Chapter 51 - Consolidated Neurovasculature of the Upper Limb

Brachial plexus

network of intermingling and intertwining nerves that supplies structures of the upper limb

English meaning of Latin plexus

twining or braid

Spinal nerve plexuses are derived only from ______

VENTRAL RAMI and NEVER from dorsal rami

Brachial plexus is formed directly from the _____ of spinal nerves ______

ventral rami

C5, C6, C7, C8 and T1

Ventral rami combine to form the _______ of the brachial plexus

trunks

Parts of brachial plexus

roots, trunks, divisions, cords, branches

(Remember To Drink Cold Boba)

Ventral rami of C5 and C6 join to form ____

upper trunk

Ventral ramus of C7 continues as ______

middle trunk

Ventral rami of C8 and T1 join to form ______

lower trunk

Trunks are found in ______

neck

Each trunk of the brachial plexus divides into ________

anterior and posterior divisions

Lateral cord is formed by _______

anterior divisions of upper trunk and middle trunk

Medial cord is formed by _________

anterior division of lower trunk

Posterior cord is formed by ______

THREE posterior divisions of upper, middle, and lower trunks

Cords are found in the ______.

axilla

Cord names (lateral, posterior and medial) indicate their location in relation to the ________

axillary artery

The cords give off a total of ____ nerves and continue DISTALLY as the ____ major nerves of the upper limb

a total of 8 nerves

4 major nerves of upper limb

Diagram of brachial plexus

C5 and C6 > Upper Trunk > Anterior Upper and Anterior Middle > Lateral Cord

C7 > Middle Trunk > Posterior Upper, Middle, Lower > Posterior Cord

C8 and T1 > Anterior Lower > Medial Cord

Branches of ventral rami

1. dorsal scapular nerve

2. long thoracic nerve

Branches of the trunks

1. nerve to subclavius

2. suprascapular nerve

Branches of the cords

1. Lateral Pectoral Nerve

2. Medial Pectoral Nerve

3. Medial Brachial Cutaneous Nerve

4. Medial Antebrachial Cutaneous Nerve

5. Upper Subscapular Nerve

6. Thoracodorsal Nerve

7. Lower Subscapular Nerve

8. Axillary Nerve

Primary nerves derived from cords

-Musculocutaneous nerve

-Radial nerve

-Median nerve

-Ulnar nerve

All branches off of the lateral cord

1. Lateral pectoral nerve

2. Lateral root of median nerve

3. Musculocutaneous nerve

All branches off of the median cord

1. Medial brachial cutaneous nerve

2. Medial antebrachial cutaneous nerve

3. Medial pectoral nerve

4. Ulnar nerve

5. Median root of median nerve

All branches off of the posterior cord

1. Upper subscapular nerve

2. Lower subscapular nerve

3. Thoracodorsal nerve

4. Radial nerve

5. Axillary nerve

Brachial plexus diagram with branches

dorsal scapular nerve: origin

ventral ramus of C5

dorsal scapular nerve: supply

rhomboid major and rhomboid minor muscles in the back

long thoracic nerve: origin

ventral rami of C5, C6 and C7

long thoracic nerve: supply

courses on the external surface of the serratus anterior muscle, which it supplies

nerve to the subclavius: origin

upper trunk

nerve to subclavius: supply

subclavius muscle

suprascapular nerve: origin

upper trunk

suprascapular nerve: supply

both supraspinatus and infraspinatus muscle

lateral pectoral nerve: origin

lateral cord

lateral pectoral nerve: supply

courses deep to the surface of the pectoralis major muscle which it supplies

medial pectoral nerve: origin

medial cord

medial pectoral nerve: supply

pierces the deep surface of pectoralis minor muscle and then pectoralis major, supplying both muscles

medial brachial cutaneous nerve: origin

medial cord

medial brachial cutaneous nerve: supply

pierces the fascia of the proximal arm and supplies the skin on the lower medial arm

medial antebrachial cutaneous nerve: origin

medial cord

medial antebrachial cutaneous nerve: supply

skin on the medial forearm

How does the medial antebrachial cutaneous nerve supply the skin of the medial forearm

descends towards the middle of the forearm, where it pierces the ante brachial fascia and supplies the skin on the medial forearm

upper subscapular nerve: origin

posterior cord

upper subscapular nerve: supply

courses into and supplies the subscapularis muscle

thoracodorsal nerve: origin

posterior cord

thoracodorsal nerve: pathway and supply

courses inferiorly and posteriorly to the deep surface of the latissimus dorsi muscle, which it innervates

lower subscapular nerve: origin

posterior cord

lower subscapular nerve: supply

divides into two muscular branches, one supplying subscapularis muscle and the other supplying teres major muscle

axillary nerve: origin

posterior cord

axillary nerve: pathway and supply

courses inferiorly to the shoulder, passes around the surgical neck of the humerus and innervates teres minor and deltoid muscle

musculocutanous nerve

continuation of lateral cord of brachial plexus

begins after the lateral root to the median nerve is given off

ulnar nerve

continuation of the medial cord

begins after the medial root to median nerve is given off

radial nerve

continuation of the posterior cord of the brachial plexus

begins after the axillary nerve is given off

median nerve

derived from the lateral root of the median nerve and the medial root of the median nerve

The four primary nerves of the upper limb

1. Musculocutaneous nerve

2. Median nerve

3. Ulnar nerve

4. Radial nerve

The musculocutaneous nerve is the continuation of the _________ of the brachial plexus, beginning after the ________ is given off

lateral cord

after the lateral root of the median nerve

Musculocutaneous nerve typically pierces the _______________ muscle.

coracobrachalis muscle

Musculocutaneous nerve descends through the ________

compartment of the arm, coursing between __________

anterior compartment of the arm

between the biceps brachii and brachialis muscles

Musculocutaneous nerve innervates _____ muscles in the arm. What are the muscle names ?

THREE

a. Coracobrachialis

b. Biceps brachii

c. Brachialis

Musculocutaneous nerve emerges _______ to the tendon of the ______ and becomes the ______

lateral to the tendon biceps brachii muscle

antebrachial cutaneous nerve (LAC)

Antebrachial cutaneous nerve (LAC): supply

skin of the lateral forearm

Median nerve originates from the _________ of the median nerve

lateral root and medial root of the median nerve.

What do the lateral and medial roots of the median nerve arise from

These roots arise from the lateral and medial cords of the brachial plexus, respectively

Median nerve descends through the ______ compartment of the arm, where it has _____ muscular or cutaneous innervation.

medial compartment of the arm

NO muscular or cutaneous innervation

Median nerve travels through the ______ where it is found ______ to the brachial artery.

cubital fossa

medial

cubital fossa

a depression on the anterior aspect of the elbow

Within the cubital fossa, median nerve gives off a branch called ______

anterior interosseous nerve (AIN).

As the median nerve enters the forearm, it courses between the ______

two heads of origin of the pronator teres muscle.

In the proximal forearm, median nerve passes _____ to the arch of the _______ with the ________

deep to the arch of flexor digitorum superficialis muscle

with the ulnar artery

The median nerve descends through the forearm, between the _____ and ______ muscles

flexor digitorum superficialis

and

flexor digitorum profundus

Median nerve innervates ___ muscles in the forearm

Name the muscles

FOUR

1. pronator teres

2. flexor carpi radialis

3. palmaris longus

4. flexor digitorum superficialis

Proximal to the flexor retinaculum, median nerve gives off a ______ branch that courses ________ to the flexor retinaculum to cutaneously innervate ______

palmar

anterior

the skin of the lateral palm.

Median nerve then courses through the _______ and enters the hand.

carpal canal

Median nerve then divides into its terminal branches at the ______ border of the flexor retinaculum:

distal

Direct branches of median nerve provide muscular innervation to _____

lumbricals 1 and 2

Digital branches of the median nerve give cutaneous innervation to _______

lateral 3.5 digits anteriorly and their tips posteriorly.

(orange in diagram)

The recurrent branch of the median nerve courses _____ into the _____ area supplying ______ muscles

proximally into the thenar area

2.5 thenar muscles

Anterior interosseous nerve arises as a branch of _______ within ______

median nerve within cubital fossa

Anterior interosseous nerve courses _____ along the ____ surface of the ______

distally along the anterior surface of interosseous membrane

Anterior interosseous nerve innervates ______ muscles in the ______

Name the muscles

2.5 muscles in the forearm

1. Flexor digitorum profundus (lateral half)

2. Flexor pollicis longus

3. Pronator quadratus

Ulnar nerve is the continuation of the ______ cord of the brachial plexus, beginning after ______

medial cord

after the medial root of the median nerve is given off

Ulnar nerve descends through the ______ compartment of the arm,

where it has _____

medial compartment of the arm

NO muscular or cutaneous innervation

Ulnar nerve pierces the ________ of the ______ as it passes from the _____

to the ________ compartment of the arm.

posterior lamina

medial intermuscular septum

medial to posterior compartment

Ulnar nerve then courses posterior to ______

posterior to medial epicondyle

Ulnar nerve enters the forearm by passing between the _______ muscle.

two heads of origin of the flexor carpi ulnaris

Ulnar nerve courses through the forearm between _____ and ______ muscles

flexor carpi ulnaris

and

flexor digitorum profundus

Ulnar nerve innervates ______ muscles in the forearm

1.5

1. Flexor carpi ulnaris

2. Flexor digitorum profundus (medial half)

Ulnar nerve courses with the _____ in the distal half of the forearm

ulnar artery

In the distal forearm, ulnar nerve gives off a ______ branch that

cutaneously innervates the _____

dorsal branch

dorsum of the medial 1.5 digits and hand.

Proximal to the flexor retinaculum, ulnar nerve also gives off a ______ branch that courses ______ to the flexor retinaculum to cutaneously innervate _______

palmar branch

anterior

skin of the medial palm

In the wrist, ulnar nerve is accompanied by the _______ as it enters the hand by passing _______ to the flexor retinaculum, outside the ______ and through _________

ulnar artery

anterior

outside the carpal canal

through Guyons canal

(black arrow)

_______ to the pisiform bone, ulnar nerve divides into its ____ terminal branches

Name the two ternminal branches

lateral

TWO terminal branches

1. Superficial branch of ulnar nerve (red arrow)

2. deep branch of ulnar nerve (blue arrow)

Superficial branch of ulnar nerve courses _____ to _____ muscle

deep

palmaris brevis muscle

Superficial branch of ulnar nerve innervates _____ muscles in the hand

ONE

Superficial branch of the ulnar nerve divides into cutaneous digital branches that supply _____

medial 1.5 digits, anteriorly

Deep branch of ulnar nerve courses between ______

TWO hypothenar muscles

Deep branch of ulnar nerve courses around the ______ to pass ________ across the palm, just anterior to the ______ muscles

hook of the hamate

laterally across the palm

anterior to the interossei muscles

Deep branch of ulnar nerve innervates _________ muscles in the ______

14.5 muscles in the hand

Radial nerve is the continuation of the _________ cord of the brachial plexus, beginning after the _____

posterior cord

axillary nerve is given off