Pectoral Region and Mammary Gland - PDF

Pectoral region Dr Vandana Dave Assistant Professor Department of Anatomy Amrita School of Medicine, Faridabad Competencies AN9.1 Describe attachment, nerve supply & action of pectoralis major and pectoralis minor AN10.11 Describe & demonstrate atta...

Pectoral region Dr Vandana Dave Assistant Professor Department of Anatomy Amrita School of Medicine, Faridabad Competencies AN9.1 Describe attachment, nerve supply & action of pectoralis major and pectoralis minor AN10.11 Describe & demonstrate attachment of serratus anterior with its action  Learning Objectives By the end of this teaching session all the students must be able to: Describe the attachment, nerve supply and action of pectoralis major Describe the attachment, nerve supply and action of pectoralis minor Describe the attachment, nerve supply and action of serratus anterior Explain the anatomical basis of Winging of scapula  Pectoral region Surface landmarks Cutaneous innervation Muscles of pectoral region Clavipectoral fascia  Surface landmarks Surface landmarks Cutaneous innervation of pectoral region Medial, intermediate and lateral supraclavicular nerves (C3,C4) Anterior and Lateral cutaneous branches of intercostal nerves (T2-T6) Area supplied by C4 directly meets the area supplied by T2  Anterior cutaneus branches of intercostal nerves Pectoralis major Origin Clavicular head The sternal half of the anterior surface of the clavicle Sterno-costal head Lateral part of the anterior surface of the sternum, upto 6th costal cartilage. 2nd to 6th costal cartilages From the aponeurosis of external oblique Insertion By a bilaminar tendon into the lateral lip of the bicipital groove of the humerus  Twisting of the fibres forms rounded anterior axillary fold. Laminae The anterior lamina, which is thicker, receives the clavicular and the uppermost sternal fibers. The posterior lamina of the tendon receives the attachment of the greater part of the sternocostal fibers. Innervation Medial and lateral pectoral nerves Actions clavicular part: flexion of arm sternocostal part: adduction, medial rotation of arm, extension of flexed arm against resistance Pectoralis major muscle Pectoralis major insertion  Inferior border of pectoralis major  Dissecting sternocostal fibres of pectoralis major  Reflecting sternocostal fibres Reflecting clavicular head of pectoralis major Structures under cover of pectoralis major  Pectoralis minor (key muscle of axilla) Origin It arises from the 3rd , 4th and 5th ribs, near their costal cartilages and from the fascia covering the external Inter-costal muscle Insertion inserted into the medial border and upper surface of the coracoid process of the scapula. Nerve supply: both medial & lateral pectoral nerve Actions: protraction of the scapula(shoulder), depresses the shoulder, acts in forced respiration Pectoralis minor muscle Medial pectoral nerve  Lateral pectoral nerve  SUBCLAVIUS Origin from the first rib at its costochondral junction. Insertion Into the groove on the inferior surface of the clavicle. Nerve supply Nerve to subclavius Action It steadies the clavicle  SERRATUS ANTERIOR Origin Arises as 8 fleshy digitation from the outer surface of the upper eight 1 ribs & fascia covering the intercostal muscles 2-3 Insertion Costal surface along the medial border of the 4-8 scapula. Nerve supply Long thoracic nerve (Nerve of Bell)  Serratus anterior/ Boxer's muscle Action called the "boxer's muscle" (protract the scapula along with pectoralis minor) overhead abduction of arm by Its inferior part which pull the lower end of the scapula laterally and forwards along with the upper and lower fibers of the trapezius Paralysis of Serratus anterior causes winging of scapula Pectoral fascia Clavipectoral fascia extends between clavicle and axillary fascia Location: deep to the clavicular head of pectoralis major  Clavipectoral fascia Attachment – Superior: splits into two lamina to enclose subclavius. Ant. Lamina attached to clavicle and post. lamina conti. with investing layer of deep cervical fascia and fused to axillary sheath Inferior: to the dome of axillary fascia in form of suspensory ligament of axilla Muscles enclosed – subclavius and pectoralis minor  Clavipectoral fascia Medial: 1st rib and costoclavicular ligament Lateral: coracoid process, coracoclavicular ligament Clavipectoral fascia The clavipectoral fascia Deltopectoral groove  Clinical Case A 55-year-old woman was submitted to surgery to remove her left breast, in which a malignant tumor had been found. Following the mastectomy, her recovery proceeded well, except that she noticed that she was experiencing weakness in her left shoulder and had considerable difficulty raising her left arm above her head, even two months after her surgery. Her husband also noticed that her left scapula seemed to protrude posteriorly (a "winged" scapula) to a greater extent than the one on her right side. Concerned, she went to see her doctor. She was referred to a neurologist, who performed electromyography (EMG) and nerve conduction studies to determine the source of the weakness.  Case based questions 1. Given the symptoms described above, what muscle was affected? Which nerve innervates that muscle? 2. How do you think the weakness in that muscle came about? 3. Why did this woman have difficulty raising her arm above her head? 4. The strength of the muscle affected in this case is often tested by having the patient press forward against a wall with both hands simultaneously. What movement of the scapula is being tested via this maneuver and what muscles contribute to that movement?  Case based questions 1. Given the symptoms described above, what muscle was affected? Which nerve innervates that muscle? The muscle affected was the serratus anterior. This muscle is innervated by the long thoracic nerve. 2. How do you think the weakness in that muscle came about? The weakness of the serratus anterior muscle was likely iatrogenic (induced by medical treatment). In the process of performing the mastectomy, the surgeon probably damaged the long thoracic nerve, which is particularly vulnerable due to its location on the superficial side of the serratus anterior as it proceeds down the thoracic wall.  Case based questions 3. Why did this woman have difficulty raising her arm above her head? The patient was unable to raise her arm above her head because the weakness of her left serratus anterior muscle made lateral rotation of the scapula very difficult, if not impossible. Without scapular rotation, she would be unable to abduct her arm much more than 90° or so. Ordinarily, the lower fibers of the serratus anterior and the upper fibers of the trapezius produce lateral rotation of the scapula. 4. The strength of the muscle affected in this case is often tested by having the patient press forward against a wall with both hands simultaneously. What movement of the scapula is being tested via this maneuver and what muscles contribute to that movement? The movement being tested in this maneuver is protraction of the scapula. This movement is produced by the actions of both the serratus anterior and pectoralis minor muscles. Winging of the scapula during this maneuver is generally associated with weakness of the serratus anterior. Mammary glands  Learning Objectives By the end of this teaching session all the students must be able to: Describe the location, extent, structure and age changes of breast Elicit the axillary group of lymph nodes Describe the blood supply and lymphatic drainage of breast Explain the applied aspect of breast  Competencies By the end of this teaching session all the students must be able to: AN9.2 Breast: Describe the location, extent, deep relations, structure, age changes, blood supply, lymphatic drainage, microanatomy and applied anatomy of breast  Mammary gland Introduction Development Location Extent Shape Deep relations Structure Blood supply & Venous drainage Nerve supply Lymphatic drainage Applied anatomy Introduction Modified sweat gland Location In superficial fascia of pectoral region lies in subcutaneous tissue except the Axillary tail of spence – extends in axilla upto 3rd rib through an opening in axillary fascia k/a foramen of Langer Development Ducts and Epithelial lining – Ectoderm Supporting tissue – Mesoderm/Mesenchyme During 3rd week of IUL, Develop as a thickened band of ectoderm (milk ridge) on each side of ventral Milk line/ line of schultz surface of embryo from axilla to inguinal region  Development In human, whole of it atrophies except in the pectoral region, if it fails to disappear, accessory breast tissue if formed A small portion in pectoral region proliferates and penetrates the underlying mesenchyme as buds By the end of prenatal life, the buds are canalized and form ducts and alveoli Nipple is flat or depressed at birth, later projects forwards Shape Hemisherical Extent 1. horizontally: from lateral border of sternum to midaxillary line 2. vertically: Located between 2nd to 6th rib Deep Relations RM space, Pec. Fs, 3 Muscles The breast is separated from pectoral fascia by RETROMAMMARY SPACE which filled by loose areolar tissue  Structures of the breast Consists of: 1. Skin: Nipple, Areola 2. Stroma: CT, Fat 3. Parenchyma/glandular tissue/mammary gland proper Modified sebaceous Suspensory gland: enlarged ligament of cooper Tubercle of Montgomery – enlarged sebaceous gland  15-20 lobes Arterial supply of breast Branches of - Internal thoracic (mammary) artery Axillary artery Posterior intercostal arteries Venous drainage of breast  Nerve supply Somatosensory nerve supply 2nd to 6th intercostal nerve through anterior and lateral cutaneous branches  Lymphatic drainage 1. Axillary LN 2. Internal mammary Deltopectoral or Cephalic node LN 3. Supraclavicular LN 4. Posterior intercostal LN 5. Cephalic LN 6. Subdiaphragmatic and superitoneal lymph plexus  Lymphatics draining the breast Superficial lymphatics: skin of breast except areola and nipple Deep lymphatics: parenchyma of breast and skin of areola and nipple Subareolar plexus of Sappey  Subareolar plexus of Sappy and most of lymph drain into anterior Ant group of LN Lymphatics from deep surface Pierce the clavipectoral fascia to drain into apical LN  Inferomedial quadrant Krukenberg’s tumor  Applied anatomy Breast cancer – One of most common cancer in female Arises from epithelial cells of lactiferous ducts Occurs in upper lateral quadrant in 60% cases, commonly affects females between age of 40-60 years Clinical features: painless lump, immobile and fixed breast, retraction of skin (Infiltration of suspensory ligament, breast becomes fixed to the pectoralis major and can not be moved ) and nipple (due to Infiltration and fibrosis of lactiferous duct) , peau d’orange appearance (pits of hair follicle appear to be retracted due to obstruction of superficial lymphatics and edema of skin due to stagnation of lymph), discharge from nipple, enlarged lymph nodes Radical mastectomy Krukenberg’s tumor – lymphatics from breast communicate with subperitoneal lymph plexus – peritoneum – ovary – secondary tumor Peau d’ orange appearance  Mondor’s disease (breast) Benign breast condition Also known as sclerosing superficial thrombophlebitis Present as palpable cord-like induration with no discoloration, It may be tensed like a bowstring by putting pressure on it.  Applied anatomy Congenital malformation of breast Athelia Polythelia  Applied anatomy Congenital malformation of breast Amastia Polymastia  Applied anatomy Congenital malformation of breast Inverted or retracted nipple Gynacomastia