Axilla Flashcards
Shape of axilla
Irregularly shaped pyramidal space with
four sides
an inlet
a floor (base)
Inlet of axilla
Lateral margin of rib I
Clavicle (anteriorly)
Superior margin of scapula to coracoid process (posteriorly)
Subclavian artery becomes axillary artery as it passes over lateral margin of rib I.
Axillary vein anterior to axillary artery, which is anterior to brachial plexus.
Inferior trunk of brachial plexus lies directly on rib I, as does subclavian artery and vein. Subclavian artery and vein separated by anterior scalene muscle as they pass over rib I.
Anterior wall of axilla
Pectoralis major and minor
Subclavius muscle
Clavipectoral fascia
Lateral wall
Intertubercular sulcus
Posterior wall
Subscapularis
teres major
latissimus dorsi
long head of triceps brachii
Floor of axilla
Skin of armpit
Opens laterally into arm
Medial wall of axilla
Upper thoracic wall
Serratus anterior muscle
Pectoralis major
Two heads - clavicular head (from medial half of clavicle) and sternocostal head.
Insertion: lateral lip of intertubercular sulcus of humerus
Medial and lateral pectoral nerves
Subclavius
Origin: first rib at junction between rib and costal cartilage
Insertion: groove on interior surface of middle 1/3 clavicle
Nerve to subclavius
Pectoralis minor
origin: Ribs III to V
insertion: coracoid process of scapula
medial pectoral nerve
Clavipectoral fascia
Thick sheet of tissue that connects clavicle to floor of axilla. Encloses subclavius and pectoralis minor and spans the gap between them
Structure passing between subclavius and pec minor through clavipectoral fascia
Cephalic vein
Thoraco-acromial artery
Lateral pectoral nerve
Structures passing beneath pec minor through clavipectoral fascia
Medial pectoral nerve
Lateral thoracic artery
leaves axilla by passing through fascia inferior to pec minor muscle
Subscapularis
Insertion: lesser tubercle of humerus
Innervation: upper and lower subscapular nerves
Medial rotation of arm
Forms the largest component of posterior wall of axilla
Tendon crosses anteriorly to joint capsule of glenohumeral joint
Teres major
Origin: posterior surface of inferior angle of scapula
Insertion: medial lip of intertubercular sulcus
Innervation: lower subscapular nerve
Medial rotation and extension of arm
Defines inferior limit of axilla laterally
Long heads of triceps brachii
Origin: infraglenoid tubercle of scapula
Insertion: olecranon process of ulna
Radial nerve
Extension of forearm
Contents of axilla
Major vessels
Nerves and lymphatics of upper limb
Proximal parts of coracobrachialis and biceps brachii
Axillary process of breast
Biceps brachii
Origin: long head (supraglenoid tubercle), short head (apex of coracoid process)
Insertion: Radial tuberosity
Innervation: musculocutaneous (C5-6)
Flexor of forearm and supinator
Tendon of long head passes over head of humerus deep to joint capsule of glenohumeral joint and enters intertubercular sulcus where it is held in position by transverse humeral ligament
Coracobrachialis
Origin: apex of coracoid process
Insertion: Linear roughening on midshaft of humerus on medial side
Innervation: musculocutaneous C5-6
Flexor of arm
Axillary artery nomenclature
Subclavian becomes axillary lateral margin of rib I
Axillary becomes brachial beneath teres major
Axillary parts
3 different pars separated by pectoralis minor which crosses anteriorly to axillary artery
Axillary branches
1st part - superior thoracic 2nd part (2) - thoraco-acromial artery, lateral thoracic 3rd part (3) - subscapular, anterior circumflex, posterior circumflex
Branches of thoraco-acromial
Deltoid - passes into clavipectoral triangle
Pectoral - supplies breast
Clavicular
Acromial
LAteral thoracic artery
Contribute to vascular supply of breast
Subscapular artery
Largest branch of axillary artery
Divides into circumflex scapular artery and thoracodorsal artery
Axillary vein
Begins at inferior margin of teres major and is a continuation of basilic vein
Goes through axilla medial and anterior to axillary artery, becomes subclavian vein after lateral border of rib I
Tributaries of axillary vein
Follows axillary artery
Brachial vein
Cephalic vein
Cephalic vein
Superficial vein on lateral and posterior part of arm
At shoulder, passes into clavipectoral triangle between deltoid, pectoralis major and clavicle. Pierces clavipectoral fascia to join axillary vein
Brachial plexus
Anterior rami of C5-C8 and most of anterior ramus of T1 Roots Trunks Divisions Cord Branches
Passes posterior to subclavian atery in the neck, whilst more distal regions surround axillary artery
Roots of brachial plexus
Enter posterior triangle of neck by passing between anterior scalene and middle scalene
Lies posterior and superior to subclavian artery
C5-T1
Trunks
passes laterally over rib I and enter axilla
Superior trunk - C5-6
Middle - C7
Inferior - C8-T1
Inferior trunk posterior to subclavian artery
Superior and middle more superior in position
Divisions
Each trunk split into anterior and posterior division
3 anterior divisions - anterior compartment of arm and forearm
3 posterior divisions - posterior compartments
Cords
related to 2nd part of axillary artery
Lateral cord - C5-C7
Medial - C8-T1
Posterior - C5-T1
Anterior compartment - medial and lateral
Posterior compartment - posterior
Branches of roots
Dorsal scapular nerve C5 - rhomboid major and minor
Contribution to phrenic nerve C5
Long thoracic nerve C5-7
Branches of trunk
Only upper trunk has branches
Suprascapular nerve C5-6
nerve to subclavius muscle C5-6 (passes anteroinferiorly to subclavian vein)
Suprascapular nerve
Infraspinatus and supraspinatus
Passes laterally through posterior triangle of neck and through suprascapular foramen
Accompanied in lateral parts of neck and posterior scapular region y suprascapular artery
Branches of lateral cord
Lateral pectoral nerve
Musculocutaenous nerve
Lateral root of median nerve
Lateral pectoral nerve
Most proximal branch from lateral cord
Passes anteriorly together with thoraco-acromial artery to penetrate clavipectoral fascia between subclavius and pectoralis minor
Innervates pec major
Musculocutaneous nerve
large terminal branch of lateral cord
Pass between biceps brachii and brachialis in the arm
Innervates all 3 flexor in anterior compartment of arm, terminating as lateral cutaneous nerve of the forearm
Lateral root of median nerve
Largest terminal branch of lateral cord and passes medially to join a similar branch from medial cord to form median nerve
Branches of medial cord
5 medial pectoral nerve medial cutaneous nerve of arm medial cutaneous nerve of forearm medial root of median nerve ulnar nerve
Medial pectoral nerve
Most proximal branch of medial cord
passes anteriorly between axillary artery and vein
Ulnar nerve
Large terminal branch of medial cord
Median nerve
Formed anterior to third part of axillary artery by union of lateral and medial roots (from lateral and medial cord)
Enters arm anterior to brachial artery
Branches of posterior cord
5
Superior subscapular nerve - subscapularis
Thoraco-dorsal nerve - latissimus dorsi
Inferior subscapular nerve - subscapularis and teres major
Axillary nerve
Radial nerve
Axillary nerve
Innervates deltoid and teres minor
Superior lateral cutaneous nerve of arm originates from axillary nerve after passing through quadrangular space and loops around posterior margin of deltoid muscle
Radial nerve
largest terminal branch of posterior cord.
Posterior cutaneous nerve of arm originates from radial nerve in axilla and innervates skin on posterior surface of arm
Injuries to brachial plexus
Spinal cord injuries in cervical region - roots of brachial plexus
Severe trauma to first rib - trunks
Division and cords - dislocation of glenohumeral joint
Lymphatics in upper limb
All lymphatics in upper limb drain into lymph nodes in axilla.
Axillary nodes drainage
Extensive area from adjacent trunk, including regions of upper back and shoulder, lower neck, chest and upper anterolateral abdominal wall
75% of mammary gland
Groups of axillary nodes
Lateral (humeral) nodes Anterior (pectoral) nodes Subscapular (posterior) nodes Central nodes Apical nodes
Lateral (humeral) nodes
receives most from the upper limb
Anterior (pectoral) nodes
located around inferior margin of pectoralis minor, receive from mammary gland
Central nodes
Receive from humeral, subscapular and pectoral nodes
Apical nodes
Most superior group of nodes in axilla and drain all other groups. Receives lymphatic vessels accompanying cephalic vein + vessels draining superior region of mammary gland
Converge to form subclavian trunk and joins venous system at the junction between right subclavian vein and right internal jugular vein. On the left thoracic duct.
