Axilla, brachial plexus and breast Flashcards
What forms the floor of the axilla?
Deep fascia, subcutaneous tissue and skin
What forms the anterior wall of the axilla?
Pectoralis major and minor
Subclavius
Clavipectoral fascia
What forms the posterior wall of the axilla?
Subscapularis
Teres major
The tendon of latissimus dorsi winding around teres major
Which extends lower, the anterior or posterior border of the axilla?
Posterior
What forms the medial wall of the axilla?
Serratus anterior
What forms the lateral wall of the axilla?
Intertubercular or bicipital groove of the humerus
The axillary artery is a continuation of which other vessel?
Subclavian artery
Where does the axillary artery begin?
The outer border of the first rib
What are the branches of the axillary artery?
Subscapular
Anterior and posterior circumflex humeral arteries
Branches to the pectoral muscles, breast and chest wall
What does the subscapular artery become?
Passes backwards to from part of the scapular anastomosis
Where do the circumflex humeral arteries anastomose?
What do they supply?
Around the surgical neck of the humerus
Glenohumeral joint and the deltoid
Which vessels form the axillary vein?
Venae comitantaes and basilic vein. It receives the cephalic vein which pierces the clavipectoral fascia
Where do axillary lymph nodes receive lymph from?
Upper limb, breast and the abdominal wall above the umbilicus
What are the domains of the brachial plexus?
Roots
Trunks
Divisions
Cords
Branches
Where do the trunks of the brachial plexus arise?
Posterior triangle of the neck
When do trunks of the brachial plexus split into anterior and posterior divisions?
Apex of the axilla
What are the cords of the brachial plexus named according to?
Their relationship to the second part of he axillary artery deep to pectoralis minor
Which part of the axillary artery are the branches of the brachial plexus related to?
The third, most distal part
What is he path of the ulnar nerve?
Arises from the medial cord of the brachial plexus
Runs along medial aspect of the arm close to coracobrachialis
Pierces intermuscular septum to lie posteriorly in the groove between the olecranon and the medial epicondyle
Passes between 2 heads of FCU
Forms palmar and dorsal cutaneous branches
Where does the palmar cutaneous branch of the ulnar nerve arise?
Mid forearm
What does the palmar cutaneous branch of the ulnar nerve supply?
Medial side of the palm
Where is the dorsal cutaneous branch of the ulnar nerve located?
What does it supply?
Winds around the ulna, deep to FCU
Ulnar one and a half fingers on their dorsal aspects
What does the ulnar nerve divide into?
Where does this division occur?
Superficial and deep motor branch
The wrist
What vessel does the ulnar nerve run alongside?
Ulnar artery
What does the superficial branch of the ulnar nerve supply?
Palmaris brevis and the skin of the ulnar one and a half fingers via 2 digital branches
What does the deep terminal branch of the ulnar nerve supply?
Muscles of the hypothenar eminence (flexor digiti minimi, abductor digiti minimi and opponens digiti minimi) , all the palmar and dorsal interossei, the ulnar 2 lumbricals and adductor pollicis
What is the path taken by the median nerve from the brachial plexus to the cubital fossa?
Arises from medial and lateral cords of the brachial plexus
Runs down anteromedial aspect of the arm with the brachial artery
Crosses anterior to artery midway down arm to lie medially before reaching the cubital fossa
What is the path taken by the median nerve after it reaches the cubital fossa?
Passes between heads of pronator teres
Passes between FDS and FDP
Emerges lateral to FDS to become superficial proximal to the wrist
Which muscles in the forearm does the ulnar nerve give branches to?
Palmaris longus and flexor carpi radialis
What branches are given off by the ulnar nerve?
Proximal to distal
Anterior interosseous branch
Palmar cutaneous branch
Recurrent muscular branch
Digital branches
Where does the palmar cutaneous branch of the median nerve arise?
What does it supply?
How does it enter the hand?
Proximal to the carpal tunnel
Skin over the thenar eminence
passes deep to the flexor retinaculum
What does the recurrent muscular branch of the median nerve supply?
Thenar muscles
flexor pollicis brevis, abductor pollicis brevis and opponens pollicis
What do the digital branches of the median nerve supply?
Thumb, index, middle and radial half of the ring fingers
Where does the anterior interosseous branch of the median nerve arise?
What does it supply?
After the median nerve has pierced pronator teres. Passes distally on the interosseous membrane .
Supplies flexor pollicis longus, radial half of FDP and ends at pronator teres
What does the radial nerve divide into?
Superficial and deep (posterior interosseous) branch
Describe the path of the superficial branch of the radial nerve
Lies deep to brachioradialis and lateral to radial artery
Distally, it passes deep to the brachioradialis tendon, curves round the lateral side of the radius and pierces the deep fascia
What does the superficial branch of the radial nerve give rise to?
Terminal digital branches
What do the terminal digital branches of the radial nerve supply?
Skin on the radial half of the dorsum of the hand, dorsal aspects of the thumb, index, middle and radial half of the ring fingers, but not beyond the distal interphalangeal joints
Where does the deep branch of the radial nerve go?
Passes between the heads of the supinator to emerge as the posterior interosseous branch
What does the posterior interosseous branch of the radial nerve supply?
Extensors of the wrist and fingers and the supinator
What is the breast composed of?
Fat, connective tissue and glandular elements
How are glandular elements arranged in the breast?
15-20 lobules, each opening independently onto the surface of the nipple
Why is interlobular connective tissue lax in the breast?
To allow for expansion of the glandular elements during pregnancy
Where is the breast located?
Attached from the second to sixth ribs, extending laterally from the lateral sternal edge to the mid axillary line
What is the level of the nipple in young people?
4th intercostal space
What is the axillary tail?
Extension of the breast tissue into the axilla
How is the breast innervated?
4th - 6th intercostal nerves
How is the nipple innervated?
Why is sensory stimulation particularly important here?
4th intercostal nerve
Part of suckling reflex (however secretory control is principally hormonal)
What is the blood supply to the breast?
Axillary, intercostal and internal thoracic arteries
Venous drainage via corresponding veins
What percentage of lymphatic drainage from the breast is via axillary nodes?
75%
How many axillary nodes are there? How are they organised?
20-30 divided into groups according to location
Which groups drain into central axillary nodes?
Where are these nodes?
Anterior/pectoral, posterior/subscapular and lateral
within axillary fat
Where does lymph drain after passing through central nodes in the axilla?
Apical nodes within apex of axilla at the lateral border of the first rib
These drain into the subclavian lymph trunk which drains into thoracic duct on the left and the right lymphatic duct on the right
