Week 2 Flashcards
Which border of the axilla is the pectoralis major part of?
Pectoralis major makes up most of the anterior wall
Which border of the axilla is the serratus anterior part of?
Medial wall
What forms the apex of the axilla? What is its importance?
The clavicle, first rib and the scapula. Structures passing into the upper limb from the thorax usually do so through the apex of the axilla
What is thoracic outlet syndrome?
The space between the clavicle and the first rib can become narrowed, and the vessels and nerves that pass through may become compressed
What can cause thoracic outlet syndrome?
Trauma (fractured clavicle) and repetitive use (lifting occupations etc)
How does thoracic outlet syndrome present?
Pain in the affected limb (where the pain is depends on the nerves affected), tingling, muscle weakness and discolouration
What forms the lateral wall of the axilla?
The intertubecular groove of the humerus and tendon of the long head of the biceps
What forms the medial wall of the axilla?
The serratus anterior and thoracic wall (ribs and intercostal muscles)
What forms the anterior wall of the axilla?
The pectoralis major, underlying pectoralis minor and the subclavius muscle
What forms the posterior wall of the axilla?
The subscapularis, teres major and latissimus dorsi
Name the vascular, muscular and lymph contents of the axilla?
The axillary artery and axillary vein, biceps brachii and coracobrachialis tendons, and the axillary lymph nodes
What are the two largest tributaries of the axillary vein?
The cephalic and basilic veins
What are the three parts of the axillary artery? What are their positions?
One medial to the pectoralis minor, one posterior to the pectoralis minor, and one lateral to the pectoralis minor; the medial and posterior parts travel in the axilla
Where does the majority of the lymph from the breast drain?
Into the axillary lymph nodes; they can be biopsied if breast cancer is suspected
What is axillary clearance? What can be damaged during the procedure?
The removal of the axillary lymph nodes; this is may be performed in patients with breast cancer, to prevent its spread. The long thoracic nerve may be damaged
What are the five parts of the brachial plexus?
Roots, trunks, divisions, cords, branches
Which rami form the roots of the brachial plexus?
Anterior rami of cervical nerves 5, 6, 7, and 8, and the first thoracic nerve, T1
What are the trunks of the brachial plexus? Which roots supply each trunk?
Superior (C5 and C6), middle (C7), and inferior (C8 and T1)
What are the three cords of the brachial plexus?
Lateral, posterior, and medial
Which divisions form the lateral cord of the brachial plexus?
Anterior superior, and anterior middle
Which divisions form the posterior cord of the brachial plexus?
Posterior superior, posterior middle, and posterior inferior
Which divisions form the medial cord of the brachial plexus?
Anterior inferior
What are the branches of the brachial plexus? Which cords do they originate from?
Musculotaneous (lateral cord)Axillary (posterior cord)Median (lateral and medial cords)Radial (posterior)Ulnar (medial)
Which roots does the musculotaneous contain fibres of?
C5, C6, C7
Describe the course of the musculotaneous nerve after it leaves the axilla
Pierces the corachobrachialis muscle, near the point of insertion on the humerus; then passes down the arm, anterior to the brachialis muscle, posterior to the biceps brachii; it emerges laterally to the biceps tendon, and continues in the forearm as the lateral cutaneous nerve of the forearm
Which roots of the brachial plexus is the axillary nerve derived from?
C5 and C6
Describe the course of the axillary nerve after formation in the brachial plexus
Travels inferiorly and laterally, exiting the axilla through the quadrangular space
What is the quadrangular space?
Route for nerves and vessels to pass from the anterior to posterior arm (below glenohumeral joint)
Which structures pass through the quadrangular space?
Axillary nerve and posterior circumflex artery
What are the superior and lateral boundaries of the quadrangular space?
Superior: subscapularis muscle and teres minor
Lateral: surgical neck of humerus
What are the inferior and medial borders of the quadrangular space?
Inferior: teres major muscleMedial: long head of triceps brachii
Which roots of the brachial plexus does the radial nerve contain fibres of?
All 5; C5, C6, C7, C8, & T1
How does the radial nerve exit the axilla? What does it innervate just after leaving?
Posteriorly; supplies branches to long and medial heads of triceps brachii
Which artery does the radial nerve accompany as it travels in the radial groove? What branch of the nerve arises here?
Profunda brachii artery; branch to the lateral triceps brachii arises here
After leaving the radial groove, describe the course of the radial nerve
Anteriorly over the lateral epicondyle of the humerus, through the cubital fossa, and into the forearm, where it divides into motor and sensory branches
Which roots does the median nerve contain fibres of?
C5, C6, C7, C8, T1
Describe the position of the median nerve relative to the brachial artery after leaving the axilla
Initially lateral to brachial artery, then halfway down crosses over to become medial, continuing into the cubital fossa
Which roots does the ulnar nerve contain fibres from?
C8 and T1
Describe the course of the ulnar nerve down the arm?
Descends down medial side of the arm, passes posterior to the medial epicondyle, pierces the two heads of the flexor carpi ulnaris in the forearm, then passes down the forearm alongside the ulna; at the wrist it travels superficially to the flexor retinaculum in the ulnar canal
Where does the arterial supply to the upper limb begin?
Subclavian artery; right branches from brachiocephalic trunk, left directly from aorta
When are the subclavian arteries called the axillary arteries?
After crossing the 1st rib (into the axilla)
Describe the position of the axillary artery relative to the pectoralis minor?
Deep
At what position does the axillary artery become the brachial artery?
Teres major muscle
What is the danger of an axillary aneurysm?
Could put pressure on brachial plexus, manifesting clinically as pain and loss of sensation in the cutaneous distribution of the affected nerves
Which veins join to form the axillary vein at the teres major?
Basilic vein and brachial veins (venae comitantes)
Which structures does the coracoid process compress when the arm is abducted?
Anterior to posterior; subclavian vein, subclavian artery, cords of the brachial plexus
Which structures are contained with the axillary sheath?
Axillary artery, axillary vein and cords and branches of the brachial plexus
Which muscles form the anterior axillary fold?
Mostly pectoralis major (pectoralis minor adds superiorly)
Which muscles form the posterior axillary fold?
Teres major and latissimus dorsi
In a female patient why would you be concerned about enlargement of lymph nodes in the axilla?
Axillary lymph receives from the breast; in breast carcinoma, malignant cells may enter the lymph and produce enlargement
Which important vein lies immediately posterior to the sternoclavicular joint?
Brachiocephalic vein
Which parts of the brachial plexus are most at risk to injury as a result of a clavicular fracture?
Trunks and divisions
How would you acutely assess motor function of a person with a clavicular fracture, with suspected nerve damage?
Don’t! You’ll get sued!
What would be observable differences in determining whether an artery or vein is ruptured as a result of trauma?
Artery may show pulsatile release of blood from an open wound; if there was damage to a major artery the patient would most likely be unconscious and dying; vein rupture would be non-pulsatile, patient conscious, haematoma forming
Why can the upper limb become swollen with lymphatic fluid following axillary clearance?
Excision of the axillary lymph and lymphatic vessels leads to disturbance of the normal lymphatic drainage of the upper limb; the lymph nodes in the axilla receive lymph from the whole of the upper limb
