Axilla & Brachial Plexus Part II Flashcards
List the contents of the axilla
Biceps brachii muscle (proximal part)
• Coracobrachialis (proximal part)
• Axillary artery
• Axillary vein
• Brachial plexus
• Lymph nodes
• Axillary process of mammary gland (breast)
Describe the location/position of the mammary gland
Within superficial fascia overlying thoracic wall
- Superolateral region extends along inferior margin of
pectoralis major muscle (toward axilla)
Extension may pass around muscle margin to penetrate deep fascia and enter axilla
What does the Axillary artery supply?
Supplies walls of axilla and related regions
Subclavian artery becomes _____________ at lateral
margin of first rib
Axillary artery
How is the axillary artery divided?
Axillary artery separated into 3 parts by pectoralis minor muscle (crosses vessel anteriorly)
- 1st part: Proximal to pectoralis minor muscle - 2nd part: Posterior to pectoralis minor muscle - 3rd part: Distal to pectoralis minor muscle
Axillary artery becomes ________ at inferior margin of the teres major muscle
Brachial artery
What branch comes out of the 1st part of the axillary artery? And what does this branch supply?
Superior thoracic artery - supplies upper regions of the medial and anterior axillary walls
What branches does the 2nd part give off? And what to these branches supply?
Thoraco-acromial artery - Anterior axillary wall and breast
Lateral thoracic artery- Medial and anterior axillary walls and breast
What branches does the 3rd part of axillary artery give off? What do these supply?
Subscapular artery - Posterior and medial axillary walls and posterior scapular region
Anterior circumflex humeral artery - Shoulder joint, head of humerus, and surrounding tissues
Posterior circumflex humeral artery - Surrounding muscles and shoulder joint
Basilic vein becomes axillary vein at the inferior margin of_________
Teres major muscle
What does the basilic vein drain?
Basilic vein drains posteromedial surface of hand and forearm
Axillary vein becomes _____________ at the lateral border of first rib
Subclavian vein
What does the cephalic vein drain?
-Drains lateral and posterior parts of hand, forearm, and arm
-Passes into clavipectoral triangle and pierces the clavipectoral fascia to join axillary vein.
Where do lymphatics from the upper limb drain into?
They drain into the axillary nodes
Other than the upper limbs, where do axillary nodes also receive drainage from?
They also receive drainage from the trunk and breast.
List the 5 groups of nodes
Humeral (lateral) nodes
Pectoral (anterior) nodes
Subscapular (posterior) nodes
Central nodes
Apical nodes
State the location of each group of nodes
-Humeral (Lateral) nodes: Posteromedial to axillary vein and receive most of lymphatic drainage from upper limb
- Pectoral (Anterior) nodes: Along inferior margin of pectoralis minor muscle
- Subscapular (Posterior) nodes: Posterior axillary wall
- Central nodes: Embedded in axillary fat (receive tributaries from above groups)
- Apical nodes: Most superior group in axilla and drain all other groups
What forms the brachial plexus?
Formed by C5 – T1 anterior rami
Where does the brachial plexus originate, and what is it related to?
Originates in neck
- Passes laterally and inferiorly over first rib
- Enters axilla
-Proximal parts are posterior to subclavian artery in neck
• Distal parts surround axillary artery
What does the brachial plexus give innervation to?
It gives innervation to the upper limb
Name the parts of the brachial plexus from medial to lateral
Roots
Trunks
Divisions
Cords
Describe the roots of the brachial plexus
Anterior rami of C5 - T1
Enter posterior triangle of neck
Passing between anterior & middle scalene muscles
Lie superior and posterior to subclavian artery
What nerve originates from root 5 and innervates the rhomboid major and minor muscles?
Dorsal scapular nerve
The ___________ nerve originates from C5-7 and innervates the serratus anterior muscle
Long thoracic nerve
Where does the Long thoracic nerve lie
Lies on superficial aspect of serratus anterior muscle
Name the trunks that originate from roots
Superior trunk:Formed by roots C5 and C6
2. Middle trunk:Continuation of root C7
3. Inferior trunk:Formed by roots C8 and T1
- Lies on first rib, posterior to subclavian artery
The trunks pass laterally over the _____________ and enter the axilla
1st rib
Describe the suprascapular nerve
Originates from superior trunk (C5 - C6)
Innervates supraspinatus and infraspinatus muscles Accompanied by suprascapular artery
Describe the nerve to subclavius muscle
Small nerve
• Originates from superior trunk (C5 - C6)
• Innervates subclavius muscle
Each trunk divides into ________________
Anterior and posterior divisions
What does the anterior division give rise to?
Anterior divisions ultimately give rise to peripheral nerves associated with anterior compartments of arm and forearm.
What do posterior divisions give rise to?
Posterior divisions ultimately give rise to nerves associated with posterior compartments
T or F: there are two peripheral nerves that originate directly from the divisions of the brachial plexus
False: No peripheral nerves originate directly from divisions of brachial plexus
How many cords originate from divisions?
3 cords
What anatomical structure are the cords related to?
Related to second part of axillary artery
Name the cords and what each cord is formed by.
Lateral cord: Formed by anterior divisions of superior and middle trunks (C5 - C7)
2. Medial cord: Continuation of anterior division of inferior trunk (C8 - T1)
3. Posterior cord: Formed by all 3 posterior divisions (C5 - T1)
T or F: Most major peripheral nerves of upper limb originate from cords
True
What nerve innervates the pectoralis major ONLY?
Lateral pectoral nerve
_______________Passes medially to join a similar branch from medial cord to form median nerve
Lateral root of median nerve
Describe the musculocutaneous nerve
•Passes laterally to penetrate coracobrachialis muscle
• Innervates flexor muscles in anterior compartment of arm
• Terminates as lateral cutaneous nerve of forearm
What nerve receives communicating branch from lateral pectoral nerve and Innervates pectoralis major and minor muscles
Medial pectoral nerve
What nerve Innervates skin on medial side of distal one-third of arm and communicates with intercostobrachial nerve
Medial cutaneous nerve of the arm
What nerve originates just distal to origin of medial cutaneous nerve of arm and innervates skin over medial surface of forearm till wrist
Medial cutaneous nerve of the forearm
What nerve Passes laterally to join similar root from lateral cord to form median nerve (anterior to third part of axillary artery)
Medial root of medial nerve
The ___________ nerve passes through arm and forearm into hand passes posterior to medial epicondyle of humerus
Ulnar
What does the ulnar nerve innervate?
Flexor carpi ulnaris and flexor digitorum profundus (medial half) muscles
- Most intrinsic muscles of hand (except thenar and two lateral lumbrical muscles)
- Skin of hand (with median and radial nerves)
How is the ulnar nerve formed? And explain is course
Formed by union of medial and lateral median nerve roots
• Courses lateral, anterior and then medial to brachial artery
What does the median nerve innervate?
Most muscles in anterior compartment of forearm (except for flexor carpi ulnaris and flexor digitorum profundus [medial half] muscles – ulnar nerve)
- Thenar muscles
- Two lateral lumbrical muscles
- Skin of hand (with ulnar and radial nerves)
List the branches of the posterior cord, as well as what they innervate
Superior subscapular nerve
• Innervates subscapularis muscle
Thoracodorsal nerve
• Innervates latissimus dorsi muscle
Axillary nerve
• Innervates deltoid and teres minor muscles
• Accompanied by posterior circumflex humeral artery
• Gives off superior lateral cutaneous nerve of arm
Inferior subscapular nerve
• Innervates subscapularis and teres major muscles
Radial nerve:
All muscles in posterior compartments of arm and forearm
- Skin on posterior aspect of arm and forearm, lower lateral surface of arm, and dorsal lateral surface of hand
The radial nerve gives off a nerve that innervates skin on posterior surface of arm. Name that nerve
Posterior cutaneous nerve of arm
Scapular winging is due to damage of the _________ nerve
Long thoracic nerve
Why is the long thoracic nerve more vulnerable to damage?
-Long thoracic nerve passes down lateral thoracic wall on the external surface of serratus anterior muscle - Just deep to skin and subcutaneous fascia
-Therefore, nerve is vulnerable to damage (loss of muscle function)
What happens when a person has scapular winging?
Loss of muscle function causes medial border and inferior angle of scapula to elevate away from thoracic wall
- Characteristic “winging” of the scapula when pushing forward with arm
• In addition, normal elevation at arm is no compromised
What is quadrilateral space syndrome?
Hypertrophy of muscles forming quadrangular space may impinge on axillary nerve and posterior circumflex humeral artery and vein
-Produces weakness in deltoid muscle and some atrophy to teres minor - Affects stability of shoulder joint
Branches of axillary artery mnemonic
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Branches of the axillary artery names
Superior thoracis artery
Thoraco- acromial artery
Lateral thoracic artery
Subscapular artery
Anterior circumflex artery
Posterior circumflex artery
