Anatomy of the Thorax Flashcards
What separates the inferior and superior mediastinum?
A horizontal plane passing through the sternal angle and TIV and TV.
Which is the most clinically important recess in the thoracic cavity and why do they occur?
The costodiaphragmatic recess.
Occur because the lung does not completely fill the potential space of the pleural cavity.
What is marked by the horizontal plane passing through the sternal angle and TIV and TV?
The border of the inferior and superior mediastinum.
Beginning and end of aortic arch
Rib 2 position.
The position where the SVC pierces the pericardium to enter the heart.
The level at which the trachea bifurcates
Where does the left brachiocephalic vein cross the midline?
Immediately posterior to the manubrium.
Give reference dermatomes.
T4 = nipples T6 = xiphoid process T10 = umbilicus.
How can the ribcage expand laterally?
The middle part of a rib is inferior to its two ends, so when it is elevated it expands the chest laterally.
The mammary glands converge to form how many lactiferous ducts?
15-20 lactiferous ducts, which open independently onto the nipple.
What separates the breast from the pectoral fascia?
A layer of loose connective tissue termed the retromammary space. It is a potential space.
What are the margins of the breast?
Ribs II to VI.
Sternum medially to the midaxillary line laterally.
Describe the innervation of the breast.
Innervated by the anterior and lateral cutaneous branches of the second to sixth intercostal nerves.
The nipple is innervated by the fourth intercostal nerve.
Describe the lymphatic drainage of the breast.
75% via lymphatic vessels which drain laterally and superiorly into axillary nodes.
Most of the remaining lymph drains into parasternal nodes deep to the anterior thoracic wall, associated with the internal thoracic arteries.
Where do axillary lymph nodes, parasternal nodes and intercostal nodes drain?
Subclavian trunks, bronchiomediastinal trunks and either the bronchiomediastinal trunk or thoracic duct respectively.
Describe the articulation of the vertebrae with the ribs.
Two demifacets are located on the vertebral body:
The superior costal fact articulates with part of the head of its own rib and the inferior costal facet articulates with the head of the rib below.
An oval facet (transverse costal facet) at the end of the transverse process articulates with the tubercle of its own rib.
What are the exceptions to the normal fashion of costovertebral articulation?
TX only articulates with its own rib and lacks inferior demifacets.
TXI and TXII articulate only with the heads of their own ribs: they lack transverse costal facets and only have a SINGLE complete facet on either side of their bodies.
Describe the atypical structure of rib I.
One articulation on its head for T1.
Flat in the horizontal plane with 2 grooves separated by the scalene tubercle.
The anterior groove is caused by the subclavian vein: the posterior groove is caused by the subclavian artery.
Describe the costovertebral articulation at the head of the rib.
The joint is divided into two synovial compartments by an intraarticular ligament, which attaches the crest to the adjacent intervertebral disc and separates the two articular surfaces on the head of the rib.
The whole joint is surrounded by a capsule.
Describe the ligamenture of the costotransverse joint.
Costotransverse ligament. Medial to the joint and attaches the neck of the rib to the transverse process.
Lateral costotransverse ligament. Lateral to the joint and attaches the tip of the transverse process to the nonarticular part of the tubercle of the rib.
Superior costotransverse ligament. Attaches the superior surface of the neck of the rib to the transverse process of the vertebra above.
What types of joint are the manubriosternal and xiphisternal joints?
They are SYMPHYSES, meaning the movement is limited.
Describe the order of the neurovascular bundle in the costal groove?
Vein most superior, then artery, then nerve.
Nerve often not protected by groove.
Where do the internal thoracic arteries arise from?
The subclavian arteries.
Which artery supplies the first two posterior intercostal arteries?
The supreme intercostal artery, itself a branch of the costocervical trunk, which rises superior from the subclavian artery.
Where do the internal thoracic arteries bifurcate and where do these arteries go?
Bifurcate at approximately the level of the sixth intercostal space.
Into the superior epigastric artery and musculophrenic artery.
Superior epigastric artery which continues inferiorly to the anterior abdominal wall.
Musculophrenic artery passes along the costal margin.
Where do anterior intercostal arteries arise from?
Those supplying the upper six intercostal spaces are from the internal thoracic artery: those supplying the lower intercostal spaces are from the musculophrenic artery.
Where do the internal thoracic veins drain into?
Brachiocephalic veins.
