Brachial Plexus and Shoulder Region & Development of the Limb Flashcards
What are the different areas of the brachial plexus?
Roots: C5-8 and T1 Trunks: superior, middle and inferior Divisions: anterior and posterior Cords: lateral, posterior and medial Branches: musculocutaneous nerve, median nerve, axillary nerve, ulnar nerve and radial nerve. There is also the long thoracic nerve and the medial and lateral pectoral nerves.
What are the important blood vessels in the axilla/upper arm region.
The subclavian artery becomes the axillary artery and then the brachial artery in the arm. The subclavian vein forms from the axillary vein, the main tributaries of which are the cephalic vein, which is lateral and the brachial and basilic veins.
What is the coracobrachialis muscle’s function? Where does it arise and insert and by what is it innervated?
The coracobrachialis helps to flex the shoulder joint and also adducts the humerus. It arises from the coracoid process of the scapula and inserts on the humerus. It is innervated by the musculocutaneous nerve.
Where does the serratus anterior arise and insert, what is its function and by what is it innervated?
The serratus anterior muscle arises from the side and front of the first 8 ribs, runs back under the scapula and inserts along its medial border. It can pull the scapula forward over the rib cage (protraction) and can rotate it downward and upward. It is innervated by the long thoracic nerve.
Where does the pectoralis minor arise and insert, what is its function and which nerve supplies it?
The pectoralis minor arises from the 3rd-5th ribs and is inserted on the coracoid process. It can cause depression of the scapula - can draw inferiorly and anteriorly and it raises the ribs in inspiration. The medial pectoral nerve innervates it.
What is the function of the pectoralis major, where does it arise and insert and what innervates it?
The pectoralis majorarises from the anterior border of the medial half of the clavicle and sternocostal head and inserts into the lateral lop of the bicipital groove of the humerus. Innervated by the lateral and medial pectoral nerves, it flexes and extends the humerus and adducts and medially rotates the humerus. It also draws the scapula inferiorly and anteriorly.
The deltoid muscle covers the shoulder, where does it arise and insert, what are its function and which nerve serves it?
The deltoid muscle’s origin is the lateral end of the clavicle and spine of the scapula and it inserts into the deltoid tuberosity of the humerus. Innervated by the axillary nerve, it plays a role in shoulder abduction, flexion and extension.
What is the axilla?
The area under the glenohumeral joint, at the junction of the upper limb and the thorax. 3D shape is like a pyramid.
What is the anatomical superior boundary of the axilla?
The opening at the apex/axillary inlet is formed by the lateral border of the 1st rib, superior border of the scapula and the posterior border of the clavicle.
What is the lateral wall of the axilla formed by?
The intertubercular groove of the humerus.
What does the medial wall of the axilla consist of?
The serratus anterior and the thoracic wall.
What does the anterior wall of the axilla contain?
The pectoralis major and underlying pectoralis minor and subclavius muscles.
What is the posterior wall of the axilla formed by?
Subscapularis, teres major and latissimus dorsi.
What are the main contents of the axilla?
Axillary artery, axillary vein (2 largest tributaries are basilic and cephalic veins), brachial plexus, biceps brachii, coracobrachialis, axillary lymph nodes.
What’s the clinical importance of the axillary lymph nodes? What’s axillary clearance and state an associated risk?
They filter lymph drained from the upper limb and the pectoral region. In women, an enlargement in a nonspecific indicator of breast cancer and it can be biopsied if this is suspected. Axillary clearance is when the nodes are removed to prevent cancer spreading. If the long thoracic nerve is damaged in this procedure, a winged scapula can result.
