Thorax

Question 1

What is the superior thoracic aperture

Answer 1

Narrow opening superiorly
Allows continuity with the neck
Consists of body of vertebra TI posteriorly, medial margin of rib I on each side and manubrium anteriorly
The superior margin of manubrium is ~ the same horizontal plane as intervertebral disc between TII and TIII
Plane of superior thoracic aperture is at an oblique angle
Structures that pass between upper limb and thorax pass over rib I and superior part of pleural cavity as they enter and leave mediastinum e.g. subclavian artery and vein

Question 2

What is the inferior thoracic aperture

Answer 2

Large and expandable opening inferiorly
Closed by the diaphragm
Structures passing between abdomen and thorax pierce diaphragm or pass posteriorly
Skeletal elements of ITA:
Body of vertebra TXII posteriorly
Rib XII and distal end of XI posterolaterally
Distal cartilaginous ends of ribs VII to X which unite to form the costal margin anterolaterally
Xiphoid process anteriorly
When viewed anteriorly ITA is tilted superiorly

Question 3

What is the thoracic cavity divided into

Answer 3

Left and right pleural cavity
Mediastinum

Question 4

What is the mediastinum

Answer 4

Thick, flexible soft tissue partition oriented longitudinally in a median Sagittal position
Contains the heart, oesophagus, trachea, major nerves and systemic blood vessels
Acts as a conduit for structures that pass completely through thorax e.g. oesophagus, vagus nerves, thoracic duct, phrenic nerves
Extends from sternum to thoracic vertebrae and from STA to ITA.
A horizontal plane passing through sternal angle and intervertebral disc between TIV and TV separates it into superior and inferior parts
Inferior part is further divided by pericardium
Middle mediastinum= pericardium and heart
Anterior mediastinum= between sternum and pericardium
Posterior mediastinum= between pericardium and thoracic vertebrae

Question 5

Pleural cavities

Answer 5

Completely separated from each other by mediastinum
Extend above level of rib, apex of each lung extends into neck
Each pleural cavity is lined by mesothelial membrane=pleura
Each lung remains attached to mediastinum by a root formed by airway, pulmonary blood vessels, lymphatic tissues and nerves
Pleura lining walls of cavity= Parietal pleura more superficial
On surface of lungs= visceral pleura

Question 6

Functions of thorax

Answer 6

Breathing- up and down movements of diaphragm and changes in lateral anterior dimensions of thoracic wall caused by movements of ribs alter volume of thoracic cavity
Protection of vital organs: because of upward domed shape of diaphragm the thoracic wall also provides protection to some abdominal viscera- liver under right dome, stomach and spleen on left

Question 7

What is the thoracic wall composed of

Answer 7

Posteriorly it’s composed of 12 thoracic vertebrae and their intervening intervertebral discs
Laterally wall is formed by ribs and 3 layers of flat muscles which span the intercostal spaces between adjacent ribs, move ribs and provide support for intercostal spaces
Anteriorly wall in made up of sternum, consists of the manubrium of sternum, the body of sternum and the xiphoid process

Question 8

What is the sternal angle

Answer 8

The manubrium of sternum, angled posteriorly on the body of sternum at the manubriosternal joint forming sternal angle
Major surface landmark

Question 9

Costal cartilage

Answer 9

The anterior end of each rib is composed of costal cartilage
Contributes to mobility and elasticity of wall

Question 10

Articulation of ribs

Answer 10

Ribs II to IX have 3 articulations with vertebral column: head of each rib articulates with body of its own vertebra with body of one above, as these ribs curve posteriorly also articulates with transverse process of its vertebra
Anteriorly costal cartilages of ribs I to VII articulate with sternum
Costal cartilages of ribs VIII to X articulate with inferior margins of costal cartilages above them
Ribs XI and XII are floating ribs do not articulate with other ribs, costal cartilages or sternum, their costal cartilages are small

Question 11

Joint between costal margin and sternum

Answer 11

Lies roughly in same horizontal plane as intervertebral disc between vertebrae TIX and TX

Question 12

The diaphragm

Answer 12

Muscle fibres arise radially from margins of inferior thoracic aperture and converge into large central tendon
Because of oblique angle of ITA the posterior attachment of diaphragm if inferior to anterior attachment
Right dome is higher than left reaching up to rib V as diaphragm contracts height of domes decreases as volume of thorax increases
Oesophagus and inferior vena cava penetrate diaphragm and aorta pass posteriorly

Question 13

Costodiaphragmatic recess

Answer 13

Lung doesn’t completely fill pleural cavity resulting in recesses, important for accommodating changes in lung volume during breathing
Largest and clinically most important recess, lies inferiorly between thoracic wall and diaphragm

Question 14

What is the axillary inlet

Answer 14

Gateway to upper limbs
Formed by:
Superior margin of scapula posteriorly
Clavicle anteriorly
Lateral margin of rib I medially
The apex of each triangular inlet is directed laterally and formed by the medial margin of the coracoid process which extends anteriorly from superior margin of scapula
Proximal parts of the brachial plexus also pass between neck and upper limb through axillary inlet

Question 15

Structures piercing diaphragm

Answer 15

Inferior vena cava pierces central tendon of diaphragm to enter right side of mediastinum near vertebral level TVIII
The oesophagus penetrates the muscular part of diaphragm to leave mediastinum and enter abdomen just to left of midline at TX
Aorta passes posteriorly at midline at vertebral level TXII

Question 16

Relation between thorax and breast

Answer 16

Branches from internal thoracic arteries and veins perforate anterior chest wall on each side of sternum to supply anterior aspects of thoracic wall
Those branches associated with second to forth intercostal spaces also supply anteromedial parts of breast
Lymphatic vessels from medial part of breast accompany perforating arteries and drain into parasternal nodes on deep surface of thoracic wall
Vessels and lymphatics associated with lateral parts of breast emerge or drain into axillary region of upper limb
Lateral and anterior branches of 4th to 6th intercostal nerves carry general sensation from skin of breast

Question 17

The horizontal plane passing through intervertebral disc between TIV and TV is most significant because

Answer 17

Passes through sternal angle anteriorly marking position of anterior articulation of costal cartilage of rib II with sternum
The sternal angle is used to find position of rib II as reference for counting ribs
Separates superior and inferior mediastinum and marks position of superior limit of pericardium
Marks where arch of aorta begins and ends
Passes through site where superior vena cava penetrates pericardium to enter heart
Level where trachea bifurcates into right and left main bronchi
Marks superior limit of pulmonary trunk

Question 18

Venous shunts from left to right

Answer 18

Blood from left has to cross midline
In adults the left brachiocephalic vein crosses the midline immediately posterior to manubrium and delivers blood from left side head and neck, upper limb and part of left thoracic wall into superior vena cava
The hemiazygos and accessory hemiazygos veins drain posterior and lateral parts of left thoracic wall, pass immediately anterior to bodies of thoracic vertebrae and flow into azygos vein on right hand side which ultimately connects with superior vena cava

Question 19

Neurovascular supply to thoracic wall

Answer 19

Arteries to the wall arise form two sources:
The thoracic aorta, in the posterior mediastinum
Pair of vessels - the internal thoracic arteries, run along deep aspect of anterior thoracic wall on either side of sternum
Posterior and anterior intercostal vessels branch segmentally from these arteries and pass laterally around wall mainly along inferior margin of each rib, running with these vessels are intercostal nerves (anterior rami of thoracic spinal nerves) which innervate the wall, related parietal pleura and associated skin

Question 20

Innervation of the diaphragm

Answer 20

By 2 phrenic nerves that originate one on each side as branches of cervical plexus in neck. They arise from anterior rami of cervical nerves C3,4,5, major contribution from C4
The phrenic nerves pass vertically through neck, superior thoracic aperture and mediastinum to supply motor innervation to entire diaphragm, including crura (muscular extensions that attach diaphragm to upper lumbar vertebrae)
In mediastinum phrenic nerves pass anteriorly to roots of lungs

Question 21

The pectoral region

Answer 21

External to the anterior thoracic wall and helps anchor the upper limb to the trunk
Consists of:
A superficial compartment contains skin, superficial fascia, breasts
A deep compartment containing muscles and associated structures
Nerves, vessels and lymphatics in the superficial compartment emerge from the thoracic wall, the axilla and the neck

Question 22

What are mammary glands

Answer 22

Modified sweat glands in the superficial fascia anterior to the pectoral muscles and the anterior thoracic wall
Consist of a series of ducts and associated secretory lobules. These converge to form 15 to 20 lactiferous ducts which open independently onto the nipple .
The nipple is surrounded by a circular pigmented area of skin called areola
A connective tissue stroma surrounds the ducts and lobules of the mammary gland, in certain regions this condenses to form well defined ligaments- the suspensory ligaments of breast , which are continuous with dermis of skin and support breast

Question 23

Tissues in the breast

Answer 23

In nonlactating women the predominant component of breast is fat
In lactating women its glandular tissue
The breast lies on deep fascia related to the pectoralis major muscle and other surrounding muscles
A layer of loose connective tissue ( the retromammary space) separates breast from deep fascia and provides some degree of movement over underlying structures
The base or attached surface of each breast extends vertically from ribs II to VI and transversely from sternum to as far laterally as the mid axillary line

Question 24

Arterial supply of the breast

Answer 24

Laterally, vessels from the axillary artery- superior thoracic, thoraco-acromial, lateral thoracic and sub scapular arteries
Medially, branches from internal thoracic artery
The second to fourth intercostal arteries via branches that perforate thoracic wall and overlying muscle

Question 25

Venous drainage of breast

Answer 25

Veins parallel the arteries and drain into axillary, internal thoracic and intercostal veins

Question 26

Innervation of the breast Nerve supply and control of lactation

Answer 26

Via anterior and lateral cutaneous branches of the fourth to sixth intercostal nerves, nipple and areola are highly sensitive to touch innervated by 4th intercostal nerve Secretion/ lactation is regulated by hormones prolactin and oxytocin which are secreted from pituitary

Question 27

Lymphatic drainage of the breast

Answer 27

~75% via lymphatic vessels that drain laterally and superiorly into axillary nodes Most of the remaining drainage is into parasternal nodes deep into the anterior thoracic wall and associated with the internal thoracic artery Some drainage may occur via lymphatic vessels that follow the lateral branches of posterior intercostal arteries and connect with intercostal nodes situated near the heads and necks of ribs

Question 28

Where do axillary nodes drain into

Answer 28

Subclavian trunks, parasternal nodes drain into the bronchomediastinal trunks intercostal nodes drain either into the thoracic duct or into the bronchomediastinal trunks

Question 29

Breast in men

Answer 29

Rudimentary and consists only of small ducts, often composed of cords of cells, that normally do not extend beyond the areola

Question 30

Staging the tumour means defining the

Answer 30

Size of the primary tumour Exact site of primary tumour Number and sites of lymph node spread Organs to which the tumour may have spread

Question 31

Muscles of the pectoral region

Answer 31

Each pectoral region contains the pectoralis major, pectoralis minor and subclavius muscles All originate from the anterior thoracic wall and insert into bones of upper limb

Question 32

Pectoralis major

Answer 32

Largest and most superficial of pectoral region muscles Directly underlies breast and is separated from it by deep fascia and the loose connective tissue of the the retromammary space Innervation by medial and lateral pectoral nerves Function: Adduction, medial rotation, flexion of humerus at shoulder joint Has a broad origin includes the anterior surfaces of the medial half of clavicle, the sternum, and first 7 costal cartilages Muscle fibres converge to form a flat tendon which inserts into the lateral lip of the intertubercular sulcus of humerus

Question 33

Subclavius and pectoralis minor

Answer 33

Underlie pectoralis major The subclavius is small and passes laterally from the anterior and medial part of rib I to the inferior surface of clavicle The pectoralis minor passes from the anterior surfaces of ribs III to V to the coracoid process of scapula Both pull tip of shoulder inferiorly A continuous layer of deep fascia= clavipectoral fascia encloses the subclavius and pectoralis minor and attaches to clavicle above and to floor of axilla below Muscles of pectoral region form anterior wall of axilla Nerves, vessels and lymphatics that pass between pectoral region and axilla pass through clavipectoral fascia between subclavius and pectoralis minor or pass under inferior margins of major and minor

Question 34

Prominent features of chest wall anterior view

Answer 34

The clavicle Roundedness of shoulders Pectoralis major Manubro-sternal joint- sternal angle (T4 T5 IVD) Sternoclavicular joint Nipples T4 Dermatome, typically 4th intercostal space Sternum Suprasternal notch/ jugular notch Decreasing width of chest with fall in height Intercostal spaces by surface palpation

Question 35

Prominent features of chest wall posterior view

Answer 35

The scapulae: blades of scapulae, inferior angles of scapulae Undulations of the vertebral column: knowledge of normal trajectory of central gutter is important, central gutter is indicative of locations of spinous processes of vertebrae Back muscles Vertebra prominens Roundedness of shoulders Decreasing width of chest with fall in height

Question 36

What is the vertebra prominens

Answer 36

7th cervical vertebra Long and prominent spinous process which is palpable from skin surface

Question 37

Palpable structures of chest wall

Answer 37

T1- superior angle of scapula T2- jugular/ suprasternal notch T3- root of spine of scapula T4/5 sternal angle; manubriosternal joint, trachea bifurcation T7 inferior angle of scapula T10 xiphoid process of sternum

Question 38

Boundaries of thorax

Answer 38

Superior- superior thoracic aperture Inferior- thoracic side/ upper part diaphragm Antero-latero-posterior- ribs Posterior- thoracic vertebrae

Question 39

What is the jugular/ suprasternal notch

Answer 39

Also known as fossa jugularis sternalis Occurs at T2 Large visible dip between neck and the two collar bones Occurs at superior border of the manubrium of the sternum, between clavicular notches

Question 40

Tissue layers of thorax from skin to parenchyma of lung

Answer 40

Skin Superficial fascia and fat Serratus anterior muscle External intercostal muscle Internal intercostal muscle Innermost intercostal muscle Endothoracic fascia Parietal pleura Pleural cavity Visceral pleura Lung

Question 41

10 layers of tissues in chest wall

Answer 41

Skin Superficial fascia Pectoral fascia (deep fascia) Pectoralis major muscle Clavipectoral fascia (deep fascia) Pectoralis minor muscle External intercostal muscle Internal intercostal muscle and ribs Innermost intercostal muscle Endothoracic fascia (or Transversalis fascia)

Question 42

The two most superficial layers of fascia in thoracic wall

Answer 42

Known as fascia pectoralis Made up of pectoral fascia and clavipectoral fascia Superficial layer= pectoral fascia- covers outside of pectoralis major muscle, separates thoracic piece of pectoralis major from breast tissue which lies in superficial fascia Deep layer= clavipectoral fascia- separates pectoralis major from minor, at top it’s fused with clavicle and coracoid process. In subclavian area from 2 sides surrounds a small chest muscle and subclavius muscle Also goes on to form axillary= fascia axillaris

Question 43

What is the deepest layer of fascia of thoracic wall

Answer 43

Endothoracic fascia

Question 44

Endothoracic fascia

Answer 44

Deepest layer of fascia in thoracic region A layer of loose connective tissue deep into intercostal spaces and ribs Separates internal thoracic wall from underlying pleura Forms outermost membrane of thoracic cavity

Question 45

Bones of the thorax

Answer 45

Manubrium Sternum Xiphoid process Coastal cartilages Clavicles Ribs - 12 pairs Thoracic vertebrae -12

Question 46

What are the atypical ribs

Answer 46

Rib I - widest, shortest, sharpest curve,flat in horizontal plane, slopes inferiorly to its attachment to manubrium has only one articular surface, superior surface of rib has tubercle- scalene tubercle which separates the two smooth grooves that cross rib midway along shaft Rib II- flat but twice as long, articulates typically Rib X-head of rib has a single facet for articulation with its own vertebra Rib XI and XII- articulate only with body of own vertebrae have no tubercles or necks, both are short, little curve, pointed anteriorly

Question 47

What are the two grooves on rib I caused by

Answer 47

Anterior groove is caused by subclavian vein Posterior groove is caused by subclavian artery

Question 48

A typical rib has

Answer 48

Head (two facets) Neck Tubercle (facet) Angle Proximal end- costal cartilage

Question 49

Anterior articulations of ribs

Answer 49

Rib I to sternum (manubrium): -fibrous joint- connected by fibrous tissue - no movement Ribs 2-7 true ribs: -synovial (gliding) joints -radiate sternocostal ligaments- fibrous bands that cross from sternal end of costal cartilage to ventral part of sternum Ribs 8-10 false: articulate with costal cartilage of rib 7 Rib 11-12: false, floating ribs

Question 50

Anatomical terminology in a typical rib

Answer 50

A rib makes contact with vertebrae 3 times: Head (2 facets) connect to the vertebral column: one facet connects to superior vertebrae, other connects to inferior vertebrae Tubercle (one facet) connects to transverse processes of the vertebrae column, this helps stabilise rib and rib cage Proximal end of the rib connects to sternum via costal cartilage Costal cartilage provides flexibility to the rib cage which is essential for movements in breathing Subcostal groove- indentation of under surface of ribs caused by pulsating of intercostal arteries

Question 51

Muscles of thoracic region that attach upper limb

Answer 51

These muscles associated with movements of upper limb: Pectoralis major - attaches to both humerus and anterior body wall of thorax Pectoralis minor- attaches to body wall and coracoid process of scapula Subclavius Serratus anterior Latissimus dorsi Rhomboid major Rhomboid minor Trapezius Muscles of the scapula Terres minor (rotation movement) Terres major (major and minor attach scapula to humerus) Deltoid

Question 52

2 categories of muscles of thoracic region

Answer 52

Muscles that attach the upper limb to axial skeleton Muscles of respiration

Question 53

Actions of pectoralis major muscle

Answer 53

Fan shaped muscle Attaches at clavicle, sternum and humerus It’s a flexor of the arm, adductor of the arm Clavicular part of pectoralis major: -Elevates the shoulder -Draws arm forward and medially Sternocostal part of pectoralis muscle: -Has same actions but also draws shoulder downwards

Question 54

Serratus anterior

Answer 54

Serrated presentation Attaches on: lateral surfaces of upper 8/9 ribs and deep fascia overlying the related intercostal spaces, costal surface of medial border of scapula It is supplied by the long thoracic nerve (root values C5 to C7) It’s actions are: -protraction and rotation of the scapula -keeps medial border and inferior angle of scapula opposed to thoracic wall -winging of scapula- when long thoracic nerve comes to harm, the medial border and inferior angle of scapula is lost

Question 55

Muscles of respiration

Answer 55

Intercostal muscles: -External -Internal (reinforced by ribs) -Innermost Transversus thoracis Lavatores costarum

Question 56

Grains of intercostal muscles run in different directions

Answer 56

Grain of internal and innermost are parallel to eachother but perpendicular to external muscle Changing the grain of muscle fibres brings about strength The different grains also allow intercostal muscles to perform inspiration and expiration

Question 57

The neurovascular bundle of intercostal muscles

Answer 57

The neurovascular bundle of intercostal muscles runs on the inferior aspect of the ribs- sub-costal groove They reside in between internal and innermost intercostal muscles Vein, artery, nerve VAN Any procedures on the thoracic wall must be carried out on the upper surface of the ribs This avoids damage to the neurovascular bundle

Question 58

Transversus thoracis muscles

Answer 58

Found on deep surface of anterior thoracic wall in same plane as innermost intercostals Originate from posterior aspect of the xiphoid process, and the adjacent costal cartilages of the lower true ribs They pass superiorly and laterally to insert into the lower borders of the costal cartilages of ribs III to VI. They most likely pull these latter elements inferiorly Lie deep to internal thoracic vessels and secure these vessels into the wall

Question 59

Surface features of pectoral region

Answer 59

External to anterior thoracic wall Clavicle: subcutaneous, palpable Sternum:midline Suprasternal notch Sternal angle Nipple: in 4th intercostal space

Question 60

Whats in pectoral region

Answer 60

Anchors upper limb to the trunk Skin, superficial fascia containing mammary glands Pectoral fascia, pectoral muscles Separated into 4 quadrants: Upper inner, upper outer, lower inner and lower outer

Question 61

L-mammae: mammary glands

Answer 61

Present in both sexes, well developed in females after puberty Modified sweat gland (apocrine) Accessory organ of female reproductive system In superficial fascia except the axillary tail Extent: -vertical: from 2nd to 6th rib -horizontal: lateral border of sternum to mid axillary line -axillary tail of spence: passes through an opening in the deep fascia (foramen of Langer) and extends into axilla at level of 3rd rib -tail is closely related to long thoracic nerve and axillary lymph nodes

Question 62

Mammary bed: deep relations of mammary gland

Answer 62

Retromammary space (lake of Mercille) loose areolar (connective) tissue that separates breast from the pectoralis major muscle. Helps mobility of breast, space for implants, passage of vessels Deep fascia covering pectoralis major muscle Some part of Serratus anterior and external oblique abdominis muscle

Question 63

Structure of the breast

Answer 63

Skin: nipple and areola Parenchyma: compound tubule-alveolar gland, 15-20 lactiferous glands drain into nipple Stroma: supporting framework, connective tissue and adipose tissue

Question 64

Skin covering the breast

Answer 64

Nipple: conical projection at level of 4th intercostal space 10cm from midline. Pierced by 15-20 lactiferous ducts. Circular and longitudinal muscles in it, rich nerve supply Areola: circular, pigmented area surrounding the nipple, modified sebaceous glands in this skin enlarge during pregnancy and lactation: tubercles of Montgomery. Lubrication prevents cracking. Lactiferous sinuses below the areola No hair or subcutaneous fat underneath nipple and areola

Question 65

Parenchyma

Answer 65

15-20 lactiferous lobules Radially arranged, so radial incisions Lactiferous sinuses: stores milk in lactating breasts Lactiferous ducts: open separately on nipple Glandular tissue is more in lactating breast Myoepithelial cells

Question 66

Connective tissue stroma

Answer 66

Breast support matrix Inframammary ligament Suspensory ligaments of Cooper: support and firmness Adipose tissue:main bulk, interlobar in position, increase at puberty

Question 67

Superficial and deep lymphatics mammary gland

Answer 67

Superficial lymphatics: skin except areola and nipple Deep lymphatics: parenchyma, areola and nipple Malignant cells can spread through lymphatics

Question 68

Superficial lymphatics

Answer 68

UO: axillary and infraclavicular nodes LO: axillary nodes UI: parasternal and supraclavicular nodes LI: parasternal, subdiaphragmatic nodes, subperitoneal lymph plexus

Question 69

Deep lymphatics

Answer 69

Parenchyma: anterior axillary lymph nodes Subareolar plexus of Sappey: nipple and areola: axillary LN Deep connective tissue: parasternal, posterior intercostal and supraclavicular LN

Question 70

Development of the mammary glands

Answer 70

Ectodermal First appear as bilateral bands of thickened epidermis called mammary lines/ridges/ milk line. From axilla to groin

Question 71

Polymastia

Answer 71

Having more than normal number of breasts. Supernumeracy breasts

Question 72

Amastia

Answer 72

Absence of breast and nipple

Question 73

Polythelia

Answer 73

Presence of additional nipples

Question 74

Athelia

Answer 74

A condition where person is born without one or both nipples

Question 75

Macromastia

Answer 75

Breast hypertrophy Excessively large

Question 76

Micromastia

Answer 76

Postpubertal underdevelopment of breast

Question 77

Applied anatomy mammary glands

Answer 77

Well developed axillary tail shouldn’t be mistaken for lipoma (benign tumours of fat) or lump Mastitis-infection of breast tissue Breast abscesses: to drain incision should be radial to avoid injury to lactiferous ducts Fibroadenoma: benign tumour, solid breast lump common in young women Upper outer quadrant is common site for malignancy Ca breast- breast cancer

Question 78

Spread of cancer cells mammary gland

Answer 78

Suspensory ligaments: breast is fixed Lactiferous ducts: retraction of nipple Superficial lymphatic vessels: oedema: Peau d’orange sign- hair follicles buried in oedema Axillary lymph nodes Opposite breast Sometimes to abdominal viscera

Question 79

Screening for breast cancer

Answer 79

Mammogram

Question 80

Self examination of breasts for early detection

Answer 80

Inspect: symmetry of breasts and nipples, change in colour of skin, retraction of nipple is sign of cancer, discharge from nipple on squeezing it Palpate: all 4 quadrants with palm of hand, note any palpable lump, raise arm to feel lymph nodes in axilla

Question 81

Modified radicle mastectomy

Answer 81

Removal of breast tissue and axillary lymph nodes

Question 82

Parietal pleura

Answer 82

Endothoracic fascia separates the parietal pleura from body wall Parts: cervical (cupula), costal, mediastinal and diaphragmatic Cervical pleura is covered by suprapleural membrane Limits expansion of lungs

Question 83

Visceral pleura

Answer 83

Close to surface of lungs

Question 84

Pleural reflections

Answer 84

Margin of lung : Midclavicular line 6th rib Midaxilalry line 8th rib Paravertebral line 10th rib Margin of pleura: Mid clavicular line 8th rib Midaxillary line 10th rib Paravertebral line 12th rib

Question 85

Pleural cavity and pleural recesses

Answer 85

Pleural cavity: thin film of fluid for reducing friction, 5-10 ml fluid Pleural recesses are the reflection points where lung does not extend fully into pleural space -Costodiaphragmatic recess -costomediastinal recess

Question 86

Nerve supply of the pleura

Answer 86

Parietal pleura: innervated by the somatic afferent nerves, sensitive to pain So inflammation of the parietal pleura causes referred pain to the cutaneous distribution of these nerves i.e to the thoracic wall, neck or anterior abdominal wall Visceral pleura: innervated by visceral nerves so it’s sensitive to stretch but insensitive to pain

Question 87

Clinical anatomy of pleura

Answer 87

Normally the two pleural layers are in close apposition and the space between them is only a potential one Accumulation of excessive fluid (pleural effusion)- no space for expansion lung Air in pleural cavity (pneumothorax) Blood (haemothorax) Pus (empyema) Lymph (chylothorax)

Question 88

Drain excess pleural fluid

Answer 88

Triangle of safety: lateral edge of pectoralis major, base of axilla, lateral edge of latissmus dorsi, 5th intercostal space Incision is made Thoracostomy is a small incision of chest wall most commonly used for the treatment of pneumothorax

Question 89

Lungs gross anatomy

Answer 89

Pair of respiratory organs Surrounded by pleural sac and attached to mediastinum only by root of lung Mediastinum is area between 2 lungs and pleura Spongy

Question 90

Lungs surface and borders

Answer 90

Apex Base 2 surfaces: medial/mediastinum surface, lateral/costal surface 3 borders: anterior border :thin, straight, posterior border: rounded, inferior border: thin and c shaped

Question 91

Hilum of lung

Answer 91

Point of entry on each lung for the bronchus, blood vessels (pulmonary arteries (deoxygenated) and veins (oxygenated)) , nerves and lymphatics Visceral pleura is reflected as parietal here In middle of lung

Question 92

Root of lung

Answer 92

Short tubular collection of structures that connect lung to structures in mediastinum Covered by sleeve of mediastinal pleura that reflects on lung surface as visceral pleura

Question 93

Pulmonary ligament

Answer 93

Thin fold of pleura projects inferiorly from root of lung and extends from hilum to mediastinum May stabilise position of inferior lobe and may accommodate the down and up translocation of structures in root during breathing

Question 94

Lobes of lungs

Answer 94

Right lung has 3 lobes and 2 fissures: oblique fissure separates inferior from superior and middle lobes Horizontal fissure separates superior from middle Left lung is smaller and has 2 lobes separated by oblique fissure The inferior portion of the medial surface of left lung is notched because of hearts projection into left pleural cavity from middle mediastinum. Cardiac notch From the anterior border of lower part of superior lobe a tongue like extension (lingula of left lung) projects over heart bulge

Question 95

Trachea

Answer 95

In the neck and superior mediastinum C6 to T4 Trachea is radiolucent as it contains air black on X-ray May be compressed or displaced by pathological enlargement of neighbouring structures Foreign bodies and aspirated material tend to pass into the right bronchus as its wider and more in line with trachea Splits into bronchi at T4/T5 Right upper bronchus is wider and shorter

Question 96

Bronchopulmonary segments

Answer 96

Smallest functionally independent unit of lung aerated by one tertiary bronchus 10BP segments on each side

Question 97

Blood supply and lymphatic drainage of lungs

Answer 97

Bronchial arteries and bronchial veins Pulmonary arteries carry deoxygenated blood to lungs and pulmonary veins carry oxygenated blood back to heart Lymphatics are drained into tracheobronchial group of lymph nodes

Question 98

Nerve supply of lungs

Answer 98

By pulmonary plexus Sympathetic from upper thoracic spinal segments: bronchodilators Parasympathetic by vagus bronchoconstrictor and secretomotor to glands

Question 99

Respiratory epithelium

Answer 99

Ciliated pseudostratified columnar epithelium

Question 100

Boundaries of the mediastinum

Answer 100

Superiorly: superior thoracic aperture Inferiorly: diaphragm Anteriorly: sternum Posteriorly: thoracic vertebrae, vertebral column Laterally: mediastinal pleura

Question 101

Contents of the mediastinum

Answer 101

Thymus gland, pericardial sac, the heart, the trachea, major arteries and veins

Question 102

Angle of Louis

Answer 102

Sternal angle/ manubriosternal angle Leydigs plane: sternal angle to lower border of T4: divides the mediastinum into superior and inferior mediastinum 2nd rib articulation: helps in counting ribs Arch of aorta starts and ends Tracheal bifurcation Azygous vein opens into SVC Thoracic duct deviates to left Bifurcation of pulmonary trunk

Question 103

Divisions of mediastinum

Answer 103

Superior Inferior: Anterior -posterior to sternum, anterior to pericardial sac Middle -pericardial sac and contents Posterior- posterior to pericardial sac and diaphragm , anterior to vertebral column

Question 104

Superior mediastinum

Answer 104

Phrenic and vagus nerves Thoracic duct Brachiocephalic veins Superior vena cava Arch of aorta Thymus Trachea Lymph nodes Oesophagus Left recurrent laryngeal nerve

Question 105

Anterior mediastinum

Answer 105

The thymus (may only be seen in children) Loose areolar(connective) tissue Sterno-pericardial ligaments (pass from posterior surface of body of sternum to fibrous pericardium) Lymph nodes Internal thoracic vessels

Question 106

Middle mediastinum

Answer 106

Heart with the pericardium and roots of great vessels Ascending aorta Pulmonary trunk Superior vena cava Inferior vena cava Pulmonary veins

Question 107

Posterior mediastinum

Answer 107

Thoracic aorta- descending aorta and its branches Azygous system of veins (drain blood from body walls and mediastinal viscera and empties it into SVC) Thoracic duct Oesophagus with vagus nerves (plexus) Sympathetic trunk and thoracic splanchnic nerves (provide sympathetic supply to abdomen)

Question 108

Outer fibrous Pericardium

Answer 108

Apex fused with outer connective tissue layer of great blood vessels (Adventitia) Base fused with central tendon of diaphragm Anteriorly it gives attachment to sterno-pericardial ligaments Maintains central position of the heart Prevents overdistension of heart

Question 109

Serous pericardium: inner serous sac

Answer 109

Developing heart invaginates this serous sac Parietal layer: close to fibrous pericardium, supplied by somatic nerves, sensitive to pain Visceral layers: epicardium, supplied by visceral nerves, not sensitive to pain

Question 110

Pericardial cavity

Answer 110

Between parietal and visceral layers Contains thin film of serous fluid which allows friction free expansion

Question 111

Pericarditis and pericardial effusion

Answer 111

Pericarditis: inflammation of the serous pericardium Effusion: collection of excess fluid Cardiac tamponade: compression- build up of fluid in pericardium resulting in compression of heart Pericardiocentesis: drain the excess fluid

Question 112

The heart

Answer 112

4 chambers Atria: thin walled, receive blood Ventricles: thick walled, pump blood into pulmonary or systemic circulation Right atrium: receives deoxygenated blood from SVC, IVC and coronary sinus Right ventricle: pumps blood in pulmonary trunk Left atrium: receives oxygenated blood from pulmonary veins Left ventricle: pumps blood into aorta

Question 113

Heart surfaces and borders

Answer 113

Anterior surface (sternocostal): formed by right atrium, right ventricle and left ventricle, left atrium Posterior surface (base): related with T5-8 vertebral bodies formed mainly by left atrium some part of right Inferior surface (diaphragmatic): right and left ventricles Right border: from SVC to IVC, formed by right atrium Left border: formed by left atrium and left ventricle Inferior border: IVC to apex, right and left ventricles Apex: in left 5th intercostal space, 1-2cm medial to midclavicular line formed by left ventricle, here cardiac impulse can be felt as apex beat

Question 114

Cardiothoracic ratio CTR

Answer 114

The ratio of the transverse heart dimension A to the maximum transverse dimensions of chest B CTR= A/B More than 0.5 is cardiomegaly

Question 115

Blood supply of heart

Answer 115

Right and left coronary arteries: branches from aortic sinuses Cardiac veins mainly drain into coronary sinus which will drain into the right atrium Narrowing of the coronary vessels can cause angina or myocardial infarction Coronary angiography can locate the narrowing/block Lymphatics drain into brachiocephalic and tracheobronchial nodes

Question 116

Mediastinum: clinical anatomy

Answer 116

Moveable partition: mediastinal shift Mediastinitis: infections of neck can travel up to posterior mediastinum Mediastinal syndrome: engorged veins, dysphagia (swallowing), dysphonia (speaking), dyspnoea (breathing) Mediastinal widening

Question 117

Cervical rib

Answer 117

Occurs in some people If present may compress lower trunk of brachial plexus at superior thoracic aperture

Question 118

International thymic malignancy interest group ITMIG

Answer 118

3 compartment cross sectional imaging model of the mediastinal compartments to diagnose mediastinal pathologies Prevascular-anterior (anterior and superior) Visceral- middle (middle and some part of posterior) Paravertebral- posterior

Question 119

Tissue layers of mediastinum

Answer 119

Fibrous pericardium Parietal layer of serous pericardium Pericardial cavity Visceral layer of serous pericardium- epicardium Myocardium- muscular component of heart Endocardium- lines chambers