Anatomy of lungs, pleura and diaphragm

Clinical Anatomy of lungs , pleura and diaphragm

Dr. Ashish kumarDept. of Chest & T.B, Santosh university

Points

1. Basic anatomy of respiratory system

2. Surface anatomy

3. Blood circulations

4. Innervations

5. Lymphatic

6. Basic anatomy of pleura

7. Basic anatomy of diaphragm

Respiratory System starts at the nares

Major Functions

Upper respiratory system:1. Air conditioning (warming)2. Defense against pathogens3. Gas Transport

Lower respiratory system:1. Speech & other respiratory

sounds2. Gas exchange (ventilation)3. Maintenance of homeostasis, e.g.

pH

Respiratory Muscles

Diaphragm: depresses on contraction inhalation

External intercostals: elevate ribs inhalation

Internal intercostals: depress ribs active exhalation

(Accessory muscles - serratus anterior, scalenes, pectoralis minor, sternocleidomastoid, internal and external obliques, transverse abdominus, rectus abdominus)

Upper Respiratory System

1. Nose

2. Nasal Cavity

3. Paranasal sinuses

4. Pharynx

Upper Respiratory System

1) Nose External and internal nares =

Nostrils Nose Hairs = vibrissae Alar cartilages on the nose Paranasal Sinuses

Upper Respiratory System

• 2) Nasal Cavity

• Nasal Conchae:

– Superior, middle and inferior

– Other name: “Turbinate bones” because they create

Upper Respiratory System

3)Paranasal Sinuses

• Named after their bones

– Frontal

– Ethmoid

– Sphenoid

– Maxillary

Upper Respiratory System

4) Pharynx

Shared passageway for respiratory and digestive systemsNasopharynx - part above uvula and posterior to internal naresOropharynx – portion visible in mirror when mouth is wide open

fauces = the openinguvula - posterior edge of soft palate

Laryngopharynx – between the hyoid bone & the esophagus

Larynx (voice box)

The larynx consists of threearticulating cartilages,

1. Thyroid2. cricoid3. Arytenoid

Lungs

Light, soft, spongy

Conical in shape, apex, base, costal surface, medial surface, hilus. Note various impressions

Right lung Three lobes; superior, middle and inferior

Oblique and horizontal fissure

Left Lung Two lobes; superior and inferior also Lingula and Cardiac notch, oblique

fissure

Right Lung

Left Lung

Right Lung

Lung Fissures:

Oblique fissure (Right & Left):

It starts at the 3rd thoracic spine while the arms are elevated, descends downwards, laterally & anteriorly along the medial border of the scapula touching the inferior angle of the scapula) cutting the midaxillary line in the 5th rib & ending at the 6th costal cartilage 3 inches from the midline.

In cadaver it arise at the 2nd thoracic spine.

The transverse fissure (Right):

It arises at the 4th costal cartilage, runs horizontally to meet the oblique fissure in the midaxillary line in the 5th rib.

Fissures & Lobes of the Lungs

Fissures & Lobes of the Right Lung

Right Upper Lobe

Right Middle Lobe

Right Lower lobe

Left Lung

Fissures of the Left Lung

Left Upper Lobe

Left Lower Lobe

Airways

Trachea, primary bronchi, secondary bronchi, tertiary bronchi out to 25 generations( terminal bronchiols)

All comprised of hyaline cartilage

Trachea Begins where larynx ends (about C6)

10-12 cm long, half in neck, half in mediastinum

20 U-Shaped rings of hyaline cartilage – keeps lumen intact but not as brittle as bone

Lined with epithelium and cilia which work to keep foreign bodies/irritants away from lungs

From Bronchi to Lungs: The Bronchial Tree

1 bronchi (enter lungs at hilus, complete cartilage rings)

2 bronchi (from now on cartilage plates)

3 bronchi

Bronchioles

Terminal bronchioles

Respiratory bronchioles

Alveolar ducts

Alveolar sacs

Conducting portion

Respiratory portion

Airways

Primary Brochi One to each lung – continuation of trachea Right bronchus is wider and shorter 2.5 cm as opposed to 5 cm

and branches from the trachea at a greater angle

Secondary bronchi – one to each lobe, three in right, two in left

Tertiary – one to each bronchopulmonary segment –approximately 10 per lung

All of the above are hyaline cartilage with no ability to change diameter

Bronchopulmonary Segments

Bronchopulmonary Segments

Bronchopulmonary Segments

Bronchioles

First level of airway surrounded by smooth muscle (not the cartilage ), therefore can change diameter as in brocho-constriction and broncho-dilation

Terminal

Respiratory

3-8 orders

alveoli

Bronchioles

Surface Anatomy

Borders of the lung:• The apex is about 2-3 cms (1 inch) above the medial 1/3 of the

clavicle, then the anterior border of both lungs run downwards & medially meeting each other in the middle line behind the angle of Louis (sternal angle).

• The anterior border of right lung continues running downwards till the 6th costochondral junction.

• The anterior border of left lung continues running downwards till the 4th costal cartilage then curves laterally ½ inch forming the cardiac notch then descends downwards till the 6th costochondral

junction.

Borders of the lung:

• The lower border of the lungs represented by a line startingfrom 6th rib in the MCL, 8th rib in the MAL & 10th rib in thescapular line.

Circulation of lungs

Two types

1. Bronchial circulation

2. Pulmonary circulation

Bronchial circulation

• The trachea (and esophagus), main-stem bronchi, and pulmonary vessels into the lung , as well as the visceral pleura in humans are supplied by the bronchial (systemic) circulation.

• The bronchial circulation has enormous growth potential. In long-standing inflammatory and proliferative diseases, such as bronchiectasis or carcinoma, bronchial blood flow may be greatlyincreased.

Pulmonary circulation

• In humans the pulmonary artery enters each lung at the hilum in a loose connective tissue sheath adjacent to the main bronchus.

• The pulmonary artery travels adjacent to and branches with each airway generation down to the level of the respiratory bronchiole.

• As blood enters the vast alveolar wall capillary network, its velocity slows, averaging approximately 1000 µm/sec (or 1 mm/sec),where gas exchange take place.

• Anatomically, the pulmonary blood vessels can be divided into two groups in

1. Extra-alveolar 2. Alveolar. Extra-alveolar

vessels lie in the loose-binding connective tissue (peribronchovascularsheaths, interlobular septa). Extra-alveolar vessels extend into the terminal respiratory units. Arteries as small as 100 µm in diameter have loose connective tissue sheaths. This is in contrast to the bronchioles, which are tightly embedded in the lung framework from the bronchioles (1 mm in diameter) onward.

Alveolar vessels lie within the alveolar walls and are embedded in the parenchymalconnective tissue

Innervation

Pleura via intercostal (thoracic) nerves.

Tracheobronchial tree motor pathway

Parasympathetic via CN X efferent function = broncho-constriction via smooth muscle, also to epithelial cells in trachea, afferent = responsible for cough reflex

Sympathetic from T1-T5 efferent = brocho-dilation

• Cholinergic, adrenergic, and peptidergic nerve Endings are present around tracheal glands and do not show patterns of slective innervation density between serous and mucous cells . Serous and mucous granule secretion is stimulated more by muscarinic than by adrenergic agents.

lymphatics

• Superficial plexuses- The superficial plexus is located n the surface of the lung just beneath the pulmonary pleura.

• Deep plexuses-accompanies the branches of the pulmonary vessels and ramifications of bronchi.

Right lung lymphatics

• Right upper lobe: • Upper 2/3rd-Right tracheobronchial nodes

• Lower l/3rd -Dorsolateral hilar nodes

• Right middle lobe: • Hilar nodes around middle lobe bronchus

• Right lower lobe: • Porsolateral part-Dorsolateral hilar nodes

• Ventromedial part- Ventromedial hilar and carinal nodes

Left lungs lymphatics

• Left upper lobe: • Apex-para-aortic node

• Other than apex-Anterior and posterior hilar nodes

• Left lower lobe • Dorsolateral part-Dorsolateral hilar nodes

• Ventromedial par^Ventromedial hilar and carinal nodes

Pleura

• Visceral pleura:

Covers and follows indentations of lung.

• Parietal pleura:

Lines thoracic cavity.

Parietal Pleura Divisions

• Costal pleura lines the ribs.

• Diaphragmatic pleura covers the diaphragm.

• Mediastinal pleura lies against the mediastinum.

• Cervical pleura extends above the level of the first rib.

Pleural Reflections

• Costodiaphragmatic recess (space):Space where costal and diaphragmatic pleura

meet.

• Costomediastinal recess (space):Space where mediastinal and costal pleura meet.

• Pulmonary ligament:Transition between visceral and parietal pleura at

root of the lung.

Pleural Lines of Reflection

• Cervical dome of pleura:Anteriorly, 1.5-2.5 cm above the sternal end of

the clavicle.

Anterior margin extends obliquely behind the sternoclavicular joint.

At sternal angle, the pleura is at the median line and two sides stay in contact until the fourth costal cartilage.

Pleural Lines of Reflection• Right side:

– Leaves sternum at 7th

costal cartilage.– At 8th costal cartilage at

midclavicular line.– At 10th rib at axillary line.– At 11th rib at scapular line.– Extends to level of body

of T12 and then ascends.

Pleural Lines of Reflection

• Left side:

– Leaves sternum at IC space 5.

– 1.5 cm from sternal margin at 6th costal cartilage.

– Follows same landmarks as right side from this point.

Diaphragm

• The diaphragm is a curved musculo fibrous sheet that separates the thoracic from the abdominal cavity.

• pierced by structures that pass between these two regions of the body.

• primary muscle of respiration.

• dome shaped and consists of a peripheral muscular part and central tendinous part.

• muscular part arises from the margins of the thoracic opening and gets inserted into the central tendon.

• attachments to the thoracic wall are low posteriorly and laterally, but high anteriorly.

• Rarely affected by intrinsic diseases

• complex embryological development is subject to number of congenital anomalies

Origin of the diaphragm• sternal part- arising from the posterior surface

of the xiphoid process.

• costal part arising from the deep surfaces of the lower six ribs and their costal cartilages & forms the right & left domes.

• vertebral/lumbar part arising from upper three lumbar vertebrae; forms the right & left crura & the arcuate ligaments.

• Crura:The right crura is from the bodies of first three lumbar vertebrae.

• The left crus, from the bodies of first two lumbar vertebrae.

• Arcuate ligaments:Lateral to the crura on both sides.

• Medial arcuate ligament is thickened upper margin of fascia that covers the psoas muscle.

• Lateral arcuate ligament is thickened upper margin of the fascia covering the quadratuslumborum muscle.

Parts of the Diaphragm

• It is studied as

(a)Central tendon

(b)Right & left crus

(c)Right & left dome

Functions of the Diaphragm

1. Muscle of inspiration: On contraction the diaphragm pulls its central tendon down and increases the vertical diameter of the thorax. The diaphragm is the most important muscle used in inspiration.

2. Muscle of abdominal straining: The contraction of the diaphragm assists the contraction of the muscles of the anterior abdominal wall in raising the intra-abdominal pressure for micturition, defecation, and parturition.

3. Weight lifting muscle: In a person taking a deep breath and holding it (fixing the diaphragm), the diaphragm assists the muscles of the anterior abdominal wall in raising the intra-abdominal pressure.

4. Thoraco-abdominal pump: The descent of the diaphragm

decreases the intrathoracic pressure & increases the intra-abdominal pressure.

This compresses the blood in the inferior vena cava and forces it upward into the right atrium of the heart.

Within the abdominal lymph vessels is also compressed, and its passage upward within the thoracic duct is aided by the negative intrathoracic pressure.

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Other minor openings

• Sympathetic trunk (pass posterior to the medial arcuate ligament on both sides).

• Superior epigastric vessels (pass between the sterna and costal origins of the diaphragm on each side).

• Left phrenic nerve (pierces the left dome of diaphragm)

• Neurovascular bundles of lower six intercostal spaces (pass between the muscular slips of costal origin of diaphragm)

Vascular supply

• Lower five intercostal and subcostal arteries- supply the costal margins of the diaphragm

• Phrenic arteries- supply the main central portion of the diaphragm.

• The phrenic veins follow the corresponding arteries on the inferior diaphragmatic surface.

Nerve supply of diaphragm

• sensory supply of the central tendon of diaphragm that is covered by parietal and peritoneal pleura is from phrenic nerve.

• Sensory supply to the periphery of diaphragm is from lower six intercostal nerves.

• The motor nerve supply of diaphragm is only from the phrenic nerve.

Phrenic nerve

• descends anterior to the pulmonary hilum, between the fibrous pericardium and mediastinal pleura, to the diaphragm, accompanied by the pericardiophrenicvessels.

• supplies sensory branches to the mediastinal pleura, fibrous pericardium and parietal serous pericardium.

• The right phrenic nerve is shorter and more vertical than the left