Pectoral Region,

Topographical Anatomy of the Thorax

• midaxillary line(TG4-01) an imaginary vertical line passing through the middle of the axilla used as a surface landmark for descriptive purposes

• midclavicular line: (TG4-01) an imaginary vertical line passing through the midshaft of the clavicle used as a surface landmark for descriptive purposes

• deltopectoral triangle: (TG2-12) a triangle in the upper chest region that is bounded medially by the clavicle, superiorly by the deltoid m., and inferiorly by the pectoralis major m.

• The deltopectoral triangle: is pierced by the cephalic vein on its course from the upper limb to join the axillary vein in the axilla

Pectoral Region, Topographical Anatomy of the Thorax contd.

• Nipple: Located superficial to the 4th intercostal space in the male and prepuberal female;

• Areola: is dark ring: surrounding nipple • location of the left nipple: – may be used to help locate the apex of heart, which is approximately

8 cm from the midline in the left 5th intercostal space; – a surface landmark used to place the stethoscope for auscultation of

the bicuspid valve– suprasternal notch the notch located at the superior border of the

manubrium of the sternum, between the sternal ends of the clavicles also known as: jugular notch

Bone Structure Description NotesRibs, Clavicle, Sternum, Scapula, Humerus

• clavicle: An "S" shaped bone located between the sternum and the scapula. – it articulates medially with the manubrium of the sternum

and laterally with the acromion process of the scapula;– it forms a strut that supports the upper limb; – it is frequently fractured; – it is the first bone to begin ossification during development

(Latin, clavicula = little key, this term was used to refer to the catch that fastens a window as well as to keys. Curved window fasteners resemble the shape of this bone)

Rib

• The bone forming the lateral thoracic wall • 12 pairs; several types are described: – typical or "true" ribs, – "false" ribs,– "floating" ribs.

• All three types of ribs have many features in common: head, neck, tubercle, angle, body, costal groove

Sternum•

The broad flat bone forming the anterior thoracic wall• It is formed by three parts: manubrium, body, xiphoid process (Latin,

sternum = breastbone, sternere = spread out)• Manubrium the superior part of the sternum (Latin, manubrium =

handle) jugular (suprasternal) notch a notch on the superior border of the manubrium it is located between the clavicular notches which articulate with the sternal ends of the clavicles (Latin, jugulum = throat) clavicular notch a notch on the superolateral border of the manubrium

• It articulates with the sternal end of the clavicle sternal angle the junction of the manubrium and body of the sternum

• It is an anterior projection located at the level of the costal cartilage of rib 2;

Sternum cond.

• It is an important landmark for internal thoracic anatomy • It is body the middle part of the sternum • it articulates with the manubrium superiorly and the

xiphoid process inferiorly;• laterally it articulates with the costal cartilages of ribs 2-7 • Xiphoid process the is the inferior part of the sternum • it is variable in size, shape & ossification; • it articulates with the body of the sternum superiorly

(Greek, xiphos = sword + eidos = appearance)

Scapula• The bone of the shoulder the scapula floats in a sea of muscles, so

it is difficult to fracture;• it articulates with the axial skeleton through only one bone - the

clavicle at the coracoclavicular and acromioclavicular joints • coracoid process: a beak-like process that projects anteriorly from

the lateral end of the superior border of the scapula • it is the attachment site for the short head of the

– biceps brachii m., – the coracobrachialis m., – the pectoralis minor m. and – the coracoacromial and – coracoclavicular ligaments (Greek, korax = crow + eidos = appearance.

The coracoid process of the scapula is shaped like a crow's beak)

Humerus•

The bone of the arm (brachium) • the humerus articulates proximally with the scapula at the glenoid fossa; • it articulates distally with the radius and ulna at the elbow joint greater

tubercle the large projection located lateral to the head of the humerus • it is the attachment site of the supraspinatus, infraspinatus & teres minor

mm. • intertubercular groove the groove on the anterior surface of the

humerus that is located between the crest of the greater tubercle and the crest of the lesser tubercle

• it is occupied by the tendon of the long head of the biceps brachii m.; • the transverse humeral ligament spans the intertubercular groove and

holds the biceps tendon in place;

Humerus contd.• it is the attachment site for

– the tendon of the pectoralis major (lateral lip), – teres major (medial lip), and – latissimus dorsi (floor) (Latin, tuber = knobby process, nodule) crest of

the greater tubercle the ridge of bone on the anterior surface of the humerus extending inferiorly from the greater tubercle

– it forms the lateral lip of the intertubercular groove; • it is the attachment site for the transverse humeral ligament and

the pectoralis major m.• crest of the lesser tubercle the ridge of bone on the anterior

surface of the Humerus extending inferiorly from the lesser tubercle

• Here it forms the medial lip of the intertubercular groove; it is the attachment site for the transverse humeral ligament and the teres major m.

Pectoralis major

Pectoralis major• origin : medial 1/2 of the clavicle, manubrium & body of

sternum, • Insertion: costal cartilages of ribs 2-6, sometimes from the

rectus sheath of the upper abdominal wall &crest of the greater tubercle of the Humerus

• Functions: flexes and adducts the arm, medially rotates the arm,

• Nerve supply: medial and lateral pectoral nerves (C5-T1), pectoral branch of the thoraco-acromial trunk.

• Clinical importance: the deep fascia on its anterior surface should not be fused to the fascia of the mammary gland - if it is, this is an important clinical sign indicating breast disease (Latin, Pectus = breast bone)

Pectoris minor.

Pectoralis minor

• Origin: Ribs 3, 4,& 5 • Insertion: Coracoid process of the scapula • Functions: Draws the scapula forward, medially, and

downward • Nerve supply: Medial pectoral nerve (C8, T1) • Arterial supply: Pectoral branch of the

thoracoacromial trunk • Clinical importance : Branches of medial pectoral

nerve usually pierce pectoralis minor to reach the pectoralis major muscle (Latin, pectus = breast bone)

Serratus anterior

• Origin: Ribs 1-8 or 9 • Insertion :medial border of the scapula on its costal (deep)

surface.• Functions(action): it draws the scapula forward; the inferior

fibers rotate the scapula superiorly • Nerve supply : long thoracic nerve (from ventral rami C5-C7) • Arterial supply :lateral thoracic a. • Clinical importance : a lesion of long thoracic nerve will cause

winging of the scapula (i.e., the medial border of the scapula falls away from the posterior chest wall and looks like an angel's wing) (Latin, serratus = to saw)

Winged scapular

Arteries

• Artery : Thoracoacromial• Source: axillary a., 2nd part • Branches:

– pectoral br., – clavicular br., – acromial br., – deltoid br.

• Supply to: – pectoralis major m., – pectoralis minor m., – subclavius m., – deltoid m.,– shoulder joint

• Notes: thoracoacromial trunk pierces the costocoracoid membrane

Veins

• Vein : cephalic v.• Tributaries: lateral side of the dorsal venous arch of the

hand; superficial veins of the forearm axillary vein superficial parts of the lateral hand and lateral forearm

• Drains: Into axillary vein• Regions Drained: superficial parts of the lateral hand

and lateral forearm • Notes :

– median cubital vein usually shunts some of the blood collected by the cephalic v. to the basilic v. (Latin/Greek, kephale = head)

Lymphatics and lymph nodes

• Structure: Axillary nodes

• Location: Axilla

• Afferents from : Cubital nodes; lymphatic vessels from the upper limb, thoracic wall and subscapular region

• Efferents to : efferents vessels form the subclavian trunk, some drainage to inferior deep cervical nodes • Regions drained : upper limb, most of the mammary gland, some of the anterolateral chest wall, posterior thoracic wall and

scapular region • Notes :• axillary nodes number from 20 to 30 and are organized in five groups based on their position within the axilla:

– 1) pectoral nodes, along the lateral border of the pectoralis major m.; – 2) lateral nodes, located along the distal axillary v.; – 3) central nodes, centrally located along axillary v.; – 4) subscapular nodes, located along the subscapular v. and its tributaries; – 5) apical nodes, located at the apex of axilla

Nerves

Nerve to pectoral region intercostal n.

source: ventral primary rami of spinal nerves T1-T11 branches: lateral & anterior cutaneous brs. intercostal muscles; abdominal wall muscles (via T7-T11); muscles of the forearm and hand (via T1) Sensory: skin of the chest and abdomen anterolaterally; skin of the medial side of the upper limb (via T1-T2) note: Intercostal n. travels below the posterior intercostal a. in the costal groove (Latin, costa = rib)

long thoracic n.source: brachial plexus (ventral primary rami of spinal nerves C5-C7) branches: no named branches motor: Serratus anterior m. sensory: no cutaneous branches location: located on the superficial surface of the Serratuslesion: anterior m.; lesion of this nerve causes scapular winging, hence the saying "C5, 6, & 7 keep the wings from heaven“

Nerves to the pectoral region contd.

pectoral, lateralsource: lateral cord of the brachial plexus Branches: no named branches pectoralis major m. no cutaneous branches lateral pectoral n. communicates with the medial pectoral n. anterior to the axillary a.; it pierces the clavipectoral fascia

pectoral, medialsource: medial cord of the brachial plexus branches: no named branches motor: pectoralis minor m., pectoralis major m. Sensory: no cutaneous branches

Notes: medial pectoral n. communicates with the lateral pectoral n. anterior to the axillary a.; it pierces the pectoralis minor m. Viscera/Fascia

The axilla

The Axilla (armpit)

Aims and objectives of the lecture

• Pectoral region– Surface anatomy– Anterior view– Anterior lateral view– Differences between

male and female

• Axilla – Anterior wall– Posterior wall – Medial wall – Bones of Axilla– Muscles & attachments

PECTORAL REGION / AXILLA

GIUDE TO SUCCESS IN ANATOMY

1. YOU can revise much of the anatomy of the limbs on oneself.

2. Otherwise choose and study a thin colleague of yours (as specimen).

3. Form a study group of odd numbers - minimum of five and maximum of seven4. Confirm your findings on cadaver (dead body) bearing in mind that that the physio- chemico-anatomical dynamics have ceased to play

5. Consult the recommended books

6. Use the internet

7. Answer past question papers.

8.Ask your teachers

Revision questions • Pectoral region• Essay questions

• Discuss the cutaneous innervations of the pectoral region• discuss the deltopectoral triangle, make a note on its clinical

importance.

– 1. The cephalic vein drains • deeply into the axillary vein at the deltopectoral triangle• Superficially to the axillary vein in the deltopectoral triangle• deeply into the cephalic vein at the deltopectoral triangle• superficially into the cephalic vein at the deltopectoral

triangle• deeply into the basilic vein at the deltopectoral triangle

– 2. the sternocostal head of pectoralis major muscle originates from the

• A. The Manubrium• B. Body of sternum• C. The clavicle• D. From A and B• E. From B and C

– 3. One of the following nerves does not supply cutaneous branches to the pectoral region

• A. Supraclavicular nerves• B. Upper thoracic nerves• C. The brachial plexus• D. None of the above • E. All of the above.

• Axilla• Multiple choice• Essay

– Discuss the boundaries of the Axilla

• Organ/Part of Organ Location/Description Notes clavipectoral fascia(N188,N428, TG2-12, TG4-07) deep fascia attaching to clavicle, surrounding subclavius m., thickened below as costocoracoid ligament, extending inferiorly to pectoralis minor as costocoracoid membrane (pierced by cephalic v., lateral pectoral n., thoracoacromial a.), encloses pectoralis minor, extends inferolaterally to attach to axillary fascia as suspensory ligament of axilla mammary gland(N182, TG2-10) located anterior to pectoralis major m. from rib 2/3 to rib 6/7 the breast, a modified sweat gland, comprises glandular tissue arranged in up to 20 lobules, surrounded by subcutaneous connective tissue and supported by suspensory ligaments lactiferous ducts(N182, TG2-10A, TG2-10B) drain the lobules of the mammary gland at the nipple beneath the nipple, the ducts dilate to form lactiferous sinuses areola(N182, TG2-10) darkly pigmented skin surrounding the nipple

Clinical Terms

• Term Definition anomalies/variations deviation or departure from the normal or common order, form, or rule gynecomastia excessive development of the male mammary glands, sometimes secreting milk.

• This can be idiopathic, r as a result of an underlying disease process. (Greek, gyn = female + mastos = breast) axillary tail (of Spence) part of the mammary gland may extend along the inferolateral edge of the pectoralis major toward the axilla (armpit), forming an axillary tail (of Spence).

• This portion of breast tissue is in the upper-outer quadrant of the breast which is important because 50% of breast cancer is located in this quadrant and in the axillary tail supernumerary nipples (polythelia) more than the normal number of nipples, may be on the breast or other parts of the body-found along the "milk line" from axilla to groin. These accessory nipples resemble raised nevi (commonly called "moles").

• supernumerary breasts (polymastia) a condition in which more than two breasts are present carcinoma any of the various types of malignant (invasive) neoplasm derived from epithelial tissue in several sites, occuring more frequently in skin, bronchi, stomach, and prostate gland in men, and in the breast, cervix, and skin in women (Greek, carcino- = cancer + -oma = tumor) mastectomy/lumpectomy amputation of the breast or of an affected portion (Greek, mastos = breast + -ectomy = excision) mastitis inflammation of the mammary gland (Greek, mastos = breast + -itis = inflammation) scintigraphy record indicating the intensity, location, and distribution of radioactivity in tissue following the use of radioactive tracer substances mammogram special imaging examination of the breast to detect breast cancer. The American Cancer Society currently recommends that screening should begin annually at the age of 40 (and earlier in those patients with a family history of breast cancer).