SMB Week 3 Flashcards
A classic chest x-ray involves which two views?
- PA (posterior - anterior)
- Lateral
True or false: a PA view x-ray over-represents the size of the heart due to greater shadowing.
False: an AP view produces greater shadowing
What does an “apple core lesion” suggest?
Colon cancer
Which imaging modality has the best soft tissue contrast?
MRI
The terminal ends of a sarcomere:
Z line
The striations seen in skeletal muscle are due to what?
Alternating bands of thick and thin filaments
Thick filaments in skeletal muscle are composed of what?
Myosin
Thin filaments in skeletal muscle are composed of what?
Actin
How does contraction of skeletal muscle happen?
Actin filaments bind to globular heads of myosin filaments, which causes a conformational change in the myosin heads, bringing the actin filaments closer together.
What are the transverse tubules in a muscle fiber?
Invaginations of the sarcolemma, which is the plasma membrane surrounding a muscle fiber
What is the function of the transverse tubules in a muscle cell?
Allows action potentials to reach the interior myofibrils of the cell.
Action potentials in muscle cells are initiated by what neurotransmitter at the neuromuscular junction?
Acetylcholine
Sites for blocking neuromuscular transmission:
- Presynaptic: Block the release of ACh
- Synaptic cleft: Block breakdown of ACh
- Postsynaptic: Block binding of ACh
Example of a presynaptic toxin:
C. botulinum
Example of a synaptic cleft toxin:
Fasciculin peptides in venom, nerve gas
Therapeutic use: myasthenia gravis
Example of post synaptic toxin:
Suxamethonium (ACh receptor agonist)
Definition of a “twitch”
Response of muscle fiber to a single action potential
Definition of sustained muscle contraction:
Many action potentials trigger multiple contractions. If frequency is high enough, muscle will respond with a “fused tetanus” response.
Definition of isotonic vs. isometric contraction:
Isotonic: tension is constant, length changes
Isometric: length is constant, tension changes
Types of isotonic contraction:
Concentric: muscle shortens (upward part of curl)
Eccentric: muscle lengthens (downward part of curl)
What is the test for De Quervain tenosynovitis?
Finklestein’s test
What are the two tests for carpal tunnel syndrome?
- Tinnel test (tap)
- Phalen’s test (dorsum of hands together)
Most common muscle involved in tennis elbow:
Extensor carpi radialis brevis
What digit can you test to isolate the extensor carpi radials brevis?
3rd (middle finger)
What is the Adson test used for?
To test for subclavian artery compression
What does the Yergason test indicate?
Stability of the long head of the biceps tendon in the bicipital groove
Most commonly injured rotator cuff muscle:
Supraspinatus
What does a positive Neer test indicate?
Subacromial bursitis
What other test is used to detect subacromial bursitis?
Hawkins test
What sort of curvature is the Adams forward bend test measuring?
Axial rotation, not medial/lateral curvature
What muscle does the Trendelenburg test test?
Gluteus medius
What does the pelvic rock test indicate?
Sacroiliac joint stability