1. Deltoid Muscle
Anterior
Posterior

2. Supraspinatus Muscle occupies the supraspinous fossa

3. Superior Transverse Scapular Ligament closes off suprascapular notch into a foramen

4. Suprascapular Nerve passes UNDER superior transverse scapular ligament

5. Suprascapular Vessels - Artery

6. Suprascapular Vessels – Artery (cartoon) passes OVER superior transverse scapular ligament

7. Suprascapular Vessels – Vein

8. Infraspinatus Muscle occupies the infraspinous fossa

9. Suprascapular n., a., v. passing the Greater Scapular Notch
Note they descend posterior to the infraspinatus muscle

10. Teres Major Muscle
Anterior
Posterior

11. Teres Minor Muscle

12. Long Head of the Triceps Brachii Muscle

13. Triangular Space Formed by:
the medial margin of the long head of the triceps brachii muscle;
the superior margin of the teres major muscle; and
the inferior margin of the subscapularis muscle.

14. Quadrangular Space Formed by:
the inferior margin of the subscapularis muscle;
the surgical neck of the humerus;
the superior margin of the teres major muscle; and
the lateral margin of the long head of the triceps brachii muscle.

15. Triangular Interval Formed by:
the lateral margin of the long head of the triceps brachii muscle;
the inferior margin of the teres major muscle; and
the medial margin of the humerus

16. Triangular Space, Quadrangular Space, and Triangular Interval… Why should I care?

17. Triangular Space, Quadrangular Space, and Triangular Interval… Why should I care?

18. Axillary Nerve

19. Posterior Circumflex Humeral Artery passing through the quadrangular space posteriorly supplies the deltoid m. and arm muscles near the surgical neck of the humerus

20. Posterior Circumflex Humeral Vein passing through the quadrangular space posteriorly

21. Circumflex Scapular Artery passing through the triangular space supplies teres major, minor, and infraspinatus m.

22. Serratus Anterior

23. Pectoralis Minor

24. Latissimus Dorsi

25. Axillary Vein Passes into the axilla through the deltopectoral/ clavipectoral triangle
Also note the
Posterior circumflex humeral v
Subscapular v
Circumflex scapular v
Internal jugular above, joins subclavian, becomes left brachiocephalic.

26. Deltopectoral Triangle
Formed by:
pectoralis major muscle,
deltoid muscle,
Clavicle
Axillary vein passes enters the axilla here

27. Axillary Vein (in deltopectoral triangle) dives through fascia just inferior to the clavicle