THE PECTORAL REGION AND AXILLA The axilla is a space above the arm pit. This space forms a pyramid with 4 walls, an apex and a base. 1. The anterior axillary wall is formed largely by the Scapula and Subscapularis Serratus Anterior Pectoralis Major Pectoralis Minor C and D Yes. No, E is the answer. The anterior axillary wall is made up of the pectoralis major and minor as well as subclavius muscles and clavipectoral fascia. 2. The posterior axillary wall is formed by Subscapularis (with Scapula behind it) Latissimus Dorsi Teres Major All of the above None of the above Hooray! Well, partly, D is the best answer. With the arm abducted, one can feel the thick muscular anterior and posterior walls. 3. The medial wall of axilla is formed by Deltoid Pectoralis Minor Upper ribs covered with Serratus Anterior and intercostal muscles Coracobrachialis Subscapularis Right. No, C is the answer. 4. The lateral wall of the axilla is the Pectoralis Major Bicipital groove of the humerus Subscapularis coracobrachialis B and D Great. No, the answer is E. The bicipital (intertubercular) groove of the humerus contains the tendon of the long head of the biceps. The lips of this groove serve as the attachment of the anterior and posterior walls of the axilla. 5. The base of the axilla pyramid is the skin and fascia of the arm pit and the apex consists of 3 bones, clavicle, upper border of the scapula and humerus sternum first rib fourth rib first cervical vertebrae Correct. No, C is correct. The first rib is the answer. Now try to visualize this space with 4 walls, base and bony apex. The contents of the axilla consist of the brachial plexus nerves and axillary vessels passing to the rest of the limb as well as the two heads of the biceps,coracobrachialis, numerous axillary lymph nodes and fatty-areolar tissue. 6. The Pectoralis Minor is a key landmark in the pectoral region. This muscle extends from the 3rd, 4th and 5th ribs to the coracoid process clavicle acromion spine of scapula scapular notch Bravo! No, A or the coracoid process is the answer. Coracoid stands for crow's beak and resembles a bent finger projection on the scapula. Another bone related to the upper extremity is the clavicle (or collary bone). Between the upper and lower muscle attachments is a free bony strip easily palpated along the entire anterior margin of the clavicle. 7. The muscles which attach to the superior surface of the clavicle are the Sterno-mastoid and the Latissimus Dorsi Pectoralis Minor Trapezius Deltoid Pectoralis Major Right. No, C or the Trapezius is the answer. The Sterno-mastoid and Trapezius are continuous at their attachment to the skull but they diverge as they descend, leaving the middle third of the clavicle free. 8. The triangle formed between the two muscles and clavicle is called the Posterior triangle of the neck Anterior triangle of the neck middle triangle of the neck A and B A and C Good. No, the answer is A 9. The muscles which attach to the anterior border of the clavicle are the Pectoralis Major and Pectoralis Minor Deltoid Subscapularis Subclavian Teres Minor Correct. No, the answer is B or the Deltoid. 10. The Pectoralis Major and Deltoid are together where they attach to the humerus but diverge when they attach to the clavicle forming another triangle, the Delto-clavicular triangle Delto-pectoral triangle Delto-coracoid triangle Delto-acromial triangle Delto-manubrial triangle Right. No, the answer is B. This triangle permits the passage of the cephalic vein, deltoid branch of the thoraco-acromial artery and lymph vessels. Now the pectoral region and axilla will be covered in more detail. The axilla is best entered through the fleshy anterir wall and fascial base as the remaining walls are bone or bony with overlying muscle. 11. A prominent muscle in the anterior wall, the Pectoralis Major, has already been mentioned. It has two heads of origin, the clavicular and Humeral First rib Sternal-costal Scapular A and C Correct. No, the answer is C, sternal-costal 12. The sternal costal head meets the sternal costal head on the other side along the midline of the body of the sternum. The sternal costal attachment moves up to meet the clavicular head costal head humeral head Very good. No, the answer is A 13. The Pectoralis Major inserts into the crest of the greater tubercle and lateral lip of the bicipital groove of the Scapula Humerus Rib Clavicle First cervical vertebrae Yes. No, the answer is B, the humerus. 14. The action of the Pectoralis Major is clear from its origin and insertion. It rotates the humerus medial as well as producing Abduction Adduction Great! No, the answer is B, adduction. 15. The cephalic vein lies between the Pectoralis Major and the Deltoid. It passes through the delto-pectoral triangle across the anterior aspect of the Pectoralis Minor and passes through the clavi-pectoral fascia to enter the Brachial vein Axillary vein Ulnar vein Subscapular vein Subclavian vein You are right. No, the answer is B, the axillary vein. 16. The axillary vein conceals the first part of the Brachial artery Innominate artery Axillary artery Carotid artery Ulnar artery Fine. No, the answer is C, the Axillary Artery. 17. The axillary fascia is part of a larger fascial sheet, the Mammary fascia Clavipectoral fascia Platysma Pre-vesicle fascia Pera-renal fascia Bravo! No, the answer is B, the Clavipectoral Fascia. 18. The clavipectoral fascia extends down from the clavicle and in so doing, encases two muscles. The first of these muscles is attached to the inferior side of the clavicle and is called the Pectoralis Minor Pectoralis Major Subclavius Subscapularis Deltoid Correct. No, the answer is C, the Subclavius. 19. The second muscle enclosed by the clavipectoral fascia is the Pectoralis Minor Pectoralis Major Subscapularis Teres Major Long head of biceps Right. No, the correct answer is A, the Pectoralis Minor. In summary, the Clavipectoral Fascia extends from the clavicle down to the dome of the Axillary Fascia, acting as a suspension ligament. Between these points, it splits to forma a sheath for the Subclavius and Pectoralis Minor muscles. The portion of the Clavipectoral Fasxia between these two muscles is called the Costo-coracoid Membrane because of its medial and lateral attachments. The Clavipectyoral Fascia (and the enclosed muscles) plus the Pectoralis Major, which lies in front of it, constitute the anterior wall of the Axilla. 19. The Posterior Wall of the Axilla consists of from above downward, Subscapularis, Teres Major, and Subclavius Latissimus Dorsi Pectoralis Minor Pectoralis Major Teres Minor Very good. No, the answer is B, Latissimus Dorsi. All but the long head of the Triceps attach to bony protrusions on the humerus with extending tendons. 20. The Subscapularis attaches to Medial lip of the bicipital groove Lesser tuberosity of humerus Floor of the bicipital groove Greater tuberosity of humerus A and C Magnificent! No, the answer is B, lesser tuberosity. 21. The Teres Major inserts on medial lip of the bicipital groove Crest of lesser tuberosity Floor of the bicipital groove Greater tuberosity A and B Good. No, the answer is E. 22. The Latissimus Dorsi inserts in Medial Lip of the bicipital groove Lesser tuberosity Floor of the bicipital groove Greater tuberosity A and C Right. No, the answer is C. 23. The Lateral Wall of the Axilla is the space on the humerus between the muscle insertions of the anterior wall (Lateral lip of the bicipital groove) and the muscle insertions of the posterior wall (Medial lip of the bicipital groove and the lesser tuberosity) which is really, the bicipital groove. This groove lodges the tendon of the long head of the Triceps Biceps Pectoralis Major Pectoralis Minor Subscapularis Right, thus the name, bicipital. No, the answer is B, thus the name, bicipital. 24. The medial wall of the Axilla is formed by ribs covered with Serratus Anterior Pectoralis Minor Intercostal muscles a and c a,b, and c Correct. No, the answer is D.