Axilla And Brachial Plexus Flashcards
What does the axilla contain?
- axillary artery, vein, and branches
- infraclavicular parts of the brachial plexus and its branches
- lymph nodes and vessels
- loose adipose tissue
Apex
- continues into the root of the neck between the external border of 1st rib, superior scapular border, posterior surface of the clavicle and medial aspect of the coracoid process
- allows for passage of nerves and vessels into the axilla
Base
- skin and thick layer of axillary fascia
- between the inferior borders of the pectoral is major anteriorly and latissimus dorsi posteriorly
- covered with hair in postpubertal persons
Anterior wall
- formed by the pectoralis Major and minor and lateral part of clavicle
- pec major covers the majority of the wall, pec minor covers its intermediate part
- clavicle and underlying subclavius muscles are located near the apex
Posterior wall
Covered primarily by subscapularis, teres major intermediate, and latissimus dorsi inferiorly
Lateral wall
Anterior and posterior walls converge toward the insertion of the muscles of the intertubercular groove
Medial wall
Thoracic cage covered by serrated anterior muscle
Axillary artery supplies what?
Upper extremity
What does the main trunk of the axillary artery begin as?
Subclavian artery
What does subclavian artery pass before becoming the ‘axillary artery’?
the first rib
As the axillary artery passes out of the axilla, it becomes?
Brachial artery
Subclavian artery
- On the right side, it branches off the brachiocephalic trunk
- On the left side, it comes from the aortic arch
- It is divided into 3 parts
Main branches of the subclavian and axillary arteries
- vertebral artery
- internal thoracic a.
- thyrocervical trunk
- dorsal scapular a.
Vertebral artery
- Blood supply to CNS
- located in the transverse foraminae of cervical vertebrae
Internal thoracic artery
- blood to diaphragm
- anastomosis with intercostal a.
- can be used in CABG surgery to anterior wall of heart
Thyrocervical trunk
- usually from the 1st part of the subclavian a.
- branches into inferior thyroid a., suprascapular a., superficial cervical a., transverse cervical a.
What divides the axillary artery into 3 parts?
Pectoralis minor
3 main branches of the axillary artery
- thoracoacromial a. (Trunk)
- lateral thoracic a.
- subscapular a.
- anterior circumflex humeral a.
- posterior circumflex humeral a.
Thoracoacromial a. (Trunk) branches
- pectoral
- acromial
- clavicular
- deltoid
Pectoral branch of thoracoacromial a.
- lies between pec. Major and pec. Minor
- anastomotic with intercostal branches of internal thoracic and lateral thoracic a.
Acromial branch of thoracoacromial a. (Trunk)
- crosses coracoid process under deltoid to supply deltoid
- anastomotic with suprascapular a., deltoid branch of thoracoacromial a., posterior circumflex humeral a.
Clavicular branch of thoracoacromial a. (Trunk)
To subclavius m.
Deltoid branch of thoracoacromial a. (Trunk)
- crosses pec. Minor
- supplies pec. Minor and deltoid
- anastomotic with acromial branch
Lateral thoracic artery
- females have lateral mammary branches to mammary gland
- supplies pec major, pec minor, and serratus anterior
Lateral thoracic artery anastomotic with?
Internal thoracic, subscapular, intercostal a., and pectoral branches of thoracoacromial a.
Subscapular artery
- largest branch of axillary
- branches into circumflex scapular a.
- supplies scapular muscles via scapular anastomosis
What does subscapular artery anastomose with?
Lateral thoracic and intercostal aa., and deep branch of transverse cervical
What scapular muscles are supplied by subscapular artery?
- supraspinatus
- infraspinatus
- subscapularis
- teres major and minor
- posterior part of deltoid
- latissimus dorsi
- some of the long head of triceps
What is the terminal branch of the subscapular artery?
Thoracodorsal artery to the latissimus dorsi
Anterior circumflex humeral artery
- from the lateral side of the axillary a.
- behind coracobrachialis and short head of biceps
- supplies humeral head and glenohumeral joint
Anterior circumflex humeral artery anastomoses with?
Posterior circumflex humeral artery
Posterior circumflex humeral artery
- goes around the posterior side of humerus thru quadrangular space
- supplies the GH joint, deltoid, teres major and minor, and long and lateral heads of triceps brachii
Posterior circumflex humeral artery anastomoses with?
- anterior circumflex humeral a.
- branches of suprascapular and thoracoacromial trunk
- descending branches anastomose with branches of the brachial a.
Cephalic vein location
- Over the anatomical snuff box
- ascends laterally to the cubital fossa
Median cubital vein
- medially directed branch of the cephalon vein
- joins the basilic vein on medial side of arm
- continues up lateral side of arm to empty in the axillary vein thru the deltopectoral groove (near acromion)
Which vein is common for venupuncture?
The medial cubital vein
Basilic vein
- begins medially on the dorsum of the hand
- ascending and wrapping on the anteromedial surface of the arm (receives median cubital vein here)
What vein becomes the axillary vein?
Basilic vein
-by perforating deep fascia just distal to the axilla, where it is paired with the axillary artery
Median vein of the forearm
- ascends on the medial (ulnar) side of the forearm
- joins the basilic and median cubital veins on the distal end of the anteromedial surface of the arm
- 2nd choice for blood donations
The brachial plexus is the union of?
- lower 4 cervical primary ventral rami (C5-C8)
- large portion of the 1st thoracic primary ventral ramus
Major “parts” of the brachial plexus
- Roots
- Trunks
- Divisions
- Cords
Roots of the brachial plexus
- ventral rami of C5-T1
- located in the root of the neck
What roots of the brachial plexus combine to form the upper trunk?
C5, C6
What forms the middle trunk?
C7
What combines to form the lower trunk?
C8, T1
Each trunk divides into what?
-an anterior (ventral) and posterior (dorsal) division
Where do the divisions of the brachial plexus take place?
At the level of the clavicle
What forms the cords of the brachial plexus?
The union of the divisions
Lateral cord of brachial plexus
-formed by combining the anterior divisions of the upper and middle trunk
(Lateral to the axillary artery)
Medial cord of brachial plexus
-formed by continuation of the anterior division of the lower trunk
(Descends behind and then medial to the axillary artery)
Posterior cord of the brachial plexus
-formed by combining the posterior divisions of all 3 trunks
(Behind the axillary artery)
Branches of brachial plexus are designated as either….?
-supraclavicular or infraclavicular depending on their relative position to the clavicle
Supraclavicular from roots:
- phrenic n.
- dorsal scapular n.
- long thoracic n.
Supraclavicular from trunks:
- n. to subclavius
- suprascapular n.
Infraclavicular from lateral cord:
- lateral pectoral n.
- musculocutaneous n.
- lateral part of median n.
Infraclavicular from medial cord:
- medial pectoral n.
- medial cutaneous n. of forearm
- medial cutaneous n. of arm
- ulnar n.
- medial part of median n.
Infraclavicular from posterior cord:
- upper subscapular n.
- thoracodorsal n.
- lower subscapular n.
- axillary n.
- radial n.
