Theme 1: Lecture 5 - Applied Anatomical Concepts Flashcards
What are the areas of breathing?
Thoracic and Abdominal
What are the types of breathing?
Quiet and forced
Boyles law
- Decrease in volume leads to an increase in pressure
- Increase in volume leads to a decrease in pressure
What are the pressure changes in inspiration?
Increase in intrathoracic volume and decrease in intrathoracic pressure
What happens in inspiration?
- Parietal pleura is pulled with the movement of the ribs and diaphragm
- Visceral pleura moves with parietal pleura (surface tension)
- Lung volume increases
- Air moves into lungs towards lower pressure
What are the pressure changes in expiration?
Decreased intrathoracic volume and higher intrathoracic pressure
What happens in expiration?
- Visceral pleura moves with elastic recoil of lungs
- Parietal pleura moves with the ribs and diaphragm as they return to rest
- Surface tension between parietal and visceral pleura prevents lung from collapsing
- Lung volume decreases
- Air moves out of the lungs towards lower pressure
What are the dimension changes in thoracic breathing?
- Transverse/lateral diameter
- Anteroposterior diameter
What are the dimension changes in abdominal breathing?
- Transverse/lateral diameter
- Anteroposterior diameter
- Vertical diameter
How does the lateral diameter of the thorax change in breathing?
- Lateral edges of ribs are elevated supero-laterally during inspiration and the lateral diameter of thoracic cavity increases
- Results in an increase in the transverse or lateral diameter of chest cavity
- AKA bucket handle movement
How does the anteroposterior diameter of the thorax change in breathing?
- Anterior ends of ribs are raised in inspiration
- Elevation causes sternum to also be raised
- Movement is facilitated by costal cartilages
- Results in an increase in anteroposterior diameter of chest cavity
- AKA pump handle movement
Origin of diaphragm
- Sternal (xiphoid process)
- Costal (costal cartilages of ribs 7-10, ribs 11 and 12)
- Lumbar (medial and lateral arcuate ligaments and lumbar vertebral bodies)
Insertion of diaphragm
Central tendon
How does the vertical diameter of the thorax change in abdominal breathing?
- Via diaphragm which forms the floor of the thoracic cavity
- Resting position of diaphragm is domed
- Upon contraction the diaphragm descends 5 -10 cm compressing abdominal organs
- Increases vertical diameter of thorax
Which muscles are involved in quiet inspiration?
- External intercostals
- Scalene muscles
- Diaphragm
Which muscles are involved in quiet expiration?
Normally a passive process. Elastic recoil of lungs expels air and chest wall falls back into resting position
What are the scalene muscles?
- They are 3 pairs of muscles, anterior, middle and posterior
- They come from the cervical spine
- Anterior and middle scalenes insert into the first rib whereas the posterior inserts into the second
Which muscles are involved in forced inspiration?
- The muscles used in quiet inspiration plus:
- Pectoral muscles
- Sternocleidomastoid (SCM)
- Latissimus dorsi
Origin and insertion of sternocleidomastoid
Origin: Sternum and clavicle
Insertion: Mastoid process (prominence behind the ear)
Latissimus dorsi
A large muscle of the back that wraps up and around and inserts into the upper limb
Which muscles are involved in forced expiration?
- Internal intercostals
- Oblique and transverse abdominal muscles
- Quadratus lumborum
Describe the diaphragm
- Sheet of skeletal muscle with a central tendon
- Pericardium attached to middle of tendon on its superior surface
- Diaphragmatic (parietal) pleura lines its superior surface
What are the openings of the diaphragm and what levels are they at?
-Opening for Inferior Vena Cava (T8)
-Oesophageal hiatus (T10)
-Aortic hiatus (T12)
The thoracic duct and azygos vein also pass through the aortic hiatus
What is the blood supply to the diaphragm?
Superior and inferior phrenic arteries
Actions of the diaphragm when altering the volume of the thorax
- Quiet inspiration (descends approx. 2cm)
- Forced inspiration (descends 7-10cm) e.g. coughing
- Aids venous return
- Hiccups
Actions of the diaphragm when altering the volume of the abdomen
- Urinating and defecation
- Lifting heavy objects (braces vertebral column)
- Child birth
Where does the phrenic nerve arise from?
Ventral rami of C3,4 and 5
Where does the phrenic nerve travel?
- Enters superior mediastinum lateral to the Vagus nerve
- Passes anterior to main bronchi/root of lung
What does the phrenic nerve innovate (motor supply)
Diaphragm (sole supply)
What does the phrenic nerve innovate (sensory supply)
- pericardium
- parietal pleura (mediastinal and central part of diaphragmatic)
- parietal peritoneum
- central region of diaphragm
What does the lumbar part of the diaphragm arise from?
medial and lateral arcuate ligaments and from the lumbar vertebral bodies via right and left crura
How is the aortic hiatus formed?
The right at left crura meet to form the median arcuate ligament to form aortic hiatus
How is the oesophageal hiatus formed?
Fibres of the right crus pass around the oesophagus forming the oesophageal hiatus
Crus/Crura
The crus of diaphragm (pl. crura), refers to one of two tendinous structures that extends below the diaphragm to the vertebral column
Pancoast tumour
- A cancer located at the apex of the lung
- If it’s on the left side, it can cause recurrent larengeal nerve compression
- Vocal cord paralysis = hoarsness
What imaging technique is used to determine coronary artery dominance
Angiogram
