Thorax Anatomy Flashcards
What vertebral level does the trachea start and end at?
C6 to T4/T5
What is the name of the hooked cartilage at the bottom of the
trachea?
Carina
- What are the three divisions of the bronchi?
Primary - Lobar - Segmental
What are the cartilaginous structures found at the top of the
airway?
Thyroid Cartilage Cricoid Cartilage
What is the clinical significance of the gap between these two structures?
In an emergency situation, a cricothyroidotomy can be performed by
piercing a hole in the median cricothyroid ligament.
How are the two primary bronchi different?
The right bronchus has a larger diameter and is more vertical
How many bronchopulmonary segments are there per lung?
10
What do the vessels, nerves and bronchi from the mediastinum
have to pass through to get to the lungs?
Root of the lung
Where is the apex of the lung?
3-4 cm above the level of the first costal cartilage
What are the three edges of the lung?
Anterior, Posterior, Inferior
What are the three surfaces of the lung?
Costal, Mediastinal, Diaphragmatic
What does the diaphragm separate?
Right lung from the right lobe of the liver
Left lung from the left lobe of the liver, the stomach and the spleen
What is found above and behind the cardiac impression on the
mediastinal surface of the lung?
The hilum of the lung where the vessels, bronchi and nerves enter the lung from the mediastinum
Describe the arrangement of the vessels and bronchi in the hilum of the lung.
The pulmonary artery is superior to the pulmonary veins. Bronchus is generally superior. The left bronchus divides into lobar bronchi within the lung. The right bronchus may divide into lobar bronchi in the hilum (before entering the lung).
Name the lobes in the right and left lung.
Right = superior, middle and inferior Left = superior, inferior
Name the fissures separating the lobes.
Right:
Superior from Middle = horizontal Middle from Inferior = oblique Left:
Superior from Inferior = oblique
What structures enter of leave the hilum of the lung?
Pulmonary artery, pulmonary veins, bronchus, pulmonary nerve plexus, lymph vessels and nodes
What is the pulmonary ligament?
Inferior fold of pleura (below the hilum)
Where do the visceral and parietal pleura become continuous?
At the hilum of the lungs
What is the gap between the inferior surface of the lung and the inferior surface of the pleura called?
Costo-diaphragmatic recess
What are the attachments of the diaphragm?
Costal margin
Xiphoid process
Ends of ribs 11 and 12 Lumbar vertebrae
How do the dimensions of the thoracic cavity change when inspiring?
Anteroposterior diameter increases
Transverse diameter increases
What causes expiration?
Expiration is PASSIVE - it is caused by the natural recoil of the lungs
What happens in forced expiration?
The abdominal muscle contracts pushing the abdominal viscera against the diaphragm and pulling the costal margin down.
What are the main contents of the mediastinum?
Trachea, Oesophagus, Aorta, Superior Vena Cava, Heart, pericardium,
thoracic duct, nerves
What are the different divisions of the mediastinum?
Superior (above sternal angle), Inferior (below the sternal angle)
Inferior is divided into anterior, middle and posterior
Describe the arrangement of the vagus nerve and phrenic
nerve in the mediastinum.
Vagus nerve runs posterior to the airways
Phrenic runs anterior to the airways and is embedded in the pericardium
What vertebral level do the phrenic nerves emerge from?
C3, 4 and 5
What is the name of the connection between the pulmonary artery and the aorta? What is this a remnant of?
Ligamentum Arteriosum - remnant of the ductus arteriosus
Where does the vagus nerve go through the diaphragm?
T10 - along with the oesophagus
Describe the position and orientation of the azygous vein.
The azygous vein runs along the right side of the vertebral bodies and arches anteriorly over the right main bronchus to join the SVC.
What are the three main branches of the aortic arch?
Brachiocephalic trunk, left common carotid, left subclavian
Describe the arrangement of the veins that drain into the superior vena cava.
Right and Left brachiocephalic veins join together to form the SVC Each brachiocephalic vein is made up of an internal jugular vein and a subclavian vein
What is the nerve that branches off the vagus in the mediastinum near the left lung?
Left recurrent laryngeal nerve
What part of the diaphragm and at which vertebral level does the IVC go through the diaphragm?
T8
Where do the right and left coronary arteries arise?
Ascending Aorta - from just above the cusps of the aortic valve
Describe the position of the ascending and descending aorta in relation to the airways.
Ascending aorta is anterior to the airways and the arch loops around the left main bronchus posteriorly and the descending aorta is posterior to the left main bronchus.
What vertebral levels do the IVC, oesophagus and aorta go through the diaphragm?
8, 10, 12
Other than the internal and external carotid arteries, what other arteries supply the head and neck?
Vertebral arteries from the subclavian arteries
Where does the oesophagus begin and end?
C7 to T11
What happens to the oesophagus at T7
The oesophagus is to the right of the aorta above T7
Beyond T7 the oesophagus starts moving towards the left
The oesophagus also starts to bend more anteriorly
How many constrictions does the oesophagus have?
Four
Where are the four constrictions of the oesophagus?
The junction between the pharynx and the oesophagus
Where the oesophagus is crossed by the arch of the aorta Where the oesophagus is compressed by the left main bronchus At the oesophageal hiatus
Describe the azygos venous system.
The azygos vein runs along the right side of the vertebral bodies and drains the right side of the chest wall. The accessory hemiazygos (superior to the hemiazygos) and the hemiazygos drain the left side of the chest wall and drain into the azygos. The azygos then arches anteriorly over the lung root and joins the superior vena cava.
Describe the relations of the azygos vein.
Azygos vein arches anteriorly over the lung root to join the superior vena cava.
What structures do the phrenic nerves provide sensory and motor innervation to?
Motor - diaphragm
Sensory - central tendon of diaphragm, mediastinal pleura, pericardium, peritoneum of central diaphragm
Describe the path of the right phrenic nerve to reach the diaphragm.
The right phrenic nerve passes along the right brachiocephalic vein, along the superior vena cava, and along the right side of the heart and pericardium to the diaphragm.
Describe the relations of the vagus nerves to the great arteries.
The vagus nerves run lateral to the two common carotid arteries.
Describe the paths of the left vagus and left phrenic nerves.
The left vagus crosses anteriorly to the aortic arch. The left phrenic
nerve crosses more anteriorly in front of the aortic arch.
Describe the path of the left recurrent laryngeal nerve.
The left recurrent laryngeal nerve is a branch of the left vagus nerve, which arches around the ligamentum arteriosum and moves up towards the larynx.
Describe the path of the right recurrent laryngeal nerve.
The right recurrent laryngeal nerve branches off the right vagus nerve more superiorly and loops around the right subclavian artery.
What structure does the right vagus nerve lie on?
Trachea
What are the main branches of the vagus nerve?
Parasympathetic to the heart and lungs (control of smooth and cardiac muscle + glands of gut and airways)
Large sensory from the gut
Recurrent laryngeal nerve is NOT parasympathetic - it runs up the neck to supply most skeletal muscles of the larynx
Which spinal nerves do the sympathetic trunk receive branches from?
T1-L2
Where do the nerves to the body wall synapse?
In the sympathetic ganglia
Where do the nerves to the internal organs synapse?
In local ganglia
What are the fibres in the lower sympathetic trunk called and
which vertebral levels do they branch off at?
Splanchnic Nerves - T5-T12
Describe the arrangement of the thoracic duct.
The thoracic duct begins as the cisterna chyli (L2) below the diaphragm just to the right of the aorta (between aorta and oesophagus).
The thoracic duct then crosses to the left side between T4-T7.
The thoracic duct drains into the left brachiocephalic vein.
What do somatic spinal nerves provide somatic sensory
innervation to?
Body wall but NOT to viscera
What is a dermatome?
An area of skin that is supplied by a single spinal nerve on one side or
from a single spinal cord level
What is a myotome?
Part of a skeletal muscle that is supplied by a single spinal nerve on one
side or from a single spinal cord level
How many intercostal nerves are there?
11 intercostal + 1 subcostal
What are the branches of the intercostal nerves?
There is a lateral cutaneous branch (anterior and posterior branches)
and an anterior cutaneous branch (medial and lateral branches)
What structures do the phrenic nerves provide sensory and
motor innervation to?
Motor = diaphragm Sensory:
Central diaphragm Mediastinal pleura Pericardium
Peritoneum of central diaphragm
Where do sympathetic preganglionic neurones to the body wall
synapse?
In the ganglia of the sympathetic trunk
Where do sympathetic preganglionic neurons to the viscera
synapse?
In unpaired ganglia
The sympathetic trunk receive which spinal nerves?
T1-L2
What is the significance of sympathetic fibres in spinal nerves T5-T12?
These are the thoracic splanchnic nerves that carry sympathetic fibres
to the abdomen.
What are the five sets of nerves that contain parasympathetic
fibres?
Occulomotor (III)
Facial (VII) Glossopharyngeal (IX) Vagus (X)
Sacral spinal nerves (S2-S4)
Which spinal nerves do sympathetic fibres to the heart and lungs come from?
T2-T4 passing through cervical and upper thoracic ganglia
Where do many of these fibres synapse?
In ganglia of the pulmonary and cardiac plexuses rather than in the trunk ganglia
What effect do sympathetic and parasympathetic nerves have on bronchioles?
Sympathetic - bronchodilation
Parasympathetic - bronchoconstriction
What are the effect of sympathetic and parasympathetic
efferents to the heart?
Sympathetic - increase heart rate and force of contraction (inotropic and chronotropic effect)
Parasympathetic - decrease heart rate and vasoconstrict coronary arteries
What are the roles of sympathetic and parasympathetic afferents from the heart?
Sympathetic - relay pain sensations from the heart
Parasympathetic - relay blood pressure and chemical information from the heart
Where does the vagus nerve arise and where does it leave he skull?
Vagus nerves arise in the medulla and it leaves the skull via the jugular
foramina
Describe the path of descent of the vagus nerve.
The two vagus nerves pass postero-laterally to the common carotid arteries.
Right vagus passes posterior to the right lung root
Left vagus nerve crosses over anterior to the aortic arch and then posterior to the left main bronchus
What are roles of sympathetic and parasympathetic efferents from the oesophageal plexus?
Sympathetic - relays pain sensation from the oesophagus Parasympathetic - senses normal physiological information from the oesophagus
Branches of the vagus provide sensory content from…?
Gut and lungs
Branches of the vagus provide sensory content from…?
Gut and lungs
State a feature of the left recurrent laryngeal nerve. What does it innervate?
It is NOT parasympathetic
It innervates most of the skeletal muscle of the larynx
How do the vagi in the posterior and anterior mediastinum
differ?
In the posterior part of the oesophagus, you form the posterior oesophageal nerve which mainly takes right vagal fibres through the diaphragm to the abdominal viscera.
The left vagus provides fibres to the oesophageal plexus and then continutes as the anterior oesophageal nerve.
How many lymph nodes are there in humans?
600-700
Describe the arrangement of the lymphatics across the body.
State where the lymphatics join the venous circulation.
Right upper quadrant drains into the right subclavian vein. Other three quadrants all drain via the thoracic duct into the left subclavian vein.
What is the size of a normal lymph node?
<2.5 cm
What is a common cause of lymphadenopathy?
Infection
What is lymph usually like?
Colourless and odourless
How is lymph from the small intestines different? What is it
called?
It is opaque and milky due to absorption of fats (chylomicrons) It is called chyle
What causes movement of lymph through the vessels?
Skeletal muscle contraction
Pulses in arteries
What prevents backflow in the vessels?
Valves
What three groups of lymph nodes does the thoracic wall drain to?
Parasternal (associated with internal thoracic arteries)
Intercostal
Diaphragmatic
Which larger lymph vessels do these three groups of nodes drain to?
Parasternal - bronchomediastinal trunk
Upper intercostal - bronchomediastinal trunk
Lower intercostal - thoracic duct
Diaphragmatic - brachiocephalic nodes + aortic/lumbar part of the thoracic duct
Superficial - axillary and parasternal nodes
Where does the thoracic duct start? State the vertebral level.
It begins with the cysterna chyli - L2
Describe the path of ascension of the thoracic duct.
The thoracic duct ascends just to the right of midline, in between the aorta and the azygos vein. It crosses over to the left side at T5 and it then empties into the left subclavian vein.
Where do the lymphatics in the lungs drain to?
Tracheobronchial nodes - this is the largest collection of lymph nodes in the body
What do the tracheobronchial lymph vessels join with and what does this form?
Tracheobronchial lymph vessels join the parasternal and brachiocephalic lymph vessels to form the BRONCHOMEDIASTINAL trunk
Describe the lymphatic drainage of the heart
Lymphatic drainage of the heart follows the coronary arteries and drains into the:
Tracheobronchial nodes
Brachiocephalic nodes
What do the nodes on the aorta receive lymph from?
Oesophagus, diaphragm, pericardium and liver
Where do the nodes on the aorta drain to?
Thoracic duct and posterior mediastinal nodes
What marks the base of the breast?
Rib 2 - Rib 6 (midclavicular line)
What muscles underlie the breast?
Pectoralis Major
Laterally: Serratus Anterior + External Oblique
What subunits are the breast made of? How many of them are
there?
Ductal Lobular Units - 15-20 of them
How many milk ducts are there in the breast?
4-18
What is interspersed between the ductal lobular units?
FAT
What structures divide the breast?
Fibrous septae - Suspensory ligaments of Cooper
What are the two views in a mammogram?
Cranio-Caudal
Medial-Lateral Oblique (MLO)
Is the upper part of a cranio-caudal mammogram the lateral or
medial side?
Lateral
What can breast cancer cause that appears as white streaks
following the ducts?
Microcalcification
What happens if the tumour interferes with the suspensory
ligaments of Cooper?
Tethering of the skin
Describe the blood supply to the breast
Rich blood supply with branches from: Internal thoracic artery Lateral thoracic artery Thoraco-dorsal artery Thoraco-acromial artery Intercostal arteries
What nerves are mainly involved in providing sensory innervation to the breast?
Anteromedial and anterolateral branches of intercostal nerves T3-T5
What nerve supplies the nipple?
lateral cutaneous branch of the intercostal nerve T4
How are benign lumps different to breast cancer?
They are smooth and longer than they are tall in the longitudinal place
Where does the lymph from the superficial and deep parts of the breast initially drain to?
Superficial - subareolar plexus
Deep - submammary plexus
Where does the lymph from the superficial and deep parts of the breast drain to after the plexuses?
Axillary group of pectoral lymph nodes
When using dye to identify the sentinal lymph node, two blobs can appear on the X ray. What is the large blob usually caused by?
Bigger blob is probably the site of injection of the dye
