Thoracic muscles (dave's notes) Flashcards
What are the thoracic muscle layers?
Outer, middle, and inner (the latter is the transversus thoracis group)
List the muscles of the outer layer
Serratus posterior superior
Serratus posterior inferior
Levator costae
External intercostals
List the muscles of the middle layer
The internal intercostals
List the muscles of the inner layer/transversus thoracis group
Subcostal muscles
Innermost intercostals
Transversus thoracis
All the outer layer is supplied …………, and ……….. posteriorly
segmentally
migrated
From where does serratus posterior superior arise and insert? What covers serratus posterior superior?
C6, T1, T2, to ribs 2-5. Covered by levator scapulae and the rhomboids
From where does serratus posterior inferior arise and insert?
From T11, T12, L1, L2, and lumbar fascia to ribs 9-12
Where does levator costar arise and insert? What is its nerve supply?
From the transverse proces to the upper border of the rib below. Supplied by the posterior rami.
Where do the external intercostals arise and insert?
These pass obliquely downwards from the sharp border above to the rounded margin below. Extends from the costotransverse ligament to the costochondral junction, blending into the anterior intercostal membrane.
Where do the internal intercostals arise and insert?
They run downwards and backwards from the costal groove to the upper border. Extend from the posterior intercostal membrane as far as the side of the sternum.
Where do the subcostal muscles lie? Where are they best developed?
In the paravertebral gutter posteriorly, and cross more than one intercostal space. They are better developed lower down than higher up.
What separates the subcostals from the innermost intercostals?
The neuromuscular plane
Describe the innermost intercostals
These lie laterally, cross more than one space, and are also better developed below than above.
Where is transversus thoracis found?
Arises from the lower end of the sternum, with digitations to either side.
