Axilla and Brachial Plexus: Learning Objectives and Review Questions

True/False

1. Pectoralis major inserts, in part, at the lateral lip of the intertubercular sulcus and, thus, contributes to on osseofibrous tunnel for the tendon of the long head of the biceps.
2. By definition, the medial lip of the intertubercular sulcus is within the axilla.
3. The axillary sheath houses the axillary artery and the cords of the brachial plexus.
4. Roots, trunks, divisions, cords, and branches define the parts of the axillary artery.
5. The ventral root of C7 is both root and a trunk of the brachial plexus.
6. The brachial plexus receives contributions from the dorsal rami.
7. The trunks of the brachial plexus extend into the axilla.
8. The middle subscapular nerve is also know as the thoracodorsal nerve and as the nerve to latissimus dorsi.
9. The long thoracic nerve innervates serratus posterior inferior and serratus posterior superior and, thus, mediates stability of the scapula.
10. The lower subscapular nerve innervates two muscles and each of these muscles laterally rotate the arm.
11. The upper subscapular nerve innervates one muscle and this muscle is a medial rotator of the arm.
12. The medial brachial cutaneous and medial antebrachial cutaneous nerves provide cutaneous sensation to the medial aspects of the arm and forearm respectively.
13. The median nerve is formed by the medial and posterior roots of the median nerve.
14. A lesion of the axillary nerve within the axilla will cause uncompensated loss of abduction and medial rotation of the arm.
15. A lesion of the nerve to the rhomboids (dorsal scapular nerve) proximal to the levator scapulae muscle results in uncompensated loss of retraction of the scapula.
16. A lesion of the musculocutaneous nerve within the axilla results in uncompensated loss of elbow flexion.
17. A lesion of the posterior cord proximal to the upper subscapular nerve results in uncompensated loss of medial rotation.
18. The dorsal scapular nerve arises from the posterior cord of the brachial plexus.
19. A lesion of the upper root of the brachial plexus would weaken protraction of the scapula.
20. The long thoracic nerve is derived from the lower 3 roots of the brachial plexus.
21. A lesion of the long thoracic nerve would severely weaken protraction of the scapula.
22. A lesion of the long thoracic nerve would affect complete abduction of the arm.
23. A lesion of the middle subscapular would weaken lateral rotation of the arm.
24. A lesion of the lower subscapular nerve would weaken medial rotation.
25. A complete lesion of the posterior cord and its branches would cause uncompensated loss of medial rotation.
26. A complete loss of the posterior cord and its branches would cause uncompensated loss of arm abduction from approximately 15 - 90 degrees.
27. Entrapment of the suprascapular nerve at the superior transverse scapular notch could cause uncompensated loss of arm abduction from 0 - 15 degrees and compensated loss of medial rotation of the arm.
28. A lesion of the lower subscapular nerve would cause weakened (compensated) arm adduction.
29. A lesion of the axillary nerve would weaken every possible movement at the glenohumeral joint with the exception of abduction from 0 - 15 degrees.
30. A total lesion of the median nerve would cause ape hand.
31. A total lesion of the ulnar nerve would cause claw hand.
32. A total lesion of the radial nerve would cause wrist drop.
33. A lesion of the radial nerve at the spiral groove would cause loss of extension at the elbow.
34. A lesion of the radial nerve at the spiral groove would cause the wrist to be flexed and adducted.
35. A lesion of the ulnar nerve at the ulnar groove would cause the wrist to be extended and abducted.
36. A lesion of the ulnar nerve within the anterior compartment of the arm would cause the wrist to be extended and abducted.
37. The ulnar nerve enters the anterior arm by passing through the heads of origin of the flexor carpi ulnaris.

Short Answer and Definitions

1. Coracoid Process
2. Quadrangular Space
3. Triangular Space
4. Deltopectoral Groove
5. Bicipital Groove/Intertubercular Sulcus
6. Clavipectoral Fascia
7. Suspensory Ligament of the Axilla
8. Winging of the scapula
9. Serratus anterior and upward rotation of the scapula
10. Anterior and posterior axillary folds
11. Clavipectoral fascia
12. Axillary lymph nodes
13. Intertubercular groove
14. Transverse humeral ligament
15. Axillary Sheath
16. Cephalic vein
17. Parts 1, 2, and 3 of the axillary artery
18. Thoracoacromial trunk
19. Circumflex scapular artery
20. Anterior and posterior humeral circumflex arteries
21. Shoulder anastomosis (Thoracoacromial trunk + deltoid and acromial branches + ant/post humeral circumflex aa + ascending branch profunda brachii artery)
22. Subscapular artery and ligation of the axillary artery
23. Ventral ramus of spinal nerve
24. Dorsal ramus of spinal nerve
25. Roots of the brachial plexus
26. Trunks of the brachial plexus
27. Posterior cord of brachial plexus (6 pts)
28. Medial antebrachial cutaneous nerve
29. Middle subscapular nerve
30. Lower subscapular nerve

Essay

1. Discuss the anatomy of the axilla. Include contents, relationships, boundaries, fascial specializations, vasculature, innervation, lymphatics, muscles and movements, and compensation in the case of nerve injury.
2. Discuss the brachial plexus. Include parts, boundaries, relationships, fascial specializations, vasculature, muscles and movements, and compensation in the case of nerve injury.
3. Discuss the subscapularis muscle. Include fascial specializations, relationships, vasculature, innervation, lymphatics, movements, and compensation in the case of nerve injury.
4. Discuss the pectoralis minor muscle. Include fascial specializations, relationships, vasculature, innervation, lymphatics, movements, and compensation in the case of nerve injury.
5. Discuss the coracobrachialis muscle. Include fascial specializations, relationships, vasculature, innervation, lymphatics, movements, and compensation in the case of nerve injury.
6. Discuss the short head of biceps muscle. Include fascial specializations, relationships, vasculature, innervation, lymphatics, movements, and compensation in the case of nerve injury.
7. Discuss the pectoralis major muscle. Include fascial specializations, relationships, vasculature, innervation, lymphatics, movements, and compensation in the case of nerve injury.
8. Discuss the latissimus dorsi muscle. Include fascial specializations, relationships, vasculature, innervation, lymphatics, movements, and compensation in the case of nerve injury.
9. Discuss the serratus anterior muscle. Include fascial specializations, relationships, vasculature, innervation, lymphatics, movements, and compensation in the case of nerve injury.
10. Discuss the teres major muscle. Include fascial specializations, relationships, vasculature, innervation, lymphatics, movements, and compensation in the case of nerve injury.
11. Discuss the branching of the axillary artery. Include relationships, fascial specializations, relationships, lymphatics, movements, and collateral circulation in the case of injury.
12. Discuss the contents of the axillary sheath, provide relations within the sheath.
13. Discuss the path of the posterior cord of the brachial plexus and its branches in the axilla, shoulder, and proximal upper extremity.
14. Discuss the vascular and nervous injuries possible by a fracture at the surgical neck of the humerus.
15. Discuss the symptoms resulting from injuries to the upper brachial plexus.
16. Discuss the symptoms resulting from injuries to the lower brachial plexus.
17. Discuss "ape hand" and median nerve injury.
18. Discuss "claw hand" and ulnar nerve injury.
19. Discuss the actions of the serratus anterior muscle and winging of the scapula.
20. Discuss the loss of action and sensation after a fracture of the surgical neck of the humerus or a downward dislocation of the shoulder.