Organization of the thorax: thoracic wall Flashcards
where is the AML (anterior medial line)
right down the front
down manubrium and sternum
through umbilicus
where is the MCL (midclavicular line)
passes through the midpoint of the clavicle parallel to the AML (on both sides)
where is the AAL (anterior axillary line)
runs vertically along the anterior axillary fold that is formed by the inferolateral border of the pectoralis major as it spans from the thoracic cage to the humerus in the arm
MAL (midaxillary line) where is it
runs from the apex (deepest part of the axillary fossa (armpit) parallel to the AAL
PAL (posterior axillary line) is where
parallel to the AAL is drawn vertically along the posterior axillary fold formed by the latissimus dorsi and teres major muscles as they span from the back to the humerus
SL where is this (scapular lines)
parallel to the posterior median line and intersect the inferior angles of the scapula
PML (posterior median line) is where
is a vertical line along the tips of the spinous processes of the vertebrae
what is the thorax and what is it composed of?
the superior part of the trunk lying between the root of the neck (superior thoracic aperture) and thoracic diaphragm (inferior thoracic aperture)
composed of thoracic wall (osteocartilaginous components, muscles, fascia, skin)
and the thoracic cavity (2 pulmonary cavities and central mediastinum)
what is the function of the thorax
protection underlying viscera
respiration
muscle attachment
what are the true ribs
1-7
attach directly the sternum
what are the false ribs
8-10
attach to the costal cartilage of rib above and form the infracostal (costal) margin
what are the floating ribs
11-12
not attached to the sternum
anteriorly end in muscle
what are the typical ribs
what are the anatomical features of typical ribs
3-9
Head- articulates with adjacent vertebral bodies
Neck- portion between the head and tubercle
Tubercle- junction of head and neck, articulates with transverse process
Angle - the anterolateral angulation of the body just lateral to the tubercle
shaft (body) - inferior portion has a concave internal surface called the costal groove
costal cartilage
what is the function of the costal groove
provides protection for intercostal vein, artery, nerve
what is the function of the costal cartilage
provides increased elasticity for thoracic wall
what is unique about the 1st rib
broad horizontal shaft with pronounced curvature
head has single facet for articulation with TV1
shaft contains grooves for subclavian artery and vein and scalene tubercle
what is unique about the 2nd rib
serratous anterior tuberosity on the superior surface
what is unique about the 10th rib
single articular facet for articulation with body of TV10
what is unique about 11th and 12th ribs
single articular facet on head
no neck/tubercle
where is the most common site of rib fractures and what are the most commonly broken ribs
near angle b/c this is weakest part of rib
middle ribs most common to break
what is flail chest
results from multiple ribs broken in 2 or more places
this causes a loose segment of thoracic wall which moves paradoxically during respiration
what are the components of the sternum
manubrium
body
Xiphoid process
manubrium parts
suprasternal notch
clavicular notch
lateral facets for articulation with costal cartilages of ribs 1 and 2
where is the sternal angle or angle of Louis located
at the manubriostenral joint
what costal cartilages does the body articulate with
costal cartilages of ribs 2-7
why is the sternal angle an important landmark
angle of Louis
because it demarcates the articulation of rib 2
also a horizontal plane passed from the sternal angle to the disc between T4-T5 marks the boundary between superior and inferior mediastinum and is called the Transverse Thoracic Plane.
what is special about the xiphoid process
cartilaginous but usually ossifies with age
lateral demi-facets for articulation with the costal cartilage of 7th rib
articulates with the body of the sternum
infrasternal angle
what is pectus excavatum
what is pectus carinatum
excavatum–> anterior thoracic wall sunken in
carinatum–> anterior thoracic wall protrusion or “pigeon” breast
anomalies resulting from malformation of sternum and ribs
can cause respiratory and cardiac problems
what are the borders (A, L, P) of the superior thoracic aperture (aka thoracic inlet)
clinical correlation?
Anterior- suprasternal (jugular) notch
Lateral-1st rib
posterior- 1st thoracic vertebra
superior aperture extends obliquely from 1st thoracic vertebra anteroinferiorly to the manubrium. The pleural space extends superiorly into the neck region. Thus, injury or surgery within this region may affect the pleural cavity and lungs (pneumothorax).
inferior thoracic aperture borders ? (aka thoracic outlet)
clinical correlation
Anterior- xiphisternal joint
Lateral- costal margin
Posterior- 12th thoracic vertebra and 11th and 12th rib
The inferior aperture extends obliquely from 12th thoracic vertebra anterosuperiorly to xiphisternal joint. The pleural space thus extends inferiorly to lie posterior to the abdominal region. Thus, injury or surgery in this region may affect the pleural cavity and lungs (pneumothorax).
which ribs only have 1 facet
1, 10, 11, 12
more rotational component and can move rib more than when you have more demifacets
what are the 5 articulations (joints) of the thoracic wall
Sternocostal Costochondral Interchondral Costovertebral Costotransverse
Sternocostal joint?
costal cartilage and sternum
7 pairs!!
what is unique about the 1st sternocostal joint
synchondrosis NO MOVEMENT
important in respiration b/c move the first rib and the rest of the ribs follow
what types of joints are the 2nd - 7th sternocostal joints
synovial plane joints
what is the costochondral joint and what type of joint is it?
why important clinically
articulation between rib and costal cartilage
synchondroses–> very little movement
***Frequently dislocated in trauma
what is the costovertebral joint
articulation between the rib head with vertebral bodies and intervertebral disc
synovial plane joints
what do the ribs 2-9 articulate with on the vertebra and what ligament supports this …
articulate with adjacent vertebral bodies and intervertebral disc
***an intra-articular ligament extends from the crest of the head to the intervertebral disc limiting movement of this joint
what do ribs 1, 10-12 articulate with on the vertebra
only with the body of the same numbered vertebra
what does the radiate ligament do?
supports the joint capsule of the rib head with the vertebra
what is the costotransverse joint
articulation between rib tubercle and vertebral transverse process
synovial joints
ribs 11-12 do not have costotransverse joints
what are the supporting ligaments of the costotransverse joint x3
lateral costotransverse ligament
superior costotransverse ligament
costotransverse ligament
the head of a typical ribs articulates with what?
and what does the costal tubercle articulate with ?
the head of a typical rib articulates with:
1) superior costal fascet of the thoracic vertebra of the same number (by its inferior articular facet)
2) the inferior costal facet of the vertebra above (by its superior articular facet)
3) the intervertebral disc between the two vertebrae
The costal tubercle articulates with the transverse process of the vertebra of the same number
what is the origin and insertion of the external intercostal muscles
origin
inferior border of ribs (1-11)
insertion
superior border of rib below (2-12)
what is the action of the external intercostal muscles
Maintain intercostal space during respiration elevate ribs (inspiration)
innervation of external, innermost, and internal intercostals
intercostal nerves
what are the attachments of the internal intercostal muscles
origin
superior border of ribs (2-12)
insertion
inferior border of rib above (1-11)
action of the internal intercostal muscles AND innermost intercostal
maintain intercostal space during respiration
depress ribs (expiration)
what are the attachments of the innermost intercostal muscles
origin
superior border of rib 2-12
insertion
inferior border of rib above 1-11
what are the three parts of the innermost intercostal muscles and what is unique about them
Discontinuous sheet of muscle:
1) transversus thoracis (sternocostalis) anteriorly
2) innermost intercostal laterally
3) subcostalis posteriorly
what are the attachments of the subcostal muscles
origin superior border of rib near angle (mostly lower ribs)
insertion
inferior border of rib 2 or 3 intercostal spaces higher
action of subcostal muscle
depress ribs (expiration)
what muscles of the thorax are for expiration
internal intercostal
innermost intercostal
subcostal
transverse thoracic
forced
anteriolateral abdominal wall muscles
what muscles of the thorax are for inspiration?
forced inspiration
inspiration:
external intercostal
forced inspiration
- levator costarum
- serratous posterior superior
- serratous posterior inferior
forced sternocleidomastoid scalenes serratous anterior pec major and minor quadratus lumborum
what are the attachments of the transverse thoracic
origin
-internal surface of the inferior sternum
insertion
inferior border of ribs 2-6
action of transverse thoracic muscle
depress ribs (expiration)
innervation transverse thoracic muscle
intercostal nerves 2-6
attachments of the levator costarum
origin
transverse processes of CV7-TV11
insertion
superior border of ribs near tubercle
levator costarum AND serratous posterior superior action
both assist with elevating ribs during forced inspiration
innervation levator costarum
Ventral rami of C8-T11
serratous posterior superior attachments
origin
nuchal ligament and spinous processes of CV7-TV3
insertion
ribs 2-5
superior border near angle
innervation of serratous posterior superior
intercostal nerves 1-4
attachments of serratous posterior inferior
origin
spinous process of TV11-Lv2
insertion
ribs 9-12
inferior border near angle
action of serratous posterior inferior
assist with forced inspiration
depress lower ribs to oppose superior movement of diaphragm (supports diaphragm during inspiration)
innervation of serratous posterior inferior
intercostal nerves 9-12
what way do the external intercostal fibers go?
what does the external intercostal muscle turn into anteriorly
ex to sex
inferio-medially
anteriorly at the costochondral joint the muscle is replaced by external intercostal membrane
what way do the internal intercostal muslces go and what do the muscles turn into posteriorly
infero-laterally
posteriorly, at the angle of ribs the muscle is replaced by internal intercostal membrane
between what two layers does the neurovascular bundle run between
between 2nd and 3rd layers (between internal intercostal and innermost intercostal muscles)
this is important clinically because when inserting a needle you want to roll OVER the superior surface of the rib to avoid this bundle
what is the deep thoracic fascia ?
what is the clinical significance ?
the endothoracic fascia
CT lining entire surface of internal thoracic wall and superior surface of diaphragm
adheres the parietal pleura to the thoracic wall
provides a cleavage plane between thoracic wall and pleura; important for surgeries requiring access to thoracic cavity
what is the thickened portion of the endothoracic fascia called near the apex?
Sibson’s fascia
muscles of the thoracic wall are continuous with the muscles of the abdominal wall
so what is each consistent with
external intercostal–> external abdominal oblique
internal intercostal–> internal abdominal oblique
innermost intercostal–> transversus abdominus
what are the three movements of the thoracic wall during respiration
increase Anterior-posterior diameter (pump handle)
Increase transverse diameter (bucket-handle motion)
Increase in vertical diameter
A-P diameter increasse (pump handle motion) consists of motion at what joint
and what joint is important in mediating this motion
rotational movement at the costotransverse joint causes elevation and depression of the most distal (anterior) portion of the upper ribs
b/c of the inferior slope of the distal portion of the ribs, anterior elevation causes an increase in the A-P diameter of the thoracic wall
first rib fixation important mediator of this***
Increase in transverse diameter (bucket handle motion) consists of what movement at what joint
gliding movement at posterior (costovertebral and costotransverse) joints
causing elevation and depression of the lateralmost portions of ribs
increase in vertical diameter is done by what muscle?
contraction of the diaphragm
what is the innervation of the thoracic diaphragm
phrenic nerve
C3, C4, C5 “keeps the diaphragm alive”
what is the diaphragm? action?
what happens during deep expiration and forced inspiration?
musculotendinous septum separating the thoracic and abdominal cavities
primary muscle of respiration, especially quiet respiration
flattens during contraction and increases intrathoracic volume
deep expiration-
-the superior surface extends to the 4th intercostal
forced inspiration?
-can move down 10 cm (about 2 vertebral bodies)
what is the innervation of the thoracic wall made up of?
and to what does it supply innervation
12 ventral rami of thoracic spinal nerves
11–> intercostal nerves
1–> subcostal nerve
innervation to the muscles of the thoracic wall (except levator costarum) and the skin of the anterolateral thoracic and abdominal wall
***provide preganglionic sympathetic nerve cells processes to the sympathetic chain via 14 pairs of white rami communicantes
***provide postganglionic sympathetic nerve cell processes via 31 pairs of gray rami communicantes
what do the postganglionic sympathetic nerve cell processes innervate?
sweat glands
smooth muscle in arrector pili
smooth muscle in blood vessels of the thoracic and abdominal wall
what is the course of the intercostal nerves
- First, travel within endothoracic fascia. in the costal groove along the inferior margin of the rib
- Near rib angle, nerves pass between 2nd and 3rd muscle layers (internal and innermost intercostal muscles.
what are the 5 branches of the intercostal nerves
Rami communicantes
Muscular branches
Collateral branch- near angle this will course along superior border of rib
lateral perforating (cutaneous) - give off near MAL -pierces lateral body wall and divides into anterior and posterior cutaneous branches
anterior peforating -given off near lateral border of the sternum, pierce anterior body wall and divide into medial and lateral cutaneous
what is unique about the ventral ramus of T1
The ventral ramus of T1 divides into a large superior trunk which goes to brachial plexus and a small inferior trunk (1st intercostal nerve).
Intercostal nerve 1 typically has no cutaneous branches; thus the T1 dermatome is not represented on the thoracic wall ***
what is unique about the lateral cutaneous branch of the intercostal nerve 2
The lateral cutaneous branch of intercostal nerve 2 (and often 3) forms the INTERCOSTOBRACHIAL cutaneous nerve, supplying skin and subcutaneous tissue of the axilla and medial brachial area.
so during mastectomy this is sometimes cut BUT Dr. lea likes to keep it so women having feeling in their armpit when they are shaving
what happens to the intercostal nerves 7-11 and the subcostal nerve as they continue anteriolaterally?
due to the ascending nature of the lower ribs these nerves continue as thoracoabdominal nerves to supply skin and musculature of abdominal wall. b/c they don’t all continue back to the xiphoid process (that’s just silly)
what is the nipple line in males representing?
T4
what is the xiphoid process representing
T6
what is the umbilicus dermatome
T10
what do the anterior intercostal arteries branch from ? and how many are there?
internal thoracic (internal mammary)
9 pairs
what does the internal thoracic branch from ? where does it travel?
and what does it directly supply/branch
what are its terminal branches?
- Branch of the subclavian artery.
- Descends along internal surface of anterior thoracic wall, lateral to sternum.
- Near 6th or 7th costal cartilage, divides into two terminal branches: musculophrenic and superior epigastric arteries.
- Directly provides anterior intercostals arteries 1-6
what is the coarse of the musculophrenic artery? what is its origin
the origin of this artery is the internal thoracic
Follows costal arch and provides anterior intercostal arteries to lower intercostal spaces.
how many intercostal arteries are in each intercostal space? what do these arteries anastomose with?
two
anastomose with posterior intercostal arteries
***perforating and muscular branches follow same pattern as nerves
how many posterior intercostal arteries are there and how many subcostal?
12 posterior intercostal
1 subcostal
what is the origin of the posterior intercostal arteries?
a. Thoracic (descending) aorta – segmentally provides posterior intercostal arteries 3-11 and subcostal artery.
what supplies blood to the posterior 1st and 2nd intercostal spaces
Costocervical trunk (branch of subclavian artery)
– provides supreme (superior or highest) intercostal artery which supplies the posterior 1st and 2nd intercostal spaces.
what are the branches of the posterior intercostal arteries? 4
b. Posterior branch (ramus) – given off near vertebral column; supplies skin, subcutaneous tissue, and intrinsic muscles of back, as well as the spinal cord and vertebral column. (same course and distribution as the doral ramus of a spinal nerve)
c. Collateral branch – given off near angle of the rib.
d. Lateral perforating (cutaneous) branch – given off near the MAL.
e. Anterior perforating (cutaneous) branch – given off in parasternal area.
what do the 1st-3rd posterior intercostal veins unite to form?
superior intercostal vein which drains directly into the azygos (right) or brachiocephalic vein (left)
anterior intercostal veins drain to what
internal thoracic veins
posterior intercostal veins drain to what
the azygos system of veins
superficial structures (including the mammary gland) drain to what?
axillary lymph nodes
where are the parasternal nodes
what do they receive
and what is its efferent
- Along the lateral border of the sternum.
- Afferents: anterior thoracic wall, superior portion of the abdominal wall, superior surface of the liver, and the medial portions of the mammary gland.
- Efferents: bronchomediastinal trunk.
where are the intercostal nodes
what are its afferents (1)
what are its efferents
- Located near the heads and necks of the ribs.
- Afferents: posterolateral thoracic wall.
- Efferents: thoracic duct or right lymphatic duct (1st – 6th spaces); also spread to abdomen and enter cisterna chyli directly (7th – 11th spaces).
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where are the anterior diaphragmatic nodes (phrenic nodes)
what are its afferents
efferents? what does it drain to…
a. Located near the xiphoid process on the superior surface of diaphragm.
b. Afferents: anterior diaphragm; superior surface of the liver.
c. Efferents: drain to parasternal nodes.
where are the lateral diaphragmatic nodes
what are its afferents
what are its efferents
a. Located where phrenic nerves pierce diaphragm.
b. Afferents: central diaphragm, superior surface of liver.
c. Efferents: to parasternal and posterior mediastinal lymph nodes
where are the posterior diaphragmatic nodes
afferents
efferents
a. Located near the aortic hiatus.
b. Afferents: posterior portion of diaphragm.
c. Efferents: posterior mediastinal nodes
the azygous system is significant clinically because…
it provides important collateral circulation between the superior and inferior vena cava
A 25 y/o male reports to the ED with a stab wound to the right chest wall. The knife penetrated the thoracic wall just to the right of the manubrium at the level of the 2nd costal cartilage. The physician is most worried about damage to which structure
superior vena cava
what is flail chest? what happens with inspiration and expiration
2 or more consecutive ribs break causing a separate floating section in the rib cage
paradoxical chest wall motion best describes this
paradoxical breathing can be described that on inhalation the flail section move inwards, expiration causes the section to move outwards
what is open pneumothorax
sucking chest wound
occurs when air is drawn in through an open chest wound
with each breath air passes through the chest wall leading to accumulation in the chest cavity
