1. Brachial Plexus & Axilla Flashcards
What are the origins of the pectoralis major?
- Clavicular head - anterior surface of the medial clavicle.
- Sternal head- anterior sternum,upper 6 costal cartilages and apaneurosis of ext. oblique
What is the innervation of the pectoralis major?
Lateral and medial pectoral nerves
What is the insertion point of the pectoralis major?
Lateral lip of intertubercular sulcus on humerus
What is the action of the pectoralis major?
- Adducts and medial rotates upper limb
- Clavicular head flexes the upper limb
What is the origin of the pectoralis minor?
3-5 ribs
What is the insertion of the pectoralis minor?
Coracoid process
What nerve supplies the pectoralis minor?
Medial pectoral nerve
What action does the pectoralis minor cause?
Stabilises scapula
Draws scapular anterioinferiorly towards ribs
What nerve innervates the coracobrachialis?
Musculocutaneous nerve
What is the origin of the coracobrachialis?
Coracoid process
Where does the coracobrachialis insert?
Medial side of the humerus at the level of the deltoid tubercle.
What is the action of the coracobrachialis?
Flexion of the arm at the shoulder joint
Weak adduction
What are the 3 origins of the deltoid?
Anterior: clavicle
Lateral: acromion
Posterior: spine of scapula
Where does the deltoid insert?
Deltoid tuberosity of humerus
What nerve supplies the deltoid muscle?
Axillary
What action does the anterior part of the deltoid muscle cause?
Flexion of the arm at the shoulder joint
What action does the lateral section of the deltoid cause?
Abduction of the arm at the shoulder joint
What does the posterior section of the deltoid cause?
Extension of the arm at the shoulder joint
What is the origin of the serratus anterior?
Ribs 2-8
What is the insertion of the serratus anterior?
The rib facing surface of medial border of scapula
What nerve supplies the serratus anterior?
long thoracic nerve
What are the actions of the serratus anterior?
Rotates the scapular, allowing arm to be raised over 90 degrees.
Holds the scapula against the rib cage
What nerve roots contribute to the musculocutaneous nerve?
C5,C6,C7
Which nerve roots form the axillary nerve?
C5 and C6
What nerve roots form the median nerve?
C6,C7,C8,T1
Which nerve receives contributions from all 5 routes?
Radial nerve
Which nerve roots contribute to the ulnar nerve?
C8, T1
What are the trunks of the brachial plexus?
Superior, Middle and Inferior
What are the divisions of the brachial plexus?
Anterior and posterior
What are the cords of the brachial plexus?
Lateral, posterior and medial
What are the branches of the brachial plexus?
Musculocutaneous nerve Axillary nerve Median nerve Radial nerve Ulnar nerve
What anatomical landmarks divide the axillary artery into its 3 sections?
Subclavian artery until it passes the FIRST RIB where it become the axillary artery until it passes the TERES MAJOR where it becomes the brachial artery.
Which muscles form the anterior border of the axilla?
Pectoralis major and minor
What is the posterior border of the axilla?
Subscapularis, teres major and latissimus dorsi
What muscles form the medial wall of the axilla?
Serratus anterior
What are the contents of the fibrous axillary sheath?
Axillary artery
Axillary vein
Brachial plexus
Describe the contents of the axilla.
Axillary artery, brachial plexus cords, axillary vein, tendon of biceps brachii and coracobrachialis
Axillary lymph nodes
The lateral, medial and posterior cords are names according to their relationship with which vessel?
Axillary artery
What structure is the lateral border of the axilla?
The intertubercular sulcus of humerus
What are the 5 principle groups of axillary lymph nodes?
Pectoral Sub-scapular Humeral Central Apical
