Muscles of the Pectoral Region Quiz

Study Notes

Pectoralis Major:
- Origin: Clavicle and ribs 2-6
- Insertion: Intertubercular sulcus of humerus
- Nerve: Lateral and medial pectoral nerves
- Action: Flexes, adducts, and medially rotates the arm
Pectoralis Minor:
- Origin: Ribs 3-5
- Insertion: Coracoid process of scapula
- Nerve: Lateral or medial pectoral nerve
- Action: Stabilizes scapula
Subclavius:
- Origin: 1st rib
- Insertion: Inferior surface of the clavicle
- Nerve: Nerve to subclavius
- Action: Anchors and depresses clavicle
Serratus Anterior:
- Origin: Ribs 1-8
- Insertion: Medial border of the scapula
- Nerve: Long thoracic nerve
- Action: Protracts and rotates scapula

Anterior Wall: Pectoralis major, pectoralis minor, and the clavipectoral fascia
Lateral Wall: Humerus
Posterior Wall: Subscapularis, latissimus dorsi, and teres major
Medial Wall: Serratus anterior overlying the thoracic wall

Axillary sheath: Encloses the axillary artery and vein.
Brachial Plexus: Its three cords and their branches.
Biceps Brachii Muscle: Short head and tendon of the long head.
Coracobrachialis Muscle:
Axillary Lymph Nodes: Five principal groups:
- Pectoral (anterior)
- Subscapular (posterior)
- Humeral (lateral)
- Central
- Apical

First Part: Between the lateral border of the 1st rib and the medial border of the pectoralis minor.
- One branch: Superior thoracic artery.
Second Part: Posterior to pectoralis minor.
- Two branches: Thoracoacromial and lateral thoracic arteries.
Third Part: From the lateral border of pectoralis minor to the inferior border of teres major.
- Three branches: Subscapular artery, anterior circumflex humeral, and posterior circumflex humeral arteries.

Three parts that correspond to the three parts of the axillary artery.
Cephalic vein enters the axillary vein superior to the pectoralis minor, close to its transition into the subclavian vein.

Efferent vessels from the apical group ultimately unite to form the subclavian lymphatic trunk.
The subclavian trunk joins other lymphatic trunks to make the right lymphatic duct.

Supraclavicular Branches:
- Dorsal scapular
- Long thoracic
- Suprascapular
- Subclavian
Infraclavicular Branches:
- Lateral pectoral
- Medial pectoral
- Medial cutaneous nerve of the arm
- Medial cutaneous nerve of the forearm
- Thoracodorsal
- Upper subscapular
- Lower subscapular

Separated from the posterior compartment by the humerus, medial, and lateral intermuscular septae.
Contents:
- Muscles of the anterior compartment
- Brachial artery
- Basilic vein
- Musculocutaneous, median, and ulnar nerves.

Biceps Brachii:
- Origin: Short head: tip of coracoid process.
- Long head: supraglenoid tubercle of scapula.
- Insertion: Radial tuberosity.
- Nerve: Musculocutaneous nerve.
- Action: Supinates the forearm and, when it is supine, flexes the forearm.
Coracobrachialis:
- Origin: Tip of coracoid process.
- Insertion: Medial surface of humerus.
- Nerve: Musculocutaneous nerve.
- Action: Helps flex and adduct the arm.
Brachialis:
- Origin: Anterior surface of the humerus.
- Insertion: Coronoid process of the ulnar tuberosity.
- Nerve: Musculocutaneous and radial nerve.
- Action: Flexes the forearm.