Axilla and the brachial plexus Flashcards
what is the axilla?
- an anatomical region (armpit) under the shoulder joint** where the arm connects to the shoulder **
- it contains a lot of neurovascular structures including the brachial plexus, the axillary artery and vein and lymph nodes
what are the major contents of the axilla?
- axillary artery
- axillary vein
- brachial plexus
- nodes
- adipose tissue
what is the anterior border of the axilla?
- pectoralis major muscle
- pectoralis minor muscle
- subclavius muscle
what is the posterior border of the axilla?
- subscapularis
- teres major
- latissimus dorsi
- scapula
what is the medial border of the axilla?
- ribs
- serratus anterior
what is the lateral border of the axilla?
the humerus
where does the pectoralis major muscle originate and insert onto?
- O: 3 places - sternal part of clavicle, the sternum and costal cartilages 1-7, and the rectus sheath
- I: humerus - lateral to the bicipital groove (crista tuberculi majoris)
what are the main actions of the pectoralis major muscle?
- arm adduction
- arm internal rotation
- arm flexion
- elevates the rib cage during inspiration
what nerve supplies the pec major muscle?
- pectoral nerves from the brachial plexus
what are the ‘3 portions’ of the pec major muscle?
- clavicular
- abdominal
- sterno costal
where does the pectoralis minor originate and insert?
- O: ribs 3-5
- I: on the coracoid process of the scapula
what are the actions of the pectoralis minor muscle?
* depression - pulls the scapula anteriorly
* also involved in** elevation of the rib cage** during inspiration
where does the subclavious muscle originate and insert onto?
- O: sternal end of rib 1 and costal cartilage
- I: lower aspect of the clavicle
what nerve supplies the pectoralis minor muscle?
pectoral nerves from the brachial plexus
what is the main action of the subclavius muscle?
- stabilisation of the clavicle during movements of the shoulder girdle
what nerve supplies the subclavius muscle?
- subclavius nerve from the brachial plexus
where does the subscapularis originate and insert onto?
- O: subscapular fossa of the scapula
- I: lesser tubercle of the humerus
what is the main function / action of the subscapularis muscle?
- medial rotation of the arm
what nerve supplies the subscapularis muscle?
the subscapular nerves from the brachial plexus
where does the latissimus dorsi originate and insert onto?
- O: (4 parts) vertebral: spinous processes T7-T12, iliac part - posterior third of crest of ilium, **scapula part: inferior angle of scapula, costal part**: 0 10-12 ribs
- I: intertubucular sulcus/ groove between pec major and teres major (lady between 2 majors)
what nerve supplies the latissimus dorsi?
- thoraco-dorsal nerve from the brachial plexus
what are the main actions of the latissimus dorsi muscle?
- arm adduction
- elevation of the trunk - think of hands on bar
- arm internal rotation
- arm extension
- depression of the scapula
where does the** teres major** originate and insert onto?
- O: lateral margin and inferior angle of the scapula
- I: intertubular groove
what is the origin and insertion of the serratus anterior?
- O : ribs 1-2 (superior), ribs 2-4 (middle) and ribs 5-9 (inferior)
- I: superior part - superior angle of scapula, middle part - medial margin of scapula, inferior part - lower angle of scapula
