Axilla and Brachial Plexus Flashcards
Where is the axilla?
Pyramidal space inferior to the shoulder joint and just superior to the armpit
Where is the medial wall of the axilla?
Superolateral aspect of the chest
Where is the axilla a gateway to?
The upper limb
Where is the pectoralis major?
Forms anterior wall of axilla, lower border is contained in the inferior edge of the anterior axillary field
What actions does pectoralis major perform?
One of main muscles of climbing (alongside latissimus dorsi), important accessory muscle of inspiration
What is the axillary vein a continuation of?
Continuation of the brachial vein (deep vein of the arm)
Where does the brachial vein become the axillary vein?
At lower border of teres major
What is the association between the teres major and the axilla?
Contributes to posterior wall of axilla, inferior border corresponds to the inferior extent of the axilla
Where can the pulsations of the subclavian artery be palpated?
Where the artery crosses the first rib
Where does the subclavian artery become the axillary artery?
At the lateral border of the first rib
Where does the brachial plexus supply and what is it formed from?
Supplies the upper limb; formed from a very specific intertwining of the anterior rami of spinal nerves C5-T1
What does the brachial plexus contain (from proximal to distal)?
Roots, trunks, divisions, cords, named nerves
What are the roots of the brachial plexus?
Anterior rami of C5-T1 spinal nerves, which mix their fibres to form trunks
What are nerve trunks?
Combinations of roots which give rise to divisions
What are the trunks of the brachial plexus?
Superior = combined anterior rami of C5-6 spinal nerves Middle = anterior ramus of C7 spinal nerve Inferior = combined anterior rami of C8 and T1 spinal nerves
What are nerve divisions?
Anterior and posterior divisions of each trunk which combine to give cords
What are the cords of the brachial plexus named according to?
Their relationship to the axillary artery
What are the cords of the brachial plexus?
Medial = direct continuation of anterior division of inferior trunk Lateral = formed from the anterior divisions of the superior and middle trunks Posterior = formed from posterior divisions of all three trunks
What are the named nerves of the brachial plexus?
Ulnar nerve = continues directly from medial cord
Musculocutaneous nerve = continues directly from lateral cord
Axillary and radial nerves = divisions of posterior cord
Median nerve = contributed to by the medial and lateral cords
Where are the roots and trunks of the brachial plexus located?
Lie mainly between the anterior and middle scalene muscles in the root of the neck
Where are the divisions of the brachial plexus located?
Lie immediately posterior to the subclavian vessels in the root (deep to the clavicle)
Where are the cords of the brachial plexus located?
Lie around the axillary artery, which is distal to the first rib
Where does the musculocutaneous nerve enter the axilla to supply?
The coracobrachialis muscle, also supplies other muscles of the anterior compartment of the arm (biceps brachii and brachialis)
Where do both the axillary nerve and the radial nerve pass through the axilla to?
Into the posterior compartment of the arm
