Thoracic anatomy notes Flashcards
Superior Mediatinum borders
Superior – Thoracic inlet. Inferior – Continuous with the inferior mediastinum at the level of the sternal angle. Anterior – Manubrium of the sternum. Posterior – Vertebral bodies of T1-4. Lateral – Pleurae of the lungs.
Three major branches of the aortic arch arise within the superior mediastinum?
Brachiocephalic artery
Left Common carotid artery
Left Subclavian artery
Right vagus nerve path
runs parallel to the trachea and passes posteriorly to the superior vena cava and the right primary bronchus.
Left vagus nerve path
enters the superior mediastinum between the left common carotid and the left subclavian arteries.
It descends anteriorly to the aortic arch, before travelling posterior to the left bronchus.
left recurrent laryngeal nerve path
arises from the left vagus nerve as it passes the aortic arch. It loops under the arch, to the left of ligamentum arteriosum, before continuing its journey to the larynx in the tracheal-oesophageal groove.
Phrenic Nerve Path
From the anterior surface of the anterior scalene muscle, the phrenic nerves (roots C3, C4 and C5) enter the superior mediastinum lateral to the great vessels.
Where do Ribs 1-7 attach
Independently to sternum
Where do Ribs 8-10 attach
Ribs 8 – 10 attach to the costal cartilages superior to them.
Where do Ribs 11 and 12 attach?
Ribs 11 and 12 do not have an anterior attachment and end in the abdominal musculature. Because of this, they are sometimes called ‘floating ribs’.
Azygos vein – Formed by?
union of the right lumbar vein and the right subcostal vein. It enters the mediastinum via the aortic hiatus and drains into the superior vena cava.
Hemiazygos vein - Formed by?
union of the left lumbar vein and left subcostal vein. It enters the mediastinum through the left crus of the diaphragm, ascending on the left side. At the level of T8, it turns to the right and combines with the azygos vein.
Accessory hemiazygos vein
Formed by the union of the fourth to eighth intercostal veins. It drains into the azygos vein at T7.
Ligaments of vertebral column
Anterior and posterior longitudinal ligaments:
Long ligaments that run the length of the vertebral column, covering the vertebral bodies and intervertebral discs.
Ligamentum flavum
Connects the laminae of adjacent vertebrae.
Interspinous ligament
Connects the spinous processes of adjacent vertebrae.
Supraspinous ligament:
Supraspinous ligament: Connects the tips of adjacent spinous processes.
11 pairs of external intercostal muscles. What are their origins and attachements?
Originate at the lower border of the rib, inserting into the superior border of the rib below
Actions and innervation of external intercostal muscles?
Elevates ribs, increases thoracic volume
Innervation - Intercostal nerves T1-t11
Internal intercostals - deep to the external intercostals. Like the external intercostals, they run from the rib above to the one below, but in an opposite direction (inferoposteriorly)
Attachments: Originates from the lateral edge of the costal groove and inserts into the superior surface of the rib below.
Actions: The interosseous part reduces the thoracic volume by depressing the ribcage, and the interchondral part elevates the ribs.
Innervation: Intercostal nerves (T1-T11).
Transversus Thoracis
continuous with transversus abdominis inferiorly.
Attachments: From the posterior surface of the inferior sternum to the internal surface of costal cartilages 2-6.
Actions: Weakly depress the ribs.
Innervation: Intercostal nerves (T2-T6).
Right crus
Arises from L1-L3 and their intervertebral discs. Some fibres from the right crus surround the oesophageal opening, acting as a physiological sphincter to prevent reflux of gastric contents into the oesophagus.
Left crus
Arises from L1-L2 and their intervertebral discs.
Three openings and structures passing through diaphragm
T8 - Inferior vena cava
T10- Oesophagus, Vagus x2, Oesophageal branches of left gastric artery.vein
T12- Aorta, Thoracic duct, Azygous vein
Blood supply to the diaphragm?
Inferior phrenic arteries - directly from the AA
What will bilateral diaphragmatic paralysis show on LFTs
Restrictive deficit
Pardoxical movements of diaphragm - down on expiration, up on inspiration
What pharyngeal pouch is thymus gland derived from?
Third pharyngeal pouch
Relevance of DiGeorge syndrome to thymus?
DiGeorge- CATCH
C ONGENITAL HEART SOUNDS A BNORMAL FASCIES T HYMIC APLASIA C LEFT PALATE H YPOPARATHYROIDISM
Susceptible to recurrent infections due to underdeveloped immune system
Blood supply to medial aspect of the breast?
Internal Mammary artery (aka internal thoracic) - branche of subcalvian
Blood supply to the lateral aspect of the breast?
1) Lateral thoracic and thoracoacromial branches – originate from the axillary artery.
2) Lateral mammary branches – originate from the posterior intercostal arteries (derived from the aorta). They supply the lateral aspect of the breast in the 2nd 3rd and 4th intercostal spaces.
3) Mammary branch – originates from the anterior intercostal artery.
Breast location in thoracic wall?
anterior thoracic wall.
extends horizontally from the lateral border of the sternum to the mid-axillary line.
2nd and 6th costal cartilages vertically
Lymphatic drainage of the breast
Axillary nodes (75%) Parasternal nodes (20%) Posterior intercostal nodes (5%)
Lymphatic drainage of the Skin overlying breast
Axillary, inferior deep cervical, inferiorclavicular nodes
Lymphatic drainage of nipple and areola
Drains to subareolar lymphatic plexus
Nerve supply to the breast
anterior and lateral cutaneous branches of the 4th to 6th intercostal nerves.
