the brachial plexus

The brachial plexus

The brachial plexus
Formation Supraclavicular portion Trunks Divisions Infraclavicular portion Cords Branches

The brachial plexus

The brachial plexus is a network of nerves that supply the upper limb

The brachial plexus

extends from the neck into the axilla

Formation

It is formed by five roots from the anterior (ventral) primary rami of C5,6,7,8, and T1

Formation

the roots of the brachial plexus should not be confused with the ventral and dorsal roots which unite to form the spinal nerves
dorsal & ventral roots of a spinal n.
The ventral rami form the roots of the brachial plexus

Supraclavicular portion

The roots lie in the neck between scalenus anterior and scalenus medius muscles
Scalenus anterior
Scalenus medius

Supraclavicular portion

C5 & C6 unite to form the upper trunk

Supraclavicular portion

C8 & T1 unite to form the lower trunk

Supraclavicular portion

C7 continues as the middle trunk

Trunks of the brachial plexus

The trunks lie in the posterior triangle of the neck and can be felt in the angle between the clavicle and sternocleidomastoid muscle
sternocleidomastoid
clavicle

Trunks of the brachial plexus

The inferior trunk lies on the first rib posterior to the subclavian artery
Inferior trunk

Divisions of the brachial plexus

Behind the clavicle, each trunk divides into anterior and posterior divisions

Trunks of the brachial plexus

the anterior divisions supply anterior (flexor) parts while the posterior divisions supply posterior (extensor) parts of the upper limb

Infraclavicular portion

The three posterior divisions unite to form the posterior cord
Posterior cord

Infraclavicular portion

the anterior divisions of the upper and middle trunks unite to form the lateral cord
lateral cord

Infraclavicular portion

the anterior division of the lower trunk continues as the medial cord
medial cord

Cords of the brachial plexus

The cords are arranged around the second part of the axillary artery as indicated by their names.

Branches of the brachial plexus

Each cord of the brachial plexus divides into a number of branches, 2 of them are terminal

Branches of the brachial plexus

there are also a number of supraclavicular branches

Bracial plexus plan

If you find it difficult the names attributed to the different parts of the brachial plexus, the diagram will remind you that the order is roots, trunks, divisions, cords, and branches

Branches of the roots

Dorsal scapular (C5) which supplies rhomboids muscles and levator scapula

Branches of the roots

Nerve to subclavius (C5 & 6) which descends in front of the brachial plexus and the subclavian artery in the neck, it may give a contribution to the phrenic nerve (C5) this branch, when present is called the accessory phrenic nerve.

Branches of the roots

The third branch is the long thoracic nerve (C5,6, & 7) descends behind the brachial plexus and supplies serratus anterior muscle

Suprascapular nerve

From the upper trunk arises the suprascapular nerve

Suprascapular nerve

The suprascapular nerve passes laterally across the neck, then through the suprascapular notch in the scapula to supply supraspinatus and infraspinatus muscles

Infraclavicular branches

The infraclavicular branches are derived from the cords Each cord divides into 2 terminal branches.

Branches of the lateral cord

The lateral cord has 3 branches mainly the lateral pectoral nerve and 2 terminal branches, the musculocutaneous and the medial root of the median nerve

Lateral pectoral nerve

The lateral pectoral nerve pierces the clavipectoral fascia to supply pectoralis major muscle

Lateral pectoral nerve

sends a communicating loop to the medial pectoral nerve, through which it supplies pectoralis minor muscle
Axillary a.
Pectoralis minor
medial pectoral n.
laterall pectoral n.
Medial cord
lateral cord
posterior cord
Axillary v.
communicating loop

Musculocutaneous nerve

pierces coracobrachialis muscle, supplying it before doing so

Musculocutaneous nerve

it then supplies the muscles of the flexor (anterior) compartment of the arm mainly biceps and brachialis therefore it is known as the BBC nerve

Musculocutaneous nerve

It ends by becoming the lateral coetaneous nerve of the forearm

Lateral root of the median nerve

The lateral root of the median nerve is the direct continuation of the lateral cord

Median nerve

The median nerve arises by medial and lateral roots from the corresponding cords of the brachial plexus



Median nerve
the medial root crosses the axillary artery to join the lateral root so the median nerve is formed at first lateral to the axillary artery.

Median nerve

The median nerve has no branches in the axilla and is responsible for the supply of the flexor compartment of the forearm and the palm.

Branches of the medial cord

The medial cord has 5 branches the ulnar nerve and medial root of the median nerve are its two terminal branches
Ulnar n.


The medial pectoral nerve passes through pectoralis minor supplying it then it supplies pectoralis major
Axillary a.
Pectoralis minor
medial pectoral n.
laterall pectoral n.
Medial cord
lateral cord
Axillary v.
Medial pectoral nerve
axillary a.
axillary v.
Medial pectoral n.
Pectoralis major

Medial cutaneous nerve of arm

The medial cutaneous nerve of the arm, is a small nerve that runs medial to the axillary vein and supplies the skin over the medial side and front of the arm
Axillary a.
Axillary v.

Medial cutaneous nerve of arm

communicates with the intercostobrachial nerve

medial cutaneous nerve of the forearm

runs between the axillary artery and vein and supplies skin of the medial side of the forearm
Axillary a.
Axillary v.

medial cutaneous nerve of the forearm

Runs between the axillary artery and vein superficial to the ulnar nerve



Ulnar nerve
is the largest branch of the medial cord runs between the axillary artery and vein but at a more posterior plane than the smaller medial cutaneous nerve of the forearm
Axillary a.
Axillary v.

Ulnar nerve

receives a branch from the lateral cord in more than 90% of cases has no branches in the axilla is mainly concerned with the innervation of the palm.

Medial root of the median nerve

crosses the axillary artery to form the median nerve lateral to the artery
Axillary a.
Axillary v.

Branches of the brachial plexus

Note that the musculocutaneous, median, and ulnar nerve form the letter M, which serves as the key to the brachial plexus

Branches of the posterior cord

The posterior cord of the brachial plexus has 5 branches the axillary and radial nerves are its 2 terminal branches.

Upper and lower subscapular nerves

The upper and lower subscapular nerves supply the upper and lower parts of subscapularis muscle

Lower subscapular nerve

the lower subscapular nerve supplies teres major muscle in addition to suscapularis

Thoracodorsal nerve

Runs between the subscapular nerves, it runs down on subscapularis towards latissimus dorsi which it supplies, it accompanies the subscapular vessels.

Axillary nerve

It is inappropriately named since it supplies nothing in the axilla The first thing it does is to quit the axilla by passing backwards through the posterior wall of the axilla

Axillary nerve

It leaves the axilla through the quadrangular space accompanied by the posterior circumflex humeral vessels just below the capsule of the shoulder joint to which it sends an articular branch (so it is sometimes called the circumflex nerve)

Axillary nerve

It winds around the surgical neck of the humerus deep to deltoid muscle which it supplies, it also supplies teres minor, and the upper lateral cutaneous nerve of the arm

Radial nerve

The radial nerve provides the major nerve supply of the extensor muscles of the upper limb (arm and forearm)

Radial nerve

It lies behind the axillary artery on the glistening tendon of latissimus dorsi muscle
latissimus dorsi tendon

Radial nerve

posterior cord
triceps (long head)
posterior cutaneous of arm
triceps (medial head)
Branches in the axilla

Radial nerve

It leaves the axilla posteriorly through a triangular space between the humerus, teres major, and the long head of triceps