where are the preganglionic cell bodies of the PANS located?
Brainstem and sacral spinal cord
53
From which regions does the SANS emerge from the CNS?
Middle (thoracic, lumbar regions)
54
From which regions does the PANS emerge from the CNS?
Top & bottom (cranial, sacral regions)
55
Where are most SANS ganglia located?
In 2 chains beside the vertebral column (sympathetic chain ganglia)
56
Where are PANS ganglia typically located?
Near or in the visceral effector organ
57
What is the length of the preganglionic neuron in the SANS?
Relatively short
58
What is the length of the preganglionic neuron in the PANS?
Relatively long
59
What is the length of the postganglionic neuron in the SANS?
Relatively long
60
What is the length of the postganglionic neuron in the PANS?
Relatively short
61
What is the pathway extent of the SANS?
Widespread effect; one preganglionic neuron synapses with many postganglionic neurons to many effectors
62
What is the pathway extent of the PANS?
Localized effect; one preganglionic neuron synapses with few postganglionic neurons to one effector
63
What is the special role of the adrenal medulla?
Modified sympathetic ganglion, no postganglionic fibers
64
What do chromaffin cells in the adrenal medulla secrete?
Epinephrine (80%) and Norepinephrine (20%) into bloodstream as hormones
65
What is the main source of circulating epinephrine?
Adrenal medulla, due to abundant PNMT enzyme
66
What determines the autonomic end-effect?
The specific receptor activated
67
What is cholinergic transmission?
Any neural transmission using Acetylcholine (ACh) as the neurotransmitter
68
What neurotransmitter and receptor are associated with SANS preganglionic neurons?
ACh released, binds to Nicotinic (Nn) receptors
69
What neurotransmitter and receptor are primarily released by SANS postganglionic neurons?
Norepinephrine (NE) released, binds to adrenergic receptors ($\alpha1, \alpha2, \beta1, \beta2, \beta3$, D1)
70
What is the exception for sweat glands in SANS postganglionic neurotransmission?
ACh released, binds to Muscarinic (M) receptors (M3 for generalized sweating)
71
What neurotransmitter and receptor are associated with PANS preganglionic neurons?
ACh released, binds to Nicotinic (Nn) receptors
72
What neurotransmitter and receptor are associated with PANS postganglionic neurons?
ACh released, binds to Muscarinic (M1-M5) receptors
73
What type of receptor is the adrenergic $\alpha1$ receptor?
Gq coupled; increases PLC, IP3, Ca2+
74
What is the effect of the adrenergic $\alpha2$ receptor?
Inhibitory effect; inhibits AC, decreases cAMP
75
What type of receptor is the adrenergic $\beta1$ receptor?
Gs coupled; activates AC, increases cAMP
76
Where is the adrenergic $\beta2$ receptor found?
Ciliary muscle, heart, tracheal/bronchial smooth muscle, bronchial glands, urinary bladder (detrusor)
77
What is the high-yield pharmacology principle regarding drug selectivity?
Drug selectivity is dose-dependent; lower doses are more selective, higher doses decrease selectivity
78
What are examples of $alpha$-receptor agonists?
* NE * E * Phenylephrine
79
What are examples of beta receptor agonists?
* NE * E * Isoproterenol * Dobutamine * Albuterol (selective $eta2$)
80
What are examples of muscarinic receptor agonists?
* ACh * Muscarine * Carbachol * Pilocarpine (for glaucoma) * Cevimeline (for Sjogren's xerostomia)
81
What are examples of muscarinic receptor antagonists?
* Atropine * Scopolamine * Tropicamide (for mydriasis) * Benztropine * Trihexyphenidyl (for Parkinson's)
82
What is the rate-limiting step in catecholamine biosynthesis?
Tyrosine hydroxylase converts Tyrosine to Dopa
83
What enzymes are involved in catecholamine metabolism?
* COMT (Catechol-O-Methyl-Transferase) * MAO (Monoamine oxidase)
84
What is Vanillylmandelic Acid (VMA) used for clinically?
Confirmatory test for pheochromocytoma
85
What does botulinum toxin do?
Inhibits the release of acetylcholine
86
What enzyme synthesizes ACh?
Choline acetyltransferase (ChAT)
87
What enzyme rapidly breaks down ACh in the synapse?
Acetylcholinesterase (AChE)
88
What are Muscarinic Receptor Antagonists?
Atropine, Scopolamine, Tropicamide (for mydriasis), Benztropine, Trihexyphenidyl (for Parkinson's) ## Footnote These drugs block muscarinic receptors and can be used for various medical conditions.
89
Name a Nicotinic Receptor Agonist.
ACh, Nicotine (dual effect) ## Footnote These substances activate nicotinic receptors, influencing neuromuscular transmission.
90
What are Non-Depolarizing Neuromuscular Blockers?
Pancuronium, d-tubocurarine ## Footnote These are nicotinic antagonists that prevent muscle contraction.
91
What is a Depolarizing Neuromuscular Blocker?
Succinylcholine ## Footnote This drug acts as both a nicotinic agonist and antagonist.
92
What is an Indirect Adrenergic Agonist (MAO Inhibitor)?
Selegiline ## Footnote This drug inhibits monoamine oxidase, increasing levels of neurotransmitters.
93
Name an Indirect Adrenergic Agonist that is an uptake inhibitor.
Cocaine ## Footnote Cocaine prevents the reuptake of norepinephrine, enhancing its effects.
94
What are Releasing Agents in Indirect Adrenergic Agonists?
Amphetamine, Tyramine ## Footnote These substances stimulate the release of norepinephrine from nerve terminals.
95
What is an Indirect Adrenergic Agonist (COMT Inhibitor)?
Entacapone ## Footnote This drug inhibits catechol-O-methyltransferase, affecting dopamine metabolism.
96
Name an Indirect Adrenergic Antagonist that inhibits NE synthesis/storage.
Reserpine, Guanethidine ## Footnote These drugs reduce the availability of norepinephrine in the synaptic vesicles.
97
What is a Central α2 Activator in Indirect Adrenergic Antagonists?
Clonidine ## Footnote Clonidine decreases peripheral sympathetic tone by activating central α2 receptors.
98
What are Reversible AChE Inhibitors?
Physostigmine, Neostigmine, Pyridostigmine, Rivastigmine, Edrophonium, Tacrine, Donepezil, Galantamine ## Footnote These drugs temporarily inhibit acetylcholinesterase, increasing acetylcholine levels.
99
Name an Irreversible AChE Inhibitor.
Carbamate insecticides, organophosphate agents, nerve agents ## Footnote These substances permanently inhibit acetylcholinesterase, leading to prolonged acetylcholine action.
100
What causes Muscarinic Syndrome?
Excessive muscarinic AND nicotinic stimulation, often from massive ACh buildup ## Footnote This typically occurs due to irreversible AChE inhibitors like organophosphates.
101
What is a natural source of Muscarine?
Amanita muscaria mushrooms ## Footnote These mushrooms contain muscarine, which can cause symptoms similar to those of muscarinic syndrome.
102
What mnemonic is used to remember the symptoms of Muscarinic Syndrome?
DUMBBELLS + CNS excitation + sweating ## Footnote Symptoms include Diarrhea, Urination, Miosis, Bradycardia, Bronchoconstriction, CNS stimulation, Emesis, Lacrimation, Salivation, Sweating.
103
What are the Nicotinic Effects in Muscarinic Syndrome?
Skeletal muscle excitation (initially) followed by paralysis, CNS stimulation ## Footnote This reflects the dual nature of the syndrome's symptoms.
104
What is the treatment for Muscarinic Syndrome (Muscarinic Effects)?
Atropine (competitive muscarinic antagonist) ## Footnote Atropine helps counteract the excessive muscarinic activity.
105
What is the treatment for Muscarinic Syndrome (Nicotinic Effects/AChE Reactivation)?
Pralidoxime (2-PAM) (AChE reactivator) ## Footnote Pralidoxime reactivates acetylcholinesterase, reversing the effects of organophosphates.
106
Provide a clinical scenario for Muscarinic Syndrome.
Gardener exposed to organophosphate insecticides via skin absorption ## Footnote This exposure leads to high levels of ACh due to AChE inhibition.
107
What is the first step in predicting the outcome of drug activity?
Identify the specific receptor subtype(s) targeted by the drug ## Footnote This step is crucial for understanding the drug's mechanism of action.
108
What is the second step in the outcome prediction approach?
Determine if the drug is an agonist (enhances) or antagonist (blocks) ## Footnote This distinction influences the expected physiological response.
109
What is the third step in predicting drug activity outcomes?
Recall the normal autonomic effect on the target organ via that specific receptor ## Footnote Understanding the baseline effect is essential for predicting changes.
110
What happens when an agonist is used?
An agonist will cause an exaggeration of the normal effect associated with that receptor ## Footnote This can lead to enhanced physiological responses.
111
What occurs when an antagonist is administered?
An antagonist will cause the opposite of the normal effect, or prevent the natural neurotransmitter from acting ## Footnote This allows the opposite system to dominate in dual innervation.
112
What are chondroblasts?
Immature cells that produce cartilage matrix ## Footnote 'Blast' indicates immature cell making ECM.
113
What are chondrocytes?
Mature cartilage cells surrounded by matrix, residing in lacunae ## Footnote 'Cyte' indicates mature cell.
114
What are lacunae?
Small cavities within cartilage matrix where chondrocytes live ## Footnote Means 'space' in Latin.
115
What are isogenous groups?
Clusters of chondrocytes formed by division of a single cell ## Footnote Key difference from bone; allows cartilage to lengthen.
116
What type of collagen is primarily found in cartilage fibrils?
Collagen type II ## Footnote Also includes collagen IX, X (growth plate), XI, and sometimes elastin.
117
What is the ground substance of hyaline cartilage composed of?
Contains GAGs: hyaluronic acid, chondroitin sulfate, keratan sulfate ## Footnote 'Hyalin' refers to its glassy appearance due to attracted water.
118
What are proteoglycan aggregates in cartilage?
Aggrecan + hyaluronan; negatively charged, attract water, resist compression ## Footnote Collagen IX & XI link aggregates to collagen.
119
What is the territorial matrix?
First, disorganized matrix produced by chondrocytes; stains darker around the cell.
120
What is the function of the perichondrium?
Dense irregular CT sheath surrounding most cartilage; provides vascular supply and contains chondroprogenitor cells.
121
What are the layers of the perichondrium?
Outer fibroblastic layer and inner chondrogenic layer.
122
What do osteoblasts do?
Secrete organic bone matrix (Type I collagen, proteoglycans, glycoproteins). ## Footnote Lay down osteoid (unmineralized matrix).
123
What are osteocytes?
Mature bone cells in lacunae, orchestrate bone remodeling by converting mechanical signals to chemical signals.
124
What are canaliculi?
Cytoplasmic processes linking osteocytes for communication and nutrient exchange.
125
What are osteoclasts?
Large, multinucleated cells specialized for bone resorption via a 'ruffled border'.
126
What constitutes the inorganic matrix of bone?
Approximately 50% of bone matrix; primarily hydroxyapatite crystals (calcium, phosphorus).
127
What is included in the organic matrix of bone?
Type I collagen, GAGs, proteoglycans, glycoproteins ## Footnote Type I collagen is crucial for lamellar arrangement.
128
What is the periosteum?
Covers outer bone surface; outer layer of collagen/fibroblasts and inner layer with osteoprogenitor cells.
129
What is the endosteum?
Single layer of osteoprogenitor cells lining all internal bone cavities.
130
What are similarities between cartilage and bone?
Both firm tissues resisting mechanical stress; cells lie in lacunae; primarily ECM with few cells.
131
What is a key difference regarding mineralization between bone and cartilage?
Bone matrix is mineralized with bony salts (hydroxyapatite), cartilage matrix is not.
132
How does vascularity differ between bone and cartilage?
Bone is vascular, requiring direct blood supply for nutrient exchange; cartilage is largely avascular.
133
What is a key difference in cell communication between bone and cartilage?
Bone has canaliculi linking osteocytes; cartilage lacks canaliculi.
134
What is the organization of collagen in mature bone compared to cartilage?
Mature bone has highly organized lamellar collagen fibrils; cartilage collagen is less organized.
135
How does bone grow compared to cartilage?
Bone grows by appositional growth ONLY; cartilage grows by both appositional and interstitial growth.
136
Why does bone lack interstitial growth?
Mineralized matrix immobilizes osteocytes, preventing them from dividing and separating within lacunae.
137
What is hyaline cartilage?
Most common type of cartilage; abundant ECM, cells in lacunae, isogenous groups, often a perichondrium.
138
Where is hyaline cartilage found?
Fetal skeleton, articular surfaces, sternal ends of ribs, trachea, larynx, nose, epiphyseal plates.
139
What characterizes elastic cartilage?
Collagen type II AND abundant elastic fibers (elastin); provides flexibility.
140
Where is elastic cartilage located?
External ear, external auditory meatus, auditory tubes, epiglottis.
141
What are unique features of fibrocartilage?
Predominantly collagen type I (unique for cartilage); no perichondrium.
142
What functions and locations are associated with fibrocartilage?
Great tensile strength, resists compression/shear; found in intervertebral discs, tendon/ligament insertions, symphysis pubis.
143
What is primary bone (woven bone)?
First type formed during fetal development and fracture repair; characterized by random collagen fiber deposition.
144
What is secondary bone (lamellar bone)?
Highly organized structure with lamellar collagen fibers in parallel layers.
145
What is the Haversian system (osteon)?
Basic structural unit of compact bone; concentric layers of bone around a central Haversian canal.
146
What are Volkmann's canals?
Perpendicular blood vessels connecting neighboring osteons, feeding Haversian canals.
147
What are interstitial lamellae?
Incomplete/disrupted lamellae between intact osteons; remnants of remodeled Haversian systems.
148
What is cartilage interstitial growth?
Mitotic division of pre-existing chondrocytes within the matrix, increasing length.
149
What is cartilage appositional growth?
Differentiation of perichondrial chondroblasts into new chondrocytes on the surface, increasing width.
150
How does bone grow?
Bone grows by appositional growth ONLY.
151
What is the process of intramembranous ossification?
Bone built directly within a membrane/mesenchyme; direct mineralization of matrix by osteoblasts.
152
What does intramembranous ossification form?
Forms woven bone first.
153
What bones are formed by intramembranous ossification?
Flat bones (skull, scapula, zygomatic).
154
What does intramembranous ossification histology appear as?
Appears as 'islands of bone' that eventually fuse.
155
What is endochondral ossification?
Bone develops by replacing a pre-existing hyaline cartilage model.
156
Where does the primary ossification center form in endochondral ossification?
Forms in the diaphysis of the cartilage model.
157
Where does the secondary ossification center appear in endochondral ossification?
Appears later in the epiphyses.
158
What are the zones of the epiphyseal plate in order?
Resting, Proliferative, Hypertrophic, Calcified, Ossification.
159
What occurs in the proliferative zone of the epiphyseal plate?
Chondrocytes divide rapidly, forming 'stacks of pancakes'; interstitial growth allows bone lengthening.
160
What happens in the hypertrophic cartilage zone of the epiphyseal plate?
Chondrocytes enlarge, accumulate glycogen, promote calcification; collagen type X is specific to this zone.
161
What occurs in the calcified cartilage zone of the epiphyseal plate?
Matrix around chondrocytes becomes lightly mineralized, leading to chondrocyte death.
162
What happens in the ossification zone of the epiphyseal plate?
Blood vessels invade, osteoblasts lay down new bone matrix on calcified cartilage remnants.
163
What is the first stage of fracture repair?
Hematoma formation & cell death; blood vessels rupture, cytokines released.
164
What occurs in the second stage of fracture repair?
Resorption; macrophages and osteoclasts clear dead cells, debris, hematoma.
165
What characterizes the third stage of fracture repair (soft callus)?
Fibrocartilage forms to bridge fracture gap, providing initial stability.
166
What occurs in the fourth stage of fracture repair (hard callus)?
Soft callus replaced by woven bone by osteoblasts.
167
What happens in the fifth stage of fracture repair (remodeling)?
Immature woven bone remodeled into mature lamellar bone, responding to mechanical stress.
168
What is the typical total fracture healing time?
Typically 6-12 weeks for fracture to heal; complete remodeling can take much longer.
169
What is osteopetrosis?
Increased bone mass due to abnormal osteoclast function, resulting in dense but brittle bones.
170
What is osteogenesis imperfecta?
Brittle bones caused by abnormality in Type I collagen synthesis/structure.
171
What are intramembranous ossification abnormalities?
Mutations in growth factor receptors disrupt ossification, leading to improper fusion of cranial/facial flat bones.
172
How often does the adult skeleton completely regenerate?
Every 10 years; constant process influenced by mechanical stimulus.
173
Why is weight-bearing important for bones?
Crucial for strengthening bones and maintaining bone mass, especially before menopause in women.
174
What are stress fractures?
Can occur from excessive pressure before bone remodels, or genetic predisposition.
175
What is the duration of a Radiology Residency?
5 years (1 prelim/transitional + 4 diagnostic) ## Footnote This includes one year of preliminary or transitional training followed by four years focused on diagnostic radiology.
176
What are the pathways for Vascular Interventional Radiology (VIR)?
Integrated 6-year pathway OR 2-year fellowship after 5 years diagnostic radiology ## Footnote This allows for specialization in interventional radiology either through an early integrated program or after completing a diagnostic residency.
177
Name some common Radiology Fellowships.
* Body * MSK * Neuroradiology * Pediatrics * Breast Imaging * Emergency Radiology (1 year, optional) ## Footnote Fellowships provide additional training in specialized areas of radiology.
178
What is a future trend in Radiology?
Role of Artificial Intelligence (AI) ## Footnote AI is expected to play a significant role in enhancing imaging analysis and workflow efficiency.
179
What terminology is used in X-ray/Fluoroscopy?
Hyper/Hypo Density ## Footnote This terminology helps describe the density of structures seen on X-ray images.
180
What terminology is used in CT imaging?
Hypo/Hyper Attenuation or Density ## Footnote These terms refer to how X-ray beams are absorbed by different tissues.
181
What terminology is used in MRI imaging?
Hyper/Hypo Intensity ## Footnote Intensity in MRI reflects the relaxation properties of tissues.
182
What terminology is used in Ultrasound imaging?
Echogenicity (hyper/hypoechoic) ## Footnote This describes how ultrasound waves reflect off tissues to create images.
183
What terminology is used in Nuclear Medicine?
Uptake (increased or decreased) ## Footnote Uptake indicates how much of a radioactive substance is absorbed by a particular tissue.
184
What is the basic physics principle behind X-ray imaging?
Ionizing radiation (photon beam), attenuation by body structures creates shades of gray ## Footnote X-ray imaging utilizes ionizing radiation to create images based on tissue density differences.
185
List some advantages of X-ray imaging.
* Inexpensive * Fast * Low radiation dose ## Footnote These factors make X-rays a commonly used first-line imaging modality.
186
List some disadvantages of X-ray imaging.
* Ionizing radiation * 2D images * Suboptimal contrast resolution * No functional info ## Footnote These limitations can affect the diagnostic capabilities of X-rays.
187
What does X-ray image density - opacity indicate?
Beam attenuated, appears white/light gray ## Footnote This is seen when dense structures absorb more X-rays.
188
What does X-ray image density - lucency indicate?
Beam passes with minimal attenuation, appears dark/black ## Footnote This is characteristic of less dense structures, such as air.
189
What are the 5 basic densities in X-ray imaging from least dense to most dense?
* Air (blackest) * Fat (darker gray than soft tissue) * Fluid/Soft Tissue (gray, e.g., blood, muscle, organs) * Calcium/Bone (white, absorbs most X-rays) * Metal (whitest, absorbs all X-rays) ## Footnote Understanding these densities is crucial for interpreting X-ray images.
190
What does AP stand for in X-ray positioning?
Anteroposterior ## Footnote In this view, the X-ray beam enters the body anteriorly.
191
What does PA stand for in X-ray positioning?
Posteroanterior ## Footnote In this view, the X-ray beam enters the body posteriorly.
192
What are the common uses of X-ray imaging in the chest?
First-line for almost any suspected chest symptom ## Footnote X-rays are commonly used to evaluate various chest conditions.
193
What are the common uses of X-ray imaging in musculoskeletal (MSK) cases?
First-line for all suspected bone pain, trauma, spine, joints, bones ## Footnote X-rays are essential in diagnosing musculoskeletal issues.
194
What is a common pitfall of using X-ray imaging for the abdomen?
Often useless as initial diagnostic test for many conditions, but used for renal stones, bowel obstruction, post-op ## Footnote While X-rays can be used in certain abdominal conditions, they may not provide sufficient diagnostic information in many cases.
195
What is the basic physics principle behind Fluoroscopy?
Continuous X-ray for real-time visualization of anatomy ## Footnote Fluoroscopy allows for dynamic imaging, often used in procedures.
196
List some advantages of Fluoroscopy.
* Real-time * Multiple angles/projections * Image magnification ## Footnote These advantages make fluoroscopy valuable for certain diagnostic and interventional procedures.
197
List some disadvantages of Fluoroscopy.
* Higher radiation (patient & physician) * Radiologist must be present ## Footnote These factors can limit the use of fluoroscopy in some cases.
198
What are the uses of Fluoroscopy in barium studies?
* Upper GI series * Small bowel follow-through * Esophagram * Enema; good first-line for non-surgical candidates ## Footnote Barium studies are often performed using fluoroscopy to visualize the gastrointestinal tract.
199
What are some interventional uses of Fluoroscopy?
* Lumbar punctures * Joint injections * Myelograms ## Footnote Fluoroscopy is commonly used in various interventional procedures to guide the physician.
200
What are common contrast agents used in Fluoroscopy?
* Barium * Gastrografin * Cysto-Conray * Omnipaque ## Footnote These agents are used to enhance imaging during fluoroscopic procedures.
201
What is the basic physics principle behind CT imaging?
Numerous narrow X-ray beams rotating around patient, data processed by computer algorithm ## Footnote This technology allows for detailed cross-sectional imaging.
202
What is CT image reconstruction?
Axial data obtained, coronal, sagittal, oblique planes reconstructed without additional scanning ## Footnote This feature enhances the diagnostic capabilities of CT imaging.
203
What is a Hounsfield Unit (HU)?
Measurement of density relative to water (0 HU); scale -1000 to +1000 ## Footnote Hounsfield units are critical for interpreting CT images.
204
Provide examples of Hounsfield Unit (HU) values.
* Air -1000 * Water 0 * Soft Tissue +40 to +80 * Bone +400 to +1000 ## Footnote These values help in differentiating between various tissues in CT imaging.
205
What is CT windowing?
Manipulating image to display specific HU ranges (level = center, width = range) ## Footnote This technique allows for enhanced visualization of specific tissues.
206
List some advantages of CT imaging.
* Fast (especially without contrast) * Good overall anatomy view * Good contrast/spatial resolution ## Footnote These advantages make CT a preferred imaging modality in many clinical situations.
207
List some disadvantages of CT imaging.
* Expensive * High radiation dose * Slower with contrast ## Footnote These limitations can affect the choice of imaging modality.
208
What are common uses of CT in the head?
* Trauma * Headache * Altered mentation * Hemorrhage * Hydrocephalus * Stroke ## Footnote CT is frequently used for evaluating critical conditions in the head.
209
What are common uses of CT in the chest?
* Trauma * Pneumonia * PE * Pneumothorax * Nodules * Cancer follow-up ## Footnote CT is essential for assessing various thoracic conditions.
210
What are common uses of CT in the abdomen/pelvis?
* Trauma * Pain * Obstruction * GI symptoms * Renal stones ## Footnote These uses highlight CT's role in abdominal diagnostics.
211
What is the purpose of CT angiography?
Evaluates vessels for aneurysms, dissections, bleeds, clots ## Footnote CT angiography provides detailed information about vascular structures.
212
What is the purpose of CT IV contrast?
Opacify vascular structures, solid organs, hollow viscous organs ## Footnote IV contrast enhances the visibility of various anatomical structures.
213
What should be evaluated before administering CT IV contrast?
Evaluate renal function (GFR > 30 based on serum creatinine) ## Footnote Ensuring adequate renal function is vital to prevent contrast-induced nephropathy.
214
When should CT IV contrast be used?
* Inflammation * Infection * Tumor/mass * Trauma (usually) * Pulmonary embolism (PE) * Vascular issues ## Footnote These conditions often benefit from enhanced imaging with contrast.
215
When should CT IV contrast NOT be used?
* Almost never for renal stones * Allergy * Poor renal function * No time ## Footnote These contraindications are critical in clinical practice.
216
When should CT oral contrast be used?
Obstruction, thin patients, GI symptoms ## Footnote Oral contrast is particularly useful for evaluating gastrointestinal conditions.
217
What are the contraindications for Barium contrast?
* GI tract perforation * Recent GI post-operative (irritant, inflammation risk) ## Footnote These contraindications are essential to prevent complications.
218
What is Iodine contrast used for in Nuclear Medicine?
Used when Barium is contraindicated (e.g., Gastrografin, Omnipaque); Gastrografin has high osmolality ## Footnote Iodine contrast serves as an alternative in certain imaging scenarios.
219
What is the basic physics principle behind Ultrasound imaging?
Transmission of sound waves (acoustic energy), reflection by tissue creates image based on acoustic properties ## Footnote Ultrasound relies on sound wave interactions to produce images.
220
List some advantages of Ultrasound imaging.
* Real-time * No radiation * Inexpensive * Portable * Assesses blood flow (Doppler) * Good for guiding procedures ## Footnote These advantages make ultrasound a versatile imaging modality.
221
List some disadvantages of Ultrasound imaging.
* Limited focal evaluation * Tech-dependent * Limited by patient cooperation * Bowel gas, obesity * Generally slower ## Footnote These limitations can affect the efficacy of ultrasound imaging.
222
What are common uses of Ultrasound in the abdomen?
First-line for liver, bile ducts, gallbladder, spleen, pancreas, kidneys ## Footnote Ultrasound is often the first imaging choice for these abdominal organs.
223
What are common uses of Ultrasound in the pelvis?
Best for uterus, ovaries, bladder, testicles ## Footnote Ultrasound provides critical information in pelvic evaluations.
224
What are common uses of Ultrasound in vascular imaging?
First-line for DVT, carotids, renal arteries; evaluates veins/arteries ## Footnote Vascular ultrasound is essential for assessing blood flow and detecting clots.
225
What are common uses of Ultrasound in thyroid evaluation?
First-line to evaluate thyroid nodules ## Footnote Ultrasound is critical for assessing potential thyroid abnormalities.
226
What are common uses of Ultrasound in breast imaging?
First-line for breast masses in women under 30 (with mammography) ## Footnote Ultrasound is particularly useful in younger women for breast evaluations.
227
What are common uses of Ultrasound in musculoskeletal (MSK) imaging?
Evaluation of tendons, ligaments; good for joint injections ## Footnote Ultrasound is valuable in assessing soft tissue structures and guiding injections.
228
What is the basic physics principle behind MRI imaging?
Strong magnetic field aligns hydrogen protons in water; RF pulse alters alignment, then protons relax and release energy detected by coils ## Footnote MRI uses magnetic fields and radio waves to create detailed images of soft tissues.
229
List some advantages of MRI imaging.
* Exceptional soft tissue detail (superior to CT) * No ionizing radiation * Multiplanar capability * Tailored exams ## Footnote These advantages make MRI particularly useful for soft tissue evaluation.
230
List some disadvantages of MRI imaging.
* Slow * Costly * Motion artifacts * Contraindicated with certain metallic implants * Requires patient cooperation (claustrophobia, stillness) ## Footnote These limitations can impact patient experience and diagnostic efficiency.
231
What are common uses of MRI in neurology?
* Acute strokes (diffusion-weighted imaging) * Masses * MS * White matter pathology * Orbits * Spine (lumbar most frequent) ## Footnote MRI is crucial for diagnosing various neurological conditions.
232
What are common uses of MRI in musculoskeletal (MSK) cases?
* Best for joints (ligaments, cartilage, tendons) * Osteomyelitis * Soft tissue injuries/masses/infection * Requires X-ray first! ## Footnote MRI is a key tool in the evaluation of musculoskeletal disorders.
233
What are common uses of MRI in abdominal/pelvic imaging?
* Liver (masses, cirrhosis) * Pancreas/adrenal masses * Kidney masses/cysts * Pelvic masses * Endometriosis * Fibroids * Cervical/rectal cancer staging ## Footnote MRI is increasingly used for detailed abdominal and pelvic assessments.
234
What is the basic physics principle behind Nuclear Medicine?
Radioactive compound + substrate injected; substrate carries compound to target where it emits gamma radiation; gamma camera detects for image ## Footnote Nuclear Medicine provides functional imaging through the use of radioactive tracers.
235
List some advantages of Nuclear Medicine.
Excellent functional information (unique strength) ## Footnote This allows clinicians to assess physiological processes in addition to anatomical structures.
236
List some disadvantages of Nuclear Medicine.
* Significant ionizing radiation * Patient remains radioactive * Poor image quality/resolution * Time-consuming * Costly * Hyperactivity often non-specific ## Footnote These factors can limit the use of nuclear imaging in some clinical scenarios.
237
What is the mechanism of a HIDA scan?
Iminodiacetic acid (IDA) + Technetium-99 (radioactive compound); taken up by liver, bile ducts, gallbladder ## Footnote This scan is useful for evaluating liver and biliary function.
238
What does a HIDA scan diagnose in cases of cholecystitis/cystic duct obstruction?
No gallbladder activity ## Footnote This finding indicates potential inflammation or blockage.
239
What does a HIDA scan diagnose in cases of common bile duct obstruction?
No small bowel activity ## Footnote This finding suggests obstruction in the biliary tree.
240
What are other uses of Nuclear Medicine?
* Bone scans for skeletal metastasis * Stress fractures * Infection ## Footnote Nuclear medicine plays a role in evaluating various bone and metabolic conditions.
241
What is the role of X-ray in back pain?
First-line for non-life-threatening back pain; initial for traumatic back pain if neurologically stable.
242
What are the advantages of using X-ray for spine imaging?
Inexpensive, quick, good for fracture detection, intraoperative/portable use.
243
What are the disadvantages of using X-ray for spine imaging?
Poor soft tissue detail, 2D, body habitus limitations, radiation exposure.
244
What are the standard views for X-ray of the spine?
At least Anteroposterior (AP) and Lateral views.
245
What additional views can be taken in X-ray imaging of the spine?
Oblique (L/R), coned-down lumbosacral junction, flexion/extension views.
246
What does the 'Scottie Dog' appearance in X-ray indicate?
Lumbar oblique view visualizes pars interarticularis, pedicle, facets, lamina, transverse process, spinous process.
247
What is the role of CT in spine imaging?
Reserved for trauma/fracture evaluation, myelograms; great for bony anatomy.
248
What are the advantages of CT for spine imaging?
Quick, exceptional bone detail, 3D reconstruction from axial slices.
249
What are the disadvantages of CT for spine imaging?
Expensive, highest radiation dose among modalities, artifacts from large body types/hardware.
250
What are the technical details of CT spine imaging?
Axial projection, coronal/sagittal reformats, bone/soft tissue windows, 3D possible.
251
What is the typical use of contrast in CT for trauma?
Typically performed without contrast in trauma.
252
Is intravenous (IV) contrast commonly used for spine CT?
Rarely given for spine.
253
What is the purpose of intrathecal contrast in CT spine imaging?
Used for myelograms to assess thecal sac/nerves, especially if MRI contraindicated.
254
What is the role of MRI in spine imaging?
Most effective for evaluating marrow, discs, nerves, ligaments. Gold standard for atraumatic back pain.
255
What are the advantages of MRI for spine imaging?
Exceptional soft tissue detail, detects active inflammation, no radiation, tailored exams, best for ligaments/tendons/cartilage.
256
What are the disadvantages of MRI for spine imaging?
Slow, expensive, very prone to motion artifacts.
257
What are the standard MRI sequences for spine imaging?
T1, T2 (axial & sagittal), STIR (total 5 sequences).
258
What does the T1 sequence in MRI show?
Fat BRIGHT, fluid DARK. Best for visualizing fat around nerves.
259
What does the T2 sequence in MRI show?
Fat intermediate, fluid BRIGHT. Best for visualizing discs, edema, inflammation.
260
What is the function of the STIR sequence in MRI?
Nulls fat (HYPOINTENSE), maximizes fluid (HYPERINTENSE). Best for visualizing bone marrow edema or fractures.
261
When is contrast given in MRI for spine imaging?
Given for suspected infection, malignancy, or postoperative evaluation.
262
What is the purpose of the spine?
Houses spinal cord/nerve roots, provides body support.
263
What is the structure of the vertebral column?
33 total vertebrae: 23 separated by discs (6 cervical, 12 thoracic, 5 lumbar); 9 fused (5 sacral, 4 coccygeal).
264
Where does the spinal cord terminate?
Terminates at L1-L2 as the conus medullaris.
265
What is the function of the filum terminale?
Continuation of pia mater, anchors cord to coccyx.
266
How are nerve roots named?
Named after the vertebral body number (VB#) pedicle under which they exit (e.g., L3 nerve exits under L3 pedicle).
267
What are the layers of the spinal meninges?
Dura Mater (outer, thick), Arachnoid Mater, Pia Mater (inner, closely applied to cord).
268
Where is cerebrospinal fluid (CSF) located?
Found in the subarachnoid space (between pia and arachnoid maters).
269
What is the composition of an intervertebral disc?
Fibrocartilaginous. Nucleus Pulposus (inner, mucoprotein gel), Annulus Fibrosus (outer, layered Type 1 & 2 collagen).
270
What is the mechanism of disc herniation?
Tears in annulus fibrosus allow nucleus pulposus gel to leak out.
271
What is the clinical consequence of disc herniation?
Leakage acts as chemical irritant, causes radiculopathy.
272
What happens to a disc herniation over time?
Does not 'go back in'; tends to dry out, dessicate, and resorb over time.
273
What does the anterior longitudinal ligament connect?
Connects to anterior surfaces of vertebral bodies.
274
What does the posterior longitudinal ligament connect?
Connects to posterior surfaces of vertebral bodies.
275
What does the ligamentum flavum connect?
Connects laminae of adjacent vertebral bodies, in posterior spinal canal.
276
Where is the interspinous ligament located?
Located between spinous processes.
277
What does the supraspinous ligament connect?
Connects tips of spinous processes.
278
What should be checked in imaging for alignment?
Check anterior and posterior columns for conditions like scoliosis.
279
What should be assessed in imaging for vertebral body height?
Assess for fractures (traumatic, compression, etc.).
280
What should be looked for in imaging regarding disc spaces?
Look for degeneration or herniation.
281
What should be ensured about pedicles in imaging?
Ensure all are present and appear normal.
282
What should be evaluated regarding overall density in imaging?
Evaluate for infiltrative processes, lesions, metabolic changes, degenerative conditions, infection.
283
What should be checked regarding facet joints in imaging?
Check for pars defects, fractures, or degeneration.
284
What should be assessed in imaging for the neural foramen?
Assess for narrowing, which could indicate nerve compression.
285
What is the definition of spondylosis?
Degenerated or herniated disc(s).
286
How can spondylosis be identified on MRI?
Differences between normal, bulging, and herniated discs.
287
What is the definition of spondylolysis?
Pars breakage or defect (unilateral/bilateral), a stress fracture through the pars interarticularis.
288
Where does spondylolysis commonly occur?
Commonly occurs at L5, much more often than L4.
289
What is the clinical correlation of spondylolysis?
Common in young athletes, may not heal over long period.
290
What imaging findings are associated with spondylolysis?
Defect in pars interarticularis. Can be difficult on MRI; Nuclear Medicine bone scan determines acuity.
291
What is the definition of spondylolisthesis?
Pars defects/breakage + vertebral body shift; anterior displacement of one vertebral body over another.
292
What does X-ray imaging reveal in cases of spondylolisthesis?
Shows anterior slippage of a vertebral body (e.g., L5 over S1).
293
How is spondylolisthesis graded?
Graded I to IV based on amount of anterior displacement.
294
What consequence can disc herniation have on facet joints?
Can lead to increased pressure on vertebral bodies and facet joints.
295
What consequence can facet joint arthropathy have?
Can lead to encroachment upon the neuroforamen.
296
What is a key sign of nerve compression on MRI?
Obliterated foraminal fat is a key sign indicating nerve compression.
297
What accounts for 60-75% of daily energy expenditure?
Resting Metabolism ## Footnote This is the primary contributor to heat production in the body.
298
What percentage of daily energy expenditure does muscle activity account for?
15-30% ## Footnote This includes exercise, NEAT, and shivering.
299
What hormone increases oxygen consumption and heat production in most tissues?
Thyroid Hormone (T3) ## Footnote T3 plays a significant role in metabolic processes.
300
What increases metabolic rate via autonomic stimulation of the adrenal medulla?
Epinephrine ## Footnote It is crucial for the body's response to stress.
301
What generates heat during digestion and absorption?
Thermic Effect of Food ## Footnote This accounts for approximately 10% of daily energy expenditure.
302
What allows heat to transfer into the body from warmer surroundings?
Warm Environments ## Footnote This concept is vital in understanding heat balance.
303
What is Nonshivering Thermogenesis?
Metabolic heat production without muscle activity ## Footnote Involves brown fat, UCP1, TRH/TSH, and sympathetic beta-3 adrenergic receptors.
304
What is the mechanism of heat loss through radiation?
Heat transfer without direct contact ## Footnote This process allows body heat to escape to the environment.
305
What is conduction in terms of heat loss?
Heat transfer through direct physical contact ## Footnote This occurs when two surfaces at different temperatures come into contact.
306
How does convection contribute to heat loss?
Heat transfer by movement of air/water across skin ## Footnote It enhances cooling by increasing airflow.
307
What is the crucial mechanism of heat loss that involves sweating?
Evaporation ## Footnote This is the phase change from liquid to gas that dissipates heat.
308
What happens during vasodilation in the context of heat loss?
Cutaneous blood vessels dilate, increasing blood flow to skin surface ## Footnote This facilitates heat dissipation.
309
What is the controlled variable in thermoregulation?
Core body temperature (36.8 ± 0.5 °C or 98.2 ± 0.9 °F) ## Footnote Maintaining this temperature is critical for physiological processes.
310
What is the body's internal 'thermostat' typically set at?
98.6°F (37°C) ## Footnote This is referred to as the thermoregulatory set-point.
311
Where are peripheral thermoreceptors located?
In skin ## Footnote They sense environmental temperature changes.
312
Where are central thermoreceptors located?
Hypothalamus, spinal cord, abdominal viscera, large blood vessels ## Footnote They monitor core temperature and can detect changes as small as 0.01°C.
313
What is the role of the hypothalamus in thermoregulation?
It acts as the internal thermostat of the body ## Footnote It integrates sensory input to control body temperature.
314
What triggers heat loss mechanisms in response to warmth?
Preoptic/Anterior Hypothalamus (POAH) ## Footnote This part of the hypothalamus responds specifically to increases in temperature.
315
What triggers heat production and conservation mechanisms in response to cold?
Posterior Hypothalamus ## Footnote This area activates responses to preserve body heat.
316
What do sympathetic cholinergic neurons activate to cool down the body?
Sweat glands ## Footnote This is part of the sympathetic response to increased body temperature.
317
What happens during the sympathetic warm-up response?
Sympathetic adrenergic neurons cause cutaneous vasoconstriction ## Footnote This helps to conserve heat.
318
What is the role of somatic motor neurons during a warm-up response?
Trigger skeletal muscle contractions (shivering) ## Footnote This generates additional heat for the body.
319
What are behavioral adjustments in thermoregulation?
Conscious actions like changing clothes, seeking shade, drinking cold water ## Footnote These actions help to regulate body temperature.
320
What is the sequence of responses to heat?
Detection -> Anterior Hypothalamic response -> Vasodilation -> Sweating -> Reduced muscle activity -> Decreased catecholamines/thyroid hormones -> Behavioral changes ## Footnote This is the body's systematic approach to managing excess heat.
321
What is the sequence of responses to cold?
Detection -> Posterior Hypothalamic response -> Vasoconstriction -> Arrector pili contraction -> Shivering/Increased muscle activity -> Non-shivering thermogenesis -> Epinephrine/Norepinephrine release -> Behavioral changes ## Footnote This outlines how the body reacts to cold exposure.
322
What is the role of the integumentary system in heat loss?
Vasodilation of skin arterioles, sweating and evaporation ## Footnote These mechanisms enhance heat dissipation.
323
How does the integumentary system retain heat?
Vasoconstriction of skin arterioles, arrector pili contraction, reduced sweat ## Footnote These actions help to conserve body heat.
324
What is hypothermia?
Core body temperature below 35°C (95°F) ## Footnote Below 32°C (89.6°F) can be lethal.
325
What defines hyperthermia?
Abnormal core temperature elevation due to failure of thermoregulation ## Footnote The hypothalamic set-point remains normal.
326
What temperature typically indicates hyperthermia?
Body temperature typically exceeds 38.5°C (101.3°F) ## Footnote This threshold marks the onset of hyperthermia.
327
What are common causes of hyperthermia?
* Environmental heat * Exercise * Medications (e.g., anticholinergics) * Neurological issues * Genetic factors (malignant hyperthermia) * Endocrine factors ## Footnote These factors can lead to an inability to dissipate heat effectively.
328
What are heat cramps?
Painful muscle cramps from electrolyte imbalances due to excessive sweating ## Footnote They highlight the importance of hydration and electrolyte balance.
329
What characterizes heat exhaustion?
Core temp typically below 40°C; symptoms include profuse sweating, weakness, dizziness, nausea, tachycardia ## Footnote It results from compromised cardiac output and dehydration.
330
What defines heatstroke?
Medical emergency with core temp above 40°C (>104°F) and CNS dysfunction ## Footnote It poses a high risk for multi-organ failure.
331
What is the immediate management for hyperthermia?
* Immediate cooling (cool environment, cold packs) * Rehydration (IV fluids) * Aggressive cooling for heatstroke (cold water immersion) * Treat underlying cause (dantrolene for malignant hyperthermia) ## Footnote Rapid intervention is crucial to prevent complications.
332
What is hyperpyrexia?
Extremely high fever, temperature > 106°F (41.1°C) ## Footnote This condition requires immediate medical attention.
333
What are common causes of hyperpyrexia?
Most commonly CNS hemorrhages; can occur in severe infections ## Footnote It indicates a severe underlying condition.
334
What is malignant hyperthermia?
Rare, inherited genetic disorder triggered by anesthetics or muscle relaxants ## Footnote It leads to uncontrolled Ca release in muscle, causing sustained contraction and hypermetabolism.
335
What is the treatment for malignant hyperthermia?
Dantrolene sodium ## Footnote It inhibits calcium release from the sarcoplasmic reticulum.
336
What is Raynaud's syndrome?
Exaggerated vascular response to cold due to hypersensitivity of alpha-adrenergic receptors ## Footnote It results in reduced blood flow to extremities.
337
What is the presentation of Raynaud's syndrome?
Decreased blood flow to fingers/toes/ears/nipples/nose; affected areas turn white then blue ## Footnote This reflects ischemia followed by hypoxia.
338
What triggers Raynaud's syndrome?
* Cold temperatures * Stress * Emotional upset ## Footnote These factors can exacerbate the condition.
339
What is erythromelalgia?
Rare episodes of intense burning pain, redness, warmth typically in hands/feet ## Footnote This condition often requires management of underlying causes.
340
What triggers erythromelalgia?
* Heat * Exercise * Stress ## Footnote These factors can provoke episodes.
341
What is primary erythromelalgia?
Genetic mutations (SCN9A sodium channels), often childhood onset ## Footnote It tends to run in families.
342
What is secondary erythromelalgia?
Associated with myeloproliferative disorders, autoimmune diseases, peripheral neuropathies, drug-induced ## Footnote This form is often linked to other medical conditions.
343
What are pyrogens?
Substances that cause fever (exogenous or endogenous) ## Footnote They play a key role in the body's response to infection.
344
What defines fever (pyrexia)?
Elevation in body temperature caused by cytokine-induced upward displacement of hypothalamic set-point ## Footnote It is often a protective response to infection.
345
What is the first step in fever production?
Pathogen entry, immune recognition ## Footnote Immune cells identify pathogens to initiate the fever response.
346
What occurs in step two of fever production?
Immune cell activation leads to inflammatory gene expression and cytokine production ## Footnote Key cytokines include TNF-α, IL-1β, and IL-6.
347
What does PLA2 do in the fever production process?
Releases arachidonic acid (AA) ## Footnote This is crucial for synthesizing prostaglandins.
348
What is the role of PGE2 in fever production?
Binds to specific EP receptors in the preoptic area of the hypothalamus ## Footnote This action is essential for resetting the hypothalamic set-point.
349
What happens in the final step of fever production?
PGE2 binding resets the hypothalamic thermoregulatory set-point to a higher temperature ## Footnote This leads to the clinical manifestation of fever.
350
What characterizes the first stage of fever?
Nonspecific symptoms (fatigue, malaise, aches), temperature not yet elevated ## Footnote This stage signals the onset of a fever.
351
What occurs during the second stage of fever, known as 'chill'?
Patient feels cold, conserves heat; hypothalamus raised set-point triggers vasoconstriction, piloerection, shivering ## Footnote This stage aims to reach the new set-point.
352
What happens in the third stage of fever, called 'flush'?
Body temperature reaches new set-point; cutaneous vasodilation, flushed skin, feeling of warmth ## Footnote This indicates that the fever is established.
353
What occurs during the fourth stage of fever (defervescence)?
High set-point resets downward; cooling via vasodilation and sweating ## Footnote This stage signifies the resolution of the fever.
354
What are exogenous pyrogens?
Originate outside the body (microbial components/toxins) ## Footnote They trigger the immune response leading to fever.
355
How do exogenous pyrogens work?
Trigger the release of endogenous pyrogens from immune cells ## Footnote This amplifies the fever response.
356
What are examples of exogenous pyrogens?
* LPS (Gram-negative, binds TLR4) * Teichoic/lipoteichoic acids (Gram-positive) * Superantigens (Staph, Strep) * Fungal components * Viral products (dsRNA) ## Footnote These substances are critical in infectious disease processes.
357
What are endogenous pyrogens?
Produced within the body (immune cells, infection, inflammation, tissue damage) ## Footnote They act directly on the hypothalamus to elevate set-point.
358
What are examples of endogenous pyrogens?
* Cytokines (IL-1, TNF-α, IL-6, Interferons) * Prostaglandins (PGE2 - key mediator) ## Footnote These molecules play a significant role in fever development.
359
What is the difference between fever and hyperthermia regarding set-point?
Fever = Elevated hypothalamic set-point; Hyperthermia = Normal hypothalamic set-point ## Footnote This distinction is crucial for understanding the underlying mechanisms.
360
How do fever and hyperthermia differ in regulation?
Fever = Hypothalamus actively regulates elevated set-point; Hyperthermia = Regulatory mechanisms overwhelmed or failed ## Footnote This impacts treatment approaches.
361
What causes fever compared to hyperthermia?
Fever = Caused by pyrogens; Hyperthermia = Failure to dissipate heat or overwhelming heat production ## Footnote This highlights the different pathophysiological processes.
362
What is the clinical presentation of fever versus hyperthermia?
Fever = Cold skin (chill phase), flushed (flush phase); Hyperthermia = Hot, dry flushed skin ## Footnote These presentations help in differential diagnosis.
363
What therapies are used for fever and hyperthermia?
Fever = Antipyretics (inhibit PGE2 production); Hyperthermia = Physical cooling, rehydration ## Footnote Antipyretics are ineffective in hyperthermia.
364
What is the mortality rate associated with fever compared to hyperthermia?
Fever = Unusual; Hyperthermia = High ## Footnote This difference underscores the severity of hyperthermia.
365
What are the bones of the forearm?
Radius, Ulna ## Footnote The radius is located on the lateral side and the ulna on the medial side of the forearm.
366
What are the critical components of the radius?
Head, Neck, Radial Tuberosity, Styloid Process, Ulnar notch ## Footnote The radial tuberosity is an important site for muscle attachment.
367
What are the critical components of the ulna?
Olecranon, Coronoid Process, Trochlear Notch, Radial Notch, Head, Styloid Process ## Footnote The olecranon forms the bony prominence of the elbow.
368
What ligaments are associated with the elbow joint?
Ulnar Collateral, Radial Collateral, Annular ligament of radius, Joint capsule ## Footnote These ligaments provide stability to the elbow joint.
369
What is the normal carrying angle in males and females?
M: 5°, F: 10-15° ## Footnote Variations from these angles can indicate conditions like cubitus varus or cubitus valgus.
370
What are the components of the radio-ulnar joint?
Proximal Radio-Ulnar Joint, Distal Radio-Ulnar Joint, Interosseous Membrane ## Footnote These components facilitate rotational movements of the forearm.
371
What is the key structure of the distal radio-ulnar joint?
Articular Disc (Triangular Fibrocartilage Complex - TFCC) ## Footnote The TFCC plays a crucial role in load transmission and stability.
372
What are the functions of the radio-ulnar joint?
Supination (palm anterior/up), Pronation (palm posterior/down) ## Footnote These movements are essential for various daily activities.
373
What are the superficial veins of the forearm?
Cephalic, Basilic, Median cubital veins ## Footnote These veins are commonly used for venipuncture.
374
What is the role of the median cubital vein?
Connects cephalic and basilic veins in cubital fossa ## Footnote This connection is important for venous drainage of the forearm.
375
Into what does the brachial artery divide in the forearm?
Ulnar and Radial Arteries ## Footnote These arteries supply blood to the forearm and hand.
376
What are the major branches of the ulnar artery?
Recurrents, Common Interosseous (Ant/Post Interosseous), Recurrent Interosseous Arteries ## Footnote These branches provide collateral circulation around the elbow.
377
Why are elbow anastomoses important?
Critical collateral circulation; ensures blood flow to distal limb if major artery compromised ## Footnote They prevent ischemia in case of arterial obstruction.
378
What is the origin of the medial antebrachial cutaneous nerve?
Medial Cord of brachial plexus ## Footnote This nerve supplies sensation to the skin of the medial forearm.
379
What is the origin of the lateral antebrachial cutaneous nerve?
Musculocutaneous nerve ## Footnote This nerve provides sensory innervation to the lateral forearm.
380
What is the origin of the posterior antebrachial cutaneous nerve?
Radial nerve ## Footnote This nerve supplies sensation to the posterior forearm.
381
What muscles does the median nerve innervate in the forearm?
Pronator Teres, FCR, FDS, lateral FDP (2nd/3rd fingers via Anterior Interosseous nerve), FPL (via Anterior Interosseous nerve), Pronator Quadratus (via Anterior Interosseous nerve) ## Footnote These muscles are primarily involved in flexion and pronation.
382
What is the sensory innervation of the median nerve in the hand?
Palm, anterior surfaces of lateral 3 ½ digits ## Footnote This includes the thumb, index, middle, and half of the ring finger.
383
What muscles does the ulnar nerve innervate in the forearm?
FCU, medial FDP (4th/5th fingers) ## Footnote These muscles are involved in flexing the fingers.
384
What is the sensory innervation of the ulnar nerve in the hand?
Medial 1/2 of 4th digit, entire 5th digit (palmar/dorsal), palmar cutaneous branch ## Footnote This nerve supplies sensation to the little finger and half of the ring finger.
385
What does the deep branch of the radial nerve (posterior interosseous nerve) innervate?
All posterior muscles of the forearm ## Footnote This includes extensors and supinators.
386
What is the function of the superficial branch of the radial nerve?
Purely sensory to the hand ## Footnote This nerve does not innervate any muscles.
387
What are the compartments of the forearm?
Anterior (Flexors/Pronators), Posterior (Extensors/Supinators) ## Footnote This compartmentalization is important for muscle function and clinical assessment.
388
What is the innervation of the pronator teres?
Median Nerve (C6, C7) ## Footnote This muscle is key for pronation of the forearm.
389
What is the innervation of the pronator quadratus?
Anterior Interosseous (Median) Nerve (C8, T1) ## Footnote This muscle assists in pronation, especially in the distal forearm.
390
What is the innervation of the supinator?
Deep Radial (Radial) Nerve (C7, C8) ## Footnote This muscle is responsible for supination of the forearm.
391
Which artery runs near the radial groove?
Deep brachial artery
392
How is the flexor digitorum profundus innervated?
Medial (4th/5th digits): Ulnar Nerve (C8, T1) | Lateral (2nd/3rd digits): Anterior Interosseous (Median) Nerve (C8, T1) ## Footnote This dual innervation allows for varied function in finger flexion.
393
What is the innervation of the flexor pollicis longus?
Anterior Interosseous (Median) Nerve (C8, T1) ## Footnote This muscle flexes the thumb.
394
What is the innervation of the abductor pollicis longus?
Posterior Interosseous (Radial) Nerve (C7, C8) ## Footnote This muscle abducts the thumb.
395
The tendon of which muscle lies just medial to the dorsal tubercle of the radius?
Extensor pollicis longus
396
What is the innervation of the extensor pollicis longus?
Posterior Interosseous (Radial) Nerve (C7, C8) ## Footnote This muscle extends the thumb.
397
What is the innervation of the extensor pollicis brevis?
Posterior Interosseous (Radial) Nerve (C7, C8) ## Footnote This muscle also extends the thumb but has a different origin.
398
What are the lateral boundaries of the anatomical snuffbox?
Abductor Pollicis Longus, Extensor Pollicis Brevis ## Footnote This area is clinically significant for radial artery palpation.
399
What is the medial boundary of the anatomical snuffbox?
Extensor Pollicis Longus ## Footnote This muscle's position is crucial for the anatomy of the snuffbox.
400
What are the contents of the anatomical snuffbox?
Radial Artery ## Footnote This artery can be palpated in this area.
401
What are the carpal bones?
8 short bones in 2 rows: Proximal - Scaphoid, Lunate, Triquetrum, Pisiform; Distal - Trapezium, Trapezoid, Capitate, Hamate. ## Footnote Mnemonic (Proximal row lateral to medial, then distal row lateral to medial): "Some Lovers Try Positions That They Can't Handle" (Scaphoid, Lunate, Triquetrum, Pisiform / Trapezium, Trapezoid, Capitate, Hamate).
402
Mnemonic for carpal bones
(Proximal row lateral to medial, then distal row lateral to medial): "**Some Lovers Try Positions That They Can't Handle**" (Scaphoid, Lunate, Triquetrum, Pisiform / Trapezium, Trapezoid, Capitate, Hamate).
403
What is the carpal arch?
Formed by carpal bones, creates a key boundary for the carpal tunnel.
404
How many phalanges does the thumb have?
2 phalanges: proximal, distal.
405
How many phalanges do the fingers (digits 2-5) have?
3 phalanges each: proximal, middle, distal.
406
What type of joint is the wrist joint (radiocarpal)?
Condyloid/ellipsoid joint.
407
Which bones articulate with the distal radius in the wrist joint?
Scaphoid and Lunate.
408
What are the movements of the wrist joint?
Flexion-extension, abduction-adduction, circumduction. ## Footnote Augmented by midcarpal/intercarpal movements.
409
What type of joint is the CMC joint of the thumb?
Saddle joint.
410
What type of joints are the CMC joints of digits 2-5?
Plane joints.
411
What type of joints are the intercarpal (IC) joints?
Plane joints.
412
What type of joints are the MCP joints?
Condyloid/ellipsoid joints.
413
What type of joints are the IP joints (PIP/DIP)?
Hinge joints.
414
What are the boundaries of the carpal tunnel?
Carpal bones (carpal arch) and Flexor Retinaculum.
415
What are the contents of the carpal tunnel?
Median Nerve, 4 Flexor Digitorum Superficialis tendons, 4 Flexor Digitorum Profundus tendons, Flexor Pollicis Longus tendon. ## Footnote Total of 10 items.
416
What is the cutaneous innervation of the Median Nerve?
Palmar aspect of lateral 3.5 digits and corresponding central palm.
417
What is the cutaneous innervation of the Radial Nerve (Superficial Branch)?
Dorsal aspect of lateral 3.5 digits - proximal phalanges/dorsum hand only, not tips.
418
What is the innervation of the Ulnar Nerve (Palmar Cutaneous Branch)?
Ulnar side of the palm.
419
What is the innervation of the Ulnar Nerve (Superficial Branch)?
Palmar aspect of medial 1.5 digits.
420
What is the innervation of the Ulnar Nerve (Dorsal Cutaneous Branch)?
Dorsal aspect of medial 1.5 digits and corresponding dorsum of hand.
421
What is the primary contributor to the Superficial Palmar Arch?
Ulnar artery.
422
What is the primary contributor to the Deep Palmar Arch?
Radial artery.
423
What is the primary contributor to the Dorsal Carpal Arch?
Radial artery.
424
Where is the Superficial Palmar Arch located, and what does it give rise to?
Lateral, deep to palmar aponeurosis; gives Common Palmar Digital Arteries -> Proper Palmar Digital Arteries.
425
Where is the Deep Palmar Arch located, and what does it give rise to?
Medial, deep to long flexor tendons; gives Palmar Metacarpal Arteries.
426
Where is the Dorsal Carpal Arch located, and what does it give rise to?
Dorsum of hand; gives Dorsal Metacarpal Arteries -> Dorsal Digital Arteries.
427
What is the most common carpal fracture?
Scaphoid fracture.
428
What can happen with a scaphoid fracture?
Disrupts blood supply to proximal portion; high risk of avascular necrosis.
429
What are the muscles in the thenar compartment? (LOAF)
Lateral 2 Lumbricals, Opponens Pollicis, Abductor Pollicis Brevis, Flexor Pollicis Brevis.
430
What is the innervation of the thenar compartment muscles?
Median Nerve - Recurrent Branch for APB, Opponens Pollicis, and superficial head of FPB; deep head of FPB by Ulnar Nerve - Deep Branch.
431
What happens in carpal tunnel syndrome?
Median nerve compression -> weakness in thenar muscles, can cause 'ape hand' deformity.
432
What is the action of the Adductor Pollicis?
Adducts the thumb.
433
What is the innervation of the Adductor Pollicis?
Ulnar Nerve - Deep Branch. ## Footnote The 3 thenar muscles and first 2 lumbricals are the two intrinsic hand muscles innervated by the median nerve, the rest including the adductor pollicis are innervated by the ulnar nerve.
434
What are the muscles in the hypothenar compartment?
Flexor Digiti Minimi, Abductor Digiti Minimi, Opponens Digiti Minimi.
435
What is the innervation of the hypothenar compartment?
Ulnar Nerve - Deep Branch.
436
What is the innervation and action of the Palmaris Brevis?
Ulnar Nerve - Superficial Branch; wrinkles hypothenar skin, aids grip.
437
What happens in Guyon's Canal Syndrome?
Ulnar nerve compression -> weakness in hypothenar muscles, Adductor Pollicis, Lumbricals 3/4, Interossei.
438
What is the innervation and action of Lumbricals 1 & 2?
Median Nerve; flex MCP joints and extend IP joints of 2nd and 3rd digits.
439
What is the innervation and action of Lumbricals 3 & 4?
Ulnar Nerve - Deep Branch; flex MCP joints and extend IP joints of 4th and 5th digits.
440
What is the innervation and action of the Palmar Interossei (PAD)?
Ulnar Nerve - Deep Branch; ADduct digits 2, 4, 5 towards axial line.
441
What is the innervation and action of the Dorsal Interossei (DAB)?
Ulnar Nerve - Deep Branch; ABduct digits 2-4 from axial line.
PCOM DO (2025-)
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