Brachial Plexus

Question 1

RTDCB

Answer 1

Rugby - Roots

Teams - Trunks

Don’t - Divisions

Cover - Cords

Bruises - Branches

Question 2

Mnemonic for Branches of the Lateral Cord

Answer 2

Rugby players are

Long - lateral pectoral nerve

Legged - lateral root of median nerve

Movers - musculocutaneous nerve

Question 3

Mnemonic for Branches of median cord

Answer 3

Make - Medial brachial cutaneous nerve

Many - Medial antebrachial cutaneous nerve

Moves - Medial pectoral nerve

Using - Ulnar nerve

Muscles - Middle root of median nerve

Question 4

Mnemonic for the branches of the posterior cord

Answer 4

ULTRA-competitive

U - Upper subscapular nerve

L - Lower subscapular nerve

T - Thoracodorsal nerve

R - Radial nerve

A - Axillary nerve

Question 5

What is the BP part of?

Answer 5

PNS

Question 6

Where does the BP begin?

Answer 6

• the brachial plexus begins in the neck between the anterior and middle scalene muscles
• It passes through the axilla or the armpit and courses through the arm to innervate the muscles, joints, and skin of the upper limb.

Question 7

How are the roots of the plexus formed?

Answer 7

by the anterior or ventral rami of the spinal nerves C5 to T1

Question 8

Where do the roots of the plexus come from?

Answer 8

• A pair of spinal nerves arise from the spinal cord
• spinal nerves pass through intervertebral foramina before dividing into an anterior and posterior ramus

Question 9

What do the rami arise to?

Answer 9

three trunks

• superior, middle, inferior

Question 10

What do the trunks give arise to?

Answer 10

anterior/posterior divison –> form three cords of the brachial plexus – the lateral cord, the posterior cord, and the medial cord. —> branches of nerves

Question 11

First root of Plexus

Answer 11

The first root arises from the anterior ramus of C5, which emerges above the fifth cervical vertebra.

Question 12

4th root of plexus

Answer 12

since there’s no eighth cervical vertebra, the fourth, root which arises from the anterior ramus of C8 emerges above the first thoracic vertebra

Question 13

5th root of plexus

Answer 13

the fifth root arising from the anterior ramus of T1 emerges below the first thoracic vertebra

• This transition is particularly important as the spinal nerves go from emerging above their respective vertebra to emerging below them

Question 14

Where do the trunks of the plexus originate from and where do they go?

Answer 14

The three trunks of the brachial plexus originate from the roots, past laterally over the first rib and enter the axilla

Question 15

First trunk of plexus

Answer 15

• Superior trunk
• formed by the union of the anterior rami of C5 and C6
• Two nerves arise from the superior trunk and they are the subclavian nerve and the suprascapular nerve

Question 16

Middle trunk of plexus

Answer 16

originates directly from the anterior ramus of C7

Question 17

Inferior trunk of plexus

Answer 17

composed of two nerves, the anterior rami of C8 and T1.

Question 18

Divisions of the plexus

Answer 18

• are the bifurcations of the trunks and are the third section of our brachial plexus
• each of the trunks give off one anterior branch and one posterior branch
• The three anterior divisions form part of the brachial plexus that ultimately give rise to nerves associated with the anterior compartments of the upper limb
• whereas the three posterior divisions combine to form parts of the brachial plexus that give rise to nerves associated with the posterior compartments of the upper limb.

Question 19

Lateral cord of plexus

Answer 19

lateral cord is formed by the union of the two anterior divisions of the superior and middle trunk.

Question 20

What nerves come off of the Lateral cord of the plexus

Answer 20

The lateral cord gives rise to a branch known as the lateral pectoral nerve before it continues into the upper limb as the musculocutaneous nerve.

Question 21

Posterior cord of the plexus

Answer 21

The posterior cord is formed by the union of all three posterior divisions

Question 22

What do the posterior cord of the plexus gives rise to?

Answer 22

gives rise to three branches before it terminates as the axillary nerve and the radial nerve – namely, the upper subscapular nerve, the thoracodorsal nerve, and the lower subscapular nerve.

Question 23

Medial cord of plexus

Answer 23

• The medial cord is actually the continuation of the anterior division of the inferior trunk

Question 24

What does the medial cord of the plexus give rise to?

Answer 24

• it gives off three branches before it terminates as the ulnar nerve, and these branches are the medial pectoral nerve, the cutaneous nerve of the arm, and the cutaneous nerve of the forearm.

Question 25

Musculocutaneous nerve

Answer 25

- the terminal branch of the lateral cord of the brachial plexus - And this nerve carries fibers from the anterior rami of spinal nerves C5, C6, and C7.

Question 26

Function of Musculocutaneous Nerve

Answer 26

this nerve provides motor innervation to the muscles of the anterior compartment of the arm - namely the coracobrachialis, the biceps brachii, and the brachialis muscle - It later becomes the lateral cutaneous nerve of the forearm which supplies sensory innervation to the lateral forearm.

Question 27

What does the musculocutaneous nerve eventually become?

Answer 27

- lateral cutaneous nerve

Question 28

Median Nerve

Answer 28

- this nerve is made up of fibers from the lateral cord and the medial cord of the brachial plexus. - The median nerve carries fibers from the anterior rami of C6 to T1

Question 29

Function of Median Nerve - Motor part

Answer 29

- The motor part of the median nerve innervates the flexor muscles of the anterior compartment of the forearm (except flexor carpi ulnaris and part flexor digitorum profundus - ulnar nerve) - It also supplies innervation to the thenar muscles and lateral two lumbricals in the hand

Question 30

Function of Median nerve - sensory part

Answer 30

- The sensory part of the median nerve gives rise to the palmar cutaneous branch which innervates the lateral part of the palm - and the digital cutaneous branch which innervates the lateral three-and-a-half fingers on the palmar surface of the hand.

Question 31

Axillary Nerve

Answer 31

- terminal branch of the posterior cord - circumflex nerve - carries fibers from the anterior rami of C5 and C6

Question 32

Function of Axillary Nerve

Answer 32

. The axillary nerve passes posteriorly around the surgical head of the humerus and provides motor innervation to the deltoid and teres minor muscles - In addition, it gives off the superior lateral cutaneous nerve, which provides sensory innervation to the skin overlying the deltoid muscle.

Question 33

What does the axillary nerve eventually turn into?

Answer 33

- it gives off the superior lateral cutaneous nerve, which provides sensory innervation to the skin overlying the deltoid muscle.

Question 34

Radial Nerve

Answer 34

- largest nerve in the upper limb and carries fibers from the anterior rami of C5 to T1

Question 35

Function of Radial nerve

Answer 35

- The radial nerve supplies motor innervation to the muscles of the posterior compartment of the arm, namely, the triceps brachii and the anconeus - It also innervates the brachioradialis and the muscles of the posterior compartment of the forearm - In addition, it gives off the inferior lateral cutaneous nerve of the arm and the posterior cutaneous nerve of the arm

Question 36

What does radial nerve eventually turn into?

Answer 36

- gives off the inferior lateral cutaneous nerve of the arm which provides sensory innervation to the skin of the lateral lower arm - posterior cutaneous nerve of the arm which provides sensory innervation to the skin of the posterior surface of the arm

Question 37

Ulnar Nerve

Answer 37

- terminal branch of the medial cord, and it carries fibers from the anterior rami of C8 and T1

Question 38

Function of Ulnar Nerve - motor

Answer 38

provides motor innervation to the: - flexor carpi ulnaris - the flexor digitorum profundus (the two medial bellies) - the intrinsic muscles of the hand except for the thenar muscles - the medial two lumbrical muscles

Question 39

Function of Ulnar Nerve - sensory

Answer 39

It also provides sensory innervation to the anterior and posterior surfaces of the medial one-and-a-half fingers and the associated palm area.

Question 40

Nerves arising from Roots

Answer 40

Dorsal scapular Nerve & Long Thoracic Nerve

Question 41

Dorsal Scapular nerve

Answer 41

- a branch arising from the C5 root of the brachial plexus, - motor innervation to the rhomboid and the levator scapulae muscles which are located in the posterior upper neck and back region

Question 42

Long Thoracic Nerve

Answer 42

originates from the anterior rami of C5 to C7 - The long thoracic nerve passes vertically down the neck through the axillary inlet and supplies motor innervation to the serratus anterior muscle.

Question 43

Nerves arising from Superior Trunk

Answer 43

Suprascapular and Subclavian Nerve

Question 44

Suprascapular nerve

Answer 44

arises from the superior trunk - carries fibers from the anterior rami of spinal nerves C5 and C6 - provides motor innervation to the supraspinatus and the infraspinatus muscles - It also supplies sensory innervation to the acromioclavicular joint and the glenohumeral joint.

Question 45

Subclavian nerve

Answer 45

- the nerve to the subclavius - arises from the superior trunk - carries fibers from the anterior rami of C5 and C6 - It provides motor innervation to the subclavius muscle (closely related to clavicle)

Question 46

Nerves arising from cords

Answer 46

Lateral cord - Lateral pectoral nerve Posterior cord - Upper subscapular nerve, Thoracodorsal nerve (middle), Inferior subscapular nerve Medial Cord - Medial pectoral nerve, medial brachial cutaneous nerve, medial cutaneous nerve,

Question 47

Lateral Pectoral Nerve

Answer 47

- arises from the lateral cord - carries fibers from the anterior rami of C5 to C7 - provides motor innervation to the pectoralis major muscle and partly innervates the pectoralis minor muscle

Question 48

Upper subscapular nerve

Answer 48

- superior subscapular nerve - carries fibers from the anterior rami of spinal nerves C5 and C6 - supplies motor innervation to the superior portion of the subscapularis muscle

Question 49

Thoracodorsal Nerve

Answer 49

- middle subscapular nerve - arises from the posterior cord and carries fibers from the anterior rami of C6, 7, and 8 - provides motor innervation to the latissimus dorsi muscle, which is a muscle of the back

Question 50

Lower supscapular nerve

Answer 50

- arising from the posterior cord, carries fibers from the anterior rami of C5 and C6 - supplies motor innervation to the inferior portion of the subscapularis and the teres major muscle.

Question 51

Medial pectoral nerve

Answer 51

arises from the medial cord and carries fibers from the anterior rami of spinal nerves C8 and T1 - provides motor innervation to the pectoralis minor muscle and partly innervates the pectoralis major muscle.

Question 52

Medial brachial cutaneous nerve

Answer 52

- medial cutaneous nerve of the arm - arises from the medial cord and carries fibers from the anterior rami of C8 and T1 - the nerve provides sensory innervation to the skin of the medial arm.

Question 53

Medial cutaneous nerve of forearm

Answer 53

originates just distal to the origin of the medial cutaneous nerve of the arm, and this nerve is also known as the medial antebrachial cutaneous nerve - arises from the medial cord and carries fibers from the anterior rami of C8 and T1 - this nerve provides sensory innervation to the skin of the medial forearm.