Great vessels Flashcards
Anatomy of the aorta (general)
The aorta is the largest vessel in the body
* Originates from the left ventricle, at the aortic valve
* Terminates by bifurcation into right and left common iliac arteries opposite L4
Three parts:
* Ascending aorta
* Arch of aorta
* Descending aorta (thoracic and abdominal)
Ascending aorta (length, course, branches)
- 5cm long
- Arises from the aortic valve at the base of the left ventricle at the level of the left 3rd costal cartillage
- Runs superiorly to the right, enters the superior mediastinum at the level of the right 2nd costal cartillage, where becomes the arch of the aorta
- 2 branches: right and left coronary arteries
Aortic arch (course, branches)
- Continuation of the ascending aorta, beginning at the level of the 2nd right sternocostal junction
- Ascends up and back, in front of trachea, then passes backwards, lying on left of trachea, arches over, behind left main bronchus
- Continues as descending aorta (thoracic) at lower border of T4
Branches:
1. Brachiocephalic artery
2. Left common carotid artery
3. Left subclavian artery
Brachiocephalic artery
- First and largest branch of the arch of aorta, passing upwards and to the right of the trachea
- Terminates by dividing into the R common carotid and R subclavian arteries behind the R sternoclavicular joint
- In 10%, gives off the thyroid ima artery (-> thyroid gland). Also occasionally arises from aorta, R common carotid or subclavian
LDescribe the left common carotid artery
- Second branch of the arch of aorta, arising immediately after the origin of the brachiocephalic artery,
- Ascends upwards to the left of the trachea, then behind the left sternoclavicular branch
- Ends by bifurcating into external and internal carotid arteries
Left subclavian artery
- Third branch of the arch of aorta
- Arises immediately after origin of left common carotid
- Ascends upwards along left side of trachea and oesophagus, arches over apex of left lung, lies on first rib
(NB R subclavian artery arises from brachiocephalic trunk)
Descending thoracic aorta (origin, termination, relation to vertebral column, branches)
- Lies in the posterior medastinum
- Superiorly lies to the left of the vertebral column, inferiorly approaches the midline and lies directly anterior to the lower thoracic vertebral bodies
- Starts as continuation of arch of aorta, ends at level of **T12 **-> passes through aortic opening of diaphragm, becomes abdominal aorta
Branches
* Visceral: pericardial, oesophageal, bronchial, mediastinal
* Somatic: posterior intercostals, subcostal, muscular, superior phrenic
Abdominal aorta (position, termination, branches)
Position
* Lies behind the peritoneum on the anterior surface of the bodies of lumbar vertebrae
* IVC lies on the right
* Left sympathetic trunk lies on the left
At level of L4, divides into right and left common iliac arteries
Branches:
* Anterior unpaired visceral branches: coeliac, superior mesenteric, inferior mesenteric
* Lateral paired visceral branches: inferior phrenic, suprarenal, renal, gonadal arteries
* Posterior paired somatic branches: 4 lumbar arteries
* Median sacral artery: originates posteriorly just superior to the bifurcation of the aorta
Superior vena cava
- Formed by the union of the right and left brachiocephalic veins behind the lower edge of the right first costal cartilage
- Has no valves
- Tributaries:** azygos vein** (may also receive pericardial and mediastinal veins
Where is the SVC visible on a PA CXR?
Part of the right superolateral border of the heart shadow
Inferior vena cava (course, surrounding structures)
- Widest vein in the body
- Formed by the union of the right and left common iliac veins in front of the body of L5, ascending on the RIGHT side of the aorta
- Pierces the central tendon of the diaphragm at the level of T8 -> very short course in thorax -> opens in the lower part of the right atrium. Opening is guarded by a valve
Inferior vena cava (tributaries)
All originate from the abdomen
* Common iliac veins
* Third and fourth lumbar veins (first and second empty into ascending lumbar vein)
* Right suprarenal vein and right gonadal (testicular or ovarian) vein [the left sided ones drain into the left renal vein]
* Renal veins
* Right inferior phrenic veins (left vein opens into left suprarenal or left hepatic)
* Hepatic veins
Pulmonary trunk (course, surrounding structures)
- Short, wide artery carrying deoxygenated blood from RV to lung
- Originates at base of RV
- Branches into R and L pulmonary arteries
- Right pulmonary artery runs to the right, behind the ascending aorta and SVC, divides into two, then enters the root of the right lung
- Left pulmonary artery runs to the left, in front of the descending aorta, divides into two, enters root of left lung
Pulmonary veins (origin, termination)
- Carry oxygenated blood from the lungs to the LA
- Two on either side: superior and inferior pulmonary veins
- Begin at hilum of each lung, pass through roots of the lungs, immediately drain into left atrium
