The Chest Wall Flashcards
What is the role of the extrinsic muscles
Helps with breathing, external to the ribs
Extrinsic muscles of the chest wall
Pectoralis major
Serratus anterior, attached to the rib and surrounded by deep fascia
Layers of the chest wall
Skin Superficial fascia Deep fascia Serratus anterior attaches to the rib Rib
External intercostal muscles
Internal intercostal muscles
Neuromuscular bundle
Innermost intercostal muscles
Endothoracic fascia Parietal pleura Pleural cavity Visceral pleura Lung
How much fluid can fill the pleural cavity
10-20ml
Describe the structure of the sternum
Function of each section
Jugular notch on manubrium sterni
Sternal angle between manubrium sterni and body
Sternal angle and manubrium sterni have 2ndary cartilaginous joint, acts as a hinge as the sternum rises
Manubrium sterni helps breathing
Xiphisternum
The types of joints present between the thoracic cage and the joint between the ribs
Possible movements
1st sternocostal primary cartilaginous, v little movement
2nd-7th sternocostal synovial joints, breathing movements
8th-10th chondrochondral synovial joints for breathing movements
Which ribs are true, false, free floating
1-7 true, attach to sternum and vertebrae
8-10 false, only attach to vertebrae and rib above
11-12 false, free floating, only attach to vertebrae
Describe the angle of the ribs in an adult
Posterior higher than anterior
What muscles support the ribcage and keep it up
What are their functions
Sternocleidomastoid
- lifts up sternum
- lifts up ribcage
- not really used in breathing
Scalenes anterior, medius, posterior
-attach to R1, R2
lifts up chest wall
prevents ribcage from dropping down
How do baby ribcages differ from adult ribcages
What happens as a result
Adult
- more angled downwards
- shorter distance between bottom ribs
Baby
- more horizontal
- greater distance between bottom ribs
As a result, babies can’t elevate the chest wall, rely on diaphragm for diaphragmatic breathing
Cannot breath thoracically
Describe the osteology of typical ribs
Sup and inf demifacet, synovial attachment to vertebrae
Interarticular crest in between
Neck
Articular and non articular part of tubercle, attach to transverse process
Shaft
Subcostal groove houses neuromuscular bundle
Location of ligaments found between ribs and vertebrae
Costotransverse ligament between rib and transverse process
Lateral costotransverse ligament between rib and the lateral part of the transverse process
Describe the osteology of the 1st atypical rib
- Short, strong, flat, v curved
- Tubercle for scalenus anterior
- Single facet on head
- Grooves for subclavian vessels for upper limbs
Describe the osteology of the 2nd atypical rib
Tubercle for scalenus posterior and serrates anterior attachment
Describe the osteology of the 10th atypical rib (occasionally)
May be a false free floating rib, only articulates with T10
Describe the osteology of the 11th, 12th atypical rib
No tubercles, no muscle attachments
No sternal attachments
Describe the locations of the facets and articulations on the thoracic vertebrae
Facet for rib tubercle on lateral part of transverse process
Pars interarticularis between lamina and pedicle on transverse process (for sup, inf spinous)
Articular facet, for rib head (costovertebral joint here)
How do the costovertebral joints in the upper ribs help with the expansion of the chest cavity
Axis of rotation along transverse process and body
Ribs rise up and forwards in a pump handle fashion
How do the costovertebral joints in the lower ribs help with the expansion of the chest cavity
Different axis of rotation to the upper ribs
Rise up and out in a bucket handle fashion
What is the 3rd method of expanding the chest cavity
Via the depression of the diaphragm
Describe the arterial vasculature of the anterior thoracic wall
Aorta
R and L subclavian
Internal thoracic
Superior epigastric and musculophrenic
Anterior intercostals come from internal thoracic
Describe the arterial vasculature of the posterior thoracic wall
Descending aorta
Thoracic aorta
Posterior intercostals
Lateral cutaneous branch connects intercostals and cutaneous arteries
Describe the venous drainage in the azygos venous system
Azygos vein on the R side of the vertebrae
Accessory hemiazygos vein drains the top half of the ribs
Hemiazygos vein drains bottom half of the ribs
Both hemiazygos join azygos and cross over at T7
Azygos vein drains into the SVC
Describe the blood supply to the pericardium
L subclavian
Internal thoracic
Pericardiacophrenic comes off internal thoracic
Ant abdominal wall comes off internal thoracic
Inf phrenic comes off pericardiacophrenics
Bronchial and esophageal arteries come off descending aorta
