Pectoral and Shoulder Regions and Axilla

Comprehensive vocabulary flashcards covering the anatomy of the pectoral region, shoulder muscles, and the boundaries and contents of the axilla based on the lecture by Prof. Anyanwu GE.

Pectoral region

The region lying on the front of the chest consisting of structures which connect the upper limb to the anterolateral chest wall.

Pectoral/shoulder girdle

The skeletal structure formed by the articulation of the scapula and the clavicle.

Sternoclavicular joint

The only small joint connecting the pectoral girdle to the rest of the skeleton.

Acromioclavicular joint

The small joint that joins the scapula and the clavicle bones to one another.

Pectoralis major

The largest muscle of the pectoral region, arising from a clavicular head and a sternocostal head, and inserting onto the lateral lip of the bicipital groove.

Pectoralis minor

A muscle originating from the $3rd$, $4th$, and $5th$ ribs that inserts on the coracoid process of the scapula to depress and protract it.

Subclavius

A muscle originating from the upper surface of the first costal cartilage that steadies the clavicle during shoulder girdle movement.

Clavipectoral Fascia

A thickened membrane of deep fascia located between the subclavius and pectoralis minor, pierced by the lateral pectoral nerve, thoraco-acromial artery, and cephalic vein.

Serratus anterior

A muscle originating from the upper eight ribs and inserting on the medial border of the scapula, responsible for protrusion (drawing the scapula forward).

Winging of the scapula

A clinical condition resulting from paralysis of the serratus anterior following injury to the long thoracic nerve, making the medial border of the scapula unduly prominent.

Deltoid

A powerful, triangular-shaped muscle with anterior, middle, and posterior fibers; it is the principle abductor of the arm and is supplied by the axillary nerve ($C5-C6$).

Supraspinatus

A bipennate muscle originating from the supraspinatus fossa that initiates abduction of the shoulder for the first $15$ degrees.

Infraspinatus

A multipennate muscle that performs lateral rotation of the shoulder and originates from the infraspinatus fossa of the scapula.

Teres Minor

A small round muscle originating from the lateral border of the scapula that acts as a synergist to the infraspinatus in lateral rotation.

Teres major

Often called an offspring of the subscapularis, this muscle extends, medially rotates, and adducts the shoulder.

Subscapularis

A bulky triangular muscle that fills the subscapular fossa and acts as the medial rotator of the humerus.

Axilla

A pyramid-shaped space between the upper part of the arm and the side of the chest that transmits neurovascular structures.

Cervico-axillary canal

Also known as the apex of the axilla, it is bounded by the clavicle, the upper border of the scapula, and the outer border of the first rib.

Axillary artery

A continuation of the subclavian artery that begins at the lateral border of the first rib and becomes the brachial artery at the lower border of the teres major.

Superior thoracic artery

The single branch arising from the first part of the axillary artery.

Second part of the axillary artery

The portion of the artery located behind the pectoralis minor muscle, giving off the lateral thoracic and thoraco-acromial arteries.

Axillary vein

A continuation of the basilic vein that ends at the lateral border of the first rib where it becomes the subclavian vein.

Vena commitantes

An interconnected venous network formed by multiple veins that run with their corresponding arteries.

Axillary nerve

A nerve arising from the posterior cord of the brachial plexus ($C5-C6$) that travels through the quadrangular space.

Regimental badge area

The area of skin covering the inferior region of the deltoid muscle, innervated by the superior lateral cutaneous nerve branch of the axillary nerve.

Apical nodes

Axillary lymph nodes located at the apex of the axilla that receive lymph from all other groups of axillary lymph nodes.

Pectoral (anterior) nodes

Lymph nodes located along the lateral border of the pectoralis major which mainly receive lymph from the anterior thoracic wall and the breast.

Humeral (lateral) nodes

Axillary lymph nodes that receive nearly all the lymph from the upper limb.

Central group nodes

Large lymph nodes situated deep to the pectoralis minor that receive lymph from the pectoral, subscapular, and humeral groups.