PHTY 142 Thorax Flashcards
Main contents of Thorax
heart
Lungs
oesophagaus
Trachea
Main Bronchi
Vagus and Thymus
Phrenic nerves
Thoracic duct
Lymph nodes
major systemic and pulmonary vasculature
Main features of the sternum
superior - manubrium and has jugular notch
Manubrium articulates with costal cartilages of first and second ribs
middle - body and articulates with second to tenth ribs
Inferior - xyphoid process
Main features of ribs
1-7 pairs have direct anterior attachment to the sternum by costal cartilage
These are true ribs attached by sternocostal joints
8-12 pairs are false ribs as costal cartilage attaches to sternum indirectly or not at all
8,9,10 pair attach to one another and then to 7th pair cartilage
11-12 pairs are floating ribs as costal cartilage does not attach to sternum at all. They attach to thoracic vertebrae
Main features of a rib
head - contains 2 articular facets
Neck
Tubercle
Tubercle attaches to transverse process of vertebrae to form vertebrocostal joint
Body
Costal angle - change in curvature
Costal groove - protects intercostal blood vessels
Articulation of rib to thoracic vertebra
posterior part of rib connects by its head and the articular part of the tubercle
Facets fit on the body of one T1 or demi facets of two adjoining vertebrae
Articular part of tubercle articulates with transverse process facet
costal cartilage
hyaline cartilage
Contribute elasticity to thoracic cage
Protects the sternum
Joints of the sternum
sternocostal - 1st costal cartilages with manubrium and the true ribs
Sternoclavicular - sternal end of clavicle with manubrium and 1st costal cartilage
Manubriosternal - manubrium and sternum
Xiphisternal - xiphoid process and body of sternum
diaphragm
Origin - xiphoid process costal cartilages of 7-12 ribs and lumbar vertebrae
Contraction of diaphragm causes it to flattern
Phrenic nerve
Insertion - central tendon
External intercostals
origin - inferior border of rib above
contraction elevates ribs for inhalation
thoracic spinal nerves T2-T12
Insertion - superior border of rib below
Internal intercostals
Origin - superior border of rib below
Contraction draws ribs closer together for exhalation
Thoracic spinal nerves T2-T12
Insertion - Inferior border of rib above
accessory muscles of respiration
sternocleidomastoid - elevate the sternum
Scalenes - elevate and fix upper ribs
Pump handle mechanism
contraction of diaphragm
Movement of 2nd to 5th ribs during inspiration
Causes anterior ends to be raised and lifts sternum upwards and forwards (elevation)
Increases the anteroposterior diameter of the thorax
Bucket handle mechanism
During inspiration
8th to 10th ribs occurs causing the shaft of the rib to move outwards and upwards
widens the infrasternal angle to increase the transverse diameter of the thorax
