Thoracic Wall: Osteology & Muscles Flashcards
what is thorax?
the part of the body between the neck and the abdomen, including the cavity enclosed by the ribs, sternum, and dorsal vertebrae, and containing the chief organs of circulation and respiration; the chest
mediastinum
central compartment
L/R pleural compartments are separated by the
mediastinum
what shape does the thoracic skeleton take the shape of? (3)
a dome, birdcage or truncated cone
where is the thoracic cavity narrowest?
superiorly, with the circumference increasing inferiorly
the floor of the respiratory diaphragm is — superiorly
convex
are the walls of the thoracic wall thick or thin?
relatively thin
what are the four functions of the thoracic cavity?
protect vital thoracic/abdominal organs from external forces
resist the negative internal pressure created by the elastic recoil of the lungs
provide attachments for and support the weight of the upper limbs
provide the origin for some upper limb muscles and attachments for muscles of the abdomen, neck, back, and respiration
true ribs
1-7
attach vertebrae to the sternum
(costal cartilage) from the sternal end to the sternum/breastbone
false ribs
8-10 have cartilages attached to the cartilages of ribs superior
(don’t have a cartilage of their own, join the intrasternal angle)
floating ribs
11-12 have cartilages ending in the posterior abdominal wall musculature
what are cartilages of 7-10 are joined to form the
infrasternal angle
ribs and costal cartilages are separated by an
intercostal space
what is the superior thoracic aperture (thoracic outlet and inlet) bounded by?
1st thoracic vertebra, 1st pair of ribs, and superior border of the manubrium
inferior thoracic aperture is closed by the
diaphragm
structures must pass through the inferior thoracic aperture – it
behind
what do the facets of the head of the ribs articulate with?
inferior and superior costal facets of the adjacent thoracic vertebrae
where does the tubercle of the ribs articulate with?
the costal facet of the transverse process of vertebrae of the same number
what is the number of ribs increased by? what is it decreased by?
increased by the presence of cervical and/or lumbar ribs
decreased by failure of the 12th pair to form
how common are cervical ribs?
fairly common
.5-2%
what do cervical ribs interfere with?
neuromuscular structures exiting the superior thoracic aperture
what is the clinical significance of supernumerary (extra) ribs
confusion in radiological diagnosis
thoracic outlet syndrome (TOS)
a group of disorders that occur when there is compression, injury, or irritation of the brachial plexus and/or subclavian vessels in the lower neck and upper chest
the manubriosternal and xiphisternal joints can fuse and become a
synostosis in older persons
failure of fusion between halves of the sternal bars during development can result in
sternal cleft or sternal foramen
cardiac/pericardial tamponade
a type of pericardial effusion in which fluid, put, or gas accumulates in the pericardium (the sac in which the heart is encodes) results in slow or rapid compression of the heart
5-4 year old patient suffering from a chest wall sarcoma that necessitated the removal of his sternum as well as a portion of his rib cage. once removed,
these bones would have been replaced with a titanium implant, which creased a new set of problems that needed to be addressed. creating the implant with 3D printing offered the advantage of the ability to completely customize the implant, dose relatively quickly, and to create a design that would counter some of the problems historically present in flat titanium implant design
precuts carinatum
abnormal development causing the sternum to protrude. can be evident at both; adolescent males during growth spurt (most common). it may occur as a solitary congenital abnormality or in association with other genetic disorders or syndromes
prevalence of PE
1 in 500-1000 children
3x in males
cause of PE
unknown
Poland
absent pectorals major
ectopia cordis
heart is on the outside of the thoracic cavity
failure of sternum to fuse
scoliosis
lateral curvature of the spine
congenital scoliosis
Caused by a bone abnormality present at birth
neuromuscular scoliosis
A result of abnormal muscles or nerves. Frequently seen in people with spina bifida or cerebral palsy or in those with various conditions that are accompanied by, or result in, paralysis
degenerative scoliosis
This may result from traumatic bone collapse, previous major back surgery, or osteoporosis
idiopathic scoliosis
The most common type of scoliosis, idiopathic scoliosis, has no specific identifiable cause. There are many theories, but none have been found to be conclusive. There is, however, strong evidence that idiopathic scoliosis is inherited
upper ribs (1-7) — at the costotransverse joints
rotate
lower ribs (8-10) — at the costotransverse joints
glide
ribs 11 and 12 do not articulate with
transverse processes
costochondral joints
primary cartilaginous joints and they usually do not experience movement
interchondral joints (2)
some are plane synovial joints (between costal cartilages 6-9)
some are fibrous (between cartilages 9 and 10)
sternocostal joints (2)
1st joint is cartilaginous
joints 2-7 are synovial plane joint
the intercostal muscles occupy the intercostal spaces and function during respiration, both by
moving the ribs and by helping to keep the intercostal spaces rigid
the intercostal muscles include (5)
external intercostal internal intercostal innermost intercostal subcostal transversus thoracis
external intercostals
attach superiorly to the inferior border of the rib above and inferiorly to the superior border of the rib below
what direction do external intercostal fibers run
anteriorly
function of external intercostals
elevate the ribs during forced inspiration
internal and innermost intercostals attach
superiorly to the rib above and inferiorly to the superior rib below
fibers run inferoposteriorly
interosseous part functions to
depress the ribs during forced respiration
internal intercostals and innermost intercostals are separated by the
intercostal neuromuscular bundle
external intercostal
breathing in
breathing out
contract
relax
internal intercostal/innermost
breathing in
breathing out
relax
contract
subcostalis attach
superiorly to internal surfaces of lower ribs near their angles and inferiorly to superior borders of ribs 2 or 3 levels below
subcostalis fibers
run in the same orientation and blending with internal and innermost intercostals
subcostalis function
probably the same as the internal intercostals
transversus thoracis attach
superiorly on the posterior sternum and inferiorly on costal cartilages 2-6
function of transversus thoracis
depress the ribs
levator costae
O:
I:
A:
O: transverse processes
I: rib below between tubercle and angle
A: elevate the ribs
serratus posterior superior
O:
I:
A:
O: spines of C7-T3
I: ribs 2-4
A: elevate ribs
serratus posterior inferior
O:
I:
A:
O: spines of T11-L2
I: ribs 8-12
A: depress ribs
in the thoracic region, the ventral rami are in the form of
intercostal nerves
roots carry
sensory or motor
rami carry
both sensory and motor, mixed
dermatome
area of the skin supplied by nerves from a single spinal root
sensory impairment for a specific dermatome is related to the
level of spinal cord injury
thoracotomy
surgical opening through the thoracic wall to access the lungs, heart, esophagus, and the thoracic vertebrae
thoracentesis
a procedure to remove fluid from the space between the lining of the outside of the lungs (pleura) and the wall of the chest
nerve root block
selective nerve root block primarily used to diagnose the specific source of nerve root pain and secondarily, for therapeutic relief of low back pain and or leg pain
thoracic epidural steroid injections are most commonly used to reduce the pain associated with
herpes zoster (shingles)
such blocks may reduce the risk of developing persistent
postherpetic neuralgia
pain that persists long after the shingles skin eruption has healed
muscles raise the ribs during
inspiration
buckle handle movement
the lateral-most parts of the ribs are elevated and the transverse diameter of the thorax increases
the ribs are also elevated at the
neck (especially ribs 2-6) results in an increase in the AP diameter of the thorax pump handle movement
Boyles law
increase in volume, decrease in pressure
air comes in with less effort
pump handle movement:
bucket handle movement:
pump handle movement: elevation of the ribs, increase in the anteroom-posterior diameter of the thoracic cavity
bucket handle movement: elevation of ribs, increase in lateral diameter of the thoracic cavity
the primary blood supply to the thoracic wall is derived from branches of the
aorta and the subclavian arteries
internal thoracic artery
descends into thorax 1.2 cm lateral to edge of sternum, and ends at the sixth costal cartilage by dividing musclophrenic and superior epigastric arteries
anterior intercostals 7-10 come from
the musclophrenic arteries
arises from the subclavian artery near its origin
intercostal veins will drain back to the (2)
musclophrenic or internal thoracic veins
internal thoracic vessels give off anterior intercostal arteries to the
first six intercostal spaces
anterior intercostal arteries anastomose with
posterior intercostal arteries (from the descending thoracic aorta) in the intercostal space
companion veins accompany the
arteries
two of the posterior intercostal arteries branch off the
superior intercostal artery in the first two intercostal spaces
the remaining posterior intercostal Arties are branches of the
descending thoracic aorta
most of the posterior intercostal veins return blood to the
azygous and hemiazygos veins
posterior intercostal vein exception
left superior intercostal
thoracentesis
insertion of the needles just superior to the rib should avoid injuring the intercostal nerve and Bessel
VAN
vein
artery
nerve
