Musculoskeletal/Skin/CT

Question 1

Answer 1

Normal Anatomy of the Knee

Question 2

The ACL extends from ____ to _____

Answer 2

lateral femoral condyle to anterior tibia

Question 3

Where does the PCL extend from and to?

Answer 3

From the medial femoral condyle to the posterior tibia

Question 4

Valgus force on the knee cause the joint to expand medially suggest what?

Answer 4

MCL injury

Question 5

What is an unhappy triad?

Answer 5

injury cuased by lateral forced being applied to a planted leg.

Consists:

• ACL damage
• MCL damage
• medial meniscus damage

Question 6

What muscle is responsible for initial abduction of the arm?

Answer 6

Supraspinatus (suprascapular nerve)

Assessed by empty can test

Question 7

What are the other rotator cuff muscles? Motions? Innervation?

Answer 7

• Infraspinatus (suprascapular nerve)-laterally rotates arm (pitching injury)
• teres minor (axillary nerve)- adducts and laterally rotates arm
• Subscapularis (upper and lower subscapular nerves)-medially roattes and adducts arm

Question 8

What wrist bone is most susceptible to avascular necrosis?

Answer 8

the scaphoid due to retrograde blood supply

(radial) So Long to Pink (ulnar)

(radial, 2nd line) Here Comes the Thumb (ulnar)

volar surface

Question 9

A fall on an outstretched hand that damages the hook of hamaet is most likely to cause ____ nerve injury.

Answer 9

Ulnar

Question 10

Dislocation of which wrist bone may cause acute carpal tunnel syndorme?

Answer 10

Lunate

Question 11

Why is sensation to the thenar eminence spared in carpal tunnel syndrome?

Answer 11

the palmar cutaneous branch enter the hand external to the tunnel (will still see some atrophy of this region)

Question 12

What are some conditions associated with carpal tunnel?

Answer 12

• pregnancy
• Rheumatoid arthritis
• diabetes
• hypothyroidism
• B2M amyloidosis

Question 13

What is Guyon canal syndrome?

Answer 13

compression of the ulnar nerve at wrist or hand. Classically seen in cyclists

Question 14

Answer 14

Normal Humerus Anatomy

Question 15

What are common causes of axillary (C5-C6) damage?

Answer 15

• fractured surgical neck of the humerus
• anterior dislocation of the humerus

Question 16

How does axillary nerve (C5-C6) damage present?

Answer 16

• atrophied deltoid
• loss of arm abduction at should (greater than 15 degrees)
• loss of senseation over deltoid muscle and lateral arm

Question 17

How does musculocutaneous (C5-C7) nerve damage present?

Answer 17

• loss of forearm flexion and supination
• loss of sensation over lateral forearm

Question 18

What are some common causes of Median (C5-T1) nerve damage?

Answer 18

• supracondylar fratcure of humerus (proximal lesion)
• carpal tunnel syndrome
• wrist laceration

Question 19

Answer 19

Distal Humerus Anatomy

Question 20

Answer 20

Distal supracondylar humerus fracture- median nerve damage likely

Question 21

Answer 21

Common Hand deformities

Question 22

How does damage to the median nerve affect the hand?

Answer 22

• Ape Hand or Pope’s Blessing
• loss of wrist flexion, flexion of lateral fingersm thumb opposition

Question 23

Answer 23

Brachial Plexus

Question 24

Disease? Cause?

Answer 24

Erb’s Palsy caused by lateral traction during delivery (infants) or tear (adults) of upper (Erb-er) TRUNK (after C5 and C6 roots have combined)

Question 25

What muscles are impaired in Erb’s Palsy?

Answer 25

• deltoid and supraspinatus (thus, no abduction)
• Infraspinatus (thus, arm becomes MEDIALLY rotated)
• Biceps brachii (=no flexion or supination)

Question 26

Disease? Cause?

Answer 26

Klumpke Palsy-caused by pulling upward force on arm during delivery or falling and grabbing a tree in adults

results in tear of LOWER trunk (C8-T1)

Question 27

What muscles are damaged in Klumpke palsy?

Answer 27

the intrinsic msucles of the hand

Question 28

How does Klumpke Palsy present?

Answer 28

Total claw hand (the lumbricals usually flex the MCP joints and extend DIP and PIP joints)

Question 29

Deformity? Cause?

Answer 29

Winged scapula caused by lesion of the long thoracic nerve

think stab wounds and axillary node dissection after mastectomy

Question 30

Wrist drop (saturday night palsy) is casued by damage to which nerve?

Answer 30

Median nerve (coming off the posterior cord)

Question 31

Role of the dorsal interossei? Palmar onterossei? Lumbricals?

Answer 31

Dorsal= abduct the fingers (DAB)

Palmar= adduct (PAD)

Lumbricals= flex the MCP; extend the PIP and DIP

Question 32

What type of muscle increases after endurance training?

Answer 32

type 1 muscle (slow twitch red fibers that use oxidative phosphorylation)

1 slow red ox

Question 33

What type of muscle increases after weight/resistance training?

Answer 33

Fast twitch, white fibers resulting from decreased mitcohondria and myoglobin concentration

Question 34

How does endochondral ossification occur?

Answer 34

cartilaginous model of bone is first made by chondrocytes and osteoclasts/blasts later replace with woven bone and then remodel to lamellar bone

In membraneous ossification, woven bone forms directly without cartilage and is later remodeled to lamellar bone

Question 35

What environment do osteoblasts need to function?

Answer 35

alkaline (via ALP activity) to catalyze mineralization of osteoid

Question 36

What do osteoblasts differentiate from?

Answer 36

mesenchymal stem cells in periosteum

Question 37

How do osteoclasts resorb bone? What do they differentiate from?

Answer 37

they secrete H+ and collagenases

from a fusion of monocyte/macrophage lineage precursors

Question 38

How does estrogen affect bone?

Answer 38

inhibits apoptosis in bone-forming osteoblasts and induces apoptosis osteoclasts

Question 39

What happens in achondroplasia?

Answer 39

failure of longitudinal bone growth (endochondral ossification) leads to short limbs due to FGFR3 activating mutation limiting chondrocyte proliferation

AD= homozygous is lethal

NOTE: Membranous ossification is not affected (calvarium and facial bones) so head is big