HS2-14 Thoracic Wall and Diaphragm Flashcards
How many thoracic vertebrae are there?
12
What is a distinguishing feature of thoracic vertebrae?
articular facets for ribs
What is the costal cartilage?
anterior end of rib
What is the costal margin?
upturned cartilages of ribs 8-10, connected to costal cartilage of rib 7
What are the two systems to classify ribs?
true-false-floating
typical-atypical
Describe the true-false-floating system of classifying ribs.
true = ribs 1-7 with direct articulation to sternum via costal cartilage
false = ribs 8-10 that articulate w/ sternum via costal margin
floating = ribs 11 and 12, w/ no attachment to sternum
Describe the typical-atypical of classifying ribs.
typical = ribs 3-9
atypical = ribs 1, 2, 10, 11, 12
What are the “typical” features of a rib (for the purposes of classification)? (4)
head
neck
tubercle
shaft
What is the costal groove?
depression on inferior border of rib
What structures are found in the costal groove? (2)
intercostal nerve
intercostal vessels
The body of the sternum articulates with which ribs?
ribs 3-6
What is the sternal angle of the sternum?
junction of manubrium and body
The sternal angle articulates with which ribs?
articulates with rib 2
What is the xiphisternal junction?
junction of body of sternum and xiphoid process
The xiphisternal junction articulates with which ribs?
rib 7
Describe the structure of the costovertebral joint.
head of rib articulates with bodies of 2 vertebrae: one at the same level as rib, and then the vertebrae above it
Describe the structure of the costotransverse joint.
tubercle of rib articulates with transverse process of vertebrae on same level
What is another name for the thoracic inlet?
superior thoracic aperture
What are the boundaries of the thoracic inlet?
vertebral body of T1
first ribs
manubrium
What is another name for the thoracic outlet?
inferior thoracic aperture
What are the boundaries of the thoracic outlet? (4)
T12
rib 12
costal margins
xiphisternal joint
What are the three layers of intercostal muscles?
external (most superficial)
internal
innermost
What are the boundaries of the external intercostal muscle?
tubercle of rib → midclavicular line
What is a visual characteristic of the external intercostal muscle?
“hands-in-pocket” fiber orientation
What happens to the external intercostal muscles as they approach the anterior aspect of the ribs?
become membranous
What are the boundaries of the internal intercostal muscles?
sternum → midaxillary line
What is the orientation of the internal intercostal muscles?
at right angle to those of external intercostal muscles
What happens to the internal intercostal muscles as they approach the posterior aspect of the ribs?
become membranous
What is the orientation of the innermost intercostal muscles?
same as internal intercostal muscle (so bsaically perpendicular to the external intercostal muscles)
Where are the innermost intercostal muscles membranous?
anteriorly AND posteriorly
The transversus thoracis consists of
several muscular slips running from sternum to 2nd-6th costal cartilages
Where are the subcostal muscles found?
posteriorly at the same level as the innermost intercostals
span more than one intercostal space
What are the three accessory muscles of respiration?
pectoralis major/minor
serratus anterior
scalene muscles
What is the origin of the intercostal nerves?
ventral rami of the first 11 thoracic spinal nerves
What is the origin of the subcostal nerve?
ventral ramus of 12th thoracic spinal nerve
What provides innervation to the intercostal muscles?
intercostal nerves
What provides innervation to the transversus thoracis?
intercostal nerves
What provides innervation to the subcostal muscles?
intercostal nerves
What innervates the superior and inferior serratus posterior?
intercostal nerves
Where do the intercostal nerves provide sensory innervation? (4)
lateral and anterior thorax
abdominal wall
parietal pleura
parietal peritoneum
What are the primary arteries of the thoracic wall? (2)
paired internal thoracic artery
paired intercostal arteries
The internal thoracic artery is a branch of
the subclavian artery
Describe the position of the internal thoracic artery relative to the sternum.
internal thoracic artery runs lateral to the sternum
What holds the internal thoracic artery against the ribs?
transversus thoracis muscle
In the thorax, the internal thoracic artery bifurcates into
musculophrenic artery + superior epigastric artery
Describe the anterior arterial supply of the thoracic wall.
ribs 1-6 = arterial supply from internal thoracic artery
ribs 7-9 = arterial supply from musculophrenic artery
ribs 10-11 = absent
Describe the posterior arterial supply of the thoracic wall.
ribs 1-2 = arterial supply from indirect branches of subclavian artery
ribs 3-11 = arterial supply from descending aorta
What are the primary veins of the thoracic wall?
paired internal thoracic veins
paired intercostal veins
Describe the venous drainage of the anterior aspect of the thoracic wall.
drain into internal thoracic vein + musculophrenic vein
Describe the venous drainage of the posterior aspect of the thoracic wall. (2)
right intercostal vein drains into azygos vein
left intercostal vein drains into hemiazygos vein
The intercostal neurovascular bundle is found in what thoracic wall structure?
intercostal groove
What is the order of the structures found in the intercostal neurovascular bundle?
vein
artery
nerve
[VAN]
The intercostal neurovascular bundle is found between what two muscle layers?
innermost and internal intercostal muscle layers
What is the chief muscle of respiration?
diaphragm
What is the anatomical function of the diaphragm?
separates thoracic and abdominal cavity
What are the components of the diaphragm?
central tendon + 3 muscular parts (sternal, costal, lumbar)
What are the three major openings of the diaphragm?
vena caval foramen
esophageal hiatus
aortic hiatus
Describe the vena caval foramen. (2)
at T8
opens into inferior vena cava
Describe the esophageal hiatus. (2)
at T10
opens into esophagus and vagal trunks
Describe the aortic hiatus. (2)
at T12
opens into descending aorta, thoracic duct, and azygos vein
What is the arterial supply to the diaphragm? (3)
pericardiacophrenic arteries
musculophrenic arteries
inferior phrenic arteries
What innervates the diaphragm?
phrenic nerve
Differentiate between the right and left hemidiaphragms in a frontal chest radiograph.
right hemidiaphragm is higher than left by 1-2 cm
What kind of joint is the costosternal joint? (2)
1st costosternal joint is cartilaginous
all other costosternal joints are synovial
The periocardiacophrenic artery is a branch of
the internal thoracic artery
Where is the neurovascular bundle located relative to its rib?
the neurovascular bundle is located below its associated rib
