Axilla Flashcards
What is the axillary sheath and what does it surround?
It’s a continuation of the fascia associated with the anterior and middle scalene muscles. It continues laterally as a tubular sheath that surrounds the nerves of the brachial plexus and the axillary artery but NOT the axillary vein.
Where is the apex of the axilla?
It’s directed upward and medialward and ends in the cervicoaxillary canal leading to the posterior triangle of the neck
What forms the base of the axilla?
the axillary fascia and skin
What form the 4 walls of the axilla?
anterior: pect major/minor and clavipectoral fascia
posterio: subscapularis, teres major, latisimus dorsi
Medial: first 4 ribs, intercostal muscles and upper serratus anterior
Lateral: humerus, coracobrachialis, biceps
Most sttructures coursing between the neck and the axilla do so via what canal?
the cervicoaxillary canal
it’s bound by the clavicle, scapula, and 1st rib.
it leads to the posterior triangle of the neck
What nerve is the lateral branch of the T2 nerve that supplies the lateral chest wall and continues into the medial area of the arm?
the intercostobrachial nerve
Where does the axillary artery begin?
At the lateral border of the 1st rib
THe first part of the axillary artery has one artery, which is…
the superior thoracic artery.
What two arteries branch off the 2nd portion of the axillary artery?
the thoroacromial artery and the lateral thoracic artery
What three arteries branch off the 3rd portion of the axillary artery?
the subscapular artery
the posterior circumflex humeral artery
the anterior circumflex humeral artery
After coming off the 3rd portin of the axillary artery, the subscapular artery divides into what two branches?
the circumflex scapular artery and the thoracodorsal artery
What does the lateral thoracic artery supply?
the breast
What does the circumflex scapular artery do?
It enters the infraspinous process and forms an anastomosis with the suprascapular artery
What does the posterior circumflex humeral artery do after it branches off the axillary artery?
It accompanies the axillary nerve through the quadrangular space and encircles the humerus to anastamose with the anterior cirmculfex humeral artery
At the lateral border of the teres major muscle, the axillary artery because the what artery?
the brachial artery
Where is the brachial plexus located?
in the axilla and in the posterior triangle of the neck
What is the posterior triangle fo the neck formed by?
the anterior border of the trapezius, the posterior border of the sternocleidomastoid and the superior border of the clavicle
What does the brachial plexus originate from?
the ventral rami (roots ) of C5-C8 and T1.
What are the levels of division in the brachial plexus?
- Roots (the ventral rami)
- Trunks (superior, middle, inferior)
- DIvisions
- Cords (Lateral, Posterior, Medial)
- Branches (nerves)
What is the very first nerve coming of C5 before the majority of the brachial plexus?
the dorsal scapular nerve to innervate the rhomboides and the levator scapulae
What is the nerve that comes off the ventral roots of C5, C6, and C7?
the Long thoracic nerve to the serratus anterior
What two neres come off the brachial plexus at the trunk level? What trunk do they come off of?
They come off the superior trunk (because it thinks it’s superior)
the suprascapular nerve (to the supraspinatus and infrapinsatus)
and the nerve to the subclavian nerve
How many divisions are there at the division level of the brachial plexus?
6: an anterior and posterior division from each trunk
What divisions combine to form the lateral cord?
What divisions combine to form the posterior cord?
What divisions combine to form the medial cord?
THe anterior divisions of the superior and middle form the lateral cord
the 3 posterior divisions form the posterior cord
the anterior division of the inferior trunk goes it alone to form the medial cord
What branches are given off by the lateral cord?
It gives off 3:
- lateral pectoral
- musculocutaneous
- the lateral root portion of the median nerve
What are the branchess of the posterior cord?
There are 5: STARS
S: upper Subscapularis
T: Thoracodorsal
A: Axillary
R: Radial
S: lower Subscapularis
What are the branches from the medial cord?
There are 5 again:
- Ulndar nerve
- Median root of the median nerve
- Medial antebrachial cutaneous
- Medial brachial cutaneous
- Medial pectoral
What 6 nerves have contribution from all the levels in the brachial plexus (C5, 6, 7, 8 T1)?
- Axillary nerve
- Radial Nerve
- Median Nerve
- Thoracodorsal nerve
- Upper subscapularis
- Lower subscapularis
WHat 2 nerves only hav econtributions from C5 and C6?
the suprascapular nerve and the subclavius nerve
What 2 nerves have contribution from C5, C6, and C7?
the lateral pectoral and the musculocutaneous
What 4 nerves have contribution only from C8 and T1?
medial pectoral
medial brachial cutaneous
medial antebrachial cutaneous
ulnar nerve
What cord innervates extensor muscles?
the posterior cord
What causes an Erb-Duchenne palsy and what are the symptoms?
It’s an UPPER brachial plexus injury to the C5 and C6 roots
this occurs with an increase in angle between the neck and shoulder during a fall or delivery
You get an adducted arm with medial rotation of the arm (causing a waiter’s tip position of the hand) and an extended elbow
Why do you get the medial rotation of the arm in Erb-Duchenne palsy?
The C5 and C6 ventral rami supply the lateral rotators (infraspinatus and teres minor) and the abductors of the arm (supraspinatus and deltoid)
so you get medial rotation and adduction
What injury causes Klumpke paralysis? What are the symptoms?
This is a lower brachial plexus injury, which occurs when the upper limb is sudddenly pulled supriorly or a baby’s limb is pulled excessively during delivery
You get atrophy of the intrinsic (short) muscles of the hand = claw hand, because C8 and T1 derive the ulnar nerve and then a few of the smaller muscle sin the hand.
What do we call the synovial joint between the acromion and the clavicle? WHat ligament goes along with this?
the acromioclavicular joint and ligament
What ligament achors the distal clavicle to the coracoid process?
the coracoclavicular ligament (composed to a trapezoid and conoid part)
What ligament extends from the acromion to the coracoid process and provides a protective arch above the head of the humerus?
the coracoacromial ligament
