Anatomy of respiration Flashcards
What rib do the scalene muscles attach to?
To the first rib at the scalene tubercle (first rib is pulled up during forced inspiration).
At what vertebral level is the suprasternal/jugular notch of the manubrium located?
At T2/T3
At what vertebral level is the sternal angle located?
At T4/T5
What structures are located at the T4/T5 vertebral level?
T4/T5 is where the trachea bifurcates and the arch of the aorta begins. Additionally, it marks the border between the superior and inferior mediastinum.
What rib is attached lateral to the sternal angle, and what is its clinical significance?
The second rib, which is an important landmark for rib counting.
What type of joint is the first sternocostal?
A synchondrosis.
What type of joints are the 2nd-7th sternocostal joints?
Synovial plane joints.
What type of joints are the costochondral joints?
Synchondrosis type.
What type of joints are the costovertebral and costotransverse joints?
Synovial joints.
What are the articulate surfaces of the costovertebral joints?
Between the head of the rib and the vertebral bodies/IV disk.
What are the articulate surfaces of the costotransverse joints?
Between the rib tubercle and the vertebral transverse process.
What ribs articulate with contiguous vertebrae at the costovertebral joints?
Ribs 2-9 articulate with two vertebral bodies.
What ligament limits movement of the costovertebral joint?
The intra-articular ligament, which extends from the head of the rib to the IV disk.
What ribs articulate only with they body of the same numbered vertebrae?
Ribs 1 and 10-12 articulate with only one vertebral body.
What joint is damaged in a rib separation?
The costochondral joint (between the ribs and the costal cartilage).
What ribs do not have costotransverse joints?
Ribs 11 and 12.
What is the role of the external intercostal muscles?
Elevate the ribs during inspiration.
What is the role of the internal and innermost intercostal muscles?
Depress the ribs during expiration.
What is the role of the subcostal muscles?
Depress the ribs during expiration.
What is the innervation of the intercostal muscles?
The intercostal nerves.
What is the role of the serratus posterior inferior?
Assists with inspiration by depressing ribs 10-12 to help the diaphragm move inferior (as opposed to the other ribs which are elevated).
What is the innervation of the serratus posterior inferior?
Intercostal nerves 9-12.
What do the anterolateral abdominal muscles assist with ?
Expiration.
What does the quadratus lumborum muscle assist with?
Inspiration by depressing the lower ribs to help the diaphragm create a more negative intra-thoracic pressure (just like the serratus posterior inferior).
What do the pectoralis major and minor muscles assist with?
Inspiration.
Where does the neurovascular bundle travel in the intercostal space?
In the inferior surface of the rib (costal groove). As such, the intercostal space should be accessed at the superior surface of the rib.
What is the orientation of the neurovascular bundle in the intercostal space?
Vein superior, artery middle, and nerve inferior (VAN)
How many pairs of intercostal nerves are there?
11 pairs
How many pairs of subcostal nerves are there?
1 pair.
What are the intercostal and subcostal nerves derived from?
The ventral rami of the 12 pairs of thoracic spinal nerves.
What does being derived from thoracic ventral rami mean about the intercostal and subcostal nerves?
That their branches include white and grey communicantes to the sympathetic chain.
What are the branches of the intercostal and subcostal nerves?
Muscular branches, lateral cutaneous branches, anterior cutaneous branches, collateral branches, and rami communicantes to the sympathetic chain.
What is the intercostal nerve that doesn’t give off lateral or anterior cutaneous branches?
The 1st intercostal nerve (the T1 dermatome is instead on the arm).
What does the right crus of the diaphragm attach to?
L1-L3 (larger than the left crus)
What does the left crus of the diaphragm attach to?
L1-L2
What is the median arcuate ligament?
A tendinous arch between the left and right crua. The aortic hiatus is within it.
What vertebral level is the caval hiatus at?
T8. It is located in the central tendon of the diaphragm, and transmits the IVC and right phrenic nerve.
What vertebral level is the esophageal hiatus at?
T10. It passes through the right crus, and transmits the esophagus and vagal trunks.
What vertebral level is the aortic hiatus at?
T12. It passes between the left and right crus, and transmits the aorta and thoracic duct.
Where do the anterior and posterior pulmonary plexuses travel?
Along the primary bronchi.
Where do the preganglionic cell bodies of the sympathetic innervation of the lungs arise?
In the T2-T6 lateral horns.
Where are the postganglionic cell bodies of the sympathetic innervation to the lungs located?
In the upper thoracic and cervical sympthetic chain ganglia
What do the sympathetic efferents of the lungs do?
Vasoconstriction, bronchodilation, inhibit gland secretion.
Where do the preganglionic cell bodies of the parasympathetic innervation of the lungs arise?
In the brain stem. They travel with the vagus nerve (CN X).
Where are the parasympathetic post-synaptic fibers found in the lungs?
Within the walls of the airways.
What do the parasympathetic efferents to the lungs do?
Vasodilation, bronchoconstriction, increase gland secretions.
What do the parasympathetic afferents transmit?
Reflexive information (from bronchial mucosa for cough reflex, stretch of bronchial muscle, baroreceptors, chemoreceptors)
What do the sympathetic afferents transmit?
Nocireceptive (acute pain)
What is an increase in A-P (anterior-posterior) diameter of the thorax called?
Pump handle motion (the sternum is like the handle to a water pump).
What is an increase in transverse diameter of the thorax called?
Bucket handle motion (the ribs are like bucket handles).
What causes the thoracic vertical diameter increase?
Constriction/flattening of the diaphragm.
What is the lumbocostal triangle?
The lumbocostal triangle is an area of muscular weakness between the costal and lumbar portions of the diaphragm,. It is a common site for abdominal herniation into the thorax.
What is the arterial supply to the diaphragm?
The pericardiophrenic and musculophrenic arteries, the superior phrenic artery, and the inferior phrenic artery.
What do the pericardiophrenic and musculophrenic arteries arise from?
The internal thoracic artery.
What does the superior phrenic artery arise from?
The thoracic aorta.
What does the inferior phrenic artery arise from?
The abdominal aorta.
What is the lymphatic drainage of the diaphragm?
The superior diaphragmatic (phrenic) LN drain to the mediastinal LN. Additionally, the inferior diaphragmatic vessels drain into the superior diaphragmatic LN or the lumbar LN.
What does the sternocleidomastoid muscle assist with?
Forced inspiration.
What do the first through third posterior intercostal veins drain into?
They fuse to form the superior intercostal vein, which drains into the azygous vein on the right and the brachiocephalic vein on the left.
What do the rest of the posterior intercostal veins drain into?
The azygous system of veins.
What do the anterior intercostal veins drain into?
The internal thoracic vein.
What is the venous drainage of the diaphragm?
The superior phrenic vein, the pericardiaphrenic and musculophrenic veins, and the inferior phrenic veins.
What does the superior phrenic vein drain onto?
The inferior vena cava.
What do the pericardiaphrenic and musculophrenic veins drain into?
The internal thoracic vein.
What does the inferior phrenic vein drain into?
The inferior vena cava on the right. On the left it merges with the suprarenal vein which drains into the left renal vein.
Where does the musculophrenic artery travel?
Along the costal margin.
Where does the internal thoracic artery travel?
Along the deep surface of the anterior chest wall, lateral to the sternum.
Where does the internal thoracic artery branch into the musculophrenic and superior epigastric arteries?
Near the 6th or 7th costal cartilages.
Where do the anterior intercostal arteries arise from?
The first 6 arise directly from the internal thoracic artery, while the 7-9th anterior intercostal arteries arise from the musculophrenic artery (branch of the internal thoracic).
Where do the posterior intercostal arteries arise from?
The first two arise from the supreme intercostal artery (a branch off the costocervical trunk). The rest (along with the subcostal artery) arise from the thoracic aorta.
What does the transverse thoracic assist with?
It helps with expiration, and is innervated by intercostal nerves 2-6.
What does the levator costarum assist with?
It assists with inspiration, and is innervated by the ventral rami of C8-T1.
What are the five accessory muscles of inspiration?
The scalene muscles, the sternocleidomastoid, the pectoralis major/minor, the serratus anterior, and the quadratus lumborum.
What is one of the roles of the endothoracic fascia?
It adheres the parietal pleura to the thoracic wall. It is a clinically relevant cleavage plane between the thoracic wall and the pleura for surgeries.
