Regional Gross Anatomy “Pectoral Region” By Vijittra Leardkamolkarn, Ph.D. Associate Professor Department of Anatomy

Pectoral region 1. Bony landmark : Sternum: Jugular notch (body of T2) Sternal angle of Louise (T4-5) Xiphosternal joint (T9) Ribs & costal cartilage

Scapular: acromian, coracoid process Clavicle: supraclavicular fossa infraclavicular fossa Humerus: head

2. Superficial structure - skin & derivative of skin (breast) Breast : nipple, areolar, mammary gland (F) 1. Surface Anatomy (position) : Nipple – 4-5” from the midline, intercostal space 4 Breast – between rib 2-7

2. Components : - subcutaneous fat, mammary gland - Lactiferous duct - Cooper’s ligament (suspensory ligament) - Retinaculum cutis fascia

The majority of the breast is in the superficial fascia, except the tail part (Tail of Spence) extends upward laterally into deep fascia at the lower border of pectoralis major. 2/3 of the gland lies on pectoralis major 1/3 of the gland lies on serratus anterior

Deltopectoral Triangle deep fascia separating deltoid and pectoralis muscles - Platysma = superficial muscle, thin plate, extends from the mandible to the clavicle

3. Muscles of pectoral region a. Pectoralis Major b. Pectoralis Minor c. Serratus Anterior d. Subclavious

a. Pectoralis Major O. middle ½ clavicle, sternum, rib 1-5 I. lateral lip of bicipital groove of humerous A. adduction, medial rotation of arm b. Pectoralis Minor O. rib 3-5 I. coracoid process of scapular A. draw the scapular down / lift up the ribs

c. Serratus Anterior O. half way of the anterior part of rib 1-8 I. medial border (anterior surface) of the scapular A. pull scapular to chest wall / lift up the ribs d. Subclavious O. 1st costal cartilage I. inferior surface of clavicle A. protecting structures underneath the clavicle

PectoralGirdle : clavicle, scapular, ribs Clavipectoral fascia / Costocoracoid membrane - deep fascia separating the pectoralis and the subclavious

Blood supply to the pectoral region 1. Axillary artery 2. Perforating branches of the internal thoracic a.

1. Axillary artery : divided into 3 parts First part : Supreme thoracic a. Second part : 1.Thoraco-acromial trunk Acromial branch Pectoral branch Clavicular branch Deltoid branch 2. Lateral thoracic a. Third part : give branches to supply head of humerus and scapular regions

1. Deep veins - axillary v. <= from the muscles Venous drainage at the pectoral region 1. Deep veins - axillary v. <= from the muscles

2. Superficial veins cephalic v. (from upper limb) at the deltopectoral triangle, it pierces the clavipectoral fascia (or infraclavicular fossa) into the axillary v. from mammary gland, it drains into deep veins => internal thoracic v. and lateral thoracic v.

1. Superficial 2. Deep Lymphatic drainage of the breast - around the mammary gland, lymphatic network is highly anastomosed / drainage is parallel the venous drainage. 2. Deep - lymph nodes are formed along the lymphatic vessels.

A. from lateral side of the breast, drains into the anterior group of the axillary lymph node (the pectoral node). B. from medial side of the breast, drains into the parasternal node (the internal thoracic node)

Nerve Supply of the pectoral region 1. - medial & lateral pectoral nerve (terminal branches from the cords of the Brachial plexus (C5-8 & T1) - nerve to subclavius (a branch from upper trunk of the Brachial plexus) - long thoracic nerve (nerve roots from C5-6-7 of the Brachial plexus)

Brachial plexus (C5-8 & T1)

2.Spinal n. / Sensory (cutaneous) n - Supraclavicular nerve (C3-4, medial, intermediate & lateral branches) - Intercostal nerve T3-7 (anterior & lateral cutaneous branches) *Dermatome at the pectoral region: C3-4, T3-7

Clinical Relevance 1. Chest wall – heart /lung sound 2.Clavipectoral fascia - protection of the vessels and nerves underneath limit spreading of the abscess from upper limb to the neck 3. Fracture of clavicle - common site is at 1/3 from the lateral 4. Breast cancer - structural abnormality - lymphatic drainage & metastasis - mastectomy

Accessory nipples may appear on the milk line

Regional Gross Anatomy “Axilla” By Vijittra Leardkamolkarn, Ph.D. Associate Professor Department of Anatomy

Axilla (Arm pit – Pyramid) Walls / Folds: .Anterior : pectoralis maj. & min., subclavious, clavipectoral fascia .Posterior : latissimus dorsi, teres major, subscapularis .Lateral : humerus, tendon of long head of biceps brachii, tendon of coracobrachialis .Medial : rib 1-3 & intercostal muscles, serratus anterior (superior part)

Muscles of Scapular region

Muscles of Scapular region 1. Deltoideus O.lateral 1/3 of clavicle, acromion, spine of scapula I. deltoid tuberosity of humerus A. abduct arm to 90 c, medial & lateral rotate arm N. axillary n.

2. Subscapularis O. subscapular fossa I. lesser tubercle of humerus A. medially rotate arm N. upper & lower subscapular nerves (C5,6) 3. Teres Major O. inferior 1/3 lateral border of scapular I. medial lip of bicipital groove A. adduction & medial rotation of arm N. lower subscapular nerve (branch of posterior cord)

4. Supraspinatus O.supraspinus fossa I. superior facet of greater tubercle of humerus A. abduction of arm N. suprascapular nerve 5. Infraspinatus O. infraspinus fossa I. middle facet of greater tubercle of humerus A. abduct & lateral rotate arm

3. Teres Minor O. superior 2/3 lateral border, dorsal surface of scapular I. inferior facet of greater tubercle of humerus A. lateral rotation of arm N. axillary nerve

Quadrangular Space: Triangular Space:

1. Axillary a. & branches 2. Axillary v. & tributaries Contents of the Axilla 1. Axillary a. & branches 2. Axillary v. & tributaries 3. Brachial plexus Axillary sheath – deep fascia that wrap around the axillary vessels and the brachial plexus formed by part of cervical fascia

1. Axillary a. & branches Third part : - anterior humeral circumflex a. - posterior humeral circumflex a. - subscapularis a.

2. Axillary v. & tributaries Superficial branch : cephalic v. Deep branch : venae comitant of brachial v. In the axilla vein lies medial to the atery. It is the most expandable structure in the axillary sheath (enlarge when the blood flow is high)

3. Brachial plexus - formed by anterior primary rami of spinal nerves level C5-8 & T1 - formed into trunk, division, cord and branches Upper trunk = C5 + C6 Middle trunk = C7 Lower trunk = C8 + T1

Most of the the brachial plexus in the axilla are cords & branches -

1. Lateral cord & branches : - musculocutaneous n. - lateral head of median n. - lateral pectoral n.

2. Medial cord & branches : - medial head of median n. - ulnar n. - medial pectoral n. - medial cutaneous nerve of arm - medial cutaneous nerve of forearm

3. Posterior cord & branches : - axillary n. - radial n. - thoracodorsal n. - upper subscapular n. - lower subscapular n.

Axillary lymph nodes - received vessels drainage from the upper limb, lateral part of the breast, superficial of thorax and abdomen (above the umbilicus) and the back.

Axillary lymph nodes - divided into 6 groups: 1. Anterior group 2. Posterior group 3. Lateral group 4. Central group 5. Apical group 6. Subclavian lymph trunk

Node & Vessel Locations: 1. Anterior group – at the lower border of pectoralis minor - drinage parallel the lateral thoracic v. 2. Posterior group – anterior to subscapularis m. - drainage parallel the subscapular v. 3. Lateral group - at the lower border of teres major - drainage parallel medial side of axillary v. 4. Central group - the outer border of 1st rib 5. Apical group – at the apex of the axilla 6. Subclavian lymph trunk

1. Nerve injury (lesion) at the axilla Lymph drainage : - anterior, posterior and lateral groups drain into the central group and then into the apical group -apical group drains into the subclavian lymph trunk Clinical Correlation 1. Nerve injury (lesion) at the axilla - long thoracic nerve - axillary nerve - lateral cord - medial cord 2.Injury to the axillary a. - fracture & dislocation of bone