Thorax

What are the components of the thorax?

• Thoracic wall

• Superior thoracic aperture

• Inferior thoracic aperture

• Diaphragm

• Mediastinum

• Pleural cavities

What are the functions of the thorax?

• Breathing

• Protection of vital organs

• Conduit (passageway) for nerves, blood vessels, and organs (e.g. esophagus)

What is the narrow superior thoracic aperture of the thoracic wall?

• Passage of nerves and blood vessels between the neck, upper limbs, and thorax

What is the inferior thoracic aperture closed off by?

Diaphragm

What do the bones of the thoracic wall protect?

Thoracic organs on all sides

What is the most superior portion of the Sternum?

Manubrium

What is the most inferior portion of the Sternum?

Xiphoid process

What ribs are the “true” ribs?

Ribs 1-7

What do the costal cartilages of the true ribs articulate with?

Directly with the sternum

What are the “false” ribs?

Ribs 8-12

What do ribs 8-10 articulate with?

Indirectly through the costal cartilage of rib 7

What are the floating ribs of the “false” ribs?

Ribs 11-12

Does the floating ribs have any costal cartilage anteriorly?

no

What is sternal angle of the Sternum?

Junction between the manubrium and body of the sternum

What does the sternal angle mark?

Costal cartilage of rib 2 at the lateral edge

What is the sternal angle a landmark for?

Listen for heart sounds and breathing

What does the Xiphoid process mark?

Inferior border of the sternum

What is the transverse thoracic plane?

Imaginary line between T4/T5 vertebral level and sternal angle

What is the significance of the Transverse thoracic spine?

• Beginning and end of the aortic arch

• Trachea bifurcation into the primary bronchi

• Superior & Inferior Mediastinum separation

Superior limit of the pulmonary trunk

• Point where superior vena cava pierces the pericardium to empty into the right atrium

Where is the typical location of nipple and areola of a female?

• Intercostal space of ribs 5 and 6

• May vary depending on size of chest and/or breast

Where is the typical location of nipple and areola of a male?

• Intercostal space of ribs 4 and 5

What does the internal thoracic artery supply?

medial breast in 2nd through 4th intercostal spaces

What is the lateral thoracic wall of the Internal thoracic artery supplied by?

Axillary artery

What does the Medial breast drain into?

Parasternal nodes on deep side of thoracic wall

What do the lymph from lateral breast drain into?

Axillary nodes

What is the sensation from breast might be carried by?

4th through 6th intercostal nerves

What are the muscles of the thoracic region?

Intercostal muscles

• External Intercostal muscles

• Internal Intercostal muscles

• Innermost Intercostal muscles

Subcostal muscles

Transversus thoracis muscle

Levatores costarum muscle (covered with spinal musculature)

Diaphragm

What is the fiber direction of the External intercostal muscles?

Down and Forward

Where is the aponeurosis of the external intercostal muscles?

Anteriorly near sternum

OIAN for External intercostal muscles

Origin: inferior margin of rib above

Insertion: superior margin of rib below

Innervation: intercostal nerves (T1 – T11)

Action: moves ribs superiorly; most active during inspiration

What is the fiber direction of the Internal intercostal muscles?

Down and Backward

Where is the aponeurosis of the Internal intercostal muscles?

Posterior near vertebrae

OIAN for Internal intercostal muscles?

Origin: superior margin of rib below deep to the attachment of the external intercostal muscle

Insertion: lateral edge of costal groove of rib above

Innervation: Intercostal nerves (T1 – T11)

Action: moves ribs inferiorly; most active during expiration

What is the fiber direction of the Innermost intercostal muscles?

Down and Back

OIAN for Innermost intercostal muscles?

Origin: internal aspect of superior border of rib below

Insertion: medial edge of costal groove of rib above

Innervation: intercostal nerves (T1 – T11)

Action: moves rib inferiorly; most active in expiration

What the subcostal muscles (subcostales)?

Irregular slips of muscle fibers

What can vary of the Subcostal muscle (subcostales)?

Number and Size

More numerous in the lower posterior regions

What is the fiber direction of the subcostal muscles?

Down and Back

How many intercostal spaces does the subcostal muscles pass over?

2-4

OIAN for Subcostal muscle

Origin attachment: internal surface of rib

Insertion attachment: internal surface of 2nd or 3rd rib above

Innervation: related intercostal nerves

Action: moves rib inferiorly; acts with internal intercostal muscle

Where is the Transverse thoracis muscle located?

Located within thorax anteriorly

OIAN for Transverse thoracis muscle

Origin: posterior xiphoid process and body of sternum

Insertion: inferior aspect costal cartilages of ribs 2-6

Innervation: intercostal nerves T2-T6

Action: depresses costal cartilages ribs 2-6; acts in exhalation; secures internal thoracic blood vessels to thorax

What is the Diaphragm?

Dome shaped musculotendinous septum between thorax and abdominal cavities

OIAN for Diaphragm

REVIEW

What are the structures that pierce the diaphragm?

Caval Hiatus

Esophageal hiatus

Aortic hiatus

What is the Caval hiatus for?

inferior vena cava at the T8 vertebral level

What is the Esophageal hiatus for?

esophagus at the T10 vertebral level

What is the Aortic hiatus for?

Abdominal aorta at T12 level

What is each hiatus (especially esophageal hiatus) present a potential site for?

abdominal organs or structures to be pushed up into the thorax, creating a hernia

What does the intercostal nerve innervate?

Muscles of thoracic wall

What does the Intercostal nerve extend anteriorly between?

internal interocostal muscle and the innermost intercostal muscle

What does the costal groove of each rib cover from superior to inferior?

VAN

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Intercostal vein

Intercostal artery

Intercostal nerve

What surrounds each lung on either side of the mediastinum?

Pleural cavities

What is the Parietal Pleura associated with?

Inner walls of thorax

What is the visceral pleura associated with?

Surface of the lungs

What is Pleural cavity?

potential space between parietal & visceral contains serous fluid to prevent friction

What are the structures of the left lung?

2 lobes

• Superior lobe (contains the lingula)

• Inferior lobe

1 fissure – Oblique fissure

What are the structure of the right lung?

3 lobes

• Superior lobe

• Middle lobe

• Inferior lobe

2 fissures

• Oblique fissure

• Horizontal fissure

Where is the Root/Hilum of lungs located?

Medial surface of lungs

What does the Root/Hilum of lungs contain?

• Pulmonary artery

• Pulmonary veins

• Main bronchus

• Nerves

• Lymphatics

What is the orientation of Phrenic nerve (C3, C4, C5)?

Lies Anterior to root

What is the orientation of Vagus Nerve (CN X)

Lies posterior to root

What does the Trachea split into at level T4-T5?

Left and Right Main bronchi

Traits of Right Main Bronchus?

Wider and Vertical

Traits of Left Main Bronchus?

Narrower and Oblique

What two structures make up the Pericardial Sac?

Fibrous pericardium

Serous Pericardium

What is the Fibrous pericardium?

Tough External Layer of Connective Tissue Layer

Where is the parietal pericardium of the Serious Pericardium?

Inside lining of fibrous pericardium

What is the visceral pericardium of Serous Pericardium?

Outer covering of heart itself

What is the Pericardial cavity?

Potential space between parietal and visceral pericardial layers

What is the Pericardial cavity filled with?

Serous fluid to allow un-inhibited movement of the heart

What is the base of the heart fixed to?

Posterior pericardial wall

What does the base of the heart contain?

• Left atrium

• Small portion of right atrium

• Proximal parts of great veins (superior and inferior vena cava, pulmonary veins)

Where is the apex of the heart located?

Forward, Downward and to the left of base

What is the apex of the heart formed by?

Inferolateral portion of left ventricle

Where is the ascending aorta?

First part of aorta inferior to the aortic arch

What branches off of the ascending aorta?

Coronary arteries

What are the branches of the left coronary artery?

Circumflex artery

Anterior interventricular artery

Where does the anterior interventricular artery lie?

Anterior interventricular sulcus

What are the branches of the Right coronary artery?

Right marginal artery

Posterior interventricular artery

Where does the Posterior interventricular artery lie in?

Posterior interventricular sulcus

What are the veins of the heart?

Coronary sinus

Great cardiac vein

Middle cardiac vein

Where does the coronary sinus collect venous drainage?

From heart and drains into the right atrium

What does the Great cardiac vein course along?

Anterior interventricular branch/artery

What does the middle cardiac vein course along?

Posterior interventricular branch/artery

From where does the right atrium receive oxygen deficient blood?

From periphery through the superior and inferior vena cava

From the right atrium where does blood flow through?

Tricuspid valve to the right ventricle

Where does the right ventricle pump oxygen deficient blood through?

Pulmonary semilunar valve to the pulmonary arteries

Where does the oxygen-deficient blood undergo “oxygentation”

Capillary beds of lungs

After oxygenation, where does the now oxygen-rich blood travel through?

Pulmonary veins to the left atrium

After the left atrium receives oxygen rich blood, where does it pump through?

Mitral (bicuspid) valve to the left ventricle

Where does the left ventricle pump oxygen rich blood through?

Aortic semilunar valve out to the periphery via aorta

What are the receiving chambers?

Atria

Where does the right atrium receive low oxygen blood from?

Superior vena cava

Inferior vena cava

Coronary sinus

What is the Fossa ovalis?

A fetal structure that allowed blood to move directly from the right atrium to the left atrium, it closes at birth, but sometimes remains open

Where does the Left atrium receive high oxygen blood from?

Pulmonary veins

What muscle is in the walls of both atria?

Pectinate muscle