MSK anatomy upper limbs

Question 1

What are alternative pathways for blood for each distal axillary artery assuming an occlusion of the proximal part of the axillary artery?

Answer 1

1. subclavian–>dorsal scapular artery–>circumflex scapular–>subscapular–>axillary
2. subclavian–>thyrocervical trunk–>suprascapular–>circumflex scapular–>subscapular

Question 2

What nerve segments are within the musculocutaneous nerve?

Answer 2

C5, 6, 7

Question 3

What spinal cord segments is the biceps reflex testing?

Answer 3

Biceps tendon is largely function of C5,6. Via musculocutaneous, even though it also contains C7

Question 4

What does it mean by “funny bone”?

Answer 4

-tingling sensations felt due to blow to ulnar nerve as it courses posterior to medial epicondyle.

Question 5

What spinal cord segments does the triceps reflex test?

Answer 5

C7 and C8 even though radial nerve as all C5-T1 segments. Branches that innervate triceps largely only C7 and 8.

Question 6

Which peripheral nerve is most vulnerable to damage from a fracture of the medial epicondyle? Where would you test sensory integrity? What forearm muscles is innervated by this nerve?

Answer 6

1. ulnar nerve
2. little finger
3. Flexor carpi ulnaris and medial 2 flexor digitorum profundus

Question 7

Which muscles of the anterior compartment of the arm contribute to flexion at the shoulder joint? at the elbow?

Answer 7

1. coracobrachialis, biceps brachii

2. elbow: biceps and brachialis

Question 8

Where is the best place to test C6, C7, and 8?

Answer 8

C6 on thumb
C7 on middle finger
C8 on pinky

Question 9

What sequence of named arteries could serve as an alternative pathway allowing blood to reach the latissimus dorsi muscle if the subscapular artery is completely occluded?

Answer 9

Options
1. subclavian to thyrocervical trunk to suprascapular to circumflex scapular to thoracodorsal
2. subclavian to thyrocervical to transverse cervical to dorsal scapular to circumflex scapular to thoracodorsal
If dorsal scapular artery arises from the subclavian instead of transverse cervical artery
3. subclavian to dorsal scapular to circumflex scapular to thoracodorsal

Question 10

If upper trunk of brachial plexus is torn, which spinal cord segments would no longer be contributing to innervation of upper limb? Which muscles would be paralyzed? Which muscles would be weakened?

Answer 10

Erb Duchenne or Waiters Tip deformity

1. C5, 6 affected
2. Muscles paralyzed
   - via suprascapular nerve: supraspinatus (abduct) and infraspinatus (lateral rotation)
   - via axillary nerve: deltoid and teres minor
3. muscles weakened
   - via musculocutaneous: biceps brachii, coracobrachialis, brachialis–>weakness in elbow flexors
   - via radial nerve: weakness of wrist extensors-triceps and posterior forearm

Question 11

What nerves are vulnerable during a radical dissection to surgically remove the breast?

Answer 11

1. Long thoracic nerve to serratus anterior, would not be able to abduct arm above 90 degrees
2. thoracodorsal nerve running superficial to latissimus dorsi

Question 12

Which peripheral nerve is most vulnerable to damage from a fracture of the medial epicondyle of the humerus? Where could you test for sensory integrity of this nerve? Which forearm muscles are innervated by this nerve?

Answer 12

1. Ulnar nerve
2. sensory test: On little finger of hand
3. Forearm muscles: Lateral 2 flexor digitorum profundus, flexor carpi ulnaris

Question 13

Where can you locate the brachial artery pulse? Radial artery at the wrist?

Answer 13

brachial: Medial to the biceps tendon

Radial artery: lateral to flexor carpi radialis tendon and in anatomical snuff box on dorsal side

Question 14

Which muscles of the anterior compartment of the arm contribute to flexion at the shoulder joint? Which muscles contribute to flexion of the elbow joint?

Answer 14

At shoulder: biceps brachii long head, coracobrachialis,

At elbow: biceps brachii, and brachialis

Question 15

Which muscles contribute to supination? to pronation

Answer 15

supination: supinator, biceps brachii
pronation: pronator teres, pronator quadratus

Question 16

What is the pathway for SS axons from biceps tendon to the spinal cord? What is pathway for SM axons from spinal cord to biceps? for biceps reflex.

Answer 16

• tendon–>musculocutaneous nerve–>brachial plexus–>ventral rami of C5/6–>spinal nerves C5/6–>DRGs of C5/6
• ventral horn C5/6–>ventral roots–>spinal nerve–>ventral rami–>brachial plexus–>musculocutaneous nerve

Question 17

Why are the extensor muscles of the forearm contracting when making a fist?

Answer 17

To prevent unwanted wrist flexion

Question 18

Which peripheral nerve is damaged if a patient presents with a flexed wrist when the forearm is held at 90 degrees flexion and is unable to straighten or extend the wrist? If all other upper limb movements are normal, where along the course of the nerve is it most likely damaged?

Answer 18

-Radial nerve at or below the mid level of humerus after it has innervated the triceps.

Question 19

Which peripheral nerve is most likely to be damaged by sharp bony fragments of a transverse compound fracture at the midpoint of the shaft of the humerus? What functional loss would result?

Answer 19

• radial

- loss of extension of wrist and digits, and weakness in abduction of the thumb

Question 20

What functional and cutaneous loss would someone experience with a lesion of the medial nerve at the wrist?

Answer 20

• denervation of thenar muscles, 1st and 2nd lumbricals,

- loss of cutaneous sensation on palmar surfaces of digits 1,2,3 and half of 4, as well as nail beds of the same digits

Question 21

Which artery is the main contributor to superficial palmar arch? To the deep palmar arch?

Answer 21

• superficial: Ulnar

- deep: radial

Question 22

What is the course of digital nerves to the nail bed of the index finger? What is the origin of these nerves? where would the doctor need to insert the needle in order to anesthetize the nail bed?

Answer 22

• common digital palmar nerves from median nerve to proper digital nerves on medial and lateral margins of index finger. They course dorsally to nail bed
• needle would be inserted on palmar side of index finger

Question 23

List from internal to external the structures at the superior most aspect of the shoulder joint, starting with tendon of long head of biceps.

Answer 23

1. biceps tendon-long head
2. synovial membrane
3. joint capsule
4. supraspinatus tendon
5. subdeltoid bursa
6. coracoacromial ligament

Question 24

Which movements occur at the radiocarpal joint? At the midcarpal joint? Which two bones are separated by the articular disk at the wrist?

Answer 24

radiocarpal: flexion and extension
midcarpal: flexion and extenion, abduction and adduction
- head of ulna and triquetral bone separated by articular disk

Question 25

Which styloid process projects more distally in a normal wrist?

Answer 25

Radial

Question 26

What motions are possible at the first metacarpal joint?

Answer 26

• flexion extension
• abduction and adduction
• rotation