Session 1.2c - Gray's Anatomy For Students - Thorax - Regional anatomy - Thoracic wall Flashcards
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How does the thoracic wall appear?
Segmental in design
What is the thoracic wall composed of?
Skeletal elements and muscles
Where is the thoracic wall bound to superiorly?
The superior thoracic aperture, bordered by vertebra TI, rib I, and the manubrium of the sternum
Where is the thoracic wall bound to inferiorly?
The inferior thoracic aperture, bordered by vertebra TXII, rib XII, the end of rib XI, the costal margin, and the xiphoid process of the sternum.
What are the skeletal elements of the thoracic wall?
The skeletal framework consists of the thoracic vertebrae, intervertebral discs, ribs and sternum
How many thoracic vertebrae are there?
Twelve THORACIC VERTEBRAE.
How are the 12 thoracic vertebrae characterised?
By articulations with ribs.
What is the shape of the body of a typical thoracic vertebra?
A typical thoracic vertebra has a heart-shaped VERTEBRAL BODY.
Describe the dimensions of the body of a typical thoracic vertebra.
Roughly equal dimensions in the transverse and anteroposterior directions (Fig. 3.18)
Describe the spinous process of a typical thoracic vertebra.
Long spinous processes (Fig. 3.18)
How do the vertebral foramen of the typical thoracic vertebra appear?
The VERTEBRAL FORAMEN is generally circular
How are the lamina of the vertebra?
The LAMINAE are broad and overlap with those of the vertebra below.
Describe the superior articular processes of a typical thoracic vertebra.
The SUPERIOR ARTICULAR PROCESSES are flat, with their articular surfaces facing almost directly posteriorly.
Describe the inferior articular processes of a typical thoracic vertebra.
The INFERIOR ARTICULAR PROCESSES project from the laminae and their articular facets face anteriorly.
Describe the transverse processes of a typical thoracic vertebra.
The TRANSVERSE PROCESSES are club shaped and project posterolaterally.
How do the vertebra articulate with the ribs?
A typical thoracic vertebra has three sites on each side for articulation with ribs.
What are demifacets?
i.e. partial facets
Where are the demifacets located?
On the superior and inferior aspects of the body
What do the demifacets articulate with?
Corresponding sites on the heads of adjacent ribs.
What does the superior facet articulate with?
The SUPERIOR COSTAL FACET articulates with part of the head of its own rib
What does the inferior costal facet articulate with?
The INFERIOR COSTAL FACET articulates with part of the head of the rib below.
What is the oval facet on the thoracic vertebra called?
TRANSVERSE COSTAL FACET
What shape is the transverse costal facet?
Oval
Where is the transverse costal facet?
At the end of the transverse process
What does the transverse costal facet articulate with?
The tubercle of its own rib
Not all vertebra articulate with ribs in a typical fashion. Which ones?
TI, TX, TXI and TXII (Fig. 3.19)
Describe the rib articulation of TI.
The superior costal facets on the body of vertebra TI are complete and articulate with a single facet on the head of its own rib - in other words, the head of rib I does not articulate with vertebra CVII.
Describe the rib articulation of TX.
Similar to TI, TX (and often TIX) articulates only with its own ribs and therefore lacks inferior demifacets on the body.
Describe the rib articulation of TXI and TXII.
These articulate only with the heads of their own ribs - they lack transverse costal facets and have only a single complete facet on each side of their bodies.
Which vertebra only articulate with their own ribs?
TI, TX (and often TIX), TXI and TXII.
Some vertebra only articulate with their own ribs. What is different about the costal facets of these?
TI - superior costal facet complete
(TIX) TX - lacks inferior demifacets
TXI and TXII - lack transverse costal facets and have a single complete facet on each side of their bodies
How many ribs are there?
Twelve pairs of ribs
What does each rib terminate as?
They terminate anteriorly in a costal cartilage (Fig. 3.20).
What do all ribs articulate with?
The vertebral column
What articulates with the sternum?
The costal cartilages of the upper seven ribs
Which are the true ribs?
The upper seven ribs
Ribs I-VII are known as what, and articulate with what?
TRUE RIBS, articulate directly with the sternum
What are ribs VIII-XII known as?
The remaining five pairs of ribs are FALSE RIBS
How many true and false ribs are there?
7 true, 5 false
What do ribs VIII to X articulate with?
The costal cartilages articulate anteriorly with the costal cartilages of the ribs above.
What do ribs XI and XII articulate with?
These have no anterior connection with other ribs or with the sternum
What are ribs XI and XII often known as?
FLOATING RIBS
Which ribs are the floating ribs?
Ribs XI and XII
What does a typical rib consist of?
A curved shaft with anterior and posterior ends (Fig. 3.21).
What is the anterior end of the rib continuous with?
Its costal cartilage
What does the posterior end of the rib articulate with?
The vertebral column
How is the posterior end of the rib characterised?
By a head, neck and tubercle.
Describe the head of the rib.
The HEAD is somewhat expanded and typically presents two articular surfaces.
What are the two articular surfaces on the head separated by?
The HEAD presents two articular surfaces separated by a CREST.
Describe the relative sizes of the two articular surfaces of the head.
The superior surface is smaller than the larger inferior facet.
What does the superior surface on the head of the rib articulate with?
The inferior costal facet on the body of the vertebra above
What does the inferior surface (facet) on the head of the rib articulate with?
The superior costal facet of its own vertebra.
Describe the neck of the rib.
The NECK is a short flat region of bone that separates the head from the tubercle.
Describe the tubercle of the rib.
The TUBERCLE projects posteriorly from the junction of the neck with the shaft and cosistd of two regions, an articular part and a nonarticular part.
Describe the articular part of the tubercle of the rib.
The articular part is medial and has an oval facet for articulation with a corresponding facet on the transverse process of the associated vertebra.
Describe the nonarticular part of the tubercle of the rib.
The raises nonarticular part is roughened by ligament attachments.
Describe the shaft of the rib.
Generally thin and flat with internal and external surfaces.
Describe the superior margin of the rib.
Smooth and rounded
Describe the inferior margin of the rib.
Sharp
What is the relationship of the shaft to the tubercle?
The shaft bends forward just laterally to the tubercle at a site termed the ANGLE.
Where does the shaft face, and how?
It has a gentle twist around its longitudinal axis so that the external surface of the anterior part of the shaft faces somewhat superiorly relative to the posterior part.
How is the inferior margin of the internal surface marked?
By a distinct COSTAL GROOVE.
Which ribs have distinct features?
Upper and lower ribs
- Rib I, II, X, XI and XII (Fig. 3.22)
Describe the orientation of rib I.
RIB I is flat in the horizontal plane.
Describe the superior and inferior surfaces of rib I.
They are broad.
Describe the orientation of rib I from its articulation with vertebra TI.
It slopes inferiorly to its attachment to the manubrium of the sternum.
Describe the head of rib I.
The head articulates only with the body of vertebra TI and therefore has only one articular surface.
Describe the tubercle of rib I.
Like other ribs, the tubercle has a facet for articulation with the transverse process.
Describe the superior surface of rib I.
It is characterised by a distinct tubercle, the SCALENE TUBERCLE.
What does the scalene tubercle do?
Separates two smooth grooves that cross the rib approximately midway along the shaft.
What runs along the anterior groove of rib I?
The subclavian vein
What runs along the posterior groove of rib I?
The subclavian artery
Anterior and posterior to the grooves by the scalene tubercle (rib I), how does the shaft appear?
It is roughened by muscle and ligament attachments.
Describe rib II.
RIB II, like rib I, is flat but twice as long.
What does rib II articulate with?
The vertebral column in a way typical of most ribs.
Describe the head of rib X.
The head of RIB X has a single facet for articulation with its own vertebra.
Describe the structure and function of ribs XI and XII.
RIBS XI and XII articulate only with the bodies of their own vertebrae and have no tubercles or necks.
Describe the appearance of ribs XI and XII.
Both ribs are short, have little curve, and are pointed anteriorly.
What does the adult sternum consist of?
The adult STERNUM consists of three major elements: - manubrium - body - xiphoid process (Fig. 3.23)
Describe the manubrium of the sternum.
Broad and superiorly positioned (Fig. 3.23)
Describe the body of the sternum.
Narrow and longitudinally oriented (Fig. 3.23)
Describe the xiphoid process of the sternum.
Small and inferiorly positioned (Fig. 3.23)
What does the manubrium of the sternum form?
Part of the bony framework of the neck and the htorax.
What occurs on the superior surface of the manubrium?
It is expanded laterally
What is found on the superior surface of the manubrium?
A distinct and palpable notch: the JUGULAR NOTCH (SUPRASTERNAL NOTCH), in the midline.
What is found either side of the jugular notch?
A large oval fossa for articulation with the clavicle.
What is found immediately inferior to the fossa, either side of the jugular notch?
Immediately inferior, on each lateral surface of the manubrium, is a facet for the attachment of the first costal cartilage.
What is found at the lower end of the lateral border of the facet that attaches to the first costal cartilage?
A demifacet for articulation with the upper half of the anterior end of the second costal cartilage.
Describe the body of the sternum.
It is flat.
What is the anterior surface of the body of the sternum marked by?
Often marked by transverse ridges
What do the transverse ridges on the body of the sternum represent?
Lines of fusion between the segmental elements called sternebrae
Where does the body of the sternum arise embryologically?
From the sternebrae (transverse ridges on sternum)
What is found on the lateral margins of the body of the sternum?
Articular facets for costal cartilages.
What does the body of the sternum have superiorly?
Each lateral margin has a demifacet for articulation with the inferior aspect of the second costal cartilage.
How many facets are there on the body of the sternum, inferior to the first demifacet?
Four facets
What do the facets of the body of the sternum articulate with?
The costal cartilages of ribs III to VI.
What is found at the inferior end of the body of the sternum?
A demifacet for articulation with the upper demifacet on the seventh costal cartilage.
What is the inferior end of the body of the sternum attached to?
The xiphoid process.
Which is the smallest part of the sternum?
The XIPHOID PROCESS.
Describe the shape of the xiphoid process.
Its shape is variable: it may be wide, thin, pointed, bifid, curved or perforated.
How does the xiphoid process begin and mature.
It begins as a cartilaginous structure, which becomes ossified in the adult.
What is found on the upper lateral margin of the xiphoid process, on each side?
A demifacet for articulation with the inferior end of the seventh costal cartilage.
What does a typical rib articulate with?
The bodies of adjacent vertebrae and the transverse process of its related vertebra.
What do the bodies of adjacent vertebrae articulate wth on the rib?
They form a joint with the head of the rib
What is the joint between a typical rib and the transverse process of its related vertebra known as?
A COSTOTRANSVERSE JOINT (Fig. 3.24)
What do the costovertebral joints and related ligaments do?
They allow the necks of the ribs either to rotate around their longitudinal axes, or to ascend and descend relative to the vertebral column.
Where do the costovertebral joints allow the necks of the ribs to rotate around their longitudinal axes?
Mainly in the upper ribs
Where do the costovertebral joints allow the necks of the ribs to ascend and descend relative to the vertebral column?
Mainly in the lower ribs.
How do the ribs aid breathing?
The combined movement of all of the ribs on the vertebral column are essential for altering the volume of the thoracic cavity during breathing.
What do the two facets on the head of the rib articulate with?
The superior facet on the body of its own vertebra and the inferior facet on the body of the vertebra above.
How is the joint between the head of the rib and the vertebra divided?
Into two synovial compartments by an intra-articular ligament
How does the intra-articular ligament of the rib/vertebral joint occur?
It attaches the crest to the adjacent intervertebral disc and separates the two articular surfaces on the head of the rib.
What are the two synovial compartments and the intervening ligament surrounded by?
A single joint capsule
What is the joint capsule around the two synovial compartments and intra-articular ligament of the rib attached to?
The outer margins of the combined articular surfaces of the head and vertebral column.
What type of joints are costotransverse joints?
Synovial joints
Where are costotransverse joints found?
Between the tubercle of a rib and the transverse process of the related vertebra (Fig. 3.24).
Describe the capsule related to the costotransverse joint.
The capsule surrounding each joint is thin.
How is the costotransverse joint stabilised?
By two strong extracapsular ligaments
- COSTOTRANSVERSE LIGAMENT
- LATERAL COSTOTRANSVERSE LIGAMENT
Where are the extracapsular ligaments that stabilise the joint capsule on the costotransverse joints?
They span the space between the transverse process and the rib on the medial and lateral sides of the joint
Where is the costotransverse ligament?
It is medial to the joint and attaches the neck of the rib to the transverse process.
Where is the lateral costotransverse ligament?
Lateral to the joiunt and attaches the tip of the transverse process to the roughened nonarticular part of the tubercle of the rib.
What and where is the superior costotransverse ligament?
This is a third ligament, which attaches the superior surface of the neck of the rib to the transverse process of the vertebra above.
What movements occur at costotransverse joints?
Slight gliding movement
Where are the sternocostal joints?
Between the upper seven costal cartilages and the sternum (Fig. 3.25)
What type of joint is the joint between rib I and the manubrium?
It is not synovial and consists of a fibrocartilaginous connection between the manubrium and the costal cartilage.
What type of joint is the second to seventh sternocostal joints?
Synovial
What do the second to seventh sternocostal joints have to reinforce it?
Thin capsules reinforced by surrounding sternocostal ligaments.
How is the joint between the second costal cartilage and the sternum divided?
Into two compartments, by an intraarticular ligament.
What does the intraarticular ligament do?
Attaches the second costal cartilage to the junction of the manubrium and the body of the sternum.
Where do interchondral joints occur?
Between the costal cartilages of adjacent ribs (Fig. 3.25)
Which costal cartilages do interchondral joints mainly occur between?
Ribs VII to X, but may also involve the costal cartilages of ribs V and VI.
What is the function of interchondral joints?
- Provide indirect anchorage to the sternum
- Contribute to the formation of a smooth inferior costal margin
What is the structure of interchondral joints?
They are usually synovial, and the thin fibrous capsules are reinforced by interchondral ligaments.
What is the joint between the manubrium and the body of the sternum?
Usually symphyses (Fig. 3.25)
What is the joint between the body of the sternum and the xiphoid process?
Usually symphyses (Fig. 3.25)
What movements occur between the manubrium and the body of the sternum during respiration?
Only slight angular movements.
What occurs between the body of the sternum and the xiphoid process with age?
The joint often becomes ossified
What is a clinically useful feature of the manubriosternal joint?
It can be palpated easily
Why can the manubriosternal joint be palpated easily?
Because the manubrium normally angles posteriorly on the body of the sternum.
What does the manubriosternal joint produce?
A raised feature referred to as the sternal angle.
What does the sternal angle mark?
This elevation marks the site of articulation of rib II with the sternum.
Why is rib I not used in palpation?
Rib I is not palpable, because it lies inferior to the clavicle and is embedded in tissues at the based of the neck.
How do you palpate/count ribs?
Rib II is used as a reference for ocunting ribs and can be felt immediately lateral to the sternal angle.
How is the sternal angle related to the vertebral column?
It lies on a horizontal plane that passes through the intervertebral disc between vertebrae TIV and TV (Fig. 3.10).
Where does the superior mediastinum separate from the inferior mediastinum?
Horizontal plane that passes through the intervertebral disc between vertebrae TIV and TV.
Where is the superior border of the pericardium found?
Horizontal plane that passes through the intervertebral disc between vertebrae TIV and TV.
What does the horizontal plane that passes through the intervertebral disc between vertebrae TIV and TV mark?
- Sternal angle
- Superior/inferior mediastinum separation
- Superior border of the pericardium
- End of the ascending aorta
- Beginning and end of the arch of aorta
- Beginning of the thoracic aorta
- Bifurcation of the trachea (just superior to the pulmonary trunk)
Fig. 3.79 and 3.86
Describe the intercostal spaces.
They lie between adjacent ribs and are filled by intercostal muscles (Fig. 3.26).
Where precisely do intercostal nerves and associated major arteries and veins lie?
In the COSTAL GROOVE along the inferior margins of the superior rib and pass in the plane between the inner two layers of muscles.
In each space, which structure is most superior?
The vein, and is therefore highest in the costal groove.
Which structure is immediately inferior to the vein in the intercostal space?
Artery
Which structure is immediately inferior to the artery in the intercostal space?
The nerve, and as the most inferior, is often not protected by the groove.
Which structure is most at risk when objects perforate the upper aspect of an intercostal space?
The nerve, as it is the most inferior (out of the intercostal nerve, artery and vein) and often not protected by the groove.
Small collateral branches of the major intercostal nerves and vessels are often present where?
Superior to the inferior rib below.
What is found deep to the intercostal spaces and ribs?
ENDOTHORACIC FASCIA
What does endothoracic fascia do?
It separates the intercostal spaces and ribs from the underlying pleura.
What is the endothoracic fascia?
A layer of loose connective tissue, which contains variable amounts of fat.
What is found superficial to the intercostal spaces?
Deep fascia, superficial fascia and skin.
What overlies the intercostal spaces?
Muscles associated with the upper limbs and back.
What do muscles of the thoracic wall include?
Those that:
- fill and support the intercostal spaces
- pass between the sternum and ribs
- cross several ribs between costal attachments
(Table 3.2 - Muscles of the thoracic wall)
(Table 3.2: Muscles of the thoracic wall)
What is the superior attachment of the external intercostal muscles?
Inferior margin of rib above
(Table 3.2: Muscles of the thoracic wall)
What is the inferior attachment of the external intercostal muscles?
Superior margin of rib below
(Table 3.2: Muscles of the thoracic wall)
What is the innervation of the external intercostal muscles?
Intercostal nerves; T1-T11
(Table 3.2: Muscles of the thoracic wall)
What is the function of the external intercostal muscles?
Most active during inspiration; supports intercostal space; moves ribs superiorly
(Table 3.2: Muscles of the thoracic wall)
What is the superior attachment of the internal intercostal muscles?
Lateral edge of costal groove of rib above
(Table 3.2: Muscles of the thoracic wall)
What is the inferior attachment of the internal intercostal muscles?
Superior margin of rib below deep to the attachment of the related external intercostal
(Table 3.2: Muscles of the thoracic wall)
What is the innervation of the internal intercostal muscles?
Intercostal nerves; T1-T11
(Table 3.2: Muscles of the thoracic wall)
What is the function of the internal intercostal muscles?
Most active during expiration; supports intercostal space; moves ribs inferiorly
(Table 3.2: Muscles of the thoracic wall)
What is the superior attachment of the innermost intercostal muscles?
Medial edge of costal groove of rib above
(Table 3.2: Muscles of the thoracic wall)
What is the inferior attachment of the innermost intercostal muscles?
Internal aspect of superior margin of rib below
(Table 3.2: Muscles of the thoracic wall)
What is the innervation of the innermost intercostal muscles?
Intercostal nerves; T1-T11
(Table 3.2: Muscles of the thoracic wall)
What is the function of the innermost intercostal muscles?
Acts with internal intercostal muscles
(Table 3.2: Muscles of the thoracic wall)
What is the superior attachment of the subcostales muscles?
Internal surface (near angle) of lower ribs
(Table 3.2: Muscles of the thoracic wall)
What is the inferior attachment of the subcostales muscles?
Internal surface of second or third rib below
(Table 3.2: Muscles of the thoracic wall)
What is the innervation of the subcostales muscles?
Related intercostal nerves
(Table 3.2: Muscles of the thoracic wall)
What is the function of the subcostales muscles?
May depress ribs
(Table 3.2: Muscles of the thoracic wall)
What is the superior attachment of the transversus thoracis muscles?
Inferior margins and internal surfaces of costal cartilages of second to sixth ribs
(Table 3.2: Muscles of the thoracic wall)
What is the inferior attachment of the transversus thoracis muscles?
Inferior aspect of deep surface of body of sternum, xiphoid process, and costal cartilages of ribs IV-VII
(Table 3.2: Muscles of the thoracic wall)
What is the innervation of the transversus thoracis muscles?
Related intercostal nerves
(Table 3.2: Muscles of the thoracic wall)
What is the function of the transversus thoracis muscles?
Depresses costal cartilages
The muscles of the thoracic wall, together with muscles between the vertebrae and ribs posteriorly do what to control breathing?
Alter the position of the ribs and sternum and so change the thoracic volume during breathing.
Which are the muscles between the vertebrae and ribs posteriorly that affect breathing?
i.e., the LEVATORES COSTARUM and SERRATUS POSTERIOR SUPERIOR and SERRATUS POSTERIOR INFERIOR muscles.
What do the muscles of the thoracic wall and levatores costarum, serratus posterior superior/inferior do as well as change thoracic volume?
Reinforce the thoracic wall
What are the intercostal muscles?
Three flat muscles found in each intercostal space that pass between adjacent ribs (3.27).
How are the intercostal muscles named?
Individual muscles in this group are named according to their positions.
Which intercostal muscles are the most superficial?
The external intercostal muscles
Which intercostal muscles lie in the middle?
The internal intercostal muscles are sandwiches between the external and innermost muscles.
Which intercostal muscles are the deepest?
The innermost intercostal muscles
What are the intercostal muscles innervated by?
The related intercostal nerves
What do the intercostal muscles provide collectively?
Structural support for the intercostal spaces during breathing.
As a group, what else do the intercostal muscles do (as well as provide support)?
They can also move the ribs.
How many external intercostal muscles are there?
11 pairs
Which muscles extend from the inferior margins (lateral edges of costal grooves) of the ribs above to the superior margins of the ribs below?
EXTERNAL INTERCOSTAL MUSCLES.
How do the muscle fibres of the external intercostals run?
When the thoracic wall is viewed from a lateral position, they pass obliquely anteroinferiorly (Fig. 3.27).
Where do the external intercostal muscles extend?
The muscles extend around the thoracic wall from the regions of the tubercles of the ribs to the costal cartilages.
What is the external intercostal membrane?
Where each layer of intercostal muscles continues as a thin connective tissue aponeurosis (termed the EXTERNAL INTERCOSTAL MEMBRANE).
When are the external intercostal muscles most active?
In inspiration
How many internal intercostal muscles are there?
11 pairs
Which muscles pass between the most inferior lateral edge of the costal grooves of the ribs above, to the superior margins of the ribs below?
INTERNAL INTERCOSTAL MUSCLES
Where do the internal intercostal muscles extend from?
Parasternal regions, where the muscles course between adjacent costal cartilages, to the angle of the ribs posteriorly (Fig. 3.27)
Where do the internal intercostal muscles continue to?
This layer continues medially toward the vertebral column, in each intercostal space, as the INTERNAL INTERCOSTAL MEMBRANE.
Describe the muscle fibres of the internal and external intercostal muscles in relation to each other.
They pass in the opposite direction.
How do the muscle fibres of the internal intercostals run?
When the thoracic wall is viewed from a lateral position, the muscle fibres pass obliquely posteroinferiorly.
When are the internal intercostal muscles most active?
During expiration
Which are the least distinct of the intercostal muscles?
The INNERMOST INTERCOSTAL MUSCLES
How do the innermost intercostal muscles run?
The fibres have the same orientation as the internal intercostals (Fig. 3.27)
When are the innermost intercostal muscles most evident?
In the lateral thoracic wall.
Where do the innermost intercostals extend?
Between the inner surfaces of adjacent ribs from the medial edge of the costal groove to the deep surface of the rib below.
What is important about the plane between the innermost and internal intercostal muscles?
The neurovascular bundles associated with the intercostal spaces pass around the thoracic wall in the costal grooves in a plane between these muscles.
The subcostales are in the same plane as which muscles?
The innermost intercostals
Describe the subcostales.
They span multiple ribs and are more numerous in lower regions of the posterior thoracic wall (Fig. 3.28A).
Where do the subcostales extend?
From the internal surfaces of one rib to the internal surface of the second (next) or third rib below.
How do the subcostales fibres run?
Their fibres parallel the course of the internal intercostal muscles and extend from the angle of the ribs to more medial positions on the ribs below.
Where are the transversus thoracic muscles found?
The TRANSVERSUS THORACIC MUSCLES are found on the deep surface of the anterior thoracic wall (Fig. 3.28B) and in the same plane as the innermost intercostals.
Where do the transversus thoracic muscles originate?
From the posterior aspect of the xiphoid process, the inferior part of the body of the sternum, and the adjacent costal cartilages of the lower true ribs.
How do the transversus thoracic muscles pass?
Superiorly and laterally to insert into the lower borders of the costal cartilages of ribs III to VI.
What is the transversus thoracic muscles function?
They most likely pull ribs III to VI inferiorly.
Where do the transversus thoracic muscles lie?
Deep to the internal thoracic vessels, and secure these vessels to the wall.
What do vessels that supply the thoracic wall consist mainly of?
Posterior and anterior intercostal arteries, which pass around the wall between adjacent ribs in intercostal spaces (Fig. 3.29).
Where do the arteries supplying the thoracic wall originate from?
The aorta and internal thoracic arteries
Where do the aorta and internal thoracic arteries arise from?
The subclavian arteries in the root of the neck
Describe the layout of the arterial supply around the thoracic wall.
Together, the intercostal arteries form a basket-like pattern of vascular supply around the thoracic wall.
Where do posterior intercostal arteries originate from?
Vessels associated with the posterior thoracic wall
Where are the upper two posterior intercostal arteries on each side derived from?
The SUPREME INTERCOSTAL ARTERY
Where does the supreme intercostal artery travel?
It descends into the thorax as a branch of the costocervical trunk in the neck.
What is the costocervical trunk a branch of?
A posterior branch of the subclavian artery (Fig. 3.29).
Where do the remaining 9 pairs (i.e. not the upper 2) of posterior intercostal arteries arise from?
The posterior surface of the thoracic aorta.
Why are the right intercostal arteries longer than the left?
Because the aorta is on the left side of the vertebral column (where they arise), those posterior intercostal vessels passing to the right side of the thoracic wall cross the midline anterior to the bodies of the vertebrae and therefore are longer than the corresponding vessels on the left.
What branches do the posterior intercostal arteries supply?
In addition to having numerous branches that supply various components of the wall, the posterior intercostal arteries have branches that accompany lateral cutaneous branches of the intercostal nerves to superficial regions.
Where do the anterior intercostal arteries originate?
Directly or indirectly as lateral branches from the internal thoracic arteries (Fig. 3.29)
Where does each internal thoracic artery arise?
As a major branch of the subclavian artery in the neck.
Where do the internal thoracic arteries pass?
Anteriorly over the cervical dome of the pleura and descends vertically through the superior thoracic aperture and along the deep aspect of the anterior thoracic wall.
Where does the internal thoracic artery lie on each side?
Posterior to the costal cartilages of the upper six ribs and about 1 cm lateral to the sternum.
Where does the internal thoracic artery divide into two terminal branches?
At approximately the level of the sixth intercostal space
What are the two terminal branches of the internal thoracic artery?
SUPERIOR EPIGASTRIC ARTERY
MUSCULOPHRENIC ARTERY
Where does the superior epigastric artery run?
It continues inferiorly into the anterior abdominal wall (Fig. 3.29)
Where does the musculophrenic artery run?
It passes along the costal margin, goes through the diaphragm, and ends near the last intercostal space.
Anterior intercostal arteries that supply the upper six intercostal spaces arise as ____?
Lateral branches from the internal thoracic artery
Anterior intercostal arteries supplying the lower spaces arise from the ___?
Musculophrenic artery
In each intercostal space, the anterior intercostal arteries usually has two branches.
Where?
One passes below the margin of the upper rib.
The other passes above the margin of the lower rib
The anterior intercostal artery usually has two branches in each intercostal space. What does the inferior branch do?
Meets a collateral branch of the posterior intercostal artery.
What is the significance of the anterior and posterior intercostal vessels overlapping?
Their distributions overlap and can develop anastomotic connections.
The ________ intercostal arteries are generally smaller than the _________ vessels.
Anterior are smaller than posterior.
What branches do internal thoracic arteries give rise to?
In addition to anterior intercostal arteries and a number of other branches, the internal thoracic arteries give rise to perforating branches that pass directly forward between the costal cartilages to supply structures external to the thoracic wall.
Where do the perforating branches of the internal thoracic arteries travel?
With the anterior cutaneous branches of the intercostal nerves.
Describe the venous drainage from the thoracic wall.
It generally parallels the pattern of arterial supply (Fig. 3.30)
Where do the intercostal veins drain?
Centrally, the intercostal veins ultimately drain into the azygos system of veins or into INTERNAL THORACIC VEINS
What do internal thoracic veins connect with?
The BRACHIOCEPHALIC VEINS in the neck.
What does the upper posterior intercostal veins on the left side often come together and form?
The LEFT SUPERIOR INTERCOSTAL VEIN
What does the left superior intercostal vein drain into?
The left brachiocephalic vein
What does the upper posterior intercostal veins on the right side often come together and form?
The RIGHT SUPERIOR INTERCOSTAL VEIN
Where does the right superior intercostal vein drain into?
The AZYGOS VEIN
Where do lymphatic vessels of the thoracic wall drain into?
Mainly into lymph nodes associated with the
- internal thoracic arteries (PARASTERNAL NODES)
- heads and necks of ribs (INTERCOSTAL NODES)
- diaphragm (DIAPHRAGMATIC NODES).
Fig. 3.31
What are the lymph nodes associated with the internal thoracic arteries called?
PARASTERNAL NODES
What are the lymph nodes associated with the heads and necks of ribs called?
INTERCOSTAL NODES
What are the lymph nodes associated with the diaphragm called?
DIAPHRAGMATIC NODES
Where are diaphragmatic nodes ofund?
- Posterior to the xiphoid
- At sites where the phrenic nerves penetrate the diaphragm.
- Also in regions where the diaphragm is attached to the vertebral column
Where do parasternal nodes drain into?
BRONCHOMEDIASTINAL TRUNKS
As well as parasternal nodes, what else drains into bronchomediastinal trunks?
Intercostal nodes in the upper thorax
Where do intercostal nodes in the lower thorax drain into?
THORACIC DUCT
Upper = bronchomediastinal trunks
What do nodes associated with the diaphragm interconnect with?
- Parasternal, prevertebral and juxta-esophageal nodes
- BRACHIOCEPHALIC NODES
- LATERAL AORTIC/LUMBAR NODES
Where are brachiocephalic nodes found?
Anterior to the brachiocephalic veins in the superior mediastinum
Where are lateral aortic/lumbar nodes found?
In the abdomen
Where do superficial regions of the thoracic wall drain mainly into?
AXILLARY LYMPH NODES or parasternal nodes.
Where are axillary lymph nodes ofund?
In the axilla
What is the innervation of the thoracic wall?
Mainly by the INTERCOSTAL NERVES
What are the intercostal nerves?
Anterior rami of spinal nerves T1 to T11
Where do the intercostal nerves lie?
In the intercostal spaces between adjacent ribs.
What is the subcostal nerve?
Anterior ramus of spinal nerve T12
Where is the subcostal nerve found?
Inferior to rib XII (Fig. 3.32)
Where does a typical intercostal nerve pass?
Laterally around the thoracic wall in an intercostal space
Which is the largest branch of the intercostal nerve?
The LATERAL CUTANEOUS BRANCH
Where does the lateral cutaneous branch of the intercostal nerve pierce?
The lateral thoracic wall
What does the lateral cutaneous branch of the intercostal nerve divide into, and what does that innervate?
An anterior and a posterior branch that innervate the overlying skin.
What do the intercostal nerves end as?
ANTERIOR CUTANEOUS BRANCHES
Where do the anterior cutaneous branches emerge?
Either parasternally, between adjacent costal cartilages, or laterally to the midline, on the anterior abdominal wall.
What do the anterior cutaneous branches supply?
The skin
In addition to these major branches of the intercostal nerve, what else can be found?
Small collateral branches in the intercostal space running along the superior border of the lower rib.
In the thorax, the intercostal nerves carry somatic motor innervation to ___?
The muscles of the thoracic wall (intercostal, subcostal, and transversus thoracis muscles)
In the thorax, the intercostal nerves carry somatic sensory innervation from ___?
The skin and parietal pleura
In the thorax, the intercostal nerves carry ______________ ___________ ______ to the ________
postganglionic sympathetic fibres; periphery
What is sensory innervation of the skin overlying the upper thoracic wall supplied by?
Cutaneous branches (supraclavicular nerves), which descend from the cervical plexus in the neck.
In addition to innervating the thoracic wall, intercostal nerves innervate other regions.
The anterior ramus of T1 contributes to ____
the brachial plexus
In addition to innervating the thoracic wall, intercostal nerves innervate other regions.
The lateral cutaneous branch of the _____ _____ ____
second intercostal nerve (the INTERCOSTOBRACHIAL NERVE)
The intercostobrachial nerve contributes to ___?
Cutaneous innervation of the medial surface of the upper arm
What do the lower intercostal nerves supply?
The muscles, skin and peritoneum of the abdominal wall.
