The brachial plexus is formed in the lower neck and axilla by the ventral rami of C5-T1 spinal nerves. It is divided into roots, trunks, divisions, and cords that wrap around the axillary artery. The cords give rise to branches that innervate the muscles and skin of the upper limb, including the lateral pectoral, musculocutaneous, median, ulnar, radial, axillary, and thoracodorsal nerves. Precisely organized, the brachial plexus efficiently distributes nerve fibers from different spinal cord segments to the upper extremity.

1. AXILLA
BRACHIAL PLEXUS
By: Dr. Musaed Al-Fayez

2. Functions of the Nerves Entering The
Upper Limb
1. Sensory innervation to the skin and joints
2. Motor innervation to the muscles
3. Influence over the diameter of blood vessels via sympathetic
vasomotor nerves
4. Sympathetic secretomotor supply to the sweat glands

3. What is a Brachial Plexus ?
Brachial Plexus are complicated
plexus of nerves present at the
root of the neck to enter the
upper limb

4. This allows the nerve fibers derived
from different segments of the
spinal cord to be arranged and
distributed efficiently in different
nerve trunks to the various parts of
the upper limb

5. Location & Formation
Brachial Plexus is present in the lower part
of the posterior triangle of the neck &
Axilla
It is formed by the union of the anterior
rami of the 5th, 6th, 7th and 8th cervical and
the 1st thoracic spinal nerves

7. Formation
The Plexus can be divided into:
• Roots
• Trunks
• Divisions
• cords

8. The roots of C5 & 6 unite to form upper trunk
The root of C7 continues as the middle trunk
The roots of C8 & T1 unite to form lower trunk

10. Divisions
Each trunk divides into anterior and
Posterior divisions

11. • The anterior divisions of the upper and middle
trunks unite to form the lateral cord
• The anterior division of the lower trunk
continues as the medial cord
• The posterior divisions of all three trunks join to
form the posterior trunk

13. Axillary Sheath
The cords become arranged around the
axillary artery in the axilla
Brachial Plexus, the axillary artery and vein
are enclosed by a sheath of fascia called
AXILLARY SHEATH

14. Relation of Cords
All three cords of the brachial plexus lie
above and lateral to the first part of axillary
artery

15. Relation of Cords
Medial cord crosses behind the artery to
reach the medial side of the second part of
the axillary artery
Posterior cord lies behind the second part of
the artery
Lateral cord lies on the lateral side of the
second part of the artery

17. Branches
The branches of the different parts of the
brachial plexus are:

18. Roots:
• Dorsal scapular nerve (C5)
• Long thoracic nerve (C5, 6 and 7)

19. Upper Trunk:
• Nerve to subclavius (C5 and 6)
• Suprascapular nerve (supplies the
supraspinatus and infraspinatus muscles)

20. Lateral Cord:
• Lateral pectoral nerve
• Musculocutaneous nerve
• Lateral root of median nerve

21. Medial Cord:
• Medial pectoral nerve
• Medial cutaneous nerve of arm and medial
cutaneous nerve of forearm
• Ulnar nerve
• Medial root of median nerve

22. Posterior Cord:
• Upper and lower subscapular nerves
• Thoracodorsal nerve
• Axillary nerve
• Radial nerve

24. Branches in Axilla
Nerve to Subclavius:
Supplies the subclavian muscle
May give contribution (C5) to the phrenic
nerve

25. Long Thoracic Nerve:
Arises from the root
Enters the axilla by passing down over the
lateral border of the 1st rib behind the
axillary vessels and brachial plexus
Supplies the serratus anterior muscle

26. Lateral Pectoral Nerve:
Arises from the lateral cord
Supplies the pectoralis major muscle

27. Musculocutaneous Nerve:
Arises from the lateral cord
Supplies the coracobrachialis muscle
Leaves the axilla by piercing this muscle

29. Lateral Root of the Median Nerve:
Is a direct continuation of the lateral cord
Is joined by the medial root to form the
median nerve trunk
Gives no branch in the axilla

31. Medial Pectoral Nerve:
Arises from the medial cord
Supplies and pierces the pectoralis minor
Muscle
Supplies the pectoralis major muscle

32. Medial Cutaneous Nerve of the Arm
Arises from the medial cord
Is joined by intercostobrachial nerve
Supplies the skin on the medial side of the
arm

33. Medial Cutaneous Nerve of the
Forearm:
Arises from the medial cord
Descends in front of the axillary artery

34. Ulnar Nerve:
Arises from the medial cord
Descends between axillary artery and vein
Gives no branches in the axilla

35. Medial Root of the Median Nerve:
Arises from the medial cord
Crosses in front of the 3rd part of axillary
artery
Joins the lateral root of the median nerve

36. Upper and Lower Subscapular Nerve:
Arise from the posterior cord
Supply the upper and lower part of the
suscapularis muscle and teres muscle (only
lower subscapular nerve)

37. Thoracodorsal Nerve:
Arises from the posterior cord
Runs downward to supply the latissimus
dorsi muscle

38. Axillary Nerve:
Is one of the terminal branches of posterior
cord
Gives branch to the shoulder joint
Divides into anterior and posterior branches

39. Radial Nerve:
Largest branch of brachial plexus
Lies behind the axillary artery
Supplies the long and medial heads of
Triceps muscle and the posterior
cutaneous nerve of the arm