Pectoral Region and Breast Flashcards
The first 10 ribs are attached to the sternum, while the 11th and 12th ribs are floating. The manubrium is joined to the body of the sternum at the sternal angle (manubriosternal joint).
The xiphoid process is joined to the body at the xiphisternal joint, both of which are fibrous joints. The first rib attaches to the manubrium, while the second rib attaches at the sternal angle.
Locating the sternal angle provides a landmark for identifying the 2nd rib, enabling one to count or identify the ribs from the skin surface.
The 2nd rib joins the sternum at the sternal angle.
The subscapular fossa is occupied by the subscapularis muscle one of the rotator cuff muscles. Three muscles attach to the coracoid process, the pectoralis minor, coracobrachialis and the short head of the biceps brachii. The supraglenoid tubercle serves as the attachment site for the long head of the biceps brachii, while the infraglenoid tubercle is the attachment site for the long head of the triceps brachii.
The anatomical neck of the humerus serves as the site of an epiphyseal plate (growth plate) and is the site for attachment of the joint capsule.
The greater tubercle serves as the site of attachment for the supraspinatus, infraspinatus, teres minor muscles of the rotator cuff.
The subscapular muscle attaches to the lesser tubercle.
The intertubercular groove hold the tendon of the long head of the biceps brachii that was attached proximally to the supraglenoid tubercle.
The gland is located in the superficial fascia and consists of 15 to 20 lobes separated by dense connective tissue.
Each lobe of the breast is divided into lobules, and each lobule contains numerous secretory units (alveoli) in the lactating breast. The lactiferous ducts lead from the nipple to the secretory units.
Ligaments of Cooper – Dense connective tissue
Ducts leading from lobes composed of lobulues of alveoli that are the secretory units
The axillary artery gives rise to a number of small branches that supply the upper or superior portions of the breast, but the major supply from the axillary to the breast is the lateral thoracic artery that supplies much of the lateral portion of the breast. The intercostal arteries and the internal thoracic artery send perforating branches from deep into the breast tissue. Venous drainage accompanies the arterial supply.
Much of the lymphatic drainage of the gland flows from the deeper regions to the areolar area (subareolar plexus of lymphatic vessels) and from here drains to the pectoral group of axillary lymph nodes.
From the medial side of the gland, lymph drains to the parasternal nodes on the ipsilateral side, but also crosses over to the contralateral parasternal nodes as well as the other breast.
Lymph from the lower parts of the breast (inferior medial) flows to the subdiaphragmatic abdominal nodes. Superiorly, lymph flows to the apical axillary nodes.
However, one should note that the majority of lymph will flow to the anterior or pectoral lymph nodes.
The cephalic vein begins as tributaries from the hand and passes rostrally on the lateral side of the forearm and arm. It passes between the deltoid and pectoralis major to the deltopectoral triangle where is passes deep to connect with the axillary vein.
Pectoralis major
Origin: medial two-thirds of the clavicle, the sternum and the anterior surface of the ribs.
Insertion: humerus lateral to the intertubular sulcus.
Innervation: medial and lateral pectoral nerves.
The thoracoacromial artery is located medial to the pectoralis minor and originates from the underlying axillary artery.
The medial and lateral pectoral nerves innervate the pectoralis major muscle.
The lateral pectoral nerve is found medial to the pectoralis minor muscle and originates from the lateral cord of the brachial plexus.
The medial pectoral nerve pierces the pectoralis minor which it innervates and continues to the pectoralis major which it also innervates. The medial pectoral nerve originates from the medial cord of the brachial plexus.
The clavipectoral fascia extends from the clavicle to the axillary fascia, and in so doing encircles the pectoralis minor muscle. The lower part of the clavipectoral fascia is referred to as the suspensory ligament.
The clavipectoral fascia extends from the clavicle to the axillary fascia, and in so doing encircles the pectoralis minor muscle. The lower part of the clavipectoral fascia is referred to as the suspensory ligament.
Note the passage of the medial and lateral pectoral nerves.
Three parts of the axillary artery are defined by the insertion of the pectoralis minor to the coracoid process of the scapula. One vessels originates from part 1, two vessels originate from part 2, and three vessels originate from part 3.
The sternoclavicular joint is supported by the anterior and posterior sternoclavicular ligaments and interclavicular ligament. The sternoclavicular joint is unique in that an articular disc divides it into two cavities.
