Download 05-Brachial_Plexus2008-10-24 09:283.4 MB

Functions of the Nerves of The Upper Limb
1. Sensory innervation to the skin and joints
2. Motor innervation to the muscles
3. Control the diameter of blood vessels via
sympathetic vasomotor nerves
4. Sympathetic secretomotor supply to the
sweat glands
What is a Brachial Plexus ?
Brachial Plexus is a network of nerves
present at the root of the neck to enter
the upper limb
Location & Formation
Brachial Plexus is present in the posterior
triangle of the neck & axilla
It is formed by the union of the anterior
Rami of the C 5th, 6th, 7th & 8th and the 1st
thoracic spinal nerve
Formation
The Plexus can be divided into 5 stages:
• 1- Stage of roots
• 2- Stage of trunks
• 3- Stage of divisions
• 4- Stage of cords
• 5- Stage of branches
Formation
The Plexus can be divided into 5 stages:
• Roots: in
the posterior∆
• Trunks: in the posterior∆
• Divisions: behind the clavicle
• Cords: in the axilla
• Branches: in the axilla
•
The first 2 stages lie in the posterior triangle,
while the last 2 sages lie in the axilla.
The roots of C5 & C6 unite to form
Upper trunk
The root of C7 continues as the
Middle trunk
The roots of C8 & T1 unite to form
Lower trunk
Divisions
Each trunk divides into:
Anterior
&
Posterior divisions
Where?
 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 cord
Axillary Sheath
The cords become arranged around the
axillary artery in the axilla
Brachial Plexus, the axillary artery and the
axillary vein are enclosed by a sheath of
fascia called AXILLARY SHEATH
Relation of Cords
All three cords of the brachial plexus lie
above and lateral to the first part of the
axillary artery
Relation of Cords
Cords are named according to their relation
to the second part of the axillary artery
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
Branches
The branches of the different parts of the
brachial plexus are:
I- Roots:
• Dorsal scapular nerve (C5)
•
Long thoracic nerve (C5, C6 & C7)
II- Upper Trunk:
•
•
•
The only trunk which gives branches is the
upper trunk, it gives:
1- Nerve to Subclavius (C5 & C6)
2- Suprascapular nerve (C5 & C6)-(supplies the
supraspinatus and infraspinatus muscles)
III- Cords:
• Lateral
Cord:
•
Lateral pectoral nerve (C5,C6 &C7)
•
Musculocutaneous nerve (C5,C6 &C7)
•
Lateral root of median nerve (C5,C6 &C7)
Medial Cord:

Medial pectoral nerve (C8 &T1)

Medial cutaneous nerve of the arm (C8 &T1)

Medial cutaneous nerve of the forearm (C8 &T1)

Medial root of median nerve (C8 &T1)

Ulnar nerve (C7,C8 &T1)
Posterior Cord:


Upper subscapular nerves (C5 & C6)
Lower subscapular nerves (C5 & C6)

Axillary nerve (C5 & C6)

Thoracodorsal nerve (C6,C7 & C8)

Radial nerve (C5,C6,C7,C8 &T1)
Branches in Axilla
Nerve to Subclavius:
Supplies the subclavius muscle
May give contribution (C5) to the phrenic
nerve
Long thoracic nerve (C5,C6 &C7):
(Nerve to serratus anterior, or nerve of Bell)
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
Lateral Pectoral Nerve:
Arises from the lateral cord
Supplies the pectoralis major muscle
Musculocutaneous Nerve:
Arises from the lateral cord
Supplies the coracobrachialis ,Brachialis and
the biceps brachii muscles
Leaves the axilla by piercing the
Coracobrachialis muscle
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
Medial Pectoral Nerve:
Arises from the medial cord
Supplies and pierces the pectoralis minor
Muscle
Supplies the pectoralis major muscle
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
Medial Cutaneous Nerve of the Forearm:
Arises from the medial cord
Descends in front of the axillary artery
Ulnar Nerve:
Arises from the medial cord
Descends between axillary artery and vein
Gives no branches in the axilla
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 on
the lateral side of 1/3rd part of axillary artery
Upper and Lower Subscapular
Nerves:
Arise from the posterior cord
Both supply the subscapularis muscle.
The lower subscapular nerve supplies also
teres major muscle)
Thoracodorsal Nerve:
Arises from the posterior cord
Runs downward to supply the latissimus
dorsi muscle
Axillary Nerve:
Is the smaller of the two terminal branches of
posterior cord
It supplies the deltoid and teres minor muscles
Gives branch to the shoulder joint
Divides into anterior and posterior branches
Radial Nerve:
Largest branch of brachial plexus
It is the continuation of the posterior cord
Lies behind the axillary artery
Supplies all muscles of the back of the upper
limb