Chapter 3: The Thorax Flashcards
what is the superior thoracic aperature open to?
open to the neck
what is the inferior thoracic aperature closed by?
the diaphragm
what are the flexible walls of the thorax formed by?
the musculoskeletal system (ribs, verts, sternum, muscles)
L and R pleural cavities surrounding lungs and mediastinum
thoracic cavity
*one of the most important functions of the thorax
breathing
what parts of the thoracic region are involved in breathing?
diaphragm
thoracic walls
ribs
provides major change in thoracic volume
diaphragm
changes in lateral and anterior dimensions of thorax during breathing
thoracic walls
what does the thorax house?
houses not only lungs, heart, and great vessels but also much of the liver, stomach, and spleen
- acts as a conduit for structures that pass through the thoracic cavity or connect to structures in the thoracic cavity
- houses the heart
the mediastinum
consists of skeletal and muscle elements
thoracic wall
what does the thoracic wall consist of posteriorly?
12 thoracic vertebrae and intervertebral discs
what does the thoracic wall consist of laterally?
ribs and intercostal muscles
what does the thoracic wall consist of anteriorly?
sternum (manubrium, body of the sternum, xiphoid process)
composed of costal cartilage
Anterior (distal) end of ribs
what do ribs articulate with?
thoracic vertebrae
how many articulations do ribs have with vertebral column?
most have 3
are classified as true, false, and floating
ribs
Bordered by vertebrae T1, medial margin of 1st rib, and manubrium
superior thoracic aperature
what is the plane of the thoracic aperture?
oblique
how do the first ribs slope?
inferiorly
what lies on either side of the entrance to the mediastinum at the aperture?
superior aspects of the pleural cavities
what do structures that pass between the thorax and limb pass over?
the pleural cavity and 1st rib
how do structures that pass to the neck go?
pass more vertically
what is a central line put in?
subclavian vein?
how is the superior thoracic aperture sloped?
Sloped downward so posterior attachment is more superior than the anterior attachment
- Large and expandable, closed by the diaphragm
* hole going into the abdomen
inferior thoracic aperture
how do structures that pass to the abdomen go?
pierce or pass posteriorly to the diaphragm
arise radially from margins and converge into a large central tendon
fibers in the inferior thoracic aperture
what are the skeletal elements that form the boundaries of the inferior thoracic aperture?
- Body of vertebrae TXII posteriorly
- Rib XII and distal end of rib XI posteriorly (floating ribs)
- Distal cartilaginous ends of rib VII-X that unite and form anterolateral border
is inferior to the anterior margin of the inferior thoracic margin
the posterior margin
how is the inferior thoracic aperture tilted?
superiorly
*houses heart and big vessels
mediastinum
- extends from sternum to thoracic vertebrae, from super thoracic aperture to inferior aperture
- most important plane in the body
- A plane through the sternal angle and intervertebral disc of TIV and TV separates the superior and inferior mediastinum
midline partition
what is the inferior mediastinum divided by?
pericardial cavity (middle mediastinum) which surrounds the heart
lies between sternum and pericardium
Anterior mediastinum
lies between the pericardium and the thoracic vertebrae
Posterior mediastinum
Situated on either side of the mediastinum
pleural cavities
What does each lung grow out of during development?
mediastinum
covered by visceral pleura membrane
the lungs
is attached to mediastinum by root (airway, blood vessels, lymphatics, nerves
the lungs
lines the pleural cavities
parietal pleura
exists between lungs and thoracic cavity wall
a potential space
exist from spaces not filled with lung
recesses
extend 2-3 cm into neck
pleural cavities
opens into the root of the neck
superior thoracic aperture
separates the thoracic and abdominal cavities
diaphragm
pierces the central tendon and enters right side of mediastinum
inferior vena cava
exits mediastinum and enters muscular part of diaphragm left of midline
esophagus
passes posteriorly to the diaphragm at midline
aorta
where do structures that pass between the thorax and abdomen go?
pass either through or posterior to the diaphragm
- secretory glands, superficial fascia, and overlying skin
* Found in the pectoral region on each side of thoracic wall
breasts
supply anteromedial parts of breast
Branches from internal thoracic arteries and veins perforate thoracic wall
from medial side of breasts and accompany perforating vessels
lymphatics
vessels and lymphatics drain in axiallary region
from lateral side of breast
carry sensation to skin of breast
Lateral and anterior branches of 4th-6th intercostal nerves
what does the plane in the mediastinum mark?
- Boundary between superior and inferior mediastinum
- Beginning and end of aortic arch
- Site where vena cava pierces pericardium
- Bifurcation of trachea
- Superior limit of upper pulmonary trunk`
enters the right of the heart
deoxygenated blood
where does blood from the left side of the body go?
must be shunted across the midline
how is blood from left side of head, neck and left arm moved across the midline?
the left brachiocephalic vein
drained by the hemiazygous and accessory hemiazygous veins
Most of the left thoracic wall
arise from the aorta and internal thoracic arteries
intercostal branches
run with intercostal vessels
intercostal nerves
arise from anterior rami of thoracic spinal nerves
intercostal nerves
reflect the segmental arrangement of thoracic spinal nerves
Dermatomes of skin
innervates mostly the upper arm
first thoracic spinal nerve
innervated by the spinal nerve of C4
the superior part of trunk
follows contours of ribs
Dermatome of T7-T12
arise from spinal nerves T1-L2
All preganglionic nerve fibers of the sympathetic system
why is the thoracic wall explandable?
due to ribs true joints with other aspects of thoracic wall and shape and orientation of ribs
why does the sternum move forward in inspiration?
Because the posterior attachment of the rib is superior to the anterior attachment
why does the thorax expand laterally during inspiration?
Because the middle part of the rib is below both anterior and posterior attachments
expands the thorax inferiorly during inspiration
the diaphragm
innervated by the phrenic nerve
the diaphragm
arises from the brachial plexus (C3-C5)
phrenic nerve
where does the phrenic nerves pass through?
neck, superior thoracic aperture and into the mediastinum
- External to the anterior thoracic wall
* Anchors and supports the upper limb
pectoral region
found in the superficial compartment anterior to the pectoral muscles
mammary glands
what does the breast consist of?
- 15-20 lactiferous ducts
- Nipple
- Areola
- Well defined suspensory ligaments are continuous with the dermis and support the breast
what is the breast made of mostly in non-lactating women?
fat
what is the breast made of in lactating women?
glandular tissue
what is the lateral arterial supply of the breast?
- axillary
- superior thoracic
- thoraco-acromial
- lateral thoracic
- subscapular
parallels arterial supply in the breasts
venous drainage
what is the innervation of the breast?
branches from 2nd-6th intercostal nerves
what are the lymphatics involved in the breast?
- axillary nodes
* parasternal nodes
enclosed in the clavipectoral fascia
The subclavius and pectoralis minor
- origin is the:
- medial half of clavicle
- anterior surface of sternum
- first 7 costal cartilages
- aponeurosis of external oblique
origin of pectoralis major
insertion is the lateral lip of intertubercular sulcus of humerus
pectoralis major
innervated by medial and lateral pectoral nerves
pectoralis major
function is adduction, medial rotation and flexion of humerus at shoulder joint
pectoralis major
originates at rib 1 at junction between rib and costal cartilage
subclavius
inserts at the groove on inferior surface of middle third of clavicle
subclavius
innervated by nerve to subclavius
subclavius
- functions to:
- pull clavicle medially
- stabilize sternoclavicular joint
- depress tip of shoulder
subclavius
originates at the anterior surface of the 3rd-5th ribs, deep fascia overlying the related intercostal space
pectoralis minor
insertion at the caracoid process of scapula
pectoralis minor
innervated by medial pectoral nerves
pectoralis minor
- functions to:
- depress tip of shoulder
- protracts scapula
pectoralis minor
what is the skeletal framework of the thoracic wall like?
segmented in design
bordered by vertebrae TI, rib 1, manubrium
superior thoracic aperture
bordered by vertebrae TXII, rib XII, end of rib XI, costal margin (see fig 3.20) and xiphoid process of the sternum
inferior thoracic aperture
heart shaped vertebral body, and articulates with ribs
thoracic vertebrae
what facets do thoracic vertebrae have?
most have superior costal facet, inferior costal facet, and transverse costal facets
lack inferior demifacets on vertebral body (only articulate with their own rib)
Vertebrae TI and TX (and often TIX)
articulate only with the heads of their own ribs and lack transverse costal facets
Vertebrae TXI and TXII
- each terminates into a costal cartilage anteriorly
* All attach posteriorly to a thoracic vertebrae
ribs
articulate directly with sternum
first 7 ribs (true ribs)
articulate anteriorly with the costal cartilages of the ribs above
ribs VIII-X
floating ribs
ribs XI and XII
what does the typical rib consist of?
curved shaft with anterior and posterior ends
terminates into costal cartilage
anterior end of rib
- articulates with thoracic vertebrae
* characterized by head, neck, and tubercle
posterior end of rib
somewhat expanded and has 2 articular surfaces separated by a crest
the head of ribs
articulates with vertebrae above
smaller superior facet of head of ribs
articulates with its own vertebrae
larger inferior facet of head or ribs
bends forward at the angle
shaft of ribs
marked by a costal groove
inferior margin of rib
what are the atypical ribs?
- rib I
- rib II
- rib X
- rib XI and XII
flat in horizontal plane with broad inferior and superior surfaces
rib I
flat but tice as long, articulates to vertebrae in usual way
rib II
head has single facet for articulation to its own vertebra only
rib X
short, little curve, no tubercles or necks
ribs XI and XII
Slopes down to manubrium, only articulates with vertebrae TI and therefore only has 1 articular surface
rib I
separates 2 smooth grooves that house the subclavian vein and artery (in rib I)
scalene tubercle
shaft is roughened by muscle and ligament attachment (of rib I)
Anterior and posterior to groove
- forms part of bony framework of thorax and neck
* part of sternum
manubrium
what are the components of the manubrium?
- Jugular notch, articular sites for clavicle and rib 1
* Demifacet for articulation with upper half of anterior end of 2nd costal cartilage
- components:
- demifacet for lower half of 2nd costal cartilage
- articular facets for ribs III-VI
- demifacet for articulation of upper half of 7th costal cartilage
- transverse ridges
body of sternum
- variable in shape, demifacet for articulation with inferior end of 7th costal cartilage
- part of sternum
xiphoid process
what does a typical rib articulate with?
- Bodies of adjacent vertebrae, forming a joint with the head of the rib
- The transverse process of its related vertebrae, forming a costotransverse joint
formed when a rib articulates with the transverse process of its related vertebrae
costotransverse process
*2 synovial joints formed (1 between each other demifacets of adjacent vertebrae)
joint with head of rib
separates the 2 synovial joints at head of rib
intra-articular ligament
surrounded by a single joint capusle
synovial joints at head of rib
- synovial joint
* stabilized by costotransverse, lateral costotransverse, and costotransverse ligaments
costotransverse joint
Joints between upper 7 costal cartilages and sternum
sternal joints
- consists of a fibrocartilagenous connection
* not synovial joint
joint between rib 1 and manubrium
what are kind of joint are the joints of ribs II-VII?
synovial joints
divided into 2 compartments by an intra-articular ligament
joint of rib II
what kind of joints are interchondral joints?
synovial joints
what kind of joints are manubriosternal and xiphisternal joints?
symphyses
lie between adjacent ribs and are filled with muscle
intercostal spaces
lie in the costal groove of the superior rib and lie in the plane of the inner 2 layers of muscle
Intercostal nerves and associated major arteries and veins
often lie superior to the inferior rib
Small collateral branches of the intercostal nerves and vessels
separates parietal pleura from ribs and intercostal space
endothoracic fascia
what are the types of intercostals?
- externals
- internals
- innermost
- 11 pairs
- fibers run obliquely anterioinferiorly
- extend from tubercles of ribs to costal cartilages *extend to costal cartilages via external intercostal membrane
externals (intercostals)
- 11 pairs
- fibers run obliquely posteroinferiorly
- extend from parasternal region to angle of rib posteriorly, where it continues as internal intercostal membrane
internal intercostals
deepest layer of intercostals
innermost
- in the same plane as the innermost intercostals
- spans multiple ribs
- more numerous in the lower regions of the posterior wall
subcostales and transverse thoracis
- found on the deep surface of the anterior thoracic wall
- in the same plane as the innermost intercostals
- lies deep to thoracic vessels and secures them to thoracic wall
transverse thoracis
superior attachment is the inferior margin of the rib above
external intercostal
inferior attachment is the superior margin of the rib below
external intercostal
innervated by intercostal nerves T1-T11
external intercostal, internal intercostal, innermost intercostal
moves the ribs superiorly during inspiration
external intercostal
superior attachment is the lateral edge of costal groove of the rib above
internal intercostal
inferior attachment is the superior margin of the rib below, deep to the attachment of related external intercostal
internal intercostal
moves ribs inferiorly during expiration
internal intercostal
superior attachment is the medial edge of costal groove of rib above
innermost intercostal
inferior attachment is the internal aspect of superior margin of the rib below
innermost intercostal
acts with internal intercostal muscles to move ribs inferiorly during expiration
innermost intercostal
superior attachment is the internal surface of the lower rib
subcostales
inferior attachment is the internal surface of second or third rib below
subcostales
innervated by related intercostal nerves
subcostales and transverse thoracis
may depress the ribs
subcostales
superior attachment is the inferior margins and internal surfaces of costal cartilages of 2nd to 6th ribs
transverse thoracis
inferior attachment is the inferior aspect of deep surface of body of sternum, xiphoid process, costal cartilages of ribs IV-VII
transverse thoracis
depresses costal cartilages
transverse thoracis
arise from aorta and internal thoracic artery respectively, forming basket like blood supply
Posterior and anterior intercostal arteries
what are other important arterial branches?
- supreme intercostal artery
- costocervical trunk
- subclavian
- anterior perforating branches
- collateral branches
- superior epigastric
- musculophrenic
generally parallels arterial supply
venous drainage
what are the exceptions to normal venous drainage?
- azygous
- hemiazygous
- accessory hemiazygou
- left and right superior intercostal veins
drain mainly into lymph nodes associated with intercostal arteries (parasternal nodes), head and neck of ribs (intercostal nodes), and diaphragm (diaphragmatic nodes)
Lymphatics of the thoracic wall
drain into bronchomediastinal trunks
parasternal and upper thorax intercostal nodes
drain into thoracic duct
lower thorax intercostal nodes
interconnect with parasternal nodes
diaphragmatic nodes
what do intercostal nerves provide?
- Somatic motor innervation for intercostal muscles
- Somatic sensory innervation for skin and parietal pleura
- Postganglionic sympathetic fibers to periphery
