The thoracic wall, diaphragm, and mechanics of breathing Flashcards
what structures are superficial to the thorax?
Skin and superficial fascia
- includes breast tissue
Bones
-Clavicle
-Scapula
Muscles and deep fascia
-Pectoralis major
Serratus anterior
Rectus abdominis
where does pectoralis major attach?
At the clavicle, sternum, costal cartilages
humerua
what innervates the pectoralis major?
medial and lateral pectoral nerves
where does serratus anterior attach?
ribs 1-9, intercostal fascia
- medial border of the scapula
what innervates the serratus anterior?
long thoracic nerve
where does the rectus abdominis attach?
Costal cartilages of ribs 5-7, xiphoid process
Pubic bones and joint
what innervates the rectus abdominis?
Anterior rami of T7-T12 spinal nerves
where is the sternocostal joint?
Between the sternum and the cartilage of the ribs
what type of joints are the sternocostal joints?
synovial
except between the sternum and R1, this is a cartilaginous joint
what is the sternocostal joint between the sternum and cartilage of R1 cartilaginous?
It does not support movement as important structures move through the anterior apature of the thoracix cage
where are the costochondral joints?
Between the ribs and cartilage
what type of joint are the costochondral joints?
cartilaginous
what are interchondral joints?
Joints between rib 6-9 costal cartilages
what type of joints are interchondral joints?
synovial
what are the anterior thoacic age joints?
Sternocostal
Costochondral
Interchondral
what are the posteruor thoracic cage joints?
Costovertebral
Costotransverse
what type of joints are costovertebral and costotransverse joints?
synovial
what is a costovertebral joint between?
Head of the rib and vertebral body
what is the costotransverse joint between?
Tubercle of the rib
Transverse process of the vertebra
what is the function of synovial joints in the thoracic cage?
They allow movement of the rib cage during respiration
what are the muscles of the thoracic wall intercostal space?
External, internal and innermost
what are the nerve of the thoracic intercostal space?
Intercostal nerves
what are the blood vessels of the thoracic intercostal space?
Anterior/posterior intercostal arteries and veins
where are the blood vessels and nerves in the thoracic intercostal space?
Between the internal and innermost intercostal muscle layers
what is the endothoracic fascia?
Connective tissue layer
where is the endothoracic fascia?
deep to the innermost intercostal muscle
what are the features of the external intercostal muscles?
fiber direction- anteriorly, inferiorly
Contract to life the thoracic cage during inspiration
what are the features of the internal and innermost intercostal muscles?
Fiber direction - posteriorly, inferiorly
Contract to lower the thoracic cage during forced expiration
what are the arteries of the intercostal space?
Anterior intercostal artery
Blood flows down to the subclavian artery, then the internal thoracic artery, then the anterior intercostal artery
The posterior intercostal artery,
Blood flows into the thoracic aorta, then the posterior intercostal artery.
what are the veins of the intercostal space?
Anterior intercostal veins
Internal thoracic vein flows into the subclavian vein
Posterior intercostal vein
Azygos system
- drain into hemiazygouse vein or accessory hemiazoygous vein depending on the location
what is the Azygos system?
Anastomotic pathway to drain blood from body wall to superior vena cava
Azygos vein
- main drainage on the right
Hemiazygos vein
Accessory hemiazygos vein
- main drainage on left
-drain into azygos vein
what are the features of the intercostal nerves?
Accompany blood vessles
Ventral ramus of spinal nerves
Supply intercostal muscles, skin and parietal pleura
what makes up the floor of the thoracic cavity?
the diaphragm
what features of the thoracic floor?
fills inferior thoracic aperture
Separates thoracic from abdominopelvic cavity
Radiating muscle fibres
Central tendon
what are the features of the diaphragm shape?
Dome-shaped with relaxed
Flat when contracted
what innervated the diaphragm?
Phrenic nerve
what is the blood supply to the diaphragm?
the internal thoracic artery
what are the apertures within the diaphragm?
Aortic hiatus
Vena caval foramen
Oesophageal hiatus
what is the function of the aortic hiatus?
T12 level
Descending aorta, thoracic duct, azygous vein run through
what is the function of the vena caval foramen?
T8 level
Inferior vena cava runs through
what is the Oesophageal hiatus?
T10 level
Oesophagus, vagus nerves
what happens in the thoracic cavity during inspiration?
External intercostal muscles contract
- the rib cage rises and expands
- diaphragm contracts to become flattened
This increases the thoracic cavity volume
Lungs stretch
Lung volume increases
Intrapulmonary pressure goes down
Air flows down the pressure gradient, moving into the lungs
what happens in the thoracic cavity during expiration?
External intercostal muscle relax
The rib cage descends and reduces
Diaphragm relaxes and rises, becomes dome shaped
Lungs recoil and the thoracic cavity volume decreases
Lung volume goes down and intrapulmonary pressure goes up
Air flows down the pressure gradient, which is now higher inside than out, so air moves out of the lungs
