Level 2 Semester 2 Anatomy Pectoral Region & Breast (Locomotor System) PDF

Level 2 Semester 2 Module (locomotor) Pectoral region & breast INSTRUCTOR INFORMATION Name: prof. Mona Hassan Department: Anatomy Office hours: Saturday  Learning Outcomes By the end of the lecture, the students will be able to: Identify and describe the...

Level 2 Semester 2 Module (locomotor) Pectoral region & breast INSTRUCTOR INFORMATION Name: prof. Mona Hassan Department: Anatomy Office hours: Saturday  Learning Outcomes By the end of the lecture, the students will be able to: Identify and describe the muscles of the pectoral region: Pectoralis major, Pectoralis minor, Subclavius & Serratus anterior. Describe the shape and position of the female breast. Describe the structure of the mammary gland. List the blood supply of the female breast. Describe the lymphatic drainage of the female breast. Describe the applied anatomy in the female breast.  Pectoralis major Origin: Clavicular head: From medial ½ of the front of the clavicle. Sternocostal head: - Sternum, upper 6 costal cartilages & aponeurosis of external oblique m. Insertion: Lateral lip of bicipital groove of the humerus. Nerve supply: Medial & lateral pectoral nerves. Action: - Adduction and medial rotation of the arm. - Clavicular head helps in flexion of arm (shoulder). - It also helps in climbing. Pectoralis minor Locates deep to pectoralis major. Origin: from 3rd , 4th , and 5th ribs close to their costal cartilages. Insertion: Coracoid process. Nerve supply: Medial pectoral nerve. Action: Depression of shoulder. Draw the ribs upward and outwards during deep inspiration. subclavius Origin: From 1st rib at its junction with the 1st costal cartilage. Insertion: Subclavian groove at the inferior surface of middle 1/3 of clavicle. Nerve supply: Nerve to subclavius from upper trunk of brachial plexus. Action: Steadies the clavicle during movement of the shoulder joint. Serratus anterior Origin: Upper eight ribs. Insertion: Ventral aspect of the medial border and inferior angle of the scapula. Nerve supply: Long thoracic nerve, (nerve of Bell or nerve to serratus anterior). Action: Draws the scapula forward (protrusion, in boxing). Rotates scapula outwards in raising the arm above 90 degree.  Winging of the scapula Due to lesion of long thoracic nerve (C5,6,7) leading to paralysis of serratus anterior causing to backward projection of medial border of the scapula.  Clavipectoral fascia It is a thickened membrane of deep fascia extending between the subclavius m. (above) to pectoralis minor m. (below). It is pierced by (CALL): C- Cephalic vein. A- Thoraco Acromial artery. L-Lateral pectoral nerve. L- Few lymph vessels. FEMALE BREAST  Parts, Shape & position of the Gland It is conical in shape. It lies in superficial fascia of the front of chest. It has a base, apex and tail. Its base extends from 2nd to 6th ribs. It extends from the sternum to the midaxillary line laterally. It has no capsule. SHAPE AND POSITION OF FEMALE BREAST 2/3 of its base lies on the pectoralis major muscle, while its inferolateral 1/3 lies on: Serratus anterior & External oblique muscles. Its superolateral part sends a process into the axilla called the axillary tail or axillary process. SHAPE AND POSITION OF FEMALE BREAST Nipple: It is a conical eminence that projects forwards from the anterior surface of the breast. The nipple lies opposite 4th intercostal space. It carries 15-20 narrow pores of the lactiferous ducts. Areola : It is a dark pink brownish circular area of skin that surrounds the nipple. The subcutaneous tissues of nipple & areola are devoid of fat. STRUCTURE OF MAMMARY GLAND It is non capsulated gland. It consists of lobes and lobules which are embedded in the subcutaneous fatty tissue of superficial fascia. It has fibrous strands (ligaments of cooper) which connect the skin with deep fascia of pectoralis major. It is separated from the deep fascia covering the underlying muscles by a layer of loose areolar tissue which forms the retromammary space. What is its Importance? (allows the breast to move freely). STRUCTURE OF MAMMARY GLAND It is formed of 15-20 lobes. Each lobe is formed of a number of lobules. The lobes and lobules are separated by interlobar and interlobular fibrous & fatty tissue, called ligaments of Cooper. (Importance)? These ligaments give the breasts support by connecting the skin of the breasts to the pectoralis muscles below them. It has from 15-20 lactiferous ducts which open by the same number of openings on the summit of the nipple. ARTERIAL SUPPLY 1. Perforating branches of internal thoracic (internal mammary) artery. 2. Mammary branches of lateral thoracic artery. 3. Mammary branches of Intercostal arteries.  VENOUS SUPPLY Veins are corresponding to the arteries. Circular venous plexus are found at the base of nipple. Finally, veins of this plexus drain into axillary & internal thoracic veins. AXILLARY LYMPH NODES They are arranged into 5 groups which lie in axillary fat : Pectoral (Anterior) group : which lies on the pectoralis minor along lateral thoracic vessels. Subscapular (Posterior) group : which lies on posterior wall of axilla on lower border of subscapularis along subscapular vessels. Brachial (Lateral) group : lies on lateral wall of axilla along 3rd part of axillary vessels. Central group : lies in axillary fat at the base of axilla. Apical group : lies at apex of axilla. Subclavian lymph trunk: it is formed by union of efferent lymph vessels of apical group. It usually opens in subclavian vein. On the left side it usually opens into thoracic duct. LYMPHATIC DRAINAGE Subareolar lymphatic plexus : Lies beneath the areola. Deep lymphatic plexus: Lies on the deep fascia covering pectoralis major. Both plexuses radiate in many directions and drain into different lymph nodes. LYMPHATIC DRAINAGE Central & lateral parts of the gland (75%) drain into pectoral group of axillary lymph nodes. Upper part of the gland drains into apical group of axillary lymph nodes. Medial part drains into internal thoracic (parasternal) lymph nodes, forming a chain along the internal thoracic vessels. Some lymphatics from the medial part of the gland pass across the front of sternum to anastomose with that of opposite side. Lymphatics from the inferomedial part anastomose with lymphatics of rectus sheath & linea alba, and some vessels pass deeply to anastomose with the sub diaphragmatic lymphatics.  APPLIED ANATOMY- CANCER BREAST It is a common surgical condition. 60% of carcinomas of breast occur in the upper lateral quadrant. 75% of lymph from the breast drains into the axillary lymph nodes. In case of carcinoma of one breast, the other breast and the opposite axillary lymph nodes are affected because of the anastomosing lymphatics between both breasts. In patients with localized cancer breast, a simple mastectomy, followed by radiotherapy to the axillary lymph nodes is the treatment of choice.  The lactiferous ducts are radially arranged from the Applied Anatomy nipple, so incision of the gland should be made in a radial direction to avoid cutting through the ducts. Infiltration of the ligaments of Cooper by breast cancer leads to its shortening giving peau de’orange appearance of the breast.  Mammary ridge Mammary ridge extends from the axilla to the inguinal region. In human, the ridge disappears EXCEPT for a small part in the pectoral region. In animals, several mammary glands are formed along this ridge. THANK YOU