Ach: Anterior Thoracic Wall Flashcards
When looking at the sternal angle, you know it is a clinical landmark for….
second rib and second intercostal space
T4/T5 plane mediastinum aortic arch tracheal bifurcation SVC entering the pericardium superior limit of the pulmonary trunk
How many ribs/vertebra make up hte bony thorax?
12 ribs
12 vertebra
sternum
What are the “true ribs”?
1-7
articulate with sternum by costal cartilages
What are the “false ribs”? Which connect to costal cartilage of rib above?
8-12
8-10
What are the floating or free ribs?
11, 12
What are the main components of a rib?
Facets- articulate with the vertebral bodies
Head
Neck
Tubercle- articulates with the transverse process
angle
costal groove
Where is the weakest part of a rib?
anterior to it’s angle
middle ribs break most often
The facets on the head of the rib articulate with?
body of the corresponding vertebra and the vertebra above
superior and inferior facet
Facet on the tubercle articulates with what?
Tip of corresponding transverse process
What do the costal cartilages articulate with?
1-7 sternum
8-10 adjacent costal cartilages
Facets on the head of rib 7 and the facet of the tubercle articulate with what vertebra?
Vertebra 7 and 6
Transverse process of rib 7
How many vertebra and intervertebral disks are there?
12
What is the thoracic inlet?
Border between the neck and thorax
manubrium
1st ribs
T1 vertebra
What is the thoracic outlet and what marks this location?
border between thorax and abdomen
costal margins of 12th ribs and the costal cartilages of ribs 7-11
The thoracic outlet is the origin for the…
respiratory diaphragm
How does the chest increase in vertical diameter?
Contract the diaphragm
How does the chest increase the transverse diameter?
BUCKET HANDLE
movement of ribs up and out
How does the chest increase the anterioposterior diameter?
PUMP HANDLE
raise sternum and anterior ends of ribs
How do you breathe?
Thoracic cage moves>
increases/decreases the intrathoracic volume>
pressure change>
air follows decrease in pressure
What is the superior thoracic aperture (thoracic inlet)? Boundaries?
Communicates with the root of the neck
T1
1st ribs and costal cartilage
Manubrium
What is the inferior thoracic aperture (thoracic outlet)? Boundaries?
Diaphragm closes the aperture
Openings in the diaphragm allow communication with the abodomen
T12
12th pair of ribs and costal margins
xiphesternal joint
How many layers of muscle fill the intercostal space?
3
Where does VAN (intercostal vein, artery, nerve) lie?
subcostal groove under the lower border of the upper rib
How many pairs of external intercostal muscles are there? How do they lie? Do the reach the sternum?
11 pair
Fibers slant DOWNWARD and FORWARD from rib above to rib below
NO
How many pairs of internal intercostal muscles are there? How do they run?
11 pair
Fibers run DEEP to and at RIGHT ANGLES to the external intercostals
How do external and internal intercostals differ in what they’re replaced by?
external- replaced by EXTERNAL intercostal membrane ANTERIORLY
internal- replaced by INTERNAL intercostal membrane POSTERIORLY
What do the innermost intercostal muscles cover?
The middle half of intercostal spaces
What are the actions of intercostal muscles?
WIDEN intercostal spaces
keep intercostal spaces RIGID during respiration
ELEVATE or DEPRESS ribs
What forms the intercostal nerves?
Ventral rami of the first 11 thoracic nerves as they enter the intercostal spaces
What forms the subcostal nerve?
Ventral ramus of the 12th nerve
lies INFERIOR to the 12th rib
A ganglion of the sympathetic trunk is associated with each ventral ramus. It connects to the nerve via rami communicantes. What is the difference between white ramus and gray ramus?
white- conveys preganglionic sympathetic fibers to the ganglion (myelinated)
gray- conveys postganglionic sympathetic fibers from the ganglion into the intercostal nerve (unmyelinated)
What are the typical branches of an intercostal nerve?
rami communicantes collateral branches lateral cutaneous branches anterior cutaneous branches muscular branches to the intercostal muscles
What nerves supply the abdominal musculature, pleura, periotoneum and skin?
Nerves from T7-12
Motor innervation: intercostal muscles
Sensory innervation: skin and pleura
What nerves supply the nipple and the umbilicus respectively?
T4
T10
How many arterial sources are there for each intercostal space? What are they?
2 that form an anastomoses
Posterior intercostal artery (branches of the thoracic aorta)
Anterior intercostal arteries in spaces 1-6 (branches of internal thoracic artery which branches from the subclavian)
Where does the internal thoracic artery run?
posterior to costal cartilage and lateral to sternum
What are the branches off the internal thoracic artery?
Pericardiacophrenic- accompanies phrenic nerve
musculophrenic- supplies spaces 7-9
superior epigastric- diaphgram and superior abdominal wall
anterior intercostal arteries
Where do they anterior intercostal veins drain?
into the itnernal thoracic veins
What systems do the posterior intercostal veins drain into?
azygos and hemiazygos system of veins
What is thoracic outlet syndrome?
Clinical syndromes caused by congenital or acquired compression of brachial plexus/subclavian veins passing through thoracic outlet to the upper limb
What are sxs of brachial plexus compression?
Pain
paresthesia
numbness of upper limbs
What are sxs of subclavian artery compression?
ischemia
pallor
coolness
decrease in limb pulses
What are sxs of subclavian vein compression?
swelling
pain
venous thrombosis
From how many ossification centers does the bony thorax develop? When does it fuse?
6 ossification centers
fuse around age 25
xiphoid process fuses 30-40
What is a symphysis and what are examples of it?
secondary cartolaginous joint
bones are joined by fibrocartilage
sternal angle
pubic symphpysis
joints between intervertebral discs
What is a synchondrosis?
primary cartilaginous joint
bones united by hyaline cartilage temporarily then converted to bone
xiphesternal joint
What do the external intercostal muscles do?
Elevates ribs
forced INSPIRATION
What do the internal intercostal muscles do?
Depresses ribs
forced EXPIERATION
