Brachial Plexus & Arm (Axilla, Arm, and Cubital Fossa)

What mnemonic helps remember the relationship between ulnar collateral and recurrent arteries?

"I Am Pretty Smart" (or "I Am Pretty Sexy")

Match the inferior and anterior arteries (based on "I Am Pretty Smart")

Inferior ulnar collateral artery pairs with Anterior ulnar recurrent artery

Match the posterior and superior arteries (based on "I Am Pretty Smart")

Posterior ulnar recurrent artery pairs with Superior ulnar collateral artery

What are the two major branches extending to the thoracic region?

1. Lateral Thoracic artery

2. Thoracodorsal artery

Name the major arteries in sequence from shoulder to elbow

Axillary artery → Brachial artery → Deep artery of arm

What is the mnemonic for the anterior compartment muscles of the brachium?

"BBC"

• Brachialis

• Biceps brachii

• Coracobrachialis

Where does the long head of biceps brachii originate (origin)?

Supraglenoid tubercle

Where does the short head of biceps brachii originate (origin)?

Coracoid process

What is the insertion point of biceps brachii?

Radial tuberosity (of radius)

What is the origin of the long head of triceps brachii?

Infraglenoid tubercle

What is the origin of the lateral head of triceps brachii?

Posterior surface of humerus proximal to radial groove
*Superior to radial groove

What is the origin of the medial head of triceps brachii?

Posterior surface of humerus distal to radial groove
*Inferior to radial groove

What is the insertion point of triceps brachii?

Olecranon process of ulna

What is the origin of brachialis?

Distal half of anterior surface of humerus

What is the insertion of brachialis?

Ulnar tuberosity and coronoid process of ulna

What nerve innervates the anterior compartment (BBC) muscles?

Musculocutaneous nerve

What nerve innervates the brachialis?

Musculocutaneous nerve

What nerve innervates the coracobrachialis?

Musculocutaneous nerve

What nerve innervates the biceps brachii?

Musculocutaneous nerve

What nerve innervates the triceps brachii?

Radial nerve

What muscle of the brachium (arm) is found in the posterior compartment?

Triceps brachii

What are the actions of biceps brachii?

Flexes forearm

Supination of radioulnar joints

What is the main action of brachialis?

Main flexor of forearm

What is the action of triceps brachii?

Extends forearm

What is the origin of coracobrachialis?

Tip of coracoid process of scapula

What is the insertion of coracobrachialis?

Medial surface of humerus

What are the actions of coracobrachialis?

Assists in flexion and adduction of humerus

Name the two rotator cuff muscles visible in posterior view of scapula

• Supraspinatus (above scapular spine)

• Infraspinatus (below scapular spine)

What nerve and artery travel together through the quadrangular space?

Axillary nerve and posterior circumflex humeral artery

List the trunks of the brachial plexus and their spinal nerve levels

• Upper trunk (C5-C6)

• Middle trunk (C7)

• Lower trunk (C8-T1)

Name the three cords of the brachial plexus

• Lateral cord

• Posterior cord

• Medial cord

What are the five terminal branches (main end branches) of the brachial plexus? (MARMU, from lateral to medial)

• Musculocutaneous nerve

• Axillary nerve

• Radial nerve

• Median nerve

• Ulnar nerve

What does the brachial plexus give rise to?

Large network of nerves that originates in the neck and extends into the axilla, giving rise to most nerves of the upper extremity

What mnemonic helps remember the major classifications of the brachial plexus?

Ron Taylor Drinks Cold Beer

What do the letters in 'Ron Taylor Drinks Cold Beer' stand for?

• R = Rami (roots)

  • 5, C5-T1

• T = Trunks

  • 3, superior, middle, inferior

• D = Divisions

  • 6

• C = Cords

  • 3, posterior, lateral, medial

• B = Branches or nerves

  • 5

*The 5 major parts of the brachial plexus in order

What are the three trunks of the brachial plexus?

• Upper/Superior

• Middle

• Lower/Inferior

What spinal levels form the superior trunk?

C5-C6

What spinal level forms the middle trunk?

C7

What spinal levels form the inferior trunk?

C8-T1

Where are the brachial plexus cords located relative to a key structure?

Around the axillary artery

What does the lateral pectoral nerve innervate?

Pectoralis major

What is the ORIGIN of pectoralis major?

Clavicle, sternum, and first 6 costal cartilages

What is the INSERTION of pectoralis major?

Intertubercular (bicipital) groove of humerus

What is the ACTION of pectoralis major?

ADducts and medially rotates humerus

What NERVES innervate pectoralis major?

Medial and lateral pectoral nerves

What are the two heads of pectoralis major?

Clavicular head and Sternal head

What is the ORIGIN of pectoralis minor?

Ribs 3-5

What is the INSERTION of pectoralis minor?

Coracoid process of scapula

What is the ACTION of pectoralis minor?

Stabilizes scapula

What NERVE innervates pectoralis minor?

Medial pectoral nerve

What is the ORIGIN of subclavius?

Rib 1 at costal cartilage

What is the INSERTION of subclavius?

Inferior surface of clavicle

What is the ACTION of subclavius?

Stabilizes clavicle

What NERVE innervates subclavius?

Nerve to subclavius

What nerve roots (ventral rami) form the brachial plexus?

C5, C6, C7, C8, T1

How many divisions come from the trunks?

Six
*Anterior and posterior divisions from each trunk (3 and 3)

What does "MARMU" stand for?

Main terminal branches of brachial plexus (from lateral to medial)

• Musculocutaneous

• Axillary

• Radial

• Median

• Ulnar

How are the divisions and cords named?

Relative to their relationship with the axillary artery

What is the mnemonic "Median does more, lateral is lazy" referring to?

The median nerve has more innervation/functions compared to lateral nerve branches

What are the nerve roots for the musculocutaneous nerve?

C5-C7

What are the nerve roots for the axillary nerve?

C5-C6

What are the nerve roots for the radial nerve?

C5-T1

What are the nerve roots for the median nerve?

C5-T1

What are the nerve roots for the ulnar nerve?

C8, T1

What nerve innervates the serratus anterior?

Long thoracic nerve (Roots: C5-C7)

What nerve innervates the pectoralis major and minor?

Medial pectoral nerve (Roots: C8-T1)

What nerve innervates the latissimus dorsi?

Thoracodorsal nerve (Middle subscapular nerve) (Roots: C6-C8)

What are the roots of long thoracic nerve?

C5-C7

What muscle does long thoracic nerve innervate?

Serratus anterior

What are the roots of dorsal scapular nerve?

C4-C5

What muscles does dorsal scapular nerve innervate?

Rhomboids and Levator Scapulae

What are the roots of suprascapular nerve?

C4-C6

What muscles does suprascapular nerve innervate?

Supraspinatus and infraspinatus

What other structure does suprascapular nerve innervate?

Superior breast and nipple

What are the roots of nerve to subclavius?

C5-C6

What muscle does nerve to subclavius innervate?

Subclavius

What are the roots of medial pectoral nerve?

C8, T1

What are the roots of medial brachial cutaneous nerve?

C8, T1

What are the roots of medial antebrachial cutaneous nerve?

C8, T1

What are the roots of lateral pectoral nerve?

C5-7

What are the roots of upper subscapular nerve?

C5-C6

What muscle does upper subscapular nerve innervate?

Subscapularis

What are the roots of thoracodorsal nerve?

C6-C8

What muscle does thoracodorsal nerve innervate?

Latissimus dorsi

What are the roots of lower subscapular nerve?

C5-C6

What muscles does lower subscapular nerve innervate?

Subscapularis and teres major

Name THREE muscles innervated by musculocutaneous nerve

Coracobrachialis

Biceps brachii

Brachialis

What muscles does axillary nerve innervate?

Deltoid

Teres minor

What muscles does radial nerve innervate?

Triceps brachii

Extensor antebrachium

What structures does median nerve innervate?

Flexors antebrachium

3 thenar muscles

1st 2 lumbercles

What muscles does ulnar nerve innervate?

Flexor carpi ulnaris

1/2 flexor digitorum profundus

Hand (except 3 thenars, 1st 2 lumbercles)

What parts of the hand does ulnar nerve innervate?

Hand EXCEPT:

3 thenar muscles
1st 2 lumbercles

Fun Task: Use your hand as a tool to memorize nerve roots! (MARMU)

How many total branches are in the brachial plexus?

16

• 11 smaller

• 5 terminal (main end)

List all 4 supraclavicular branches of the brachial plexus

1. Dorsal scapular nerve

2. Suprascapular nerve

3. Nerve to the subclavius

4. Long thoracic nerve

What are all branches from the MEDIAL cord?

1. Medial pectoral nerve

2. Medial antebrachial cutaneous

3. Medial brachial cutaneous

4. Median nerve (medial root, C8-T1)

5. Ulnar nerve

What are all branches from the LATERAL cord?

1. Lateral pectoral nerve

2. Musculocutaneous nerve

3. Median nerve (lateral root, C6-C7)

What are all branches from the POSTERIOR cord?

1. Upper subscapular nerve

2. Thoracodorsal nerve (aka middle subscapular)

3. Lower subscapular nerve

4. Axillary nerve

5. Radial nerve

List all infraclavicular branches of the brachial plexus (3 cords, 7 branches, 5 main end branches)

Medial cord
- Medial pectoral nerve
- Medial brachial cutaneous
- Medial antebrachial cutaneous
- Median nerve (medial root)
- Ulnar nerve

Lateral cord
- Lateral pectoral nerve
- Musculocutaneous nerve
- Median nerve (lateral root)

Posterior cord
- Upper subscapular nerve
- Thoracodorsal nerve
- Lower subscapular nerve
- Axillary nerve
- Radial nerve

What are the spinal roots of the LATERAL cord?

C5, C6, C7