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Anatomical Dissections: Respiratory System - Coggle Diagram
Anatomical Dissections: Respiratory System
Thoracic Skeleton
Describe the Thoracic Skeleton
Thoracic skeleton consists of 12 Thoracic Vertebrae
12 Pairs of Ribs with the Coastal Cartilage, and the Sternum
The female thorax is generally narrower and shorter than the male equivalent.
List the function of the Thoracic Skeleton
Thoracic Skeleton:
Participates in Respiratory movement
Provides a measure of protection to vital organs
Elements of the Thoracic Segment
Describe the structure of the Thoracic Segment
The Rib is split into the following two components:
Bony Part (Costal Bone)
Bony Part is made up of the:
Head
Neck
Costal tubercle
Body (including the Costal Angle)
Costal Part called the Costal Cartilage
Sternum which articulates with the Costal cartilage of the True ribs only
Describe the different types of Ribs and their Anterior Articulation
True Ribs
True Ribs are the 1st to the 7th Ribs
Anterior Articulation: True Ribs articulate with the Sternum
False Ribs
False Ribs are the 8th to the 10th Ribs
Anterior Articulation: False Ribs articulate with the Rib above
Floating Ribs
Floating Ribs are the 11th and 12th Rib
They do not have an Anterior Articulation
Sternum
Describe the structure of the Sternum
The Sternum is a dagger-like bone consisting of the:
Manubrium (the handle)
Body (Blade)
Xiphoid Process (tip of blade)
The Sternal Angle is the Junction of the Manubrium and the Body of the Sternum
The Sternal angle is elevated and marks the articulation of the Second Rib
Sternal angle is projected posteriorly to intersect with the T4/T5 vertebrae and it is an important landmark for internal structures
The Sternum has the following Notches:
Jugular notch or the Suprasternal notch
Clavicular Notch
Name one non-bony anatomical structure that arises or ends at feature called the Sternal Angle
Answer: Arch of the aorta/bifurcation of trachea/bronchi originate
Joints of the Thoracic cage
Diaphragm is the chef Muscle for quiet respiration
The muscles of the Thoracic wall contribute to the deep inspiration
Rib cage Movement:
During Inspiration, there is an increase in the Transverse and Anteroposterior Dimensions as well as the Infrasternal Angle
The downward movement of the Diaphragm further increases the volume of the thoracic cavity
Sternocostal Joints:
True Joints
True joints are generally found only at the from the 2nd to 5th Ribs
Synchondroses
1st, 6th and 7th Ribs attache to the Sternum via the Synchondroses
Xiphisternal Junction or Xiphisternal Joint or Xiphisternal synchondrosis
Xiphisternal joint marks the part of the sternum where the body of the sternum and the xiphoid process meet.
Costovertebral Joints:
Costo-Transverse Joint
This is the joint created by the articulation of the Costal Tubercle of the Ribs with the Transverse Process of the corresponding Thoracic vertebrae
Costo-Vertebral Joint
This is the joint that is created by the Head of a Rib which articulates with the Vertebral body of a Thoracic vertebra.
The Intercostal Muscles
Intercostal muscles lie in between the each of the adjacent pair of ribs and function in Respiration
There are three types of Intercostal Muscles:
External Intercostal Muscle
External intercostal muscles are the most Superficial
Their fibres run towards the Medial direction and Downwards
Between the Costochondral Junction and the Sternum the External Intercostal Muscles are replaced by the thin, transparent External Intercoastal Membrane
Internal Intercostal Muscles
Internal Intercostal Muscles are deep to the external intercostal muscles
Their fibres run at a Right Angle to those of the external intercostal muscles
Posteriorly the Internal Intercostal Muscles are replaced by the Internal Intercostal membrane
Both of these intercostal layers are thin
Innermost Intercostal Muscles
Innermost Intercostal Muscles is the deepest layer and lies on the surface of the Rib cage
Innermost intercostal muscle is represented by three separate parts:
Sternocostalis
Sternocostalis is called the Transversus Thoracis muscle
It is found anteriorly, behind the Sternum
Innermost Intercostal
Innermost Intercostal muscle lies laterally at the angles of the ribs
Subcostalis
Subcostalis lies posteriorly in the Paravertebral regions
Muscles of the Thoracic Wall
Describe the Origin, Insertion, Innervation and the Action of the Scalene muscles
Anterior Scalene muscle
Origin: C3–C6 (transverse processes, anterior tubercles)
Insertion: 1st rib (anterior scalene tubercle)
Innervation: Anterior rami of the c4-c6 spinal nerves
Action:
With Mobile ribs: Elevates upper ribs during inspiration.
With fixed ribs: Flexes cervical spine to the same side (unilaterally); flexes neck (bilaterally)
Middle Scalene muscle
Origin: C1-C2 (Transverse process), C3-C7 (Transverse process and Posterior tubercle)
Insertion: 1st Rib
Innervation: Anterior rami of the C3-C8 spinal nerves
Action:
With Mobile ribs: Elevates upper ribs during inspiration.
With fixed ribs: Flexes cervical spine to the same side (unilaterally); flexes neck (bilaterally)
Posterior Scalene Muscles
Origin: C5-C7 (Transverse process, posterior tubercle)
Insertion: 2nd Rib (outer surface)
Innervation: Anterior rami of C6-C8 spinal nerves
Action:
With Mobile ribs: Elevates upper ribs during inspiration.
With fixed ribs: Flexes cervical spine to the same side (unilaterally); flexes neck (bilaterally)
Intercostal Muscles
Describe the Intercostal Muscles according to Origin, Insertion, Innervation and Action
External Intercostal muscle
Origin and Insertion: Lower margin of the rib to the Upper margin of the next lower rib
Courses obliquely downward and downward from the costal tubercle to chondro-osseus junction
Innervation: 1st to 11th intercostal nerves
Action:
During inspiration they elevate the ribs
Supports the intercostal spaces
Stabilizes the chest wall
Internal Intercostal Muscles
Origin and Insertion: Lower margin of the rib to the Upper margin of the next lower rib
Courses obliquely forward and upward from the costal angle to sternum
Innervation: 1st to the 11th intercostal nerves
Action:
During expiration they depress the ribs
Supports the intercostal spaces
Stabilizes the chest wall
Innermost Intercostal Muscles
Origin and Insertion: Lower margin of the rib to the Upper margin of the next lower rib
Courses obliquely forward and upward from the costal angle to sternum
Innervation: 1st to the 11th intercostal nerves
Action:
During expiration they depress the ribs
Supports the intercostal spaces
Stabilizes the chest wall
Subcostal muscles
Describe the Origin, Insertion, Innervation and Action of the Subcostal Muscle
Origin and Insertion: Lower margin of the Lower rib to the Inner surface of the Ribs two to three ribs below
Innervation: Adjacent intercostal nerves
Action: During expiration they depress the ribs
Transversus Thoracic Muscles
Describe the Origin, Insertion, Innervation and Action of the Transversus Thoracic Muscles
Origin: Sternum and Xiphoid process
Insertion: 2nd to 6th ribs (Costal cartilage, Inner surface)
Innervation: 2nd to 6th intercostal nerves
Action: During expiration they weakly depress the ribs
Nerves and Blood Supply to the Anterior and Posterior Thoracic Walls
Describe the general Nerves and Blood Supply to the Anterior and Posterior Thoracic Walls
The Neurovascular Bundle is located between the Internal and Innermost intercostal muscles
Each intercostal space contains a neurovascular bundle comprising of the Intercostal vein, Intercostal artery and Nerve
Intercostal muscles are innervated by the Anterior (ventral) Rami spinal thoracic nerves (T1-T11) known as the Intercostal nerves
Intercostal nerves terminate as cutaneous branches that innervate the skin
T12 forms the Subcostal nerve
Blood Supply: Arterial Blood supply of the Chest Wall
Describe the Arterial Blood supply of the Anterior Chest Wall
The Anterior Intercostal arteries arise from from the Internal Thoracic Artery of the Subclavian artery
Anterior intercostal arteries supply the first 6 Intercostal spaces
At the 6th Intercostal space the Internal Thoracic artery divides into to the Superior Epigastric Arteries and the Musculophrenic Artery
Superior epigastric artery enters the Rectus sheath of the anterior abdominal wall to supply the sheath and its contents
Musculophrenic artery supplies the Lower intercostal spaces and can be traced along the Costal margin
Describe the Arterial Blood supply of the Posterior Chest Wall
Superior Thoracic artery supplies the 1st and 2nd Intercostal spaces
Posterior intercostal arteries supply the remaining 9 intercostal spaces
The Posterior Intercostal arteries arise from the Descending Aorta
Venous Blood Supply
Describe the Venous Drainage of the Anterior Chest Wall
Anterior intercostal spaces are drained by the Anterior Intercostal Veins
Anterior Intercostal Veins empty into the Internal Thoracic veins
Internal Thoracic veins drain into the Subclavian Vein
There are two Internal Thoracic Veins with one on either side of each the internal thoracic artery
Describe the Venous Drainage of the Posterior Chest Wall
Posterior Intercostal veins mainly drain into the Azygous System which then empties into the heart via the Superior vena cava
The posterior chest wall is drained by the following Veins:
Azygous Vein
Azygous Vein drains the Posterior Intercostal Veins on the Right side from the 4th to 11th intercostal spaces
Azygous vein empties into the Superior vena cava
Hemi-Azygous Vein
Hemi-Azygous Vein drains the Posterior Intercostal Veins on the Left side from the 1st to the 12th intercostal spaces
Hemi-Azygous empties into the Azygous vein
Accessory Hemi-Azygous Vein
Accessory Hemi-Azygous Vein drains the 1st to 4th Intercostal spaces in the Right Side
Accessory Hemi-Azygous Vein empties into either the Azygous Vein or Hemi-Azygous Vein
Pleura of the Lungs
Describe the Pleura of the Lungs
The Pleura is a serous membrane arranged in a closed invaginated sac that encloses the lungs and lines the thoracic cavity
Pleura has has the following divisions:
Visceral Pleura
Visceral Pleura covers the surfaces of the lung and dips into the fissures between the lobes
Parietal Pleura
Parietal Pleura lines the inner chest wall surfaces such as the:
Costal Pleura: lines the thoracic walls
Mediastinal Pleura: Mediastinum
Diaphragmatic Pleura: lines the Upper surface of the Diaphragm
The Visceral and Parietal Pleura are separated by the space called the Interpleural space or Pleural Space
In a health individual this space is empty, except for a small amount of serous fluid
Pleura has Pleural Recesses, which are regions of the anterior and posterior pleural cavity not occupied by the lungs
These potential spaces can collect fluid, they are called the:
Costodiaphragmatic recess
Costomediastinal recess
The Right and Left pleural cavities are discrete structures and are not connected to one another
Lungs
Describe the structure of the Lungs
Lungs have an Apex, Base and Surfaces
The Apex of the Lungs is the blunt superior end of the Lung
It projects upwards above the level of the 1st rib and into the floor of the neck
The Base of the Lungs is the inferior surface of the Lungs which sits on the Diaphragm
The Lungs has three specific surfaces:
Costal Surfaces that is in contact with the Thoracic cage
Mediastinal Surface that is in contact with the mediastinum
Diaphragmatic Surface that is in contact with the Superior surface of the Diaphragm
Lungs
Describe the structures of the Lungs
The Lungs are split up into Lobes by the Fissures
The Right Lung has 3 Lobes
Superior Lobe
Middle Lobe
Inferior Lobe
The Lobes of the Right Lung are separated by two Fissure:
Horizontal fissure separates the Upper and middle Lobe
Oblique fissure separates the Middle and Lower Lobe
The Left Lung has two Lobes
Superior Lobe
Inferior Lobe
The Lobes of the Left lung are separated by one Fissure:
Oblique Fissure
The Oblique fissure is indicated by an oblique line starting posteriorly at the level of the spine of T3
And passing around the side of the chest following the 5th interspace or the 6th rib to reach the inferior border of the Lungs at the 6th Costal cartilage, about 5 cm from the edge of the Sternum
The Horizontal fissure on the Right Lung ONLY is marked a horizontal line passing from the level of the 4th costal cartilage anteriorly and intersecting the Oblique Fissure in the Posterior axillary Line
Lung Borders and Lung Features
List the Borders of the Lungs
The Lungs have three Borders:
Anterior Border (cardiac Notch)
Inferior Border
Posterior Border
Left Lung also has a Lingula which refers to the tip or tongue-like projection of the upper lobe of the left lung
Describe the Features of the Lungs
On the Medial Surface of the Lungs, the Lungs have a Root and Hilum
The Root and Hilum have the following structures (from Superior to inferior):
Pulmonary Arteries
Bronchus (with two holes)
2 Pulmonary veins
Bronchial vessels
Lymphatic vessels
Nerves
Lung Impressions
Describe the Lung Impressions for each Lung
Left Lung Impressions:
Aortic arch and Descending Aorta
Subclavian artery
Left Ventricle
Right Lung Impressions:
Oesophagus
Superior Vena Cava
Azygous Arch
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Posterior Mediastinum
Describe the Posterior Mediastinum according to its borders and contents
The Borders of the Posterior Mediastinum are marked as follows:
Lateral Border is marked by the Mediastinal pleura
Anterior Border is marked by the Pericardium
Posterior Border is marked by the T5 to T12 vertebrae
Inferior Border is marked by the Diaphragm
The Contents of the Posterior Mediastinum are:
Thoracic aorta
Oesophagus
Thoracic duct (Lymphatic drainage)
Azygous system of veins
Sympathetic trunk
Autonomic Nervous System
Describe the structure of the Autonomic Nervous System in relation to the Respiratory System
ANS has a Sympathetic Trunk
Sympathetic trunk is a chain of sympathetic ganglia located lateral to the vertebrae in the posterior mediastinum
The nerves provide sympathetic innervation tot he thoracic and abdominal viscera
Sympathetic trunk interacts with the Anterior rami of the spinal nerves via the rami communicants
Autonomic plexus is formed from the Pulmonary branches of the vagus and the Sympathetic Trunk
It innervates the Bronchial and the Visceral pleura
Parasympathetic innervation to the thoracic viscera is from the Vagus nerves
Left Vagus Nerve crosses over the Aortic arch
Right Vagus Nerve crosses over the Subclavian artery
Diaphragm
Describe the structure of the Diaphragm
The Diaphragm is a Dome shaped structure
Right Dome descends as far as the 4th Interspace in the midclavicular line on full expiration
Left Dome is about 2cm lower than the Right Dome
It is located on the floor of the Thoracic Cavity and the roof of the Abdominal Cavity
The Diaphragm has the following Peripheral Attachments:
Xiphoid process
Costal cartilages of the ribs
Lumbar vertebra and Arcuate Ligaments (Medial, and Lateral)
Crura are parts arising from the Vertebrae
Right Crura is at the L1, L2, and L3)
Left Crura is at the L1, L2
Central Tendon is formed by the muscle fibres
Central tendon is horizontal and it is located it is located at the level of the Spine of T8 (Xiphisternal plane)
Diaphragm is innervated by the Phrenic Nerves (C3-C5)
Right phrenic nerve pierces the Central Tendon
Left phrenic nerve pierces the Left Dome
Phrenic nerves provide motor and sensory innervation ot the Diaphragm
Blood supply of the Diaphragm is via the Inferior Phrenic Artery and also the Musculophrenic Artery and others
Pathways through the Diaphragm
Describe the Pathways through the Diaphragm
Caval Hiatus
Caval Hiatus is located at the level of T8
The following structures pass through the Caval Hiatus:
Inferior vena cava
Terminal branches of the Right Phrenic nerve
Oesophageal Hiatus
Oesophageal Hiatus is located at the level of T10
The following structures pass through the Oesophageal Hiatus:
Oesophagus
Right and Left Vagus nerves
Oesophageal branches of the Left gastric artery/vein
Aortic Hiatus
Aortic hiatus is located at the T12
The following structures pass through the Aortic Hiatus:
Aorta
Thoracic Duct
Azygous vein
Diaphragm is split into the following parts:
Costal part
Lumbar part
Sternal part
Describe the structure of the Diaphragm according to Origin, Insertion, Innervation and Action
Costal Part
Origin: 7th to 12th ribs (inner surface, lower margin of the costal arch)
Insertion: Central Tendon
Innervation: Phrenic nerves (C3-C5 cervical plexus)
Action: Principle muscle of respiration (Diaphragmatic and thoracic breathing)
Aid in compressing abdominal viscera
Lumbar Part
Origin:
Medial part: L1-L3 vertebral bodies, intervertebral disks and anterior longitudinal ligament as right and left Crura
Lateral part: Lateral and medial arcuate ligament
Insertion: Central Tendon
Innervation: Phrenic nerve (C3-C5, cervical plexus)
Action: Principle muscle of respiration (Diaphragmatic and thoracic breathing)
Aid in compressing abdominal viscera
Sternal part
Origin: Xiphoid process (Posterior part)
Insertion: Central Tendon
Innervation: Phrenic nerve (C3-C5, cervical plexus)
Action: Principle muscle of respiration (Diaphragmatic and thoracic breathing)
Aid in compressing abdominal viscera
