Upper Extremity: Axilla and Brachial Plexus Flashcards
Axilla
- Passageway from neck to upper limb
- Begins at cervico-axillary canal (clavicle, 1st rib, superior scapula)
Boundaries of axilla
- Apex (superior): cervico-axillary canal
- Base (inferior,floor): axillary fascia
- Anterior: pectoralis major and minor
- Posterior: latissimus dorsi, teres major, subscapularis
- Medial: thoracic wall (ribs 1-5, intercostal muscles, serratus anterior)
- Lateral: intertubercular sulcus of the humerus
Content of axilla
- Axillary artery/vein
- Cords and branches of the brachial plexus
- Lymphatics and axillary lymph nodes
Axillary sheath surrounds
- Axillary vessels
- Brachial plexus cords
Subclavian branches that contribute to the scapular region
- Dorsal scapular
- Branch from either transverse cervical or subclavian directly
- Suprascapular
3 parts of the axillary artery
- Part 1: outer border of rib 1 up to pectoralis minor
- Part 2: posterior to pectoralis minor
- Part 3: outer edge of pectoralis minor to inferior edge of teres major
Branches of axillary artery 1st part
- Superior thoracic artery (Highest or supreme thoracic artery)
Branches of axillary artery 2nd part
- Thoracoacromial artery
- Acromial branch
- Clavicular branch
- Pectoral branch
- Deltoid branch (accompanies cephalic vein)
- Lateral thoracic artery
Branches of axillary artery 3rd part
- Subscapular artery
- Anterior circumflex humeral artery
- Posterior circumflex humeral artery
Subscapular artery branches
- Circumflex scapular artery
- Thoracodorsal artery
Anterior circumflex humeral artery
- Supplies surgical neck/humeral head/GH joint
Posterior circumflex humeral artery
- Supplies surgical neck/humeral head/GH joint
- Can anastomosis with profunda brachii artery
Arterial anastosomes around the scapula
- Provide alternate means of blood supply
- Occlusion/ligation of subclavian or axillary arteries
Arteries involved with collateral circulation around scapula
- Transverse cervical
- Descending scapular (dorsal scapular)
- Suprascapular
- Subscapular and circumflex scapular
- Branches from posterior intercostals (2-7)
Axillary lymph nodes
- Anterior (pectoral)
- Posterior (subscapular)
- Lateral (humeral)
- Central
- Apical
Anterior (pectoral) axillary lymph nodes
- Located around the lateral thoracic vessels/pec minor
Posterior (subscapular) axillary lymph nodes
- Located along posterior axillary fold and subscapular vessels
Lateral (humeral) axillary lymph nodes
- Located along lateral wall of axilla, medial and posterior to axillary vein
- Receive most lymph from upper extremity except that which parallels the cephalic vein
Central axillary lymph nodes
- Located deep to pec minor
- Receives lymph from anterior, posterior, and lateral axillary nodes
Apical axillary lymph nodes
- Located at the apex of axilla
- Lymph directly from pectoral region and lateral upper extremity
Apical node pathway
Apical nodes –> subclavian lymphatic trunk –> right lymphatic duct (right) and thoracic duct (left)
Brachial plexus
- Origin of the nerves of the upper limb
- Most branches arise in the axilla (not all)
- Formed by anterior rami of C5 – T1 (sometimes C4 and T2 may contribute)
Brachial trunks (superior, middle, and inferior trunks)
- Each divides into an anterior and posterior division at the cervico-axillary canal
Superior trunk of brachial plexus
- Union of C5,6 roots (anterior rami)
Middle trunk of brachial plexus
- C7 root
Inferior trunk of brachial plexus
- Union of C8,T1
Anterior divisions from superior and middle trunk
- Unite to form the lateral cord
Anterior division from the inferior trunk
- Forms the medial cord
Posterior divisions from all 3 trunks
- Unite to form the posterior cord
Roots (ventral rami)
- Pass between anterior and middle scalene muscles
- Receive sympathetic fibers from middle and inferior cervical (stellate) ganglia
Supraclavicular/infraclavicular branches
- Some branches arise from the roots and upper trunk
- No branches from the divisions
- Most branches arise from the cords
Branches from roots (ventral rami)
- Dorsal scapular (C5, sometimes C4)
- Long thoracic (C5-7)