ANA 202 Thorax Flashcards
What forms the thoracic wall anteriorly
sternum and costal cartilages
What forms the thoracic wall posteriorly
thoracic part of the vertebral column
What forms the thoracic wall laterally
The ribs and intercostal spaces
What forms the thoracic wall inferiorly
Diaphragm
What forms the thoracic wall superiorly
suprapleural membrane
The diaphragm separates__from___
Thoracic cavity from abdominal cavity
The thoracic cavity is divided into
mediastinum
the laterally placed pleurae and lungs (right and left)
Thoracic cage includes
•12 thoracic vertebrae
• intervertebral (IV) discs
• 12 pairs of ribs and their costal cartilages
• sternum
Ribs and their cartilages are separated by ____________
intercostal spaces
Typical ribs
3rd- 9th
Atypical ribs
1,2,10-12th
What are the categories of ribs?
True (vertebrocostal) ribs
False (vertebrochondral) ribs
Floating (vertebral, free) ribs
Problems that can occur in people with a 13th rib
Between the clavicle and 1st rib
It compresses the subclavian artery, restricting blood flow to the upper limb, causing numbness
Which are true ribs
1st-7th ribs
Which are false ribs?
8th, 9th, and usually 10th ribs
Which are floating ribs?
11th, 12th, and sometimes 10th ribs
What are true ribs?
They attach directly to the sternum through their own costal cartilages
What are false ribs?
Their cartilages are connected to the cartilage of the rib above them; thus their connection with the sternum is indirect
What are floating ribs?
•Their cartilages are rudimentary
• they do not connect even indirectly with the sternum
• instead they end in the posterior abdominal musculature
Characteristics of a typical rib
include the 3rd-9th ribs
•a curved shaft (body) with 2 ends;
• anterior end
•posterior end
•The anterior end is continuous with its costal cartilage
•The posterior end articulates with the vertebral column and is characterized by;
•a head
•Neck
• tubercle
Describe the head of the posterior end of a typical rib
Posterior end of a typical rib
head
•Is expanded (wedge shape)
•two articular surfaces (superior and inferior) separated by a crest
• The smaller superior surface articulates with the inferior costal facet on the body of the vertebra above, whereas the larger inferior facet articulates with the superior costal facet of its own vertebra
Characteristics of the first rib
broadest
shortest
most sharply curved of the seven true ribs
•has a single facet on its head for articulation with the T1 vertebra only
• has two grooves crossing its superior surface for the subclavian vessels
• the grooves are separated by a scalene tubercle and ridge
Parts of the sternum
- Manubrium
- Body
- Xiphoid Process
What is the joint between the manubrium and sternum?
Manubriosternal joint
The diaphragm work with which cavity for breathing?
Pleural cavity
Describe the shaft of the posterior end of the typical rib
Shaft:
• generally thin and flat with internal and external surfaces
•it bends anterolaterally at the costal angle
•The inferior margin of the internal surface is marked by a distinct costal groove
Describe the neck of the posterior end of the typical rib
•separates the head from the tubercle
Describe the tubercle of the posterior end of the typical rib
• projects posteriorly from the junction of the neck with the shaft
•consists of 2 regions
• articular part (smooth)
• nonarticular part (rough)
Function of the intervertebral disc
•to absorb the stress and shock that is placed on the vertebral column when a person walks, runs, moves, bends, or twists
• prevent the vertebral bodies from grinding against each other
Parts of the intervertebral discs
•annulus fibrosus (which means, roughly, the fibrous ring)
•nucleus pulposus (which means the pulpy interior)
In between the manubrium and body of the sternum lie a slightly projecting called__________
sternal angle (of Louis)
Location of the sternal angle of Louis
located opposite the 2nd pair of costal cartilages at the level of the IV disc between the T4 and T5 vertebrae
Describe the manubrium of the sternum
Manubrium:
•superior part of the sternum
• it lies at the level of the bodies of the T3 and T4 vertebrae
•Its thick superior border is indented by the jugular notch (suprasternal notch)
• On each side of this notch, a clavicular notch articulates with the sternal (medial) end of the clavicle
• Just inferior to this notch, the costal cartilage of the 1st rib fuses with the lateral border of the manubrium
Describe the body of the sternum
body of the sternum(T5- T9 vertebral level)
•is longer, narrower, and thinner than the manubrium
•its lateral borders has costal notches for articulation with the 3rd-6th costal cartilages
Describe the Xiphoid process of the sternum
The xiphoid process (T10 vertebral level)
• is the smallest and most variable part of the sternum
•It is relatively thin and elongated but varies considerably in form. The process is cartilaginous in young people but more or less, ossified in adults older than 40 years
• In elderly people, the xiphoid process may fuse with the sternal body
Causes of chest pain
• chest pain can result from pulmonary disease, it is probably the most important symptom of cardiac disease
•However, chest pain may also occur in intestinal, gallbladder, and musculoskeletal disorders
Describe the fracture of the 1st rib
The 1st rib is rarely fractured. However when broken, structures crossing its superior aspect may be injured, including:
The brachial plexus of nerves
subclavian vessels
Which are the most commonly fractured ribs?
Middle ribs
What is referred pain?
pain perceived at a location other than the site of the painful stimulus/ origin
What is the weakest part of the rib?
The weakest part of a rib is the region just anterior to its angle
Problems of a fractured rib
direct violence may fracture a rib anywhere, and its broken end may injure internal organs such as a lung and/or the spleen
• Fractures of the lower ribs may tear the diaphragm and result in a diaphragmatic hernia
•Multiple rib fractures can result into a flail chest
What is a flail chest?
•Flail chest is an extremely painful injury and impairs ventilation, thereby affecting oxygenation of the blood
a traumatic disorder that happens when three or more ribs located next to each other are fractured in two or more places. This causes your chest wall to become unstable, interfering with breathing
•During treatment, the loose segment may be fixed by hooks and/or wires so that it cannot move
What are Supernumerary Ribs?
Supernumerary Ribs
•People usually have 12 ribs on each side, but the number is increased by the presence of cervical and/or lumbar ribs, or decreased by failure of the 12th pair to form
• Cervical ribs are relatively common and may interfere with neurovascular structures exiting the superior thoracic aperture Lumbar ribs are less common
What are sternal fractures?
Sternal fractures
•The most common site of sternal fracture in elderly people is at the sternal angle, where the manubriosternal joint has fused
• The fracture results in dislocation of the manubriosternal joint
Describe the superior thoracic aperture and what structures pass through
aka the anatomical thoracic inlet
Shape: kidney shaped
Boundaries:
Anteriorly: superior border of the manubrium
Posteriorly: T1 vertebra
Laterally: 1st pair of ribs and their costal cartilages
Structures passing through:
Trachea
esophagus
Nerves
vessels that supply and drain the head, neck, and upper limbs
Note;
The adult superior thoracic aperture measures approximately 6.5 cm anteroposteriorly and 11 cm transversely
What are the muscles of the thoracic wall?
Serratus posterior superior
Serratus posterior inferior
Levator costarum
External intercostal
Internal intercostal
Innermost intercostal
Subcostal
Transversus thoracis
Describe the inferior thoracic aperture
Aka anatomical thoracic outlet
larger than the superior thoracic aperture
Shape: oblique
Boundaries:
Anteriorly: xiphisternal joint
Posteriorly: 12th thoracic vertebra
Anterolaterally: joined costal cartilages of ribs 7-10, forming the costal margins
Posterolaterally: 11th and 12th pairs of ribs
it is closed by the diaphragm, and structures passing between the abdomen and thorax pierce or pass posteriorly to the diaphragm
Which structures pass through the inferior thoracic aperture?
esophagus
inferior vena cava, or pass posterior to it (e.g., aorta
Which muscles alter the position of the ribs and sternum and so change thoracic volume during breathing
They also reinforce the thoracic wall
The levatores costarum, serratus posterior superior and serratus posterior inferior muscles)
Describe the arterial supply by the posterior intercostal arteries
Of the 1st and 2nd intercostal spaces arise from the supreme (superior) intercostal artery, a branch of the costocervical trunk of the subclavian artery
Of the 3rd-11th intercostal spaces ( arise from the thoracic aorta)
subcostal arteries of the subcostal space (T12) arise posteriorly from the thoracic aorta
Describe the arterial supply by the anterior intercostal arteries
The internal thoracic arteries: arises from inferior surfaces of the first parts of the subclavian arteries and supply the 1st – 6th intercostal spaces
What are the two arteries given rise to at the 6th intercostal space
Musculophrenic arteries
Superior epigastric arteries
What are the two arteries given rise to at the 6th intercostal space
Musculophrenic arteries
Superior epigastric arteries
The musculophrenic arteries supplies__________
the 7th- 9th intercostal spaces anteriorly
How many intercostal veins are there?
2 anterior intercostal veins
1 posterior intercostal vein
the right side of the posterior intercostal space is drained mainly by the__________
azygos vein
the left side of the posterior intercostal space is drained mainly by the_______________
left superior intercostal vein,
hemiazygos and accessory hemiazygos veins
Function of the azygos vein
It drains the right side of the thoracic verterbrae
It forms an important channel connecting the superior vena cava with the inferior vena cava
Describe the formation of the azygos vein
It is formed at the level of the 12th thoracic vertebra by the union of
• right ascending lumbar veins
• right subcostal veins
What are the tributaries of the azygos vein?
• Right superior intercostal veins (formed by the union of 2nd, 3rd and 4th right posterior intercostal veins)
• 5th -11th right posterior intercostal veins
• Hemiazygos veins at the level of T8
• Accessory hemiazygos vein at the level of T8
• Several oesophageal, mediastinal and pericardial veins
Describe the Hemiazygos vein
• Also called the inferior hemiazygos vein
• It is the mirror of the lower part of the azygos vein
• drain most of the posterior intercostal veins on the left side of the body
What are the tributaries of the hemi azygos vein
9th -11th left posterior intercostal veins
Describe the Accessory hemiazygos veins and it’s tributaries?
Accessory hemiazygos veins
• Called the superior hemiazygos vein
• It is a mirror image of the upper part of the azygos vein Tributaries:
• 5th- 8th left posterior intercostal veins
Where do the posterior intercostal veins drain on the right side?
• 1st right posterior intercostal vein (supreme intercostal vein) which drain directly into the right brachiocephalic vein
• Azygos vein which drain into the superior vena cava
Where do the posterior intercostal veins drain on the left side?
• 1st left posterior intercostal vein, which drains into the left brachiocephalic vein
• Left superior intercostal vein (formed by the union of 2nd, 3rd and 4th left posterior intercostal veins) which drains into the left brachiocephalic vein
• Hemiazygos and accessory hemiazygos veins
The anterior intercostal spaces is drained by_______________
• Internal thoracic vein
• Musculophrenic vein
Describe the Internal thoracic vein
• Arises from the superior epigastric vein
• drains the 1st -6th anterior intercostal spaces
• Accompanies the internal thoracic artery
• Terminates in the brachiocephalic vein
Where does the musculophrenic vein drain?
drains the 7th- 9th anterior intercostal spaces
What’s separates the intercostal muscle from the underlying pleural cavity containing the lungs?
The endothoracic fascia
The external intercostal muscles functions in
Inspiration
The internal intercostal muscles function in
Expiration
The serratus posterior superior functions in
Inspiration
The serratus posterior inferior functions in
Expiration
The superior and inferior vena are connected by what structure?
The azygos vein
What are the parts of the mediastinum?
Superior mediastinum
Inferior mediastinum consisting of: anterior, middle and posterior mediastinum
What is the mediastinum?
the compartment of the thoracic cavity between the pleural cavities where the heart and other visceral organs are found
What is the ligament that attaches the sternum the the pericardium?
Sternopericardial ligament
Discuss the jugular/suprasternal notch
Located in the midline of the anterior part of the thorax. On either side of this notch is the clavicle. It articulates with the sternum medially and acromion laterally
Significance of the jugular notch
Deviation of the trachea can be felt at this notch
The sternal angle of Louis is about 5 cm from the jugular notch
It is at the same level as the second costal cartilage
useful when counting ribs to identify landmarks as ribs are often impalpable
Why is the first rib impalpable?
Because it is posterior to the clavicle
contents of the mediastinum
➢Thymus
➢The heart
➢Aorta
➢The trachea and esophagus
➢The thoracic duct and lymph nodes
➢The vagus and phrenic nerves
➢The sympathetic trunks.
Role of the mediastinum
Additionally, the mediastinum serves as a passageway for structures such as the eosophagus, thoracic duct, and various components of the nervous system as they traverse the thorax on their way to the abdomen.
What is the space between the diaphragmatic surface and costal surface of the lung?
Costodiaphragmatic recess at the level of the 6th - 8th rib
Clinical significance of the Costodiaphragmatic recess
Accumulated fluid in the Costodiaphragmatic recess could restrict breathing in and a removed by piercing with a needle
Pleural effusion
Procedure to extract excess fluid at the level of the 6th and 8th rib
Describe the boundaries of the superior mediastinum
It is posterior to the manubrium of the sternum and anterior to the bodies of the first four thoracic vertebrae.
Its superior boundary is an oblique plane passing from the jugular notch upward and posteriorly to the superior border of vertebra TI.
Inferiorly, a transverse plane passing from the sternal angle to the intervertebral disc between vertebra TIV/V separates it from the inferior mediastinum.
Laterally, it is bordered by the mediastinal part of the parietal pleura on either side.
The major structures found in the superior mediastinum include…
❑ thymus,
❑ right and left brachiocephalic veins,
❑ left superior intercostal vein,
❑ superior vena cava,
❑ arch of the aorta with its three large branches,
❑ trachea,
❑ esophagus,
❑ phrenic nerves,
❑ vagus nerves,
❑ left recurrent laryngeal branch of the left vagus nerve,
❑ thoracic duct, and
❑ other small nerves, blood vessels, and lymphatics
What is the thymus?
It is an asymmetric, bilobed structure.
Involved in the early development of the immune system, the thymus is a large structure in the child, begins to atrophy after puberty, and shows considerable size variation in the adult
In the elderly adult, it is barely identifiable as an organ, consisting mostly of fatty tissue that is sometimes arranged as two lobulated fatty structures.
Role of the thymus
Fights inflammatory conditions, building the immune system
One of its main secretions is the hormone thymosin. Thymosin stimulates the maturation of T cells, which are derivatives of white blood cells that circulate our system.
Blood supply to the thymus
▪ Arteries to the thymus consist of small branches originating from the internal thoracic arteries.
▪ Venous drainage is usually into the left brachiocephalic vein and possibly into the internal thoracic veins.
Events that take place at the sternal angle of Louis
R: rib 2
A: aortic arch
T: tracheal bifurcation
P: pulmonary trunk bifurcation
L: ligamentum arteriosum
A: azygos vein drains into SVC
N: nerves (cardiac plexus)
loop of recurrent laryngeal nerve
parasympathetic: contributions to the cardiopulmonary plexuses via the vagus nerves
sympathetic: branches of the cardiopulmonary splanchnic nerves
T: right-to-left movement of the thoracic duct
What are the branches of the first part of the subclavian artery?
Thyrocervical trunk
Vertebral artery
Internal thoracic artery (has the anterior intercostal arteries)
What are the branches of the second part of the subclavian artery?
Costocervical trunk (has the superior thoracic artery and deep cervical artery )
What are the branches of the arc of aorta?
- Brachiocephalic trunk( which gives off right subclavian artery and right common carotid artery
- Left common carotid artery
- Left subclavian artery
Clinical correlation of azygous vein
In case of an obstruction of the superior vena cava, it serves as the main collateral channel to shunt blood from the upper body to the inferior vena cava
Formation of the hemi azygous vein
formed by the union of the left ascending lumbar vein and left subcostal vein
Discuss the Xiphoid process
Is located at the epigastric region
•It is 14.5cm from the Sternal angle
