thorax Flashcards
where is the thorax?
the superior part of the trunk, lying between the neck and the abdomen.
what are the 3 divisions of the thorax?
- mediastinum- contains all contents of thorax except lungs
2 and 3. paired lateral pulmonary cavities- occupied but the lungs
what makes up the thoracic cage?
the bones of the thorax which includes 12 pairs of ribs and their associated costal cartilages, 12 thoracic vertebrae and their intervening intervertebral discs and the sternum
what is the primary function of the thoracic cage?
protect the thorax and some abdominal contents
what are the 3 parts of the sternum?
the manubrium, body, and xiphoid process
what can be found on the superior surface of the manubrium?
the jugular notch and paired clavicular notches
what does the first rib articulate with?
the lateral borders of the sternum to form a synchondrosis
what is the junction between the manubrium and body called?
manubiosternal joint or sternal angle (angle of Louis)
where does the second rib articulate?
manubiosternal joint
what does the body articulate with?
ribs 3-6 with the 7th rib attaching at the junction of the body and the xiphoid joint= xiphisternal joint
where does the xiphoid process lie?
around the level of T10 vertebral body
what does the xiphoid process represent?
the inferior limit of the thoracic cavity (projected onto the anterior wall of the thorax)
describe the ribs
curved, flat bones that form most of the cage typical ribs (3-9) exhibit head, neck, tubercle, angle, and body. the facets on the heads articulate with the vertebrae of the same numerical level and the one superior (except 1st rib only articulates with T1 and ribs 10-12 with their respective vertebrae)
what are the true ribs?
1-7 attach directly to the sternum via their costal cartilage
what are the false ribs?
8-10 articulate via their costal cartilage to the next superior rib
what are the floating ribs?
11-12 end in the abdominal musculature
what are costal grooves?
concavities on the inferior, internal borders of the ribs for the intercostal nerves and vessels
where are intercostal spaces seen?
between each successive rib and are named for each superior rib
where are costovertebral joints?
between heads of ribs and vertebral bodies
where are costotransverse joints?
between tubercles of ribs and transverse processes (facets) of thoracic vertebrae
where are costochondral joints?
between ribs and costal cartilage
where are sternocostal joints?
between costal cartilages and the sternum
which joints are synchondroses?
all costochondral joints, 1st sternocostal joint, and xiphisternal joint
where do symphyses occur?
posteriorly between thoracic vertebral bodies and anteriorly at the manubriosternal joint
what is the superior thoracic aperture?
the communicating passageway between the thorax and neck/upper extremity. aka thoracic inlet
what is the posterior boundary of the thoracic inlet?
vertebra T1
what is the lateral boundary of the thoracic inlet?
1st ribs and their costal cartilage
what is the anterior boundary of the thoracic inlet?
the superior border of the manubrium
what structures pass through the thoracic inlet?
trachea, esophagus, nerves and vessels that supply/drain the head, neck and upper extremity
what is the inferior thoracic aperature also known as?
anatomical thoracic outlet
what is the posterior boundary of the thoracic outlet?
T12 vertebrae
what is the posterolateral boundary of the thoracic outlet?
the 11th and 12th ribs
what is the anterolateral boundary of the thoracic outlet?
the costal margins (made up of costa cartilages 7-10)
what is the anterior boundary of the thoracic outlet?
the xiphisternal joint
what is thoracic outlet syndrome?
compression of vessels and nerves emerging from the thorax and heading toward the neck and upper extremity. obstructions/compressions usually occur outside of the thorax, and the manifestations are in the upper limbs
when are the external intercostals most active?
during inspiration
when are the internal intercostals most active?
during expiration
where do the internal thoracic arteries and veins travel?
at either side of the sternum (tributaries of the subclavian)
what is the longitudinal increase during inspiration due to?
the descent of the diaphragm
what is the transverse increase is due to? (easier to understand)
intercostal muscle contraction at the middle of the lower ribs (the middle of the rib is lateral on the thoracic cage). due to the nature of the costotransverse joints between ribs 8-10 and their corresponding vertebrae
at what levels are the costotransverse joints planar?
the more inferior levels (ribs 8-10)
what is the transverse increase is due to? (harder to understand)
since the ribs slope inferiorly as they project, anteriorly, the “pump handle” movement raises the anterior parts of the ribs, especially ribs 5-7 and the result during inspiration is the AP increase in the thoracic dimension, this is due to the nature of the costotransverse joints between ribs 1-7 and their corresponding vertebrae -> the movement here is more rotational around a transverse axis through the head and neck of the ribs.
what are the contents of the pulmonary cavities?
the lungs and pleura
what does the mediastinum do?
completely separates the two pulmonary cavities and contains all other thoracic structures: heart, thoracic parts of great vessels, part of the trachea, esophagus, thymus gland, etc
where is the endothoracic fascia?
lines the entire thoracic wall superficial to the double-layered pleura. attaches the parietal pleura from the inferior aspects of the lungs to the diaphragm
what does the endothoracic fascia cover?
the apices of the lungs superior to the 1st rib
what is the pleural cavity?
potential space other than a very thin capillary layer of serous fluid, allows for cohesion of the lung to the thoracic wall during respiratory movements.
what are the surfaces of the parietal pleura named for?
the structures they contact (mediastinal part, diaphragmatic part, costal part, cervical
how many lobes does the right lung have?
3 (superior, inferior, middle)
what are the names of the two fissures of the right lung?
oblique and horizontal
what is the pleura sleeve?
the reflection of pleura where all tubular structures enter/exit the lung. it is the area of continuity between the visceral and parietal layers of pleura. occurs at the hilum
what is the root of the lung?
the actual structures passing into and out of the lung at the hilum
what are the root structures?
main bronchus, pulmonary artery, and superior and inferior pulmonary veins
what is the pulmonary ligament?
a double-layered pleural structure continuous with the “sleeve” but inferior to the root
how many lobes does the left lung have?
2 (superior and inferior)
what is the name of the fissure separating the lobes of the left lung?
oblique fissure
what is the lingula?
the inferior, anterior projection of the superior lobe that tucks around the apex of the heart. the position of the heart prevented the lingula from becoming a “middle lobe”
what is the cardiac notch?
formed on the anterior border of the lung since the apex of the heart occupies this area
where does the trachea begin and terminate?
at the inferior border of the cricoid cartilage and terminates into the right and left main bronchi at the level of the sternal angle. descends anterior to the esophagus and enters the superior mediastinum
what are tracheal rings?
c shaped cartilages which support the airway
what is the carina?
a small vertical reflection of cartilage in the midline at the inferior end of the trachea
which bronchi is wider and shorter?
the left
what do the secondary bronchi do?
supply a lobe of the lung (2 on left, 3 on right) branch into tertiary bronchi supplying a bronchopulmonary segment of lung. pyramidal shaped with their apices toward the root and their bases on the pleural surfaces
why is the mediastinum highly mobile?
air movement, food and liquid movement, blood vessels transmitting blood
where does the transverse thoracic plane of the mediastinum run?
the horizontal plane running from the sternal angle anteriorly to the T4-T5 IV disc
what are the divisions of the mediastinum?
superior to the transverse thoracic plane is the superior mediastinum. inferior to the plane is the inferior mediastinum subdivided into anterior, middle and posterior compartments
what constitutes the middle mediastinum?
the pericardium and all its contents
what is the pericardium?
a fibroserous membrane covering the heart that begins at the great vessel. it is a closed sac with two layers (external fibrous pericardium and parietal layer of serous pericardium)
what does the external fibrous pericardium blend with?
the tunica adventitia of the great vessels superiorly and the central tendon of the diaphragm inferiorly
what is the heart innervated by?
the cardiac nerve plexus which lies on the inferior, anterior surface of the trachea
what does the cardiac nerve plexus consist of?
autonomic fibers from the vagus n and from sympathetic nerves
what does the phrenic nerve supply in regards to pericardium?
general sense (pain) to pericardium
what is the pericardiophrenic artery?
a branch off the internal thoracic artery and supplies most of the blood to the pericardium. it is accompanied by vein of the same name. travels with the phrenic nerve
describe the flow of blood starting with the right heart?
superior vena cave/inferior vena cava -> right atrium -> tricuspid valve -> right ventricle -> pulmonary valve -> pulmonary trunk -> R/L pulmonary a -> pulmonary veins -> left atrium -> bicuspid valve -> left ventricle -> aortic valve -> ascending aorta
describe how the heart is a double pump?
the right side supplying the central circulation to the lungs (a low pressure/ low resistance circuit) and the left tot he peripheral structures of the body (higher pressure and resistance).
what do valves function to do?
prevent backflow
what is the apex and base of the heart formed by?
the base is superior mainly the left atrium but some of the right atrium.
the apex is inferior and the inferolateral part of the left ventricle
what are the four surfaces to the heart and formed by what?
anterior (“sternocostal” formed by right ventricle)
diaphragmatic (“inferior” formed by mainly the left ventricle)
right pulmonary (formed by right atrium)
left pulmonary (formed mainly by the left ventricle)
what are some key things to look for with the right atrium and what are they?
auricle- muscular pouch projecting anterosuperiorly
sinus venarum- the smooth surface onto which the SVC, IVC and coronary sinus open
pectinate muscles- anterior wall
crista terminalis- internal vertical ridge separating smooth from rough surface
fossa ovalis- on the interatrial septum
what is the sinuatrial (SA) node?
the pacemaker of the heart is typically located just anterolateral to the junction of the SVC and right atrium
what are some key things to look for with the left atrium and what are they?
auricle with pectinate muscles
valve of the fossa ovalis
opening into the left ventricle covered by the mitral valve
what are some key things to look for with the right ventricle and what are they?
atrioventricular orifice with the tricuspid valve covering it- 3 cusps anterior, septal, and posterior
chordae tendinae attaching cusps to papillary muscles
moderator band carrying the right branch of the bundle of his
trabeculae carneae
conus arteriosus
pulmonic valve
what are some key things to look for with the left ventricle and what are they?
increased thickness of the ventricular walls
mesh of trabeculae carneae covering the majority of the inner wall surface
conical nature of the entire cavity
anterior and posterior papillary muscles
mitral valve guarding the AV opening
aortic vestibule
what provides blood supply to the heart?
the coronary arteries
where does the right coronary artery arise from?
the right aortic sinus and travels in the coronary groove
what branches does the right coronary artery give off?
branches to the SA node, right border of the heart (“right marginal”) and the posterior interventricular artery
what makes a heart right dominant?
if the right coronary artery gives off the posterior interventricular artery
where does the left coronary artery arise from?
the left aortic sinus and after a short distance divides into the anterior interventricular branch and the left circumflex
what completes the anterior blood supply to the left ventricle?
lateral diagonal branch and left marginal
where is almost all venous blood from the heart returned to?
the right atrium via coronary sinus which receives the great, middle, and small cardiac veins
what do the anterior cardiac veins empty directly into?
the right atrium
