Applied Anatomical Concepts Flashcards
Respiration
The release of energy from food
Gaseous exchange needs to occur so you need a exchange system
Inspiration
Increase in intra-thoracic diameter/volume
Decrease in intra-pleural pressure
Bc parietal pleura is pulled outwards
Parietal and visceral pleura are tightly adhered (surface tension)
Result = air flows into lungs due to lower pressure compared to atmospheric pressure
Inspiration can be thoracic or abdominal
Expiration
Decrease in intra-thoracic diameter/volume
Increased intra-pleural pressure results in air being expelled from lungs
Normally a passive process (quiet) due to elastic recoil of lungs and chest wall falls back into resting position
Forced (active) expiration (e.g. coughing, playing wind instruments, exertion) is a result of accessory muscles contracting eg. abdominal muscle
Capacity changes
During inhalation thoracic capacity/volume increases via increases in:
Lateral/Transverse diameter
Anterior Posterior diameter
Vertical diameter
Lateral Diameter of Thorax
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
Anterior Posterior Diameter of Thorax
Anterior ends of ribs are raised during inspiration
Elevation causes sternum to also be raised
Movement is facilitated by costal cartilages
Results in an increase in antero-posterior diameter of chest cavity
Thoracic Breathing - Quiet
Quiet inspiration (minor rib movement) involves:
External intercostals
Diaphragm
Scalene muscles
Quiet expiration is passive
Thoracic Breathing - Forced
Forced inspiration (extensive rib movement) additionally involves: Pectoral muscles Sternocleidomastoid Latissimus dorsi
Forced expiration involves:
Internal intercostals
Oblique and transverse abdominal muscles
Quadratus lumborum
Vertical Diameter of Thorax
Via diaphragm which forms floor of thoracic cavity
Descends upon contraction up to 5 -10 cm compressing abdominal organs
↑ vertical diameter of thorax
Known as Abdominal breathing
Diaphragm
Sheet of skeletal muscle with a central tendon
Said to have 2 hemi-diaphragms (right and left)
Forms floor of thoracic cavity
Descends during inspiration
Compresses abdominal contents until coming to a stop
Aids with: coughing, laughing, urinating and defecation, lifting heavy objects (braces vertebral column)
Diaphragm origins
Origins divided into 3 sections:
Sternal part has 2 muscular slips sometimes leaving the anteromedian gap
Costal part from inferior 6 costal cartilages
Lumbar part gives rise to the medial and lateral arcuate ligaments and is anchored by the musculotendinous Right and Left Cura
Diaphragm - more detail
Fibres rise vertically before inserting into tendon
Pericardium attached to middle of tendon on its superior surface
Diaphragmatic (parietal) pleura lines its superior surface
Blood supply: Superior & Inferior phrenic arteries
Veins: Internal thoracic, IVC and azygos
Phrenic nerve
Arises from ventral rami of C3, C4, C5
Enter superior mediastinum located lateral to the Vagus nerve
Motor: diaphragm (sole supply)
Sensory: central region of diaphragm, pericardium, mediastinal pleura
Right Phrenic Nerve
passes on right wall of SVC to right side of pericardium, descends on pericardium over right atrium to diaphragm (near IVC orifice)
Left Phrenic Nerve
runs over aortic arch and pulmonary trunk, descends on pericardium over left ventricle to diaphragm (near cardiac apex)
Innervation of myocardium
Sinoatrial node is regulated by Autonomic nerves via the Cardiac Plexus
Parasympathetic fibres - Vagus nerve
Sympathetic fibers - T1-5 levels of spinal cord and associated paravertebral ganglia
Recurrent Laryngeal nerve compression
Causes vocal cord paralysis
Cancer of Upper lobe of either lung is a potential cause
