The axilla is a pyramidal space located between the upper arm and neck. It has anterior walls formed by the pectoralis major and minor muscles, a medial wall formed by the serratus anterior muscle and ribs, and a posterior wall formed by the subscapularis, teres major, and latissimus dorsi muscles. The axilla contains the brachial plexus nerves, axillary artery, axillary vein, and lymph nodes.

1. The Axilla
A pyramidal space at the junction
between the neck and the upper limb

5. Apex
Interval between middle
third of clavicle and 1st
rib

6. Anterior Wall
• Pectoralis Major
•Pectoralis Minor

7. Anterior Wall
• Pectoralis Major
•Pectoralis Minor

8. Anterior Wall
• Pectoralis Major
•Pectoralis Minor

9. Anterior Wall
• Pectoralis Major
• Pectoralis Minor

10. Medial Wall
• Serratus Anterior
• Ribs

11. Medial Wall
• Serratus Anterior
• Ribs

12. Posterior Wall
• Subscapularis
• Teres Major
• Latissimus Dorsi

13. Posterior Wall
• Subscapularis
• Teres Major
• Latissimus Dorsi

14. Posterior Wall
• Subscapularis
• Teres Major
• Latissimus Dorsi

15. Posterior Wall
• Subscapularis
• Teres Major
• Latissimus Dorsi

16. Lateral Wall
Intertubercular Sulcus
of the Humerus

17. Contents of Axilla
• Cords and branches of
brachial plexus
• Axillary Artery
• Axillary Vein

18. Contents of Axilla
• Cords and branches of
brachial plexus
• Axillary Artery
• Axillary Vein

19. Contents of Axilla
• Cords and branches of
brachial plexus
• Axillary Artery
• Axillary Vein

20. Contents of Axilla
• Cords and branches of
brachial plexus
• Axillary Artery
• Axillary Vein

21. Contents of Axilla
• Cords and branches of
brachial plexus
• Axillary Artery
• Axillary Vein
(also lymph nodes and
fat)

27. Summary of Muscles

28. Anterior Wall
Pectoralis Major
Origin Clavicular head: anterior surface
of medial half of clavicle;
Sternocostal head: anterior
surface of sternum, superior six
costal cartilages, and aponeurosis
of external oblique muscle
Insertion Lateral lip of intertubercular
groove of humerus
Action Adducts and internally rotates
humerus
Nerve Supply Lateral and medial pectoral
nerves (C5, C6, C7, C8, and T1)
Blood Supply pectoral branch of
thoracoacromial trunk

29. Anterior Wall
Pectoralis Minor
Origin 3rd to 5th ribs near their costal
cartilages
Insertion Medial border and superior
surface of coracoid process of
scapula
Action Stabilises scapula, pulls it
inferiorly and anteriorly
against thoracic wall
Nerve Supply Medial and lateral pectoral
nerves; (C8 and T1)
Blood Supply Pectoral branch of the
thoracoacromial trunk

30. Medial Wall
Serratus Anterior
Origin Lateral surfaces of upper 8 or 9
ribs at the side of chest
Insertion Medial border of scapula
Action Pulls scapula forward and
upward; stabilises medial
border of scapula
Nerve Supply Long thoracic nerve (C5, C6,
C7)
Blood Supply Circumflex scapular artery

31. Subscapularis
Origin Subscapular fossa of scapula
Insertion Lesser tuberosity of humerus
Action Internal rotation and
adduction of the arm
Nerve Supply Upper and lower subscapular
nerves (C5, C6 and C7)
Blood Supply Subscapular artery
Posterior Wall

32. Posterior Wall
Teres Major
Origin Dorsal surface of inferior angle
of scapula
Insertion Medial lip of intertubercular
groove of humerus
Action Adducts and medially rotates
arm
Nerve Supply Lower subscapular nerve (C6
and C7)
Blood Supply Subscapular and circumflex
scapular arteries

33. Posterior Wall
Latissimus Dorsi
Origin Spinous processes of inferior 6
thoracic vertebrae, all lumbar
vertebrae and dorsal crest of
sacrum, thoracolumbar fascia,
iliac crest, and inferior 3 or 4
ribs
Insertion Floor of intertubercular groove
of humerus
Action Extends, adducts, and
internally rotates humerus;
pulls body up toward arms
during climbing
Nerve Supply Thoracodorsal nerve (C6, C7,
and C8)
Blood Supply Thoracodorsal artery