Lungs, Pleura, Heart, and Mediastinum Notes

Lungs and Pleura (Practical)

Objectives

• Describe the Pleural Cavities and Costo-Diaphragmatic Recesses.

• Identify the Surface Markings of the Borders, Lobes, and Fissures of the Lungs.

• Describe a Typical Bronchopulmonary Segment and Indicate its Clinical Importance.

• Describe the Blood Supply and the Lymphatic Drainage of the Pleura and Lungs.

• Identify the Trachea, Hila, and Lungs in Chest Radiographs.

Thoracic Cavity

The thoracic cavity is subdivided into:

1. Two pleural sacs & lungs.

2. Mediastinum: Partition between two lungs.

Pleura

The pleura is a closed serous sac invaginated from its medial aspect by the lung, forming two layers: visceral and parietal. These layers are separated by the pleural cavity, which is a potential space containing a thin film of serous fluid that facilitates lung movement and minimizes friction.

Divisions of the Pleura

• Visceral (Pulmonary) Pleura: Inner layer, covers the lung and is closely adherent to it.

• Parietal Pleura: Outer layer, subdivided into:

  1. Cervical Pleura: Covers the apex of the lung.

  2. Costal Pleura: Continuous with the mediastinal pleura at the costomediastinal reflection and with the diaphragmatic pleura at the costodiaphragmatic reflection.

  3. Mediastinal Pleura: Covers the sides of the mediastinum.

  4. Diaphragmatic Pleura: Covers the upper surface of the diaphragm.

Pleural Recesses

The pleural recesses are narrow spaces not occupied by the lung except in forced inspiration.

1. Costomediastinal Recess: Receives the expanding anterior border of the lung during forced inspiration.

2. Costodiaphragmatic Recess: Receives the expanding inferior border of the lung during forced inspiration.

Pulmonary Ligament

The pulmonary ligament is a loose, empty double-layer fold of pleura. Its function is to provide a dead space which allows the distention of the pulmonary veins when the venous return from the lung increases and also allow free movement of the root of the lung during respiration.

Nerve Supply of the Pleura

• Visceral (Pulmonary) Pleura: Supplied by anterior and posterior pulmonary plexuses; not sensitive to somatic stimuli like pain and temperature.

• Parietal Pleura: Receives the same innervation as the thoracic wall, mediastinum, and diaphragm.

  • Cervical: 1st intercostal nerve.

  • Costal: Corresponding intercostal nerve.

  • Mediastinal and Central Diaphragmatic: Phrenic nerve.

  • Peripheral Diaphragmatic: Lower intercostal nerves.

Blood Supply of the Pleura

• Visceral Pleura: Same vessels as the lung (bronchial vessels).

• Parietal Pleura: Same vessels as the thoracic wall (internal thoracic and intercostal arteries).

Applied Anatomy - Pleura

1. Irritation of the Pleura: A rich sensory nerve supply characterizes the parietal pleura. If the pleural surfaces become dry and rough, friction results in severe pain with movements of respiration.

   • Inflammation of the costal pleura or peripheral diaphragmatic pleura leads to referred pain in the thoracic or anterior abdominal walls depending on which intercostal nerve is affected.

   • Irritation of the mediastinal or central diaphragmatic pleura results in referred pain at the tip of the shoulder because the phrenic nerve (C3,4,5) shares the same cervical spinal segments as the supraclavicular nerves (C3,4).

2. Abnormal Fillings of the Pleural Cavity:

   • Pneumothorax: Air enters, leading to lung collapse.

   • Haemothorax: Filled with blood.

   • Pyothorax (Empyema): Filled with pus.

   • Pleural Effusion: Filled with excess serous fluid.

3. Aspiration: Fluid drainage from the pleural cavity is done using a large, wide-bore needle introduced in the 7th intercostal space (midaxillary line). Safe puncture is midway between intercostal space boundaries to avoid injury of the neurovascular bundle.

Lungs

The lungs are the organs of gaseous exchange. Before birth, they are firm and sink in water. Each lung features an apex, base, two surfaces (costal, medial), and three borders (anterior, posterior, inferior).

Lung Features

• Apex: Rounded upper end projecting into the thoracic inlet, reaching the neck of the 1st rib and lies one inch above the medial third of the clavicle. Covered by the cervical pleura.

• Base: Concave lower surface resting on the diaphragm, separated by the diaphragm.

Surfaces

1. Costal Surface: Related to ribs, costal cartilages, and intercostal spaces.

2. Medial Surface: Marked by the hilum, divided into:

   • Vertebral (Posterior) Part: Related to vertebral bodies, intercostal nerves and vessels, and sympathetic chain.

   • Mediastinal (Anterior) Part: Contains the hilum, grooves, and impressions that differ between the lungs.

Borders

1. Anterior Border: Thin and sharp; the right lung is straight, while the left lung features the cardiac notch and lingula.

2. Inferior Border: Forms the boundary of the base.

3. Posterior Border: Thick and rounded.

Hilum

• Right Lung:

  • Principal bronchus (most posterior).

  • Superior lobar bronchus (above principal bronchus).

  • Superior pulmonary vein (most anterior).

  • Inferior pulmonary vein (most inferior).

  • Pulmonary artery (between principal bronchus and superior pulmonary vein).

• Left Lung:

  • Principal bronchus (most posterior).

  • Superior pulmonary vein (most anterior).

  • Inferior pulmonary vein (most inferior).

  • Pulmonary artery (above and in front of principal bronchus).

Fissures and Lobes

1. Oblique Fissure: Deep fissure on both lungs, cutting into the costal and mediastinal surfaces towards the hilum.

2. Horizontal Fissure (Right Lung Only): Separates the upper lobe from the middle lobe.

Lobes

• Right Lung: Superior, Middle, and Inferior lobes.

• Left Lung: Superior and Inferior lobes.

Mediastinal Surface Impressions

• Right Lung: Cardiac impression, superior vena caval groove, groove for the arch of azygos vein, tracheal groove, and esophageal groove.

• Left Lung: Cardiac impression, groove for the arch of the aorta, grooves for the left common carotid and left subclavian arteries, esophageal groove, and groove for the descending thoracic aorta.

Bronchopulmonary Segments

A bronchopulmonary segment is a functionally independent unit of lung tissue supplied by a segmental bronchus and pulmonary artery branch, with its own lymphatics and innervation. These wedge-shaped segments have their apex at the hilum and base at the lung surface, separated by connective tissue septa containing pulmonary veins.

Autonomic Innervation

Anterior and posterior pulmonary plexuses. Sympathetic fibers from the 2nd, 3rd, and 4th thoracic sympathetic ganglia.

Blood Supply

• Pulmonary Vessels: Pulmonary artery and veins.

• Bronchial Vessels: Bronchial arteries from the 3rd right posterior intercostal artery (right) and descending thoracic aorta (left); bronchial veins drain into the azygos vein (right) and superior hemiazygos vein (left).

Lymphatic Drainage

From periphery to the hilum; vessels in the walls of the bronchioles pass to segmental and lobar bronchi, then to the hilum. The drainage flows through bronchopulmonary, tracheobronchial, paratracheal, and mediastinal lymph nodes, eventually opening into the right brachiocephalic vein (right side) or the thoracic duct (left side).

Distribution of Segments

• Right Lung (10 Segments):

  • Upper Lobe: Apical, Posterior, Anterior

  • Middle Lobe: Lateral,Medial

  • Lower Lobe: Superior, Medial Basal, Anterior Basal, Lateral Basal, Posterior Basal

• Left Lung (8 Segments):

  • Upper Lobe: Apicoposterior, Anterior, Superior Lingular, Inferior Lingular

  • Lower Lobe: Superior, Anterior Basal, Lateral Basal, Posterior Basal

Clinical Importance

• After the first breath, the lung becomes spongy and floats in water.

• Diseased bronchopulmonary segments can be surgically excised (segmentectomy).

• Infections remain restricted to a segment.

• Knowledge of segmental bronchi allows for proper posture for draining a lung abscess.

Heart (Practical)

• Describe the anatomy of the four chambers of the heart and their valves

• Compare and contrast the walls and internal features of the atria and the ventricles

• Draw a simple diagram of the pulmonary trunk, aorta, and aortic arch

• Draw a simple diagram of the brachiocephalic veins, superior and inferior vena cava

• Draw and label two simple diagrams illustrating the blood supply of the heart

• Describe the origin of the right and left coronary arteries

• Describe the course, main branches, and territories of the right coronary artery

• Describe the course, main branches, and territories of the left coronary artery

• Identify the coronary arteries and their branches on angiograms

• Describe the course of the coronary sinus and identify its opening in the right atrium

• Understand the difference between the intrinsic conducting system and extrinsic innervation of the heart

• Know the general anatomical position of the sinuatrial node and atrioventricular node

Right Atrium

Forms the right border of the heart and is separated from the left atrium by the interatrial septum. The right auricle projects forwards and to the left, overlapping the ascending aorta.

The interior is divided into Atrium Proper and Sinus Venarum, demarcated by the Crista Terminalis which extends between the openings of the SVC and IVC.

• Atrium Proper: The anterior, rough part contains Musculi Pectinati extending from the crista terminalis into the right auricle.

• Sinus Venarum: The posterior smooth part that receives the openings of the SVC, IVC, Coronary Sinus, Anterior Cardiac Veins, and Venae Cordis Minimi.

• Interatrial Septum: Features the Fossa Ovalis and Annulus Ovalis (Limbus Fossae Ovalis).

Right Ventricle

Forms most of the inferior border. Its wall is 9 mm thick. The cavity is semilunar in cross-section.

The cavity is divided into:

• Inflow Part: Through the tricuspid orifice.

• Outflow Part: The pulmonary orifice, which is smooth and connects to the infundibulum or conus arteriosus.

Features of Inflow Part:

• Trabeculae Carneae: Muscular ridges.

• Papillary Muscles: Small, conical projections attached by chordae tendinae to the cusps of the A-V valve; each muscle is attached to 2 adjacent cusps.

  • Anterior Papillary Muscle: chordae tendinae are attached to anterior and posterior cusps of the tricuspid valve.

  • Posterior Papillary Muscle: Connected to the posterior and septal cusps.

  • Septal Papillary Muscles: Their chordae tendinae are attached to the anterior and septal cusps.

• Septomarginal Trabecula (Moderator Band): Muscular band from the interventricular septum to the base of the anterior papillary muscle. It prevents overdistension of the right ventricle.

Orifices and Valves:

• Right Atrioventricular Orifice: The oval aperture between the right atrium and right ventricle, guarded by the right (tricuspid) valve.

• Right Atrioventricular Valve: 3 cusps (anterior, posterior, septal).

• Pulmonary Orifice: A circular aperture at the upper end of the infundibulum is guarded by the pulmonary valve.

• Pulmonary Valve: 3 semilunar cusps (2 anterior and 1 posterior).

Left Atrium

It forms most of the base and the upper border of the heart. The left auricle projects forward from its upper left part. It is separated from the right atrium by the interatrial septum.

Posteriorly, it is separated from the descending thoracic aorta and esophagus by the oblique sinus of the pericardium.

• Cavity has a smooth wall.

• Orifices:

  • Four pulmonary veins.

  • Left atrioventricular orifice.

  • Venae cordis minimi.

Left Ventricle

Forms most of the left aspect of the heart and the left 1½ cm of the inferior border and the apex of the heart. The internal wall is 27 mm thick. Its cavity is divided into inflow and outflow parts.

• Inflow Part: Extends from the left atrioventricular orifice to the apex of the heart and has trabeculae carneae and papillary muscles. There are

  • Anterior papillary muscle

  • Posterior papillary muscle

• Outflow Part: Smooth part extending from the apex of the heart to the aortic orifice. The upper part is called the Aortic Vestibule.

Mitral Valve: Composed of 2 cusps (anterior and posterior).

Aortic Orifice: Surrounded by a fibrous ring guarded by the aortic valve.

Aortic Valve: Consists of 3 cusps (2 posterior and 1 anterior); the aortic sinuses are dilatations above the aortic orifice.

Conducting System

SA node lies in the lateral wall of the right atrium at the junction of the SVC & right atrium. The AV node lies in the lower part of the interatrial septum near the opening of the coronary sinus. The AV bundle descends from the AV node to the upper membranous part of the interventricular septum.

Blood Supply of the Heart

• S-A Node: Usually by the right coronary artery

• A-V Node: Usually by the right coronary artery (posterior interventricular branch)

• AV Bundle: Usually dual blood supply from both coronaries

Mediastinum (Practical)

Objectives

• Indicate in simple diagrams the subdivisions of the thoracic cavity and list their contents.

• Describe the subdivisions of the mediastinum and their contents.

• Discuss the lymphatic drainage of the thorax and describe the course of the thoracic duct.

• Make and recognize a diagram showing the distribution of the vagus nerves in the thorax.

• Briefly describe the thoracic sympathetic trunk, ganglia, and splanchnic nerves.

• Describe the relations of the esophagus in the thorax.

• Recognize the major structures of the heart and mediastinum on CT images at two transverse levels in the thorax (T4/5 and T8).

Definition

The mediastinum is the central compartment of the thoracic cavity, which contains the heart, vessels, esophagus, trachea, phrenic and cardiac nerves, thoracic duct, thymus, and lymph nodes of the central chest.

Subdivisions

• Superior mediastinum

• Inferior mediastinum

  • Anterior mediastinum

  • Middle mediastinum

  • Posterior mediastinum

Superior Mediastinum

Venous Layer

• Rt and Lt brachiocephalic veins.

• Upper part of SVC.

• Rt pherenic nerve

Arterial Layer

• Arch of the aorta and its branches.

• Bifurcation of pulmonary trunk.

• Ligamentum arteriosum.

• Lt vagus and Lt pherenic.

• Lt recurrent laryngeal nerve

Inferior Mediastinum

• Anterior Mediastinum:

  • Remains of thymus

  • Superior and inferior sternopericardial ligaments

  • Mediastinal branches of internal thoracic artery

• Middle Mediastinum:

  • Pericardium and the structures within:

    • Heart

    • Ascending aorta

    • Pulmonary trunk

    • Terminal parts of right and left pulmonary veins

    • Lower ½ of superior vena cava

    • Terminal part of inferior vena cava.

• Posterior Mediastinum:

  • Descending thoracic aorta

  • Esophagus

  • Thoracic duct

  • Rt and Lt Vagi

  • Rt and Lt Sympathetic chains

  • Azygos, sup. Hemiazygos, and inf. Hemiazygos.

Nerves of the Mediastinum

The mediastinum contains the right and left vagus nerves, the recurrent laryngeal nerves, and the phrenic nerves.

Lymphatic Drainage

The Thoracic duct begins at the upper end of the cisterna chyli at the upper border of T12. It Enters the thorax through the aortic opening, traverses the posterior mediastinum behind the oesophagus. At Opposite T5, it inclines left, runs upwards. It terminates at the root of the neck in the angle, formed by the junction of the left subclavian and internal jugular vein

Sympathetic Chain

The sympathetic trunk is formed of sympathetic ganglia and the communications between them. It is present in the thorax and extends up to the neck and down to the abdomen and pelvis. The thoracic part contains 12 ganglia.
A) Greater splanchnic (T5-T9)
B) Lesser splanchnic (T10 - T11)
C) Least splanchnic (T12)

Horner Syndrome: Due to injury of the sympathetic chain Injury causes

1. Ptosis (eyelid drop).

2. Myosis (constriction of the pupil).

3. Anhydrosis

4. Enophthalmos

Ascending Aorta

Begins at the aortic orifice opposite the 3rd left intercostal space ends behind the 2nd right sternocostal. It has Rt and Lt coronary branches

Aortic Arch

Begins at the 2nd right sternocostal and passes upwards, and to the left.
It ends at disc between T4 and T4. Branches: 3 large branches from the arch are the brachiocephalic, left common carotid and left subclavian arteries

Descending Aorta

It begins at the disc between T4 and T5. It ends at the lower border of T12, by passing through the aortic opening of the diaphragm.

Branches from the descending aorta are:

1. posterior intercostal arteries (from 3rd to 11th).

2. subcostal arteries.

3. Two left bronchial arteries.

4. Four or five oesophageal branches.

5. Few small twigs to the pericardium, mediastinum, and diaphragm.

Applied Anatomy

• Coarctation of the aorta

• Aortic aneurysm

Clinically Important Points

• 1- Coarctation of the aorta: aortic coartication (narrowing) may involve the segment from the left subclavian artery to the ductus arteriosus. The latter remains patent and maintains the circulation to the lower parts of the body.

• If the obstruction is distal to the attachment of the ligamentum arteriosum, the circulation to the lower limb is maintained via collaterals between branches of the subclavian arteries and those of the descending aorta.

• 2- Aortic aneurysm: this is a localized dilatation of aorta which may compress the contents of superior mediastinum causing mediastinal syndrome. Rupture of weakened wall of aortic aneurysm causes severe haemorrhage which is often fatal if surgical intervention is not prompt

• 3- Clinically, embolism of the pulmonary trunk by a blood clot is a common cause of sudden death.

Vagus Nerve

Entry into the thorax occurs via the inlet of the thorax. It Pulmonary, cardiac, oesophageal branches, and left recurrent laryngeal branch
Scalenus anterior
Inf. thyr.
Trans. Cerv.
Supra-scap.

CB [032] The Coronary Circulation and the Conductive System of the Heart

Aim

To describe the blood supply of the heart and to trace the conducting system of the heart.

Objectives

By the end of this module, you should be able to:

• Draw and label two simple diagrams illustrating the blood supply of the heart.

• Describe the origin of the right and left coronary arteries.

• Describe the course, main branches, and territories of the right coronary artery.

• Describe the course, main branches, and territories of the left coronary artery.

• Identify the coronary arteries and their branches on angiograms.

• Describe the course of the coronary sinus and identify its opening in the right atrium.

• Understand the difference between the intrinsic conducting system and extrinsic innervation of the heart.

• Know the general anatomical position of the sinuatrial node, the atrioventricular node, and the distribution of the AV bundle.

The Fibrous Skeleton of the Heart

• It provides attachment for cusps, leaflets of valves, & myocardium.

• It is an electrical insulator, separating impulses of atria & ventricles.

The Conducting System of the Heart

The conducting system of the heart consists of highly specialized conducting muscle fibers for initiating impulses and conducting them rapidly through the heart.

SAN (Sinuatrial Node): Initiates the heartbeat.

AVN (Atrioventricular Node):

The AV bundle (atrioventricular bundle of His)
The AV bundle (atrioventricular bundle of His) is the only muscular connection between the myocardium of the atria & ventricles. It is from fibrous skeleton descends in the membranous interventricular septum divides into right & left branch

• Right bundle branch

• Left bundle branch

Cardiac pain (Anginal pain)
Pain from the myocardium enters the spinal cord via the upper 4 or 5 thoracic nerves (T1-5) as afferent fibers accompanying sympathetic nerve fibers. Pain is referred to areas of skin supplied by these nerves, often described as a tight, crushing pain felt over the middle of the sternum, the left side of the chest, and the medial side of the left arm (T1-2).

Arterial Blood Supply of the Heart

The right and left coronary arteries originate from their respective aortic sinuses at the root of the ascending aorta, immediately above the aortic valve. They both follow a course around the heart in the groove between the atria & ventricles (coronary groove or sulcus).

Right Coronary Artery (RCA)

• Is From the right aortic sinus, passes between the right auricle & infundibulum and down the coronary sulcus Then. To the left in the posterior part of the coronary sulcus it ends by anastomosing with the circumflex artery of the left coronary

• Marginal branch: To the inferior border of the heart (right ventricle).

• Posterior Interventricular Artery: Supplies the AV node (90%), both ventricles & post 1/3 of the interventricular septum.

• Rt. Conus a. to pulmonary trunk

Left Coronary Artery (LCA)

• From the left aortic sinus Descends between the infundibulum & left auricle in the coronary sulcus and divides into Anterior Interventricular artery (Left Anterior Descending; LAD)

• Circumflex artery (CX) LAD: Descends the anterior interventricular groove till the apex of the heart to anastomose with the posterior interventricular artery and give:

  • Left conus a. to the infundibulum.

  • Anterior surface of both ventricles.

  • Ant. 2/3 of the interventricular septum.

• Circumflex Artery Continuation of left coronary artery, runs in the post. coronary groove Anastomoses with RCA and gives:

• Atrial & ventricular (left atrium & ventricle).

Variations Blood supply of the conducting system of the heart

• the SAN Usually by the right coronary.

• AVN Usually right coronary (posterior interventricular branch)

• AV Bundle Usually dual blood supply from both coronaries

Cardiac Veins

Excess tissue fluid passes into lymphatics that follow the coronary arteries to mediastinal lymph nodes Coranary sinus & its tributaries
Great cardiac vein: In anterior inter-ventricular groove (with LAD)
Middle cardiac vein: Ascends in posterior interventricular groove (with post. Interventricular artery).
Small cardiac veins: Runs with marginal artery and then down the coronary sulcus with the right coronary to the back of the heart. Posterior vein of left ventricle

1. A patient complains of sharp chest pain that worsens on deep inspiration. Which pleura is most likely involved?
   A. Visceral pleura
   B. Mediastinal pleura
   C. Costal pleura
   D. Cervical pleura
   E. Diaphragmatic pleura

2. Pain from the diaphragmatic pleura is referred to which area?
   A. Chest wall
   B. Neck
   C. Back
   D. Shoulder
   E. Jaw

3. The pleural cavity lies between which two structures?
   A. Costal pleura and ribs
   B. Parietal and visceral pleura
   C. Lungs and thoracic wall
   D. Mediastinum and diaphragm
   E. Lung apex and cervical pleura

4. Which nerve innervates the central diaphragmatic pleura?
   A. Intercostal nerve
   B. Long thoracic nerve
   C. Vagus nerve
   D. Phrenic nerve
   E. Subcostal nerve

5. Which recess is accessed during thoracentesis?
   A. Costomediastinal recess
   B. Costodiaphragmatic recess
   C. Cervical recess
   D. Posterior mediastinum
   E. Pericardial sac

6. Cervical pleura extends through which structure?
   A. Aortic arch
   B. Thoracic inlet
   C. Esophageal hiatus
   D. Mediastinal pleura
   E. Diaphragm

7. Which structure lies deepest to the costal pleura?
   A. Rib
   B. Lung
   C. Intercostal muscles
   D. Endothoracic fascia
   E. Thoracic duct

8. Visceral pleura is insensitive to pain because:
   A. It is thin
   B. It lacks sensory nerves
   C. It is poorly vascularized
   D. It is supplied by phrenic nerve
   E. It has no lymphatics

9. The pleura covering the apex of the lung is called:
   A. Costal pleura
   B. Cervical pleura
   C. Mediastinal pleura
   D. Diaphragmatic pleura
   E. Visceral pleura

10. Which pleura lines the pericardium?
    A. Cervical pleura
    B. Costal pleura
    C. Diaphragmatic pleura
    D. Mediastinal pleura
    E. Visceral pleura

• A foreign body is most likely to lodge in which bronchopulmonary segment when a patient is supine?
  A. Apical segment
  B. Superior segment of lower lobe
  C. Anterior segment of upper lobe
  D. Posterior segment of upper lobe
  E. Medial segment of middle lobe

• Which structure separates bronchopulmonary segments?
  A. Pulmonary arteries
  B. Pulmonary veins
  C. Bronchi
  D. Lymphatics
  E. Bronchial arteries

• How many bronchopulmonary segments are typically found in the right lung?
  A. 8
  B. 10
  C. 12
  D. 6
  E. 9

• Which lobe of the lung contains the lingula?
  A. Right superior
  B. Right middle
  C. Right inferior
  D. Left superior
  E. Left inferior

• The horizontal fissure of the lung separates:
  A. Right superior and inferior lobes
  B. Left superior and inferior lobes
  C. Right superior and middle lobes
  D. Left superior and lingula
  E. Right middle and inferior lobes

• The cardiac notch is a feature of:
  A. Right lung
  B. Left lung
  C. Both lungs
  D. Trachea
  E. Diaphragm

• Segmentectomy of lung segments is possible because:
  A. Each segment shares veins
  B. Segments are not vascularized
  C. Each has its own bronchus and artery
  D. All segments have lymph nodes
  E. Segments are fused

• The oblique fissure lies between:
  A. Right middle and superior lobes
  B. Right superior and inferior lobes
  C. Left superior and inferior lobes
  D. Both B and C
  E. Only A

• The most anterior structure at the lung hilum is typically:
  A. Bronchus
  B. Pulmonary artery
  C. Superior pulmonary vein
  D. Inferior pulmonary vein
  E. Bronchial artery

• The pulmonary ligament allows movement of:
  A. Arteries
  B. Trachea
  C. Pulmonary veins
  D. Lymph nodes
  E. Bronchi

21. The moderator band is found in which chamber of the heart?
     A. Left atrium
     B. Right atrium
     C. Left ventricle
     D. Right ventricle
     E. None

22. The crista terminalis separates which two areas in the right atrium?
     A. Fossa ovalis and valve
     B. Pectinate and smooth wall
     C. Coronary sinus and IVC
     D. SVC and AV node
     E. Tricuspid valve and atrial wall

23. The left atrium receives oxygenated blood from:
     A. Coronary arteries
     B. Pulmonary veins
     C. Aortic arch
     D. Superior vena cava
     E. Bronchial arteries

24. Which chamber forms the apex of the heart?
     A. Right atrium
     B. Left atrium
     C. Right ventricle
     D. Left ventricle
     E. Interventricular septum

25. Trabeculae carneae are found in:
     A. All chambers
     B. Atria only
     C. Ventricles only
     D. Left atrium only
     E. Right atrium only

26. The conus arteriosus leads into:
     A. Aorta
     B. Pulmonary trunk
     C. Left atrium
     D. Right atrium
     E. Coronary sinus

27. The fossa ovalis is a remnant of:
     A. Ductus arteriosus
     B. Foramen ovale
     C. Sinus venosus
     D. Bulbus cordis
     E. Truncus arteriosus

28. Which structure prevents backflow during ventricular systole?
     A. Chordae tendineae
     B. Moderator band
     C. Coronary sinus
     D. Papillary muscles
     E. Both A and D

29. The heart lies mostly:
     A. In the right hemithorax
     B. In the midline
     C. In the left hemithorax
     D. Behind the sternum
     E. Posterior to esophagus

30. The interatrial septum contains which feature?
     A. Crista terminalis
     B. Moderator band
     C. Fossa ovalis
     D. Aortic sinus
     E. AV node

🟦 Section 4: Valves & Auscultation (Q31–Q40)

31. Where is the mitral valve best auscultated?
     A. 2nd left ICS
     B. 4th left ICS
     C. 5th left ICS midclavicular line
     D. Lower right sternal edge
     E. 2nd right ICS

32. Which valve is heard best at the left lower sternal edge?
     A. Aortic
     B. Pulmonary
     C. Mitral
     D. Tricuspid
     E. None

33. A murmur at the 2nd right intercostal space suggests pathology in which valve?
     A. Pulmonary
     B. Mitral
     C. Tricuspid
     D. Aortic
     E. None

34. The pulmonary valve is heard best at:
     A. 2nd right ICS
     B. 5th left ICS
     C. 2nd left ICS
     D. Apex
     E. Midsternal line

35. The tricuspid valve is best heard:
     A. Apex
     B. 2nd right ICS
     C. 2nd left ICS
     D. Left lower sternal edge
     E. Right 5th ICS

36. The aortic valve has how many cusps?
     A. 1
     B. 2
     C. 3
     D. 4
     E. Variable

37. The mitral valve is also called the:
     A. Bicuspid valve
     B. Tricuspid valve
     C. Semilunar valve
     D. Pulmonary valve
     E. Coronary valve

38. Which valve lies between the right atrium and right ventricle?
     A. Mitral
     B. Aortic
     C. Tricuspid
     D. Pulmonary
     E. Coronary

39. During systole, which valves are open?
     A. Aortic and pulmonary
     B. Mitral and tricuspid
     C. All closed
     D. All open
     E. Only mitral

40. Which valve is most commonly affected in rheumatic fever?
     A. Tricuspid
     B. Aortic
     C. Mitral
     D. Pulmonary
     E. Coronary sinus

🟧 Section 5: Coronary Circulation (Q41–Q50)

41. Which artery supplies the SA node in most individuals?
     A. Left coronary artery
     B. Right coronary artery
     C. Circumflex artery
     D. LAD
     E. Posterior interventricular artery

42. Which vein ascends in the anterior interventricular groove?
     A. Middle cardiac vein
     B. Small cardiac vein
     C. Great cardiac vein
     D. Posterior vein of LV
     E. Oblique vein of LA

43. The coronary sinus drains directly into the:
     A. Right atrium
     B. Left atrium
     C. Right ventricle
     D. Pulmonary trunk
     E. Aorta

44. The artery that runs in the anterior interventricular groove is:
     A. Circumflex
     B. RCA
     C. LAD
     D. Posterior descending artery
     E. Oblique

45. Which artery typically determines coronary dominance?
     A. LAD
     B. RCA
     C. Circumflex
     D. SA nodal
     E. Pulmonary

46. The small cardiac vein runs with which artery?
     A. LAD
     B. Circumflex
     C. Posterior descending
     D. Right marginal
     E. Great cardiac

47. The artery that supplies the posterior interventricular septum is usually:
     A. LAD
     B. Circumflex
     C. RCA (via PDA)
     D. Aorta
     E. Pulmonary

48. In left-dominant circulation, the posterior descending artery arises from:
     A. RCA
     B. LAD
     C. Circumflex
     D. Aorta
     E. Pulmonary trunk

49. Which structure runs in the coronary sulcus?
     A. LAD
     B. Right coronary artery
     C. Posterior interventricular artery
     D. Pulmonary vein
     E. Aorta

50. Which of the following veins directly joins the great cardiac vein before entering coronary sinus?
     A. Middle cardiac vein
     B. Small cardiac vein
     C. Oblique vein of LA
     D. Posterior vein of LV
     E. Right marginal vein

🟨 Section 6: Mediastinum (Q51–Q60)

51. The superior mediastinum ends at which vertebral level?
     A. T1
     B. T2
     C. T3
     D. T4
     E. T5

52. The anterior mediastinum lies between:
     A. Lungs and esophagus
     B. Sternum and pericardium
     C. Trachea and vertebral body
     D. Diaphragm and aortic arch
     E. Heart and diaphragm

53. The vagus nerve passes ___ to the lung root.
     A. Anterior
     B. Posterior
     C. Superior
     D. Lateral
     E. Medial

54. The thoracic duct crosses to the left side at which level?
     A. T2
     B. T4
     C. T5–T6
     D. T8
     E. T10

55. Which mediastinal compartment contains the thymus in infants?
     A. Posterior
     B. Superior
     C. Middle
     D. Anterior
     E. Both B and D

56. Which vein arches over the right main bronchus?
     A. Brachiocephalic
     B. Azygos
     C. Hemiazygos
     D. Subclavian
     E. Coronary sinus

57. Compression of which nerve causes hoarseness in aortic arch aneurysm?
     A. Phrenic
     B. Right recurrent laryngeal
     C. Left recurrent laryngeal
     D. Vagus
     E. Sympathetic chain

58. A mediastinal mass behind the esophagus is most likely in which compartment?
     A. Anterior
     B. Posterior
     C. Middle
     D. Superior
     E. Inferior

59. Which structure lies directly anterior to the thoracic vertebral bodies in the posterior mediastinum?
     A. Azygos vein
     B. Esophagus
     C. Phrenic nerve
     D. Trachea
     E. Left main bronchus

60. The azygos vein drains into:
     A. Coronary sinus
     B. Pulmonary vein
     C. Superior vena cava
     D. Inferior vena cava
     E. Right atrium

Pleura (Q1–Q10)

1. C. Costal pleura

2. D. Shoulder

3. B. Parietal and visceral pleura

4. D. Phrenic nerve

5. B. Costodiaphragmatic recess

6. B. Thoracic inlet

7. D. Endothoracic fascia

8. B. It lacks sensory nerves

9. B. Cervical pleura

10. D. Mediastinal pleura

🟨 Lungs & Segments (Q11–Q20)

11. B. Superior segment of lower lobe

12. B. Pulmonary veins

13. B. 10

14. D. Left superior

15. C. Right superior and middle lobes

16. B. Left lung

17. C. Each has its own bronchus and artery

18. D. Both B and C

19. C. Superior pulmonary vein

20. C. Pulmonary veins

🟥 Heart Anatomy (Q21–Q30)

21. D. Right ventricle

22. B. Pectinate and smooth wall

23. B. Pulmonary veins

24. D. Left ventricle

25. C. Ventricles only

26. B. Pulmonary trunk

27. B. Foramen ovale

28. E. Both A and D

29. C. In the left hemithorax

30. C. Fossa ovalis

🟦 Valves & Auscultation (Q31–Q40)

31. C. 5th left ICS midclavicular line

32. D. Tricuspid

33. D. Aortic

34. C. 2nd left ICS

35. D. Left lower sternal edge

36. C. 3

37. A. Bicuspid valve

38. C. Tricuspid

39. A. Aortic and pulmonary

40. C. Mitral

🟧 Coronary Circulation (Q41–Q50)

41. B. Right coronary artery

42. C. Great cardiac vein

43. A. Right atrium

44. C. LAD

45. B. RCA

46. D. Right marginal

47. C. RCA (via PDA)

48. C. Circumflex

49. B. Right coronary artery

50. C. Oblique vein of LA

🟨 Mediastinum (Q51–Q60)

51. D. T4

52. B. Sternum and pericardium

53. B. Posterior

54. C. T5–T6

55. E. Both B and D

56. B. Azygos

57. C. Left recurrent laryngeal

58. B. Posterior

59. B. Esophagus

60. C. Superior vena cava