MSK and CT Flashcards
Osteogenesis imperfecta is due to mutations in what?
COL1A1 and COL1A2
What are the layers of the epidermis from surface to base?
Statum corneum (keratin), lucidum, granulosum, spinosum, basale
What is the role of integrins?
Maintain integrity of basolateral membrane of epithelial cells by binding to collagen and laminin in BM
What is the role of hemidesmosomes?
Connect keratin in basal cells to underlying BM.
What is the role of desmosomes?
Structural support via keratin interactions
What is the role of e-cadherin?
Part of adherens junction - below tight junction, forms “belt” connecting actin cytoskeletons of adjacent cells. Loss of e-cadherin promotes metastasis.
What is bullous pemphigoid?
Autoantibodies to hemidesmosomes
What is pemphigus vulgaris?
Autoantibodies to desmosomes
The rotator cuff muscles are innervated primarily by which spinal nerves?
C5-C6
What is does the supraspinatus do?
(suprascapular nerve) Abducts arm initially before the action of deltoid; most common rotator cuff injury
What is does the infraspinatus do?
(suprascapular nerve) Laterally rotates arm; pitching injury
What is does the teres minor do?
(axillary nerve) Adducts and laterally rotates arm
What is does the subscapularis do?
(subscapular nerve) Medially rotates and adducts arm
What are the four muscles of the rotator cuff?
Supraspinatus, infraspinatus, teres minor, subscapularis
Dislocation of which wrist bone may cause carpal tunnel syndrome?
Lunate
What is Guyon canal syndrome?
Compression of the ulnar nerve at the wrist or hand, classically seen in cyclists
Erb palsy (“waiter’s tip”) is due to injury of what?
Traction or tear of upper trunk: C5-C6 roots
What are the causes of Erb palsy?
Infants - Lateral traction on neck during delivery
Adults - Trauma
Klumpke palsy is due to injury of what?
Traction or tear of lower trunk (C8-T1)
What are the causes of Klumpke palsy?
Infants - Upward force of arm during delivery
Adults - Trauma (grabbing a tree branch when falling)
Thoracic outlet syndrome is due to injury of what?
Compression of lower trunk and subclavian vessels
What are the causes of thoracic outlet syndrome palsy?
Cervical rib injury; Pancoast tumor
Winged scapula is due to injury of what?
Lesion of long thoracic nerve
What are the causes of winged scapula?
Axillary node dissection after mastectomy, stab wounds
Describe Type 1 muscle
Slow twitch; red fibers
Describe Type 2 muscle
Fast twitch; white fibers - weight training results in hypertrophy of these
What is the difference between endochondral ossification and membranous ossification?
Endochondral ossification needs a cartilagenous model of bone made first. Membranous does not; calvarium and facial bones.
What is the function of PTH?
At low, intermittent levels, exerts anabolic effects. Chronic high PTH levels cause catabolic effects on bone.
Describe achondroplasia
Failure of endochondral ossification (only). Constitutive activation of fibroblast growth factor receptor (FGFR3) actually inhibits chondrocyte proliferation.
What is the inheritance pattern of achondroplasia?
Most mutations occur sporadically but condition also demonstrates autosomal dominance
What are treatment options for senile osteoporosis?
Bisphosphonates, PTH, SERMs, denosumab (monoclonal Ab against RANKL)
What is osteopetrosis?
Failure of normal bone resorption due to defective osteoclasts. Thickened, dense bones that are prone to fracture. Bones fill marrow space leading to pancytopenia and extramedullary hematopoiesis.
What is a treatment option for osteopetrosis?
Bone marrow transplant is potentially curative since osteoclasts are derived from monocytes
Describe Paget disease of bone (osteitis deformans)
Common, localized disorder of bone remodeling caused by increase in both osteoblastic and osteoclastic activity. Serum Ca, phosphorus, and PTH all normal. Increased ALP. Mosaic pattern of woven and lamellar bone; long bone chalk-stick fractures. Increased blood flow from increased arteriovenous shunts may cause high-output HF. Increased risk of osteogenic sarcoma.
What is the most common site of oseteonecrosis?
Femoral head - due to insufficiency of medial circumflex femoral artery
What is the most common benign tumor of bone?
Osteochondroma