Part 2: Thoracic Wall + Diaphragm Flashcards
What are the joints of the rib?
Joint of head of ribs
Joints at the tubercles (costotransverse joints)
Costochondral
Sternocostal
Describe the joints of the head of the ribs
Rib articulates with body of vertebrae. By way of 2 joints - lower articulates to vertebrae of rib and upper to the vertebrae above. Ridge between articulates with IV disc. 3 pronged radiate ligament to each vertebrae and IV disc lies anteriorly for reinforcement. Exceptions are T1, T11 +T12 which only articulate with their own vertebrae
Describe the joints at the tubercles
Rib tubercles articulate with transverse process. Medial facet articulates with tip of transverse process with small synovial joint.
Lateral facet is non-articular and gives attachment to lateral costotransverse ligament
Describe the 3 costotranverse ligaments
Costotranverse ligament - back of neck of rib to front of transverse process
Lateral costotransverse - lateral facet to transverse process
Superior costotransverse - crest of rib to under surface of transverse process of above veterbrae
Describe the costochondral joints
Each rib makes a primary cartilaginous joint with costal cartilage. No movement takes place at these joints.
Describe the interchondral joints
Costal cartilages 6+7, 7+8, 8+9 are joined to adjacent surfaces by small synovial joints
Describe the sternocostal joints
Should be called sternochondral joints. Rib 1 articulates with manubrium with a primary cartilaginous joint giving fixation necessary for stability of clavicle and pectoral girdle. Next 6 costal cartilages articulate with sternum via synovial joints
Describe the manubriosternal joint
Contains hyaline surfaces with intervening disc of fibrocartilage making it a secondary cartilaginous joint
Describe the xiphisternal joint
Fibrocartilaginous disc between cartilage covered surfaces
Serratus posterior superior is part of the outer muscles of thoracic wall, where does it pass? What is its action?
From C6, 7, T1, 2 to ribs 2-5 covered by levator scapulae and rhomboids
Elevates upper ribs in inspiration
Serratus posterior inferior is part of the outer muscles of thoracic wall, where does it pass? What is its action?
T11, 12, L1, 2 and lumbar fascia to ribs 9-12
Depresses lower ribs in expirations
Levator costae is part of the outer muscles of thoracic wall, where does it pass? What is its action?
12 pairs spreadin from near tip of transverse process of C7-T11 to insertion in upper border same rib.
Presumably aids in elevation of ribs. Only thoracic muscle to be supplied by posterior rami as originated with back muscles
External intercostals are part of the outer muscles of thoracic wall, where does it pass?
Pass obliquely downwards from sharp border of rib above to rounded border of rib below. Extend from costotransverse ligament to costochondral junction blending into anterior intercostals membrane.
Internal intercostals are part of the middle muscles of thoracic wall, where does it pass?
Downwards and backwards from costal groove to upper border. Extends from posterior intercostal membrane as far as side of sternum
What are the muscles of the inner layer of thoracic wall and how are they positioned?
Subcostal muscles - posterior - cross more than 1 vertebral space
Innermost intercostals - Lateral - cross more than 1 space
Transverse thoracis - Anterior - digitations each side of sternum
Where does the NVP lie in the thoracic wall?
Runs between middle and inner layer. Protected under the lip of superior rib
What nerves supply thoracic muscles?
Anterior rami of spinal nerves supply all muscles but levator costae (posterior rami)
Describe the course of the intercostal nerves
Continuation of spinal nerve once posterior rami has branched off. Runs between middle and inner layer of muscles. Main nerve has lateral cutaneous branch and a terminal anterior cutaneous branch
Lower 5 intercostals slope downwards and supply anterior abdominal wall.
1st nerve is small and supplies no skin.
What is the blood supply of the thoracic wall?
Intercostal arteries arise at back and front
Posterior - super intercostal artery supplies upper 2 spaces (comes off subclavian trunk)
Spaces 3-11 are supplied by thoracic aortic branches
Anterior - Upper 6 from internal thoracic, then musculophrenic in 7-9 spaces
What is the venous drainage of the thoracic wall?
Intercostal veins drain both posteriorly and anteriorly.
1st space - drains to vertebral/brachiocephalic vein
2-3 - superior intercostal vein -> R to azygous and L to brachiocephalic
Lower 8 - azygous on R, hemiazygous on L
Where does the internal thoracic artery arise and where does it go?
1st part subclavian passes vertically down lateral to sternum. Divides into superior epigastric and musculophrenic at costal margin
What is the suprapleural membrane?
Dense layer of tissue attached to inner border of 1st rib and costal cartilage and posteriorly to transverse process of C7 where muscles fibres found (scalenus minimus). Gives rigidity to thoracic inlet to prevent gross distortion during respiration
Which layer is the diaphragm derived from?
Innermost layer
How is the diaphragm anchored to vertebrae?
Crura anchor to vertebrae
R: L1-3, L: L1-2
