Anatomy - Cardiorespiratory System Flashcards
The ‘body’ of the sternum articulates with which ribs…
the 2-7 ribs
- second rib articulates with the angle of Louis)
- seventh rib articulates with the inferior part of the body and the superior part of the xiphoid process
The costal cartilage of ribs 1-7 articulates directly with…
- the sternum at sternocostal joints
- ‘true’ ribs
The costal cartilages of ribs 8-10 unite and join…
- the seventh cartilage
- ‘false’ ribs
True or false? Costal cartilage of 7-10 forms costal margin (which is palpable)
true
True or false? Ribs 11 and 12 are short
true - they do not articulate with the sternum (‘floating’ ribs)
Typical ribs
- look similar and share common anatomical features
- 3-9
- head, neck and tubercle and body (shaft)
Atypical ribs
- look different to typical ribs and/or lack some of the features of typical ribs
- 1,2, 10-12
- e.g. 1,11,12 are much shorter
The thoracic vertebrae articulate with the posterior parts of the ribs at what joint?
costovertebral joints
What does the tubercle of ribs articulate with?
the transverse process of the vertebrae
Superior thoracic aperture
- the ‘passageway’ through which structures pass between the neck and thorax
- manubrium, first ribs and first thoracic vertebrae
Sternoclavicular joint
between manubrium and clavicle
Costal margin
lower edge of the chest formed at the bottom edge of the rib cage
What is the skin of the thoracic wall innverated by?
spinal nerves T1-T12 (containing somatic sensory, motor and sympathetic fibres)
Somatic sensory fibres in the spinal nerves carries what information?
sensation of the skin of the thoracic wall reaches conscious perception
What do the Somatic motor fibres in spinal nerves T1-T12 innervate?
innervate skeletal muscles of thoracic wall
What do Somatic sympathetic fibres innervate?
innervate sweat glands and smooth muscle of blood vessels and hair follicles in skin
Dermatome
area of skin innervated by a single spinal nerve
What are the breasts also known as?
the mammary glands
In females, to where does the breast tissue extend towards?
anterior axilla (this part is known as the axillary tail)
What does the breast contain?
- fat
- glandular/secretory tissues arranged in lobules
- ducts (which cover the nipple)
- connective tissue and ligaments
- blood vessels and lymphatics
Areola
the region of the breast of pigmented skin surrrounding the nipple
Blood supply of the breast
- internal thoracic artery
- axillary artery
(blood returns to axillary and internal thoracic veins)
Internal thoracic artery
- courses deep to the lateral edge of the sternum
- gives rise to anterior intercostal arteries that supply the breast and intercostal spaces
What nerves supply the breast?
- somatic nerves
- sympathetic fibres
via intercostal nerves
(somatic sensory fibres innervate the skin of the breast and sympathetic fibres innervate smooth muscle in the blood vessel wall and nipple)
How does the lypmph drain from the breast?
most drains to lymph nodes in axilla
Why are the patterns of lymph drainage in the breast complex?
because axillary nodes communicate with other groups of lymph nodes in the thorax
What are the five groups of lymph nodes?
- central
- pectoral
- humeral
- subscapular
- apical
Apical nodes
- in apex of axilla
- recieve lymph from all other lymph nodes in axilla
- since they drain most of lymph from breast, they are often involved in the spread of breast cancer
What are the three layers of muscle in each intercostal space?
- external intercostal
- internal intercostal
- innermost intercostal
Pectoralis major including origin and insertion
most superficial muscle of anterior chest wall (attaches to the upper humerus, the clavicle and upper six ribs)
Pectoralis minor- including origin and insertion
- smaller muscle that lies deep to pectorals major
- attaches to scapula (coracoid process) and ribs 3-5
Serratus anterior
- superficial muscle that sweeps around lateral aspect of the thoracic cage
- attaches to the scapula (medial border) and upper eight ribs
What are the functions of the muscles: pectoralis major/minor and serratus anterior?
- to move upper limb (PRIME FUNCTION)
- can function as accessory muscles of breathing and hence can move ribs if humerus and scapula are fixed
- use of these muscles is sign of respiratory distress
How do the pectoralis major/minor and serratus anterior move upper limb?
- pectoralis major adducts the humerus
- pectoralis minor and serratus anterior protract the scapula
Rib fractures
- result from blunt trauma to chest wall
- painful (worse on inspiration)
- isolated fracture treated conservatively but adequate pain relief required
- multiple more serious and complex and can lead to dysfunctional movements of chest wall and inadqequate ventilation
Shingles
- common skin condition affecting older people mostly
- red, painful, itchy rash on chest or abdomen
- one side of body only
- strip-like distribution (as it affects dermatomes)
- caused by reactivation of herpes zoster virus if previously had chicken pox
(virus lays dormant in dorsal root ganglion and when reactivated causes rash and pain in dermatome associated with affected spinal nerve)
Breast cancer
- metastasizes to axillay lymph nodes first
- malignant axillary node may be palpable as a lump before noticed as mass in breast
- if breast lump determined as malignant then axillary lymph nodes are biopsied to assess if malignency has metastasized to them, if so, are removed
- removal can cuase fluid accumulation = swelling LYMPHOEDEMA
What do the intercostal spaces contain?
- three layers of intercostal muscles + associated membranes
- intercostal neurovascular bundle (intercostal nerve, artery and vein)
True or false? the three layers of intercostal muscle fibres run in different directions to each other
false
How are the fibres arranged in external intercostal muscle?
antero-inferiorly
How are the fibres arranged in internal intercostal muscle?
- fibres run perpendicular to those of the external intercostal
- postero-inferior
In what part of the intercostal space does the external intercostal muscle become membranous?
- anterior
- forms external intercostal membrane
In what part of the intercostal space does the internal intercostal muscle become membranous?
- posterior
- form internal intercostal membrane
What is the third layer of intercostal muscle?
- innermost intercostal
- fibres are in same direction as those of the internal intercostal
What lies deep to the innermost intercostal?
endothoracic fascia
Where does the neurovascular bundle lie in the intercostal space?
- in the plane between the internal and innermost intercostal muscle
- inferior border of rib superior to the space
- lies in a shallow costal groove deep to surface of rib
(supplies the intercostal muscles, the overlying skin and underlying parietal pleura)
Where does the anterior intercostal artery rise from?
internal thoracic artery (branch of the subclavian artery)
Where does the posterior intercostal artery rise from?
from the descending aorta in the posterior thorax
Where does the anterior and posterior intercostal vein drain into?
Anterior drain into the internal thoracic vein and posterior intercostal vein drains into the azygos system of veins
True or false? intercostal nerves are somatic
True - motor and sensory fibres too
(innervate the intercostal muscles, skin of chest wall and parietal pleura)
What are the two layers of pleurae covering the lungs?
- parietal pleura (lines inside of thorax, visible with naked eye)
- visceral pleura (covers surface of lungs + extends into fissures)
What lies in between the parietal and visceral pleura?
pleural cavity (VERY THIN)
Pleuras- including secretion and innervation
- the two layers are continuous with each other
- pleural cels produce a small amount of pleural fluid filling the pleural cavity
- innervated by intercostal nerves that innervate overlying skin of chest wall (somatic sensory fibres)
Parts of parietal pleura
- cervical pleura (covers apex of lung)
- costal pleura (lies adjacent to ribs)
- mediastinal pleura (adjacent to heart)
- diphragmatic pleura (adjacent to diaphragm)
Costodiaphragmatic recess
- ‘gutter’ around periphery of diaphragm
- costal pleura beceomes continuous with diaphragmatic pleura
- lungs expand into during deep inspiration
Costomediastinal recess
- smaller
- lies at junction of costal and mediastinal pleura
- lungs expand into during deep inspiration
What type of sensory nerve innervates the visceral pleura?
autonomic sensory nerve (sensation does not reach conscious perception)
Lingula
an anterior extension of the superior lobe in the left lung which extends over the heart
(remnant of middle lobe)
anterior border (lung)
sharp and tapered
posterior border (lung)
thick and rounded
inferior border (lung)
sharp and tapered
Where are the impressions (indentaitons) made by the left ventricle and descending aorta seen on the lung?
mediastinal surface of the left lung
Where are the impressions (indentations) made by the superior vena cava and azygos vein seen on the lung?
mediastinal surface of the right lung
Root of lung
- lies between heart and lung
- comprises the pulmonary artery, pulmonary veins and main bronchus
- pleura encloses root of lung like a sleeve
Hilum
- region on the mediasternal surface of the lung where the pulmonary artery, veins and main bronchus enter and exit the lung
- hilum on right is ANTERIOR to pulm. artery
- hilum on left is INFERIOR to pulm. artery
Why is a foreign body entering the trachea more likely to enter the right main bronchus than left?
the right is shorter, wider and decends more vertically than the left
Lobar bronchi
- division of bronchus
- three in right
- two in left
- each gives rise to segmental bronchi
How many segmental bronchi in each lung?
10
Bronchopulmonary segment
an independent region of the lung supplied by a segmental bronchus (breakdown into bronchioles)
True or false? Bronchial veins return blood to the azygos system of veins
true
Parasympathetic fibres in the lungs stiumlate…
- contriction of bronchial smooth muscle (bronchoconstriction)
- secretion from the glands of the bronchial tree
Sympathetic fibres in the lungs stimulate…
- relaxation of bronchial smooth muscle (bronchodilation)
- inhibits secretion from the glands
Visceral afferents also known as…
visceral sensory fibres (relay sensory information from the lungs and visceral pleura to the CNS - do not reach conscious perception)
How does lymph drain from the lungs?
into the venous system via the thoracic duct/ right lymphatic duct
Where can the apex of the heart be found?
- projects into the lower neck
- superior to medial end of clavicle
Where is the inferior border of the lungs?
- 6th rib anteriorly (midclavicular line)
- 8th rib laterally (midaxillary line)
- 10th rib posteriorly (at the vertebral column)
Where does the parietal pleura extend to?
- 8th rib anteriorly (midclavicular line)
- 10th rib laterally (midaxillary line)
- 12th rib posteriorly (at the vertebral column)
Where do the oblique fissures of the left and right lungs extend to?
- 4th rib posteriorly to 6th costal cartilage anteriorly
- deep to the 5th rib
Where does the horizontal fissure of the right lung extend to?
- anteriorly from 4th costal cartilage and intersects the oblique fissures
Diaphragm
- broad, thin sheet of skeletal muscle
- separates thoracic and abdominal cavities
- superior thoracic surface adjacent to parietal pleura
- apertures in diaphragm allow passage of structures between thorax and abdomen
- function: mechanics of breathing
- innervated by phrenic nerves
Where is the diaphragm attached?
- xiphoid process
- costal margin
- tips of 11th and 12th ribs
- lumbar vertebrae
True or false? the central part of the diaphragm is not muscular but fibrous
True - known as the central tendon
Diaphragm contraction
- muscle fibres of right and left domes pulled towards their peripheral attachments
- domes flatten
- increases intrathoracic volume for lungs to expand
Diaphragm relaxation
- domes return to superior shape
- decreases volume and drives expiration of air from lungs
Phrenic nerves
- left and right innervate left and right sides
- somtic nerves
- formed in nerck by fibres from C3 C4 and C5 spinal nerves therefore motor + sensory
- innervate diaphragm
- course over the pericardium and pierce the diaphragm
- descend through the neck and enter the thorax through the superior thoracic aperture
What three planes does the dimension of the thoracic cavity change during ventilation?
- vertically - due to contraction and relaxation of diaphragm
- laterally - due to contraction of the intercostal muscles (which moves the ribs)
- antero-posteriorly (AP) - due to movement of the sternum secondary to movement of the ribs
Ventilation
- pleural fluid creates surface tension between parietal pleura lining the thoracic cavity and visceral pleura on surface of lung
- surface tension keeps lung and thoracic wall together (change volume together)
- it also keeps the two pleural membranes in contact with each other preventing lung from collapsing away from the thoracic wall
- if surface tension breaks then ventilation may become dysfunctional
Muscles involved in vigorous breathing
- intercostal muscles important
- active expiration uses internal intercostal muscles
Muscles involved in very vigorous or forced breathing
- acessory muscles contribute to movement of ribs to aid ventilation
Accessory muscles
- sternocleidomastoid
- pectoralis major
- pectoralis minor
- serrated anterior
Pleuritic chest pain
- pleura inflamed/injured
- sharp pain
- well localised + worse on inspiration
- pain felt from parietal pleura only
Pneumothorax
- presence of air in pleural cavity
- usually caused by trauma but can happen spontaneously
- if air keeps entering pleural cavity but cannot escape tension pneumothorax develops in which a rapidly increasing volume of air progressively compresses the lung, heart, great vessels and opposite lung
- rapidly fatal without immediate intervention
- presented wiht severe respiratory distress
Haemothorax
- a collection of blood in the pleural cavity
- occurs secondary to trauma when blood vessels are torn or cut
Pleural effusion
- presence of excess fluid in pleural cavity
- not a diagnosis (fluid could be pus from infection, blood or malignancy)
- chest drain used to remove air/fluid from pleural space
- must consider surface anatomy of heart and lungs to ensure tip of drainage tube does not injure them
- incision made in lower part of chosen intercostal space to avoid neurovascular bundle (lies in costal groove of rib superior to space)
Mesothelioma
malignancy of pleura
Pulmonary embolism (PE)
- blood clot in pulmonary circulation
- forms deep in veins in one of legs and carried in venous circulation back to right side of heart into pulmonary trunk
- large clot lodging pulmonary trunk or one of pulmonary arteries cuases severe respiratory distress and may be rapidly fatal
- smaller that occlude smaller pulmonary vessels may cuase infection of part of lung they supply
Dyspnoea
- breathlessness or shortness of breath
- use of accessory muscles is sign of respiratory distress
- upper limbs ‘fix’ steady (holding ont side of bed or chair) allowing upper limb muscles that attach to chest wall to move ribs and aid ventilation
Paralysis of diaphragm
- injury to phrenic nerve, C3-5 spinal nerves of C3-5 spinal cord segments on one side may paralyse ipsilateral side of diaphgram
- may not cause symptoms in healthy patient
- patients with bilaateral paralysis of diaphragm require ventilatory support
What is the mediastinum?
- the part of the thoracic cavity that lies between the lungs
- contains all thoracic viscera apart from the lungs
- divided into superior and inferior compartment
Where does the mediastinum extend from?
- superior thoracic aperature superiorly to the diaphragm inferiorly
- sternum anteriorly to the thoracic vertebrae posteriorly
What does the mediastinum contain?
- the heart and pericardium
- great vessles that enter+leave the heart
- veins that drain the chest wall
- trachea and main bronchi
- oesophagus
- nerves (somatic and autonomic)
- lymphatics
- thymus gland
What is the pericardium?
the fibrous sac around the heart
Inferior mediastinum
- divided into three: anterior, middle and posterior
(inferior) Anterior mediastinum
- lies between the posterior aspect of the sternum and anterior aspect of pericardial sac
- narrow space containing the thymus gland in children and its remnant in adults
(inferior) Middle mediasternum
- contains the heart inside the pericardial sac, pulmonary trunk and ascending aorta
(inferior) Posterior mediasternum
- lies between the posterior aspect of the pericardial sac and vertebrae
Contents of the superior mediasternum
- arch of aorta and its three branches
- superior vena cava and its tributaries
- trachea
- oesophagus
- phrenic nerves (left and right) and vagus nerves (left anf right)
- thoracic duct
- thymus gland
What are the vena cava tributaries?
the left and right brachiocephalic veins
What are the three parts of the aorta in the thorax?
- ascending aorta (short first part giving rise to coronary arteries)
- arch of aorta (curves posteriorly and lies in superior mediastinum)
- descending (thoracic) aorta descends through posterior mediastinum into abdomen posterior to diaphragm
What three major branches rise from the arch of the aorta in the superior mediastinum?
- brachiocephali trunk (bifurcates into right common carotid artery and right subclavian artery)
- left common carotid artery
- left subclavian artery
What does the Right common carotid artery supply?
supplies the right side of the head and neck, including brain
Right subclavian artery
supplies right upper limb
Left common carotid artery
supplies left side of the head, neck and brain
Left subclavian artery
supplies left upper limb
Arch of aorta- what does it contain
- contains aortic bodies (where chemoreceptors are located)
What do the chemorecpetors in the arch of the aorta monitor?
arterial oxygen and carbon dioxide (this visceral sensory information travels back to CNS along the path of the vagus nerve resulting in reflex responses that regualte ventilation)
What is ligamentum arteriosum?
- a fibrous cord-like connection between the pulmonary trunk and arch of aorta
- it is the remnant of the ductus arteriosus
What is the ductus arteriosus?
- a foetal circulatory shunt
- it diverts most of the blood entering the pulmonary trunk directly into the aortic arch (gas exchange occurs in placenta in foetus)
- only a small amount of blood circulates through the foetal lungs (enough for them to develop)
What happens when the baby starts to use their lungs at brith?
the ductus arteriosus closes and blood in the pulmonary trunk enters the lungs
Superior Vena Cava
- returns blood to heart from head, neck and upper limbs
- it and its tributaries lie in the superior mediastinum
- it is formed by the union of the left and right brachiocephalic veins
What forms the brachiocephalic veins?
the union of the internal jugular vein (which darins the head and neck) and the subclavian vein (which drains the upper limb) forms each brachiocephalic vein
Inferior Vena Cava
- return blood to heart from all regions inferior to diaphragm (abdomen, pelvis and lower limbs)
- thoracic part is very short (as soon as it enters the thorax through the diaphragm it enters the right atrium)
Trachea- including termination
- semi-rigid due to C-shaped incomplete rings of cartilage
- extends from larynx in middle of neck into the superior mediastinum
- is palpable just superior to the suprasternal notch
- termiantes at level of sternal angle (+ junction between T4 and T5 vertebrae) by bifurcating into the left and right main bronchi
Oesophagus
- muscular tube that extends from pharynx in midline of neck to the stomach
- ‘waves’ of contractions of smoot muscle in oesophageal wall move swallowed food and fluid distally (peristalsis)
- lies in midline of thorax in superior mediastinum, posterior to trachea
- decends into posterior mediastinum
Peristalsis
a series of wave-like muscle contractions that move food through the digestive tract
Vagus nerves
- left and right arise from brainstem
- contain somatic: sensory, motor and also parasympathetic fibres
- innervate structures of the thorax and abdomen, in addition to head and neck
- they descend through the neck alongisde the internal carotid artery and internal jugular vein and enter the thorax via superior thoracic aperture
- each give rise to reaccurent laryngeal nerve (RLN)
- descend in the thorax posterior to the root of the lung
- contribute parasympathetic fibres to the heart, lungs, and oesophagus
- they transverse the diaphragm and convey parasympathetic fibres to most of the abdominal viscera
Reacurrent laryngeal nerves
- left and right
- ascend back up into the neck to innervate the muscles of the larynx
Left RLN
loops under the arch of the aorta before ascending back up the left side of the neck (alongside the trachea) to the larynx
Right RLN
descends anterior to the right subclavian artery and then loops under the inferior border of the artery before ascending back up the right side of the neck (between the trachea and oesophagus) to the larynx
Thoracic duct
- major channel for lymphatic drainage from most regions of the body
- it ascends through the posterior mediastinum and into the superior mediastinum where it empties into the venous system at the union of the left internal jugular vein and left subclavian vein
Thymus gland
- a lymphoid organ
- lies anteriorly in the superior mediastinum
- important in children but atrohpies with age
- eventually becomes fatty
Pericardium
- tough fibrous sac that encloses the heart like a loose-fitting bag
Why is the pericardium loose?
to allow for movement of the heart within it
What two layers is the pericardium composed of?
- tough outer fibrous layer (attached superiorly to the great vessels and inferiorly to the central tendon of the diaphragm)
- thin inner serous layer which has two parts: parietal layer lines the inner aspect of fibrous pericardium and visceral layer covering the surface of the heart
- the two layers are continuous with each other
Pericardial cavity
- narrow space between the two layers of serous pericardium
- contains small amount of pericardial fluid that lubricates the serous membranes and allows them to slide over each other with movements of the heart.
What innervates the fibrous pericardium?
the sensory branches from the left and right phrenic nerves