Lecture 6 - SQ

Question 1

1. Which of the following muscles are innervated either directly or indirectly off the posterior cord of the brachial plexus: subscapularis, teres major, latissimus dorsi, teres minor?

Answer 1

1. All of the muscles in this list are innervated by nerves that originate in the posterior cord.

Question 2

2. In what position of the arm is the long thoracic nerve to the serratus anterior-most susceptible to trauma? If the nerve were lacerated, what would be the res

Answer 2

2. With the arm abducted the nerve is at risk of injury, since it lies subcutaneous on the thoracic
   wall and superficial to the muscle it innervates. Paralysis of the serratus anterior following
   laceration of its nerve leads to a “winged scapula.”

Question 3

3. What nerve is at most risk of injury during a fracture of the surgical neck of the humerus?

Answer 3

3. The axillary nerve. The resultant motor loss would be paralysis of the deltoid muscle leading
   to weak abduction at the shoulder joint.

Question 4

4. Name a single muscle which can concurrently extend, adduct and medially rotate the humerus.

Answer 4

4. Latissimus dorsi.

Question 5

5. What is crutch palsy?

Answer 5

5. Crutch palsy is most commonly due to compression of the radial nerve in the axilla. This
   condition gets its name “crutch palsy” because it is traditionally caused by extended use of
   crutches that are too tall for the patient.