Axilla + Brachial Plexus

Axilla Boundaries - Apex (3)

1. Rib

2. Scapula

3. Clavicle

The brachial plexus can be seen in between which two mm. in the apex of the axilla?

Between anterior and middle scalene mm.

Axilla Boundaries - Base

Skin of axilla

Axilla Boundaries - Anterior Wall (4)

1. Pectoralis major m.

2. Pectoralis minor m.

3. Subclavius m.

4. Clavipectoral fascia

Pectoral fascia will become the ___?

Axillary fascia

The ___ fascia bends into the axillary fascia?

Clavipectoral

Axilla Boundaries - Lateral Wall

Humerus

Axilla Boundaries - Medial Wall (2)

1. Serratus anterior m.

2. Thoracic wall

Axilla Boundaries - Posterior Wall (4)

1. Subscapularis m.

2. Teres major m.

3. Latissimus dorsi m.

4. Long head of triceps brachii m.

Contents of the Axilla (6)

1. Axillary a.

2. Axillary v.

3. Axillary lymph nodes

4. Brachial plexus (specifically the cords)

5. Coracobrachialis m.

6. Biceps brachii mm.

The axillary a. is a continuation of the ___ a. after it passes under the ___?

Subclavian a., clavicle

Each section of the axillary a. has the ___ number of branches?

Same

Where do the 3 section of the axillary a. occur?

1st = Above (proximal to) the pec minor m.

2nd = Beneath pec minor m.

3rd = Below (distal to) pec minor m.

Axillary a. 1st Section

Superior thoracic a.

Superior Thoracic a. Location

Between the clavicle and axillary a.

- Supplies the superior thoracic cavity

Axillary a. 2nd Section

1. Thoraco-acromial trunk

2. Lateral thoracic a.

Thoraco-acromial Trunk Branches (4)

1. Acromial

2. Clavicular

3. Pectoral

4. Deltoid

What n. does the lateral thoracic a. run with?

Long thoracic n.

Axillary a. 3rd Section

1. Subscapular a.

- Circumflex scapular a.

- Thoracodorsal a.

2. Anterior circumflex humeral a.

3. Posterior circumflex humeral a.

What muscle does the subscapular a. sit in front of?

Subscapular m.

Where does the thoracodorsal a. course to?

Latissimus dorsi m.

Deep vv. of the Arm

- All correspond with the named a.

- Paired brachial vv. (brachial vv. and basilic v. merge to form the axillary a.)

Superficial vv. of the Arm (3)

1. Cephalic v.

2. Median cubital v.

3. Basilic v.

Cephalic v.

- Remains superficial

- Drains into axillary v.

- Lateral

Basilic v.

- Dives deep through the fascia about 1/2 way up the arm

- Medial

Brachial Plexus VR

C5-T1

What mm. does the Brachial Plexus inn.

All mm. of the UL/superficial back except for trapezius m.

Do the BP roots have sensory/motor/both components?

Both (think of them like rami)

How many trunks does the BP have?

3

- Superior (formed from top 2 roots)

- Middle (formed from middle root)

- Inferior (formed from bottom 2 roots)

What do the BP trunks run with?

Subclavian a.

Where are the BP divisions located?

Posterior to the clavicle

Each BP has a ___ and a ___ division?

Anterior, posterior

- 3 total anterior and 3 total posterior divisions

The BP cords are deep to ___?

Pectoralis minor m.

How are the BP cords named?

In reference to their position around the axillary a.

3 BP Cords

1. Medial

2. Posterior

3. Lateral

5 Terminal Branches of the BP

1. Musculocutaneous n. (from lateral cord)

2. Ulnar n. (from medial cord)

3. Radial n. (from posterior cord)

4. Axillary n. (from posterior cord)

5. Median n. (from medial and lateral cords)

What m. does the musculocutaneous n. pierce in the arm?

Coracobrachialis m.

The musculocutaneous n. inn. all of the ___?

Anterior arm

What does the musculocutaneous n. terminate as?

Lateral cutaneous n. of the forearm

The ulnar n. passes ___ to the medial epicondyle?

Posterior

Ulnar n. Inn.

- Inn. 1.5 mm. in anterior forearm

- Inn. most hand mm.

The ulnar n. is important for ___?

Hand dexterity

Ulnar n. Cutaneous Inn.

Medial 1.5 digits, wrist to fingertips

Where does the median n. pass through?

Cubital fossa

Median n. Inn.

- Does nothing in the arm

- Inn. 6.5 mm. in the anterior forearm and a minority in the hand

Median . Cutaneous Inn.

1. Lateral 3.5 digits palm to fingertip

2. 3.5 digits mid-finger to fingertip on dorsum

The radial n. Is a continuation of the ___?

Posterior cord

The radial n. passes over the tendon of ___ before passing ___ to the humerus along the radial groove.

Latissimus dorsi m., posterior

The radial n. passes ___ to the lateral epicondyle of the humerus to enter the ___ forearm?

Anterior, posterior

The radial n. inn. the entire ___?

Posterior forearm

Radial n. Cutaneous Inn.

Posterior/posterior lateral arm, forearm, and for sum of the hand

The Axillary n. is a branch of the ___?

Posterior cord

The Axillary n. passes ___ to the surgical neck of the humerus in the quadrangular space?

Posterior

The Axillary n. inn. which two mm.?

1. Deltoid

2. Teres minor m.

Axillary n. Main Functions (2)

Shoulder abduction and ER

Radial n. Main Function

Extension

Axillary n. Cutaneous Inn.

Skin over the deltoid

4 nn. Of the Supraclavicular BP Branch

1. Dorsal scapular

2. Long thoracic

3. Suprascapular

4. Subclavian

Where can dorsal scapular n. be found?

Under the rhomboid mm.

7 nn. Of the Infraclavicular BP Branches

1. Lateral pectoral

2. Medial pectoral

3. Medial cutaneous n. of arm

4. Medial cutaneous n. of forearm

5. Upper subscapular

6. Lower subscapular

7. Thoracodorsal

Upper BP Injury

Excessive increase in the angle between the neck and shoulder

What does an upper BP injury stretch?

C5 + 6 VR

Lower BP Injury

Rapid increase in the angle of the shoulder joint (abduction or flexion)

What does a lower BP injury stretch?

C8 + T1 VR