Thorax Flashcards
What are the two joints connecting the ribs to the vertebral column and what is the overall name
Costovertebral joints: Joints of the heads of the ribs and by the tubercles - the costotransverse joints.
What are the anterior joints of the ribs
Upper 7: articulate with the sternum at the sternocostal joints.
Next 3: articulate with each other
Last 2: Free ribs
Describe the joints of the heads of the ribs
Two articular facets with a ridge in between.
The lower one with its own vertebra, upper one with the vertebra above.
Attached to the ridge between the two and the body of the vertebra above is the intra-articular ligament. The radiate ligament consists of three bands: upper passes across the joint to the body of the vertebra above, the central horizontally and the deep to the anterior longitudinal ligament.
What are the exceptions to the rule for the joints of the heads of the ribs
The first rib articulates with the T1 vertebra only.
the last two ribs only articulate with their own vertebrae. In these instances the radiate ligament consists of two bands (not three).
Describe the costotransverse ligament
3 ligaments: costotransverse, lateral costotransverse, superior costotransverse.
Describe the costochondral joints
Primary cartilaginous joint that each rib makes with its costal cartilage
What type of joint are interchondral joints and which ribs are involved with these
The costal cartilages of 6 and 7, 7 and 8, 8 and 9 are joined to parts of adjacent surfaces of each other by small synovial joints.
Why is the first sternocostal joint different from the others
First costal cartilage articulates with the manubriaum by a primary cartilaginous joint, allowing no movement
What type of joint is the sternocostal joint of ribs 2-7
Synovial joint
Describe the manubriosternal joint
Surfaces are covered by a hyaline cartilage with an intervening disc of fibrocartilage.
How many layers of thoracic muscles are there?
3
- outer
- middle
- inner
What is serratus posterior superior
Outer layer muscle of the thoracic wall. Arises from the spinous processes of the lower two cervical and the upper two thoracic vertebrae. Slopes down and is inserted into the angles of ribs 2-5
What runs on the anterior surface of serratus posterior superior
Dorsal scapular nerve and vessels
What is serratus posterior inferior
Arises from the lower two thoracic and upper two lumbar spinous processes. Inserted just lateral to the angles of the lowest four ribs
What distinguishes the levator costae muscls
They are the only thoracic muscles to be supplied by the posterior rami of spinal nerves (C8-T11). 12 pairs of fan shaped muscles from the tip of a transverse process and inserted into the upper border of the rib below, lateral to its tubercle.
What way do the fibres of the external intercostals go
Obliquely downwards and forwards.
What happens to the fibres of the external intercostals at the costochondral junction.
It is replaced by the anterior intercostal membrane which extends to the side of the sternum.
What is the middle layer of thoracic musculature
Internal intercostal muscles. Fibres run downwards and backwards and extend to the sternum. At the back it is replaced by the posterior intercostal membrane. This extends from the angle of the rib to the superior costotransverse ligament at the posterior limit of the space
How many muscles in the inner layer of thoracic wall
3
- innermost intercostal
- Transversus thoracis: arise from the lower end of the sternum (and are anterior)
- Subcostal muscles: posterior
What is the order of the neuromuscular bundle in the intercostal spaces
Above to downwards: vein, artery , nerve. It runs in the plane between the internal intercostal and innermost intercostal. They are protected by the downward projection of the lower border of the rib.
What artery supplies the upper 2 posterior spaces
Superior intercostal artery - a branch of the costocervical trunk, origin is the second part of the subclavian artery (behind scalenus anterior)
What supplies the remaining 9 posterior intercostal spaces
Posterior intercostals - separate branches fo the descending thoracic aorta.
What vessel supplies the upper 6 spaces anteriorly
The internal thoracic artery
What vessel supplies the lower 7th, 8th and 9th spaces
Musculophrenic artery - gives off two anterior intercostal arteries that pass backwards to make end-to-end anastomosis with the posterior vessels
What vessel supplies the last 2 ribs
There are no anterior intercostal arteries in the last two spaces.
Venous drainage of the anterior intercostal space
2x anterior intercostal veins that drain into the musculophrenic and internal thoracic veins
Venous drainage of the posterior lower 8 spaces
One posterior vein that drains into the azygos vein on thee right and the hemiazygos and accessory hemiazygos on the left.
Venous drainage of the 1st posterior intercostal space
Supreme intercostal vein - this drains into either the vertebral vein or the brachiocephalic vein of its own side.
Venous drainage of the 2nd and 3rd posterior intercostal space
Collected into a single trunk on each side - the superior intercostal vein.
Drainage of the superior intercostal vein on the righ
Azygos vein
Drainage of the superior intercostal vein on the left
Forward over the arch of the aorta, superficial to the vagus nerve and DEEP to the phrenic nerve, to empty into the left brachiocephalic vein.
How does the internal thoracic artery supply the anterior body wall from the clavicle to the umbilicus
Anterior intercostal arteries. Divides into the superior epigastric and musculophrenic arteries.
Venous drainage of the internal thoracic
Internal thoracic artery is accompanied by two venal comitantes that empty into the brachiocephalic vein.
Anterior attachment of the suprapleural membrane
Inner border of the first rib and costal cartilage
Posterior attachment of the supra pleural membrane
Tranverse process of C7 vertebra.
What muscle can be found in the posterior attachment of the sub pleural membrane
Scalenus minimus
Embryology of the diaphragm: what layer of muscles does iit originate from
The inner layer (transverses)
Which dome of the diaphragm is higher and what levels do the right and left reach
Right: 4th space (nipple)
Left: 5th space
Central tendon: level with the xiphisternal joint
What is the right crus
Largest of the crura. Attached to the upper three lumbar vertebrae. Some of the right crus fibres slope to the left surrounding the oesophageal orrifice in a sling-like loop.
Attachment of the left crus
upper two lumbar vertebrae and disc.
What level is the median arculate ligament
T12
What is the medial arcuate ligament
Thickening in the psoas fascia extending from the lower part of the body of L1 to a ridge on the anterior surface of the transverse process of L1
What is the lateral arcuate ligament
Extends across to the 12th rib at the lateral. border of quadrates lumborum. (transverse process of L1 tot he 12th rib).
What structure is the central tendon of the diaphragm attached to
The fibrous pericardium.
What structure pierces the central tendon
The vena cava
Location of the aortic opening in the diaphragm and what it transmits
T12 vertebra.
Midline arch between the overlapping right and left crural fibres, behind the diaphragm.
Transmits the aorta with the azygos to the right and the thoracic duct leading up from the cisterns chyli.
Location of the oesophageal opening and what it transmits
Opposite T10 vertebra
Usually slightly to the left of the midline and behind the seventh costal cartilage.
Lies in the fibres of the left crus but a sling of fibres from the right passes over it to loop around it
It transmits the oesophagus along with the oesophageal branches of the left gastric artery, accompanying veins and lymphatics.
What attaches the oesophagus to the oesophageal opening
The phreno-oesophageal ligament
- this is stretched in the ‘sliding’ type of hiatus hernia.
Location of the vena caval foramen and what it transmits
Opposite the T8 vertebra to the right of the midline behind the sixth right costal cartilage.
What pierces the diaphragm at the same level as the vena caval foramen
right phrenic nerve
What are the smaller structures that pierce the diaphragm.
Hemiazygos vein - left crus
Greater, lesser and least splanchnic nerves pierce each crus.
Sympathetic trunk- medial arcuate ligament.
Blood supply of the diaphragm
Costal margin - supplied by the lower five intercostal and subcostal arteries.
The main area supplied by the right and left inferior phrenic arteries from the abdominal aorta.
Nerve supply of the diaphragm
Each half is supplied by its own phrenic nerve nerve. The part of the right crus that lies to the left of the oesophageal opening is supplied by the left phrenic.
The lower intercostal nerves send some proprioceptive fibres to the periphery of the diaphragm but no motor fibres.
Where do the right and left phrenics pierce the diaphragm
Right - passes through the foramen for the inferior vena cava.
Left pierces the muscular part in fromt of the central tendon.
Why is there more dead space on the right side of the superior mediastinum
Right side of the superior mediastinum = veins. Veins expand during increased blood flow.
Boudaries of the superior mediastinum
Manubrium. Posterior boundary = bodies of first four thoracic vertebrae.
Contents of the superior mediastinum
Arch of the aorta Brachiocephalic trunk Trachea Left vagus and apex left lung. Right and left brachiocephalic veins
What differs in the course of the vagus nerve on the left sup. mediastinum compared with right.
Great arteries keep the left vagus and apex of the left lung away from contact with the trachea.
Describe the arch of the aorta in the superior mediastinum
at the manubriosternal joint the ascending aorta becomes the arch which passes OVER the left bronchus to reach the body of T4 to the left of the midline.
What crosses the arch of the aorta
Left phrenic and left vagus.
Left recurrent laryngeal hooks around the ligament arteriosum to pass upwards on the right side of the arch, in the groove between the trachea and oesophagus.
What is contained in the adventitial layer of the arch of the aorta
baroreceptors - innervated by vagal fibres which pass to the nucleus of the tracts solitarius.
What lies under the arch of the aorta.
Aortic bodies - detect hypoxia and are involved in respiratory refexes
What lies in front of the brachiocephalic artery
The termination of the left brachiocephalic vein
What is the branch of the brachiocephalic artery in sup. mediastinum
Thyroidea ima artery. rare. may originate from the arch of the aorta
Course of the left subclavian artery in the sup. mediastinum
Arises behind the left common carotid then arches over the left lung apex (which it grooves).
What is the ligamentum arteriosum
It’s the shrivelled fibrous remnant of the ductus arteriosus.
Origin and insertion of ligament arteriosum
Commencement of the left pulmonary artery to the aortic arch.
What is closely associated with the ligamentum arteriosum
Left recurrent laryngeal nerve hooks around it. Superficial part of the cardiac plexus lies anterior to it. Deep part is on its right, in front of the left main bronchus.
Location of the formation of the brachiocephalic vein
Confluance of the internal jugular vein an subclavian vein medial to scalenus anterior and in front of the first part of the subclavian artery.