MSK 1 Flashcards
Marfan syndrome is caused by a defect in what protein? Where can this protein be found?
Fibrillin-1 is a component of microfibrils that form the sheath around elastin fibers. It serves as a scaffold for elastin that’s extruded from connective tissue fibers. It can be found in blood vessels, periosteum, and the suspensory ligaments of the lens.
Why and how is it that muscles suddenly relax if they exert too much force (ex. weight training)?
Golgi tendon organs are sensory receptors found at the junction of the muscle and tendon. These receptors are sensitive to inc. muscle tension exhibited when a muscle actively contracts against resistance. If there’s too much inc. tension, GTOs send a signal via Ib sensory axons to the spinal cord, and a signal is sent back via alpha motor neurons to inhibit contraction, causing sudden muscle relaxation. This prevents musculoskeletal injury.
By what mechanism is the contraction of all myofibrils in a muscle coordinated?
T-tubules are distributed UNIFORMLY across the muscle fibers. When depolarization occurs, the entire muscle will contract. Lack of T-tubules would lead to uncoordinated contraction.
What role do osteoclasts play in Paget disease of the bone?
Osteoclasts are derived from mononuclear cells w/c fuse to form a mature multinucleated osteoclast. They differentiate w/ the release of M-CSF and RANK-L from osteoblasts. In Paget’s dse of the bone, there is an increase in osteoclasts, w/ excessive bone turnover and disorganized bone remodeling.
What ligament dissects the sciatic foramen into Greater and lesser sciatic foramina? What structure occupies most of the Greater sciatic foramen?
Sarcospinous ligament dissects the sciatic foramen.
The piriformis muscle occupies most of the greater foramen.
What structures run above the piriformis muscle in the Greater sciatic foramen? Below the piriformis muscle?
> Above: superior gluteal vessels and nerve.
>Below: inferior gluteal vessels, internal pudendal vessels, sciatic nerve and other nerves.
How does an anterior dislocation of the humerus present? What nerve may it affect?
Flattened deltoid, protruding acromion, anterior axillary fullness.
>Injury to Axillary nerve (deltoid, teres minor) – insensitivity of overlying skin of lateral shoulder
A midshaft humeral fracture may affect which nerve and artery?
Radial nerve
Deep brachial artery (profunda brachii)
SLE is associated w/ anti-Smith antibodies. What is the Smith protein?
The Smith protein normally complexes w/ snRNA in the cytoplasm to form snRPS, w/c are essential for spliceosomes.
What are the borders of the scalene triangle? Compression of _____ of the brachial plexus in this triangle may cause _____ syndrome. What are possible causes of this syndrome?
> Scalene triangle: anterior and middle scalene muscles, first rib.
Compression of the Lower trunk of the brachial plexus in this triangle may cause Thoracic outlet syndrome.
Causes: anomalous cervical rib, scalene muscular anomalies, injury (repetitive overhead arm movements)
What is the pathophysio of Osgood-Schlatter disease?
Repetitive quadriceps contraction and chronic avulsion can separate the patellar ligament from the tibial tuberosity. While healing, callous formation causes the tubercle to elevate and become prominent. The patient will feel focal pain and swelling at the tibial tuberosity.
