08-09-22 - Thoracic Wall 1 and 2 Flashcards
Learning Outcomes
- Describe how the ribs, vertebrae, costal cartilages and sternum form the thoracic cage with particular reference to the anterior and posterior articulations of the ribs
- List the functions of thorax
- List the relations of the sternal angle
- Define the borders of the thoracic inlet and thoracic outlet
- List the structures that pass through the thoracic inlet and outlet
- Explain the signs and symptoms of thoracic outlet syndrome
- Describe anatomy, neurovascular supply and lymphatic drainage of the breast
- Explain the boundaries and clinically important relations of the breast
- Remember the functions of muscles attached to the thoracic cage
- Explain the anatomical basis of movements of the thorax
- Describe the organization and functions of the intercostal musculature
- Describe the arrangement, blood supply, venous and lymphatic drainage and innervation of the thoracic wall
- Describe the features of intercostal nerves and their cutaneous distribution
- List the structures through which a needle must pass when inserting a chest drain
- Identify anatomical structures on medical images through the thorax
What is referred to by the term ‘thorax’?
What is the shape of the thorax?
What is the difference between the thoracic (rib) cage and the thoracic wall?
What 4 things does the thoracic cage consist of?
What 6 things does the thoracic wall consist of?
Describe where the anterior and posterior ribs lie on this x-ray.
- ‘Thorax’ refers to the area of the body between the neck and abdomen
- The thorax is in the shape of a truncated cone
- The thoracic (rib) cage is the structure that the thoracic wall is built on
• The thoracic cage consists of:
1) Sternum
2) 12 pairs of ribs and their costal cartilages
3) 12 thoracic vertebrae
4) 12 Intervertebral disks
• The thoracic wall consists of:
1) Thoracic cage
2) Skin
3) Subcutaneous tissue
4) Thoracic muscles and fascia
5) 3 layers of muscles extending between the intercostal spaces (external, internal, innermost)
6) Mammary gland/breast tissue
How are ribs referred to in Latin?
How many ribs do we have?
What are the 3 different types of ribs?
What number of ribs fall into these categories?
How does each type articulate with the sternum?
- Ribs are referred to as ‘costa’ in Latin
- We have 12 pairs of ribs
• 3 Different types of ribs:
1) True ribs (1-7) – attach directly to the sternum through costal cartilage, which gives flexibility for respiration
2) False ribs (8-10) attach to the sternum indirectly through the costal cartilage of the 7th rib
3) Floating ribs (11-12) – do not articulate with the sternum
What numbers of ribs are considered typical?
What are the 7 parts of the typical rub?
- The number of typical ribs is debated, but generally falls somewhere between 2-10 (will never be asked this)
- A typical rib consists of 7 parts:
1) Head
2) Neck – between the head and tubercle
3) Tubercle
4) Body (shaft)
5) Costal angle – lateral border of intrinsic back muscles. The region where the rib is the most strongly bent located on the proximal part of the body of the rib.
6) Ridge – divides articular surface of the head into demi facets
7) Costal groove – on the inner surface and close to the inferior borders. Used for the intercostal nerves and vessels
Labelled thoracic vertebrae
How do costovertebral joints form?
What are exceptions?
What type of joints are these?
How are they supported?
What else is part of this joint?
How many costal facets are found on each vertebra?
Do spinous process of thoracic vertebrae overlap?
How do the vertebrae articulate?
What 2 ways is flexion and extension prevented in the thoracic region?
- Costovertebral joints form when demi facets on the head of each rib (except 1, 11 and 12) articulate with the superior costal facet of its corresponding thoracic vertebra and the inferior costal facet of the vertebrae above
- These joints are synovial, and are supported by a capsule with ligaments.
- The intervertebral disc is also part of this joint
- The costal facets of the vertebrae are found at the arc of a circle, and can vary in numbers from 1 to 1.5 to 2 depending on the vertebrae:
- T1 - 1.5 costal facets
- T2-T9 - 2
- T10 – 1.5
- T11 – T12 – 1 oval costal facet each (only articulate with corresponding ribs)
- Spinous processes of thoracic vertebrae overlap, with the vertebrae articulating through superior and inferior articular facets on the articular processes
- Flexion and extension in the thoracic region is prevented through:
1) Superior and inferior articular processes being vertical
2) Articular facets facing slightly medially (allows some rotation but no flexion)
How do costotransverse joints form?
What are exceptions?
How do the costotransverse joints vary on different vertebrae?
Why is this significant?
How do costovertebral and costotransverse joints form on rib 6?
What 3 ways do spinous processes on thoracic vertebrae vary?
Which vertebrae fall into each category?
- Costotransverse joints form between the tubercle of the rib (not present on 11 and 12) and the transverse costal facet of the transverse process of its corresponding vertebrae
- The costotransverse joints 1 to 7 have curved facets, which allows for rotatory movement
- The costotransverse joints 8, 9 and 10 have flat facets, which allows for gliding movement
- This is significant in respiratory movements of the thoracic wall
- Rib 6 articulates with the inferior costal facet of T5, the superior costal facet of T6 and the transverse process of T6
• Variation in the Spinous processes of thoracic vertebrae vary:
1) Horizontal - 1st, 2nd, 11th, 12th vertebrae
2) Oblique – 3rd, 4th, 9th, 10th
3) Long and vertical – 5th, 8th
Why is the first rip not palpable?
How can the first rib be found?
What are 3 reasons why rib 1 is considered atypical?
What is the scalene tubercle on rip 1 used for?
- Rib 1 is not palpable as it is too deep
- Rib 1 can be found by finding rib 2 using the sternal angle
• Rip 1 is considered atypical because:
1) Rib 1 has 2 extra grooves: 1 for the subclavian artery and inferior trunk (C8 and T1) of the brachial plexus, and 1 for the subclavian vein
2) It does not have a ridge, meaning it has 1 articular facet on its head that articulates only with the T1 vertebra.
3) Rib 1 does not have a costal groove
• The scalene tubercle on rib one is for the attachment of the anterior scalene muscle
What ribs are floating ribs?
What are 3 reasons floating ribs are considered atypical?
How is rib 12 related to the pleura
- Ribs 11 and 12 are considered floating ribs
- Floating ribs are not attached to the sternum
• Floating ribs are atypical because:
1) The heads of floating ribs only articulate with vertebra of their level
2) They do not articulate with the transverse process of vertebrae
3) They do not attach to the sternum
• Rib number 12 is attached to the pleura of the lungs
Types of joints flow chart
What 3 bones does the sternum consist of?
How are these bones connected?
What is the sternal angle?
Where is the sternal angle located (7 reference points)?
Where is the solar plexus found?
What process occurs in the axial skeleton into adulthood?
What does this allow the sternum to be used for?
- The sternum consists of the manubrium, the body and with xiphoid process (xiphisternum)
- The manubriosternal and xiphisternal joints are secondary cartilaginous joint (symphyses), meaning they allow limited or no movement
- The sternal angle is the angle at which the manubrium and body of the sternum articulate
• The sternal angle is located:
1) The 2nd costal cartilage anteriorly
2) Intervertebral disc between T4 and T5 vertebrae
3) The proximal and distal boundaries of the aortic arch (between ascending aorta and aortic arch, and descending aorta and aortic arch)
4) The bifurcation of the trachea
5) The superior limit of the pulmonary trunk (main output of right heart – forms into pulmonary arteries)
6) Azygos vein opening to SVC
7) Ligamentum arteriosum – small ligament attaching the aorta to the pulmonary artery
- The solar plexus is found in the region of the xiphoid process (T6 dermatome)
- In the elderly, haematopoiesis is mostly confined to vertebrae, ribs and sternum (axial skeleton
- This allows for the sternum to be used as a site for bone marrow aspiration
What are costochondral joints formed between?
What type of joints are these?
How much movement do they allow?
What are costosternal joints formed between?
What types of joints are these?
How much movement does this allow?
How does costal cartilage (CC) articulate with the sternum?
How does the orientation of CC changes as you go down the ribcage?
Why is this important?
- Costochondral joints are formed between all ribs and costal cartilage
- These joints are primary cartilaginous (hyaline cartilage) joints, meaning they allow little to no movement
- Costosternal joints are formed between the costal cartilage of ribs 1-7 and the sternum
- Costosternal joint 1 is a primary cartilaginous joint (synchondroses), which allows little movement or no movement
- Costosternal joint 2-7 are synovial joints (diarthroses), which allows movement for respiration.
- The costal cartilage of ribs 8-10 articulate with the costal cartilage of rib 7, allowing it to articulate with sternum indirectly
- At ribs 1-4, the costal cartilage is horizontal, at ribs 5-10, the costal cartilage is more oblique
- This change in shape is important for respiration
What is the thoracic inlet (superior aperture) used for?
What 3 things is the thoracic inlet bounded by?
How is the thoracic inlet orientated?
How is the lung orientated in relation to the thoracic inlet?
Why might this be a problem?
What 5 other structures pass between the thorax and the neck?
What 3 structures pass between the thorax and upper limb?
Where do they lie?
- The thoracic inlet (superior aperture) is used for allowing structures to enter/exit the thoracic cavity
- The thoracic inlet is bounded by:
1) T1 vertebra
2) 1st rib and its costal cartilage
3) Manubrium
- The thoracic inlet slopes antero-inferiorly to the level of T2/T3 from the transverse plane
- The apex of the lung extends 2-3cm above the anterior part of the 1st rib and clavicle through the thoracic inlet.
- This may be problematic, as the apex of the lung can be punctured when trying to catheterise the subclavian vein
• 5 other structures that pass through between the thorax and the neck:
1) Vessels that supply and drain the head and neck
2) Trachea
3) Oesophagus
4) Vagus and recurrent laryngeal nerves
5) Phrenic nerves (roots C3-C5 supplies diaphragm)
• Structures that pass between the thorax and upper limb lie on the first rib, below the clavicle
• These structures include:
1) Subclavian veins
2) Subclavian artery
3) Inferior trunk of the brachial plexus
What 4 things is the thoracic outlet bound by?
How is the thoracic outlet closed?
What is the costal margin (aka costal arch)?
What is thoracic outlet syndrome?
What 3 vessels can be compressed?
What are 3 ways this can happen?
Why is the name ‘thoracic outlet syndrome’ considered a misnomer (inaccurate)?
• The 4 things the thoracic outlet is bound by:
1) T12 vertebra
2) 11th and 12th ribs
3) Costal cartilages of ribs 7-10
4) Xiphoid process
- The thoracic outlet is closed incompletely by the diaphragm
- The costal margin (aka costal arch) is the lower edge of the thorax formed by the costal cartilage at the bottom of the rib cage
- Thoracic outlet syndrome is when vessels sitting that run from the thorax to the upper limb through the thoracic inlet become compressed
- These vessels can include the brachial plexus and subclavian artery/vein, which sit on top of rib 1 and inferiorly to the clavicle
• This compression can be between:
1) The scalene muscles
2) Rib 1 and the clavicle
3) Coracoid process of the scapula and pec minor muscle
• The term thoracic outlet syndrome is considered a misnomer as it actually affects vessels at the thoracic inlet.
What is the breast?
What 3 things do breast consist of?
What are breasts made from?
What are the 2 parts of the outer breast?
How does the breast structure compare between men and women?
What are milk lines?
Where do breasts develop?
What are Montgomery tubercles and glands?
What is their function?
- The breast is an accessory gland consisting of mammary glands, skin and connective tissues
- Breasts are made from modified sweat glands
- The outer breast has a hyperpigmented areola which surrounds the nipple
- The breast of males and pre-pubertal females share a similar structure
- Milk lines are lines along which breasts can develop
- Breasts typically develop in the thoracic region, but 1 in 500 people have 1 or more additional breasts that have developed somewhere else along the milk line
- Montgomery tubercles are visible portion of areolar glands on the skin surface of the areola
- Areolar glands (Montgomery glands) are sebaceous glands of the breast
- These glands allow the babies to creative suction on the nipple when breast feeding.
In adult females, where is the base and lateral/medial borders of the breast found?
Where might the lateral border of the breast extend to?
What is the axillary process?
Where might it extend to?
- In adult females, the base of the breast is typically located somewhere between the 2nd-6th ribs, with there being potential to be found at the 7th rib
- The medial border of the breast is the lateral border of the sternum
- The lateral border of the breast is the mid-axillary line
- The upper lateral area of the breast can potentially extend towards the axilla through the axillary process, and may extend as far superiorly as the apex of the axilla by perforating deep fascia
- The axillary process (aka the axillary tail of spence) is an extension of the upper lateral quadrant of the breast tissue which travels into the axilla
What is breast tissue itself found inside?
What 3 muscles does the breast sit on top of?
What is found between the deep superficial fascia and muscles?
What does the internal structure of the breast tissue consist of?
What is this internal structure surrounded by?
How are suspensory ligaments (Cooper ligaments) of the breast formed?
What are the 2 functions of Suspensory ligaments?
What can be found between the 2 deepest layers of breast connective tissue?
What function does this structure have?
How can this structure be used to spot breast cancer?
What is a cosmetic use of this structure?
What is mammography?
- The breast tissue itself is found inside the superficial and deep layers of superficial fascia
- The 3 muscles the breast sits on top of:
1) Pectoralis major
2) Serratus anterior
3) External oblique muscles
- The deep superficial layer of fascia is separated from the muscle by deep (pectoralis) fascia
- The internal structure of the breast tissue consists of 15-25 lobes comprised of lobules and ducts
- This internal structure is surrounded by fat and a well-developed connective tissue called stroma
• Suspensory ligaments (cooper ligaments) of the breast are formed in certain regions through the condensing of connective tissue
• Suspensory ligament’s function:
1) Connect deep fascia of the breast to the dermis of the skin
2) Support of the breast
- Between the deep layer of superficial fascia and the deep fascia, a potential space called the retromammary space can be found
- The retromammary space provide some degree of movement of the breast over the underlying structures
- Cancer of deep breast structures will lead to the breast being less mobile
- The retromammary space can be used as a space for breast implants
- Mammography is the process of using low energy x-rays to examine the human breast for diagnosing and screening
What are the names of the arteries that supply the breast?
How are the veins draining the breast organised?
What are the 2 places they drain to?
- The arterial supply of the breast originates from the subclavian:
1. The internal thoracic artery - Branch of subclavian
- Gives off the medial mammary branches and the anterior intercostal arteries
- The axillary artery
- Continuation of the subclavian
- Gives off the lateral thoracic artery and thoraco-acromial artery
- Veins that drain the breast follow the arteries
- These veins drain to:
- Axillary veins
- Internal thoracic veins
How is the breast divided when talking about lymph node drainage?
What lymph nodes are most of the breasts drained by?
What is important about this?
What lymph nodes do each area of the breast drain to?
- When dealing with lymph node drainage, the breast is divided into 4 quadrants with the areola in the centre
- Most of the breasts are drained by axillary lymph nodes, meaning it is important to examine the axillary lymph nodes to scan for cancer of the breast.
- Areola and lateral quadrant drained by axillary lymph nodes
- Medial quadrants drained by parasternal lymph nodes
- Inferior quadrants drained by inferior phrenic lymph nodes
Pectoralis major/minor and serratus anterior/posterior muscles diagrams
How many intercostal spaces are there?
What are they filled with?
Where does each layer of muscle extend to?
What is each muscular layer replaced by in different areas?
What is the purpose of each layer of muscle?
- There are 11 pairs of intercostal spaces
- Each space is filled with 3 layers of muscles:
1. External Intercostal muscles - Extend from the inferior edge of the rib above, to the superior edge of the rib below
- Anteriorly, the muscle fibres are replaced by external intercostal membrane
- External intercostal muscles raise the ribs during inspiration
- Prevent indrawing during inhalation
- Indrawing is the inward movement of the lower chest wall when a person breathes in, which is a sign of respiratory distress
- Internal intercostal muscles
- Extends from the lateral edge of costal groove the rib above to the superior edge of the rib below
- Posteriorly, muscle fibres are replaced by internal intercostal membrane
- Aids elastic recoil by moving ribs inferiorly in expiration
- Prevent indrawing during respiration under normal circumstances
- Elastic recoil refers to the lung’s intrinsic tendency to deflate following inflation
- Innermost intercostal muscles
* Divided into 3 parts: - Innermost intercostal itself
- Act with internal intercostal muscles
- Deep surface is covered with endothoracic fascia
- Neurovascular intercostal bundle travels between the internal and innermost layers
- Transversus thoracis
- Lies posterior to the sternum
- Internal aspect of ribs and costal cartilage 3 to 6
- Goes from the sternum to the xiphisternum and costal margin
- Subcostalis
- Lies on the posterior wall
- Found on the lower ribs internal surface and goes down to the inner surface of 2-3 ribs below
What are roots formed from?
What are the 2 different kinds of roots?
How are spinal nerves formed?
What do spinal nerves divide in to?
- Rootlets converge to form roots
- There are 2 kinds of roots:
- Ventral – motor (efferent)
- Doral – sensory (afferent)
- Ventral and dorsal roots converge to become a spinal nerve, which is mixed motor and sensory
- Spinal nerves divide to form ventral and dorsal rami, which are mixed motor and sensory nerve fibres
Where do spinal nerve roots exit the spinal canal?
What 3 things are intercostal spinal nerves at risk of?
What can this lead to?
Do anterior rami of thoracic spinal nerves from plexuses?
What do they form?
What are the exceptions to this?
Where can intercostal nerves be found?
What are they accompanied by?
- The spinal roots exit the spinal canal through the intervertebral foramen
- Intercostal spinal nerves may be at risk of compression by:
- Arthritis (e.g facet joint arthritis)
- Fracture (e.g osteoporotic fracture)
- Disc prolapses
- This may cause local and spinal intercostal pain
- Anterior rami of thoracic spinal nerves do not form nerve plexuses
- They maintain their segmented pattern and become intercostal nerves
- The exception to this is T1, and the lateral cutaneous branch of T2, with T1 joining the brachial plexus
- Intercostal nerves, together with the intercostal vein and artery (VAN with vein at the top), lie in the costal groove at the inferior edge of the rib
- They can be found between the internal and innermost intercostal muscles
What are intercostal nerves formed by?
Do intercostal muscles have motor or sensory fibres?
What 2 cutaneous sensory branches are given off by intercostal nerves?
Name the structures in the anterior thoracic wall region the anterior rami of the following groups of nerve roots innervate:
- C3-C4
- T1
- Lateral cutaneous branch of T2
- T2-T11
- Intercostal nerves are formed by anterior (ventral) rami
- Intercostal muscles have both motor and sensory fibres (mixed fibres), with sensory branches supplying the skin, and motor branches supplying the muscles
- There are also visceromotor branches that go to vessels
- After anterior (ventral) rami form intercostal nerves, they give off a lateral cutaneous branch and travel through the costal groove
- The intercostal nerves become superficial parasternally (behind sternum) and give off an anterior cutaneous branch
- Both of these branches are sensory branches that supply the skin.
- C3-C4 anterior rami
- These roots form the supraclavicular nerve of the cervical plexus
- This nerve descends over the clavicle and innervates as far as the 2nd costal cartilage on the anterior thoracic wall
- T1 anterior rami
- Has no cutaneous distribution over the anterior thoracic wall
- Joins the inferior trunk of the brachial plexus and supplies the medial arm, forearm and small muscles of the hand
- Innervates muscles of the first intercostal space
- Lateral cutaneous branch of T2 anterior rami
- T2 gives off a large lateral cutaneous called the intercostobrachial nerve
- This supplies the thorax wall in the axilla and the upper medial part of the upper limb
- It is at risk during breast surgery
- T2-T11 anterior rami
- Provides motor fibres to intercostal and abdominal muscles
- Gives sensory supply to the skin and parietal pleura
How many anterior intercostal arteries are there per intercostal space?
What 2 branches of the subclavian artery provide blood to the thoracic wall?
What areas do they supply?
Where can the thoracic aorta be found?
What are visceral and parietal arteries in the thorax?
What 3 structures in the thoracic wall do parietal branches of the thoracic aorta supply?
How many posterior intercostal arteries are there per intercostal space?
How do anterior and posterior intercostal arteries link?
What is coarctation of the aorta?
- There are 2 anterior intercostal arteries per space in intercostal spaces 1-6
- Branches of subclavian that supply the thoracic wall:
1. Internal thoracic artery (ITA) - Lies along the margins of the sternum
- Supplies anterior intercostal spaces 1-6
- Terminates as the superior epigastric and musculophrenic arteries
- Musculophrenic arteries supply anterior intercostal spaces 7-10
- There is no arterial supply for the 11th anterior intercostal space
- Costocervical trunk
* Gives off supreme intercostal arteries, which supplies posterior intercostal arteries for intercostal spaces 1 and 2
- The thoracic aorta can be found between T4/5-T12 (T4/5 - sternal angle boundary)
- Visceral arteries supply organs in the thorax, while parietal branches supply the wall of the thorax
- Parietal branches of the thoracic aorta:
- Posterior intercostal arteries 3-11 – 2 arteries per intercostal space
- Subcostal artery - Inferior to the 12th rib and supplies the posterior abdominal wall
- Superior phrenic artery – supplies diaphragm and part of the thoracic wall. Occurs at the aortic hiatus of T12: An opening in the diaphragm through which the aorta passes into the retroperitoneal space
- Anterior and posterior intercostal arteries anastomose
- Coarctation of the aorta is a birth defect in which a part of the aorta, usually the tube that carries oxygen rich blood to the body, is narrower than usual
Arterial supply of thoracic wall diagram
Where do anterior intercostal veins drain to?
What 2 places do the posterior intercostal veins drain to?
- Anterior intercostal veins drain to the internal thoracic vein, which drains into the brachiocephalic vein
- Posterior intercostal veins drain either to:
- The brachiocephallic vein
- Superior vena cava via the azygos system
What 2 things does the azygos system drain?
Where does the azygos system begin?
Where does it pass through?
Where does the azygos system ascend?
What structures does it pass?
Where does it open up?
Where does it arch?
What structures does it connect?
The azygos system drains:
- Posterior wall of the thorax
- Part of the posterior abdominal wall
- The azygos system begins from the lumbar and subcostal veins and/or the direct branch of the inferior vena cava
- The azygos system passes through the diaphragm with the aorta and thoracic duct
- It ascends in the posterior mediastinum (area in thoracic cavity surrounded by the left and right pleural sacs) and passes posterior to the right lung hilum
- it arches above the right pulmonary hilum.
- It drains into the superior vena cava just before it pierces the pericardium at the level of the sternal angle
- It connects the superior and inferior vena cava
What is another name for the hemiazygos system?
What other vein does it have connections with?
Where does it pass through?
How does the hemiazygos join the azygos system?
- The hemiazygos system is also known as the inferior hemiazygos vein
- The inferior hemiazygos vein has connections with the left renal vein
- The hemiazygos vein passes through or behind the left crus of the diaphragm
- The crus of diaphragm (pl. crura), refers to one of two tendinous structures that extends below the diaphragm to the vertebral column
- At approximately the level of T9, the hemiazygos crosses to the right and joins the azygos
What is another name for the accessory hemiazygos?
Where is it located?
What 3 places can the superior hemiazygos open into?
- The accessory hemiazygos is also referred to as the superior hemiazygos
- The super hemiazygos descends from the 4th intercostal space and crosses to the right at approximately T8
- It can open into:
- Azygos
- Hemiazygos
- Both
Venous drainage of the thoracic wall.
Label numbers 1-5
What 2 places does lymph in the anterior thoracic wall drain to?
What 3 places does lymph in the posterior thoracic wall drain to?
Where do more superficial structures drain?
- Lymph in the anterior thoracic wall drains to:
- Parasternal lymph nodes - alongside internal thoracic (mammary) artery
- Bronchomediastinal trunks
- Lymph in the posterior thoracic wall drains to:
- Intercostal nodes
- Thoracic duct (inferiorly)
- Bronchomediastinal trunks (superiorly)
- More superficial structures drain to the axillary lymph nodes
What are 5 structures that pass through the diaphragm?
What level do they pass through?
- 5 structures that pass through the diaphragm:
- IVC – pass through the caval opening on the central tendon of diaphragm at T8 (along with terminal branches of the right phrenic nerve)
- Oesophagus - passes through oesophageal hiatus which is located at T10 in the right crus of the diaphragm
- Thoracic duct – passes through aortic hiatus at T12
- Descending thoracic aorta - passes through aortic hiatus at T12
- Azygos - passes through aortic hiatus at T12
