BRACHIAL PLEXUS By Prof. Saeed Makarem

Functions of the Nerves of The Upper Limb Sensory innervation to the skin and joints Motor innervation to the muscles 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

Roots: in the posterior∆ Trunks: in the posterior∆ 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)

Lateral Cord: III- Cords: 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

Arises from the medial cord Is joined by intercostobrachial nerve 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

Arises from the medial cord Descends in front of the axillary artery 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