Anatomy Lecture 3.1 Brachial Plexus

What are the normal spinal levels?

C5, C6, C7, C8, T1 (Normal Brachial Plexus)

What are the variants of the Brachial Plexus?

Prefixed (C4-C8)

Postfixed (C6-T2)

What is the function of the nerve fibers?

Nerve Fibers converge, mingle, separate, reconverge, mingle and then separate again

They form the peripheral nerves that innervate the upper extremity

What is the order of the Brachial Plexus?

Roots—>Trunks—>Divisions—>Cords—>Terminal Branches

How many roots are in the brachial plexus?

5 roots

How many trunks are there in the brachial plexus?

3 trunks

How many division are there in the brachial plexus?

6

How many cords are in the brachial plexus?

3

How many terminal branches are in the brachial plexus?

5

What are the trunks of the brachial plexus, and what are their nerve roots?

Superior Trunk=C5, C6

Middle Trunk=C7

Inferior Trunk=C8, T1

What does each trunk of the brachial plexus divide into?

The Anterior Division and Posterior Division

How many total divisions are there in the brachial plexus?

6 divisions: 3 anterior divisions, 3 posterior divisions

What are the cords of the Brachial Plexus, and how are they named?

Lateral Cord, Posterior Cord, and Medial cord

The cords are named relative to the axillary artery

What are the 3 anterior divisions?

Superior Trunk Anterior Division

Middle Trunk Anterior Division

Inferior Trunk Anterior Division

What are the 3 posterior divisions?

Superior Trunk Posterior Division

Middle Trunk Posterior Division

Inferior Trunk Anterior Division

What are the five terminal branches?

Musculotaneous Nerve, Median Nerve, Ulnar Nerve, Axillary Nerve, Radial Nerve

What are the roots of the musculotaneous nerve, and its continuation

C5, C6, C7

Continuation: Lateral cutaneous nerve

What is the function of the Musculutaneous Nerve?

Flexors of forearm

What are the muscles innervated by the musculotaneous nerve?

Coracobrachialis, biceps brachii, brachialis

What are the roots of the Median Nerve, and what additional function is it responsible for?

The roots of the median nerve are C5, C6, C7, C8, T1

What are the functions of the Median Nerve?

Pronators, most finger flexors, wrist flexors, thenar muscles, and cutaneous innervationAx

What are the roots of the axillary nerve?

C5, C6

What are the functions of the axillary nerve?

Think: Shoulder/Humeral Shaft

What structures are innervated by the axillary nerve, and where does it originate?

Deltoid, skin over deltoid

Originates Posterior Cord

What are the roots of the Radial nerve, and what is its origin?

C5, C6, C7, C8, T1

Origin: Posterior Cord

What muscles are innervated by the radial nerve, and what is its function?

Triceps, brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum, supinator

Function: Extension

Dorsal Scapular Nerve

Roots- C5

Muscles- Rhomboids, levator scapulae

Think: Upper/Shoulder

Roots of Subclavius

Nerves to subclavius are C5, C6

Suprascapular Nerve

Roots- C5, C6

Structures- Rotator cuff

Lateral Pectoral Nerve

Roots- C5, C6, C7

Innervates Pectoralis Major

Long Thoracic Nerve

Roots- C5, C6, C7

Innervates Serratus Anterior (linked w/winged scapula)

Upper Subscapular Nerve

Roots- C5, C6

Thoracodorsal Nerve

Roots: Branch of posterior cord

Innervates Latissimus Dorsi

Lower Subscapular Nerve

Roots- C5, C6

Medial Pectoral Nerve

Roots- C8, T1

Innervates Pectoralis Minor

Medial Cutaneous Nerve of Arm

Roots- C8, T1

What originates from the Posterior Cord?

Axillary nerve, radial nerve, upper subscapular nerve, thoracodorsal nerve

Upper Extremity Dermatomes

C2, C3, C4, C5, C6, C7, C8, T1

Ulnar Nerve

Roots: C7, C8, T1

Functions: Intrinsic hand muscles, some finger flexors, some wrist flexion

Innervates: Flexor digitorum profundus (medial portion), flexor carpi ulnaris

Roots of median nerve

C5, C6, C7, C8, T1

Functions of median nerve

Pronators, most finger flexors, wrist flexors, thenar muscles, cutaneous innervation

What nerve continues as the lateral cutaneous nerve?

Musculotaneous nerve