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 4Breast – 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 major1/3 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 MajorO. middle ½ clavicle, sternum, rib 1-5I. lateral lip of bicipital groove of humerousA. adduction, medial rotation of arm

b. Pectoralis MinorO. rib 3-5 I. coracoid process of scapularA. draw the scapular down / lift up the ribs

c. Serratus AnteriorO. half way of the anterior part of rib 1-8 I. medial border (anterior surface) of the scapularA. pull scapular to chest wall / lift up the ribs

d. SubclaviousO. 1st costal cartilage I. inferior surface of clavicleA. protecting structures underneath the clavicle

Clavipectoral fascia / Costocoracoid

membrane- deep fascia separating the pectoralis and the subclavious

PectoralGirdle : clavicle, scapular, ribs

-Blood supply to the pectoral region1. Axillary artery

2. Perforating branches of the internal thoracic a.

1. Axillary artery : divided into 3 partsFirst 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

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.

Lymphatic drainage of the breast

1. Superficial - 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 sound2.Clavipectoral fascia - protection of the vessels and nerves underneath-limit spreading of the abscess from upper limb to the neck3. Fracture of clavicle- common site is at 1/3 from the lateral4 . 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 humerusA. abduct arm to 90 c, medial & lateral rotate armN. axillary n.

2. SubscapularisO. subscapular fossa I. lesser tubercle of humerusA. medially rotate armN. upper & lower subscapular nerves (C5,6) 3. Teres Major O. inferior 1/3 lateral border of scapular I. medial lip of bicipital grooveA. adduction & medial rotation of armN. lower subscapular nerve (branch of posterior cord)

4. SupraspinatusO.supraspinus fossa I. superior facet of greater tubercle of humerusA. abduction of arm N. suprascapular nerve

5. InfraspinatusO. infraspinus fossa I. middle facet of greater tubercle of humerusA. abduct & lateral rotate armN. suprascapular nerve

3. Teres MinorO. superior 2/3 lateral border, dorsal surface of scapular I. inferior facet of greater tubercle of humerusA. lateral rotation of armN. axillary nerve

Quadrangular Space:

Triangular Space:

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. & tributariesSuperficial 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 + C6Middle trunk = C7Lower 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 group6. 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 rib5. Apical group – at the apex of the axilla6. Subclavian lymph trunk