Overview of the Thorax Flashcards
What are the true ribs?
1st - 7th rib
What are the false ribs?
8th - 10th ribs
What are the floating ribs?
11th-12th ribs
What are the atypical ribs?
1st - Scalene tubercle; single facet for articulation with only the T1 vertebra.
2nd - Tubercle for origin of serratus anterior muscle.
10th - Only one facet for articulation with only one vertebra.
11-12th - No necks or tubercles; free floating; articulate with only one vertebra.
What are the features of typical ribs?
Head - superior and inferior facets and a crest
Neck - crest
Tubercle - attachment site for muscle
What are the parts of the sternum?
Manubrium (T3 - T4)
Body (T5 - T9)
Xiphoid process (T10)
What are the joints of the sternum?
Manubriosternal joint
Xiphisternal joint
Where is the sternal angle palpated?
T4
Where is the sternal angle palpated?
T4
What[’s the most common site of sternal fracture?
At the sternal angle (T4)
What are the boundaries of the thoracic inlet (superior thoracic aperture)?
T1, the 1st ribs and their cartilages, and the manubrium.
What are the contents of the thoracic inlet?
Trachea, esophagus, nerves and blood vessels that either supply or drain the head, neck and upper extremities.
What are the boundaries of the thoracic outlet (inferior thoracic aperture)?
T12, the 11th and 12th floating ribs, costal cartilages of the 7 - 10th ribs, and the xiphisternal joint
What passes through the thoracic outlet/diaphragm?
“I ate 10 eggs at 12” I8:10E:A12
Inferior vena caval hiatus
Esophageal hiatus
Aortic hiatus
What are the muscles of the thoracic cage (outermost to innermost)
External intercostal
Internal intercostal
Innermost intercostal
Transversus intercostal
What are the functions of the muscles of the thoracic cage?
External intercostal - elevates ribs in inspiration
Internal intercostal - lowers ribs in forced expiration
Innermost intercostal - Elevates ribs on inspiration
Transversus intercostal - Lowers ribs and costal cartilages
What are the orientations of muscle fibers and direction of pull during contraction for the intercostal muscles?
Direction of pull is in the opposite direction of the orientation of the muscle fibers!!
External intercostal - fibers angled down toward front pockets, but pull is upward toward scapula for inspiration
Internal intercostal - fibers angled upward toward breasts, but pull is backward toward back pockets from expiration
Innermost intercostal - fibers angled down toward back pockets, but pull is upward toward breasts for inspiration
What is the change in the vertical diameter of the chest upon inspiration and expiration?
The vertical diameter increases upon inspiration as the diaphragm descends, and decreases upon expiration as the diaphragm ascends.
What is the change in the transverse diameter of the chest upon inspiration and expiration?
“Bucket handle motion”
The transverse diameter increases as intercostal muscles contract for inspiration.
What is the change in the anteroposterior diameter of the chest upon inspiration and expiration?
“Pump handle motion”
Sternal ends of ribs 2 - 6 rises.
What innervates the diaphragm?
C3,4,5 - phrenic nerve
“3,4,5 keeps the diaphragm alive”
What is the vasculature of the thoracic wall?
(V.A.N, vein at the top, artery in the center, nerve at the bottom)
The intercostal vein, artery and nerve lay within the costal groove of each rib.
What vessel can be punctured during chest tube entry?
The nerve is relatively exposed during procedures through the ribs (chest tubes, etc.) so enter at the superior surface of the rib at the intercostal space.
What are the arteries of the anterior thoracic wall and where do they come from?
The anterior intercostal arteries supply the anterior thoracic wall and they come from the M.I.S - musculophrenic, internal thoracic, and supreme thoracic arteries.
What are the arteries of the posterior thoracic wall and where do they come from?
The posterior intercostal arteries supply the posterior wall and they come from the aorta and costocervical trunk.
Where do the intercostal veins drain?
Into the azygos and hemiazygos veins.
What is the nerve supply of the intercostal muscles?
Intercostal muscles are innervated by the intercostal nerves, which are VENTRAL RAMI of thoracic nerves
What are the dermatomes of the thoracic region?
C4 - clavicles and jugular notch
T2 - sternal angle
T4 - level of the nipples
What are the boundaries of the superior mediastinum?
Superior - thoracic inlet
Inferior - T4-T5
If you’re a child, what is located in your anterior mediastinum?
The lower portion of the thymus.
What are the 7 contents of the superior mediastinum?
Aortic arch (brachiocephalic trunk, left common carotid, left subclavian artery)
Esophagus
Phrenic & Vagus nerves (recurrent laryngeal nerve)
Superior vena cava (Left and right brachiocephalic veins come together to form vena cava)
Thoracic duct
Thymus
Trachea
