Blue Boxes

Question 1

levels of viscera relative to mediastinal divisions

Answer 1

the superior and inferior mediastinum are divided by the transverse thoracic plane. when a person is standing/supine will change where the viscera is in the subdivisions of the mediastinum. viscera is higher when supine, gravity pulls viscera down when standing/sitting upright
supine:
arch of aorta lies superior to transverse thoracic plane
bifurcation of trachea is transected by transverse thoracic plane
central tendon of diaphragm is at xiphisternal junction/ T9
standing upright:
arch of aorta is transected by transverse thoracic plane
tracheal bifurcation lies inferior to transverse plane
central tendon of diaphragm is in middle of xiphoid

Question 2

mediastinoscopy and mediastinal biopsies

Answer 2

mediastinoscope: an endoscope can be inserted using a small incision at the root of the neck just superior to the jugular notch
mediastinoscopy: surgeons view/biopsy mediastinal LN to determine if cancer has metastasized

Question 3

widening of mediastinum

Answer 3

often observed after trauma from a head on collision which produces a hemorrhage into the mediastinum from lacerated great vessels
malignant lymphoma
hypertrophy of the heart (often a result of congestive heart failure) commonly widens inferior mediastinum

Question 4

surgical significance of the transverse pericardial sinus

Answer 4

by passing a surgical clamp/ligature around the ascending aorta and pulmonary trunk and inserting tubes of a coronary bypass machine, the surgeons can stop/divert blood in these arteries while performing cardiac surgery

Question 5

Pericarditis, pericardial rub, and pericardial effusion

Answer 5

pericarditis: inflammation of the pericardium; usually causes chest pain or friction that can be heard during auscultation (rustle of silk) thats termed a pericardial friction rub
pericardial effusion: passage of fluid from pericardial capillaries into the pericardial cavity/accumulation of pus
noninflammatory pericardial effusions often occur with congestive heart failure

Question 6

cardiac tamponade

Answer 6

fluid enters the pericardial cavity and compresses the heart due to the hardiness of the fibrous pericardium
reduces cardiac output - can be lethal

Question 7

periocardiocentesis

Answer 7

drainage of fluid from the pericardial cavity
usually necessary to relieve cardiac tamponade
needle can be inserted 1) through 5th or 6th intercostal space near sternum or 2) superoposteriorly via the infrasternal angle

Question 8

chest pain

Answer 8

most important symptom of cardiac disease - may also occur in GI, gallbladder, and MSK disorders
must discriminate such pain with minor causes of pain
heart attack described usually as crushing sub-sternal pain that does not disappear with rest

Question 9

Rib fractures

Answer 9

short, broad 1st rib is rarely fractured due to its protected position - if broken, structures crossing its superior aspect may be injured (brachial plexus, subclavian vessels)
middle ribs most commonly fractured as a result of traumatic blow or crushing injury
weakest part - just anterior to its angle
lower ribds may result in diaphragmatic hernia

Question 10

flail chest

Answer 10

multiple rib fractures may allow a sizeable segment of the anterior and/or lateral thoracic wall to move freely
loose segment moves paradoxically

Question 11

thoracotomy, intercostal space incisions and rib excision

Answer 11

thoracotomy - surgical creation of an opening through the thoracic wall to enter a pleural cavity
anterior thoracotomy - h shaped cuts through the perichondrium of one or more costal cartilages and shelling out costal cartilage to enter thoracic cavity
posterior thoracotomy incisions - posterolateral aspects of 5th-7th intercostal spaces

Question 12

supernumerary ribs

Answer 12

cervical supernumerary ribs - may interfere with neurovascular structures exiting the superior thoracic aperature
lumbar ribs less common

Question 13

protective function and aging for costal cartilages

Answer 13

costal cartilages provide resilience to the thoracic cage, preventing many blows from fracturing the sternum/ribs
chest compression may produce injury within the thorax even in the absence of a rib fracture

old people- costal cartilages lose elasticity and become brittle; may undergo calcification making them radiopaque

Question 14

ossified xiphoid process

Answer 14

early 40s people notice “pit in stomach” == ossified xiphoid - normal development

Question 15

sternal fractures

Answer 15

not common - seen in traumatic compression of thoracic wall (like in car accidents)
fracture of sternal body usually comminuted fracture (break resulting in several pieces)
displacement uncommon due to investment of deep fascia and sternal attachments of pec major
most common fracture is sternal angle in old people - results in dislocation of the manubriosternal joint
may get heart/lung injury, making these fractures serious af

Question 16

median sternotomy

Answer 16

sternum is divided in the median plane and retracted to gain access to the thoracic cavity for surgical operations in the mediastinum
flexibility of ribs/costal cartilages enables spreading of halves of the sternum

Question 17

sternal biopsy

Answer 17

sternal body often used for bone marrow needle biopsy

for specimens for transplantation/detection of cancer

Question 18

sternal anomalies

Answer 18

develops through sternal bands/bars : fusion of bilateral, vertical condensation of precartilaginous tissue
complete sternal cleft - uncommon, may result in ectopia cordis
sternal foramen - perforation that remains because incomplete fusion
pectus excavatum - funnel chest
pectus cavinatum - pigeon breast
xiphoid commonly perforated in elderly due to age

Question 19

thoracic outlet syndrome

Answer 19

superior thoracic aperture
thoracic outlet - emphasizes arteries and T1 spinal nerves that emerge from the thorax through this aperture to enter lower neck/upper limbs
thoracic outlet syndrome - some occlusion of structures passing the aperture

Question 20

dislocation of ribs

Answer 20

displacement of costal cartilage from the sternum
dislocation of a sternocostal joint - displacement of interchondral joints
common in body contact sports - complications may result from pressure on/damage to nearby nerves, vessels, muscles
patient produces lump-like deformity at displacement site

Question 21

separation of ribs

Answer 21

dislocation of the costochondral junction between rib and costal cartilage
in 3-10 ribs, tearing of the perichondrium and periosteum usually occurs
rib may move superiorly, overriding rib above and causing pain

Question 22

paralysis of diaphragm

Answer 22

caused by injury of phrenic nerve (motor supply) affects only one hemidiaphragm
can be detected by paradoxical movement

Question 23

dyspnea: difficulty breathing

Answer 23

individuals with respiratory problems utilize accessory respiratory muscles to assist the expansion of their thoracic cavity
lean on their knees or on the arms of a chair to fix their pectoral girdle so these muscles can act on their rib attachments and expand the thorax

Question 24

extrapleural intrathoracic surgical access

Answer 24

relatively loos nature of the thin endothoracic fascia provides a natural cleavage plane, allowing surgeons to separate the costal parietal pleura lining the lung from the thoracic wall
allows intrathoracic access to extrapleural structures like LN

Question 25

Herpes zoster infectino of psinal ganglia

Answer 25

zoster virus causes a classic dermatomally distributed skin lesion – shingles – after infecting spinal ganglia
produces sharp burning pain in dermatome supplied by nerve
affected skin becomes red, vesicular eruptions appear

Question 26

intercostal nerve block

Answer 26

local anesthetic of an intercostal space is produced by injected anesthetic around intercostal nerves between paravertebral line and the area of required anesthesia
complete block does not occur unless 2+ intercostal nerves are anesthetized

Question 27

Cardiac catherization

Answer 27

radiopaque catheter is inserted into a peripheral vein and, while being observed, is passed into Right atrium, right ventricle, pulmonary trunk and pulmonary arteries
intracardiac pressures can be recorded and blood samples may be taken

Question 28

embryology of the right atrium

Answer 28

primordial atrium becomes the right auricle - rest of atrium comes from sinus venosus (coronary sinus also comes from this structure)
line of fusion of the primordial atrium and sinus venarum is indicated internally by the crista terminalis and externally by the sulcus terminalis

the SA node is located just in front of the opening of the SVC at the superior end of the crista terminalis – aka the border between the primordial atrium and the sinus venosus - its namesake

before birth, IVC directs most oxygenated blood returning from the placenta in umbilical vein toward foramen ovale to left atrium
at first breath, pressure in left atrium rises enough to close this temporary valve between atria

Question 29

atrial septal defects

Answer 29

congenital anomaly in the interatrial septum, usually incomplete closure of the foramen ovale results in an ASD
left to right shunt
clinically significant ASDs allow oxygenated blood from the lungs to be shunted from the left atrium back into the right atrium
causes enlargement of the RA and RV, dilation of the pulmonary trunk, overwhelming pulmonary circulation

Question 30

ventricular septal defects

Answer 30

the membranous and muscular portions of the interventricular septum develop separately and is the site of VSDs
left to right shunt
large enough shunts will increase pulmonary blood flow, leading to pulmonary disease and eventually cardiac failure

Question 31

percussion of the heart

Answer 31

percussion defines the density and size of the heart
tap the chest with a finger while listening and feeling for differences in sound
3rd, 4th, 5th intercostal spaces from left anterior axillary line to right anterior axillary line
heart will sound dull, other intercostal spaces will resonate

Question 32

stroke or cerebrovascular accident

Answer 32

thrombi form on walls of LA in some heart disease, if they detach/break off and pass into systemic circulation, they may occlude peripheral arteries
occlusion of an artery supplying the brain results in a stroke or cerebrovascular accident (CVA)
affects vision, cognition, or the motor function of parts of the body supplied by ischemic region of brain