MSK

Question 1

• loss of motor function of the intrinsic hand muscles
• numbness along inner aspect of hand, forearm, and upper arm
• total claw hand
• possible horner syndromer

Most likely d/t injury to

Answer 1

Lower trunk of brachial plexus = Klumpke paralysis

MC causes: grabbing something to stop oneself
-delivering a baby w/ arms in the extended position above the head

Question 2

• loss of motor function to deltoid ms and teres minor (abduction and lateral rotation)
• sensory loss in upper lateral portion of arm

Most likely d/t

Answer 2

Axillary nerve

• fracture fo surgical neck of the humerus
• dislocation of head of the humerus

Question 3

• wrist drop
• loss of motor function to major extensor ms of arm and forearm
• sensory loss on radial dorsal portion of the hand

Most likely d/t injury to

Answer 3

Radial n

• med humeral fractures
• saturday night palsy: falls asleep w/ arm over back of chair

Question 4

MC injury that causes ulnar nerve damage

Answer 4

Trauma to elbow (where is passes through cubital tunnel)

Question 5

Stretching a muscle does what to its passive and active tension

Answer 5

Increases passive tension
Decreases active tension

Depends on overlap between actin and myosin:
-stretching a ms decreases degree of overlap and thus decreases active tension force

Question 6

• numbness and pain on left aspect of forearm and hand
• claw hand
• can raise arm over head
• decreased radial pulse
• tx: incision of anterior scalene ms (watch out for phrenic n)

Dx
Borders
What is being compressed

Answer 6

Thoracic outlet syndrome

Borders: scalene ms, first rib, clavicle

Compressing: subclavian artery and vein; lower trunk of brachial plexus

Question 7

Diseases involved in collagen deficiency

Answer 7

Scurvy
Osteogenesis imperfecta
Ehlers-Danlos syndromes
Menkes Disease

Question 8

10 y/o boy presents with

• hyper-extensible joints
• frequent joint dislocations
• easy bruising
• PE: short for his age, small jaw

Dx
What is abnormal
Mutation

Answer 8

Ehlers Danlos

Type 1 Collagen (skin, bone, tendon, vasculature)

PLOD1: encodes enzyme lysyl hydroxylase

Question 9

X linked recessive dz characterized by

• sparse, depigmented hair
• seizures
• failure to thrive
• neurodegeneration
• pts nml die before 10 years of age

D/t mutation that leads to loss of copper distribution

Dx
Mutation

Answer 9

Menkes disease

ATP7A

• copper is needed for many enzymes to function
• ex. Lysyl oxidase cannot crosslink triple helix collagen molecules

Question 10

Pt presents w/

• dislocated lens in one or both eyes
• defects in aorta: increased risk of aortic rupture
• tall, slender, w/ elongated fingers and toes

Dx
Defect in
Mutation

Answer 10

Marfan syndrome

Defect in elastin

Mutation: fibrillin-1