anatomy 3.1

the thorax wall is formed by the

thoracic vertebrae, ribs, sternum, and associated muscles, providing protection and flexibility

the thorax cavity contains

lungs, heart and major vessels and is divided into the two pleural cavities and the mediastinum

the thoracic wall and diaphragm change thoracic volume to

facilitate respiration

the thorax serves as an important passageway between

the neck and abdomen for major vessels, nerves, the trachea and esophagus

thorax cavity is divided into

2 pulmonary cavities and the mediastinum

the superior aperture opens to the neck and diaphragm closes the thorax inferiorly

during deep inspiration the lung expands into the

costodiaphragmatic recess

fluid can accumulate here

look at slide 9 axilla

resonance is produced when

percussing lung fields and flatness over solid organs

true ribs

1-7 attach directly to sternum via costal cartilages

false ribs

8-10

attach the costal margin

floating ribs

11-12 no anterior attachment

jugular (suprasternal notch)

superior border of manubrium

sternal angle (angle of louis)

manubriosternal joint; level of 2nd costal cartilage and T4-T5 IV disc

xiphisternal joint

level of T9 vertebra

marks the level of the central tendon of diaphragm and inferior border of the heart

ribs 3-9 are typical and have the following features

head

neck

tubercle

superior and inferior articular facets

body or shaft

angle

costal groove

costal cartilage

flail chest

multiple fractures involving adjacent ribs can create a free-moving segment of the chest wall, resulting in a paradoxical movement during inspiration

rib fractures commonly occur near the

costal angle

fracture can injure underlying intercostal vessels, nerves or lung

atypcial ribs

1,2, 10-12

rib 1 features

broad flat, mostly sharply curved

grooves for subclavian vessels

one articular facet

scalene tubercle

rib 2 features

tubercules

ribs 10-12 have a single

articular facet on the rib head

ribs 11 and 12

are floating so no necks or tubercles

costovertebral joints

rib heads to thoracic vertebral bodies

costotransverse joints

rib tubercles to transverse processes

costochondrial joints

ribs to costal cartilages

sternocostal joints

costal cartilages to sternum

interchondral joints

between adjacent costal cartilages

manubriosternal and xiphisternal joints

between parts of the sternum

pectus carinatum

pigeon chest

pectus excavatum

funnel chest

breast usually extend vertically

from 2nd-6th rib and from the sternum to midaxillary line

breasts are composed of

mammary glands, adipose tissue and suspensory (cooper) ligaments

mammary glands are

modified sweat glands organized into lobes and lobules

each lobe of breast drains through a

lactiferous duct, which opens at the nipple

dermatome of nipple

T4 which is innervated by 4th intercostal nerve

areola is the

pigmented area surrounding the nipple and contains specialized sebaceous glands

about 2/3rds of the breast

overlies pec major and the remaining portion overlies serratus anterior

the breast is separated from the pectoral fascia by the

retromammary space

the retromammary space contians

LCT allowing breast to move freely over the chest wall

this is the location of breast implants or cardiac pacemakers

most of breast cancers arise from

the epithelium of ducts or lobules of the mammary gland

tumor invasion of suspensory (cooper) ligaments may

shorten the ligaments producing skin dimpling or distortion

intercostal muscles

support and stabilize the intercostal spaces during respiration

prevent bulging during expiration and retraction during inspiration

act mainly isometrically during quiet breathing

assist with rib movement during forced inspiration and expiration

external intercostal muscles

extend from rib tubercles to costochondral junction

fibers run "hand in pockets"

elevate ribs and expand the thoracic cavity during inspiration

internal intercostals

extend from sternum to rib angles

fibers run inferoposteriorly

depress ribs during forced expiration

interchondral part may assist in elevating ribs

transversus thoracis muscle

located on internal surface of anterior thoracic wall

extends from posterior sternum to costal cartilages (2-6)

weakly depresses the ribs assists in forced expiration

fibers from transversus thoracis muscles run

superolaterally and are continuous inferiorly with transversus abdominis

COPD patients may recruit accessory respiratory muscles to assist breathing like

pec major/minor, scalene and serratus anterior

posterior intercostal arteries

1 and 2 are from supreme intercostal artery

3-11 are from thoracic aorta

they travel with intercostal vein and nerve in costal groove (VAN)

anterior intercostal arteries

1-6 are from internal thoracic artery

7-9 are from musculophrenic artery

absent in 10 and 11 spaces

they also anastomose with posterior intercostal arteries

venous drainage for anterior intercostal veins

anterior intercostal veins-> internal thoracic veins-> brachiocephalic veins

venous drainage for posterior intercostal veins

mainly azygos/hemiazygos system-> superior vena cava

how many intercostal nerves

11

they are from the anterior rami of T1-T11

T12 forms the subcostal nerve

the intercostal nerves travel between the

internal and innermost intercostal muscles in the costal groove

main neurovascular bundle is arranged in

VAN from superior to inferior

collateral branches of intercostal nerves run

along the superior border of the rib below

internal nerves carry

motor, sensory and sympathetic fibers to intercostal muscles, skin, blood vessels, sweat glands and arrector pilli muscles

C3,C4,C5 dermatomes

neck and shoulder

T4 dermatome

nipple line

T6 dermatome

xiphoid process

T10 dermatome

umbilicus

Intercostal nerve block

local anesthetic is injected around the intercostal nerve and its collateral branches between the paravertebral line

diaphragm

a dome-shaped musculotendinous structure that separates the thoracic and abdominal cavities

consists of right and left domes with muscle fibers converging on a central tendon

the right dome lies slightly higher than

the left bc of liver

diaphragm functions as the

primary muscle of inspiration

motor innervation to diaphragm is

phrenic nerve (C3-C5)

during inspiration the diaphragm

contracts and descends, increasing thoracic volume

rib movements also change the

dimensions of the thoracic cavity during breathing

during inspiration the rib cage

expands vertically, laterally and in the anterioposterior dimensions

during expiration it contracts

pump-handle movement

mainly upper ribs-> increases anteroposterior diameter

bucket-handle movement

mainly lower ribs-> increases transverse diameter

diaphragm contraction

increases the vertical diameter of the thoracic cavity

hemidiaphragm

paralysis of half of the diaphragm bc of injury to phrenic nerve

visceral pleura

on organ

parietal pleura

part on outside

pleural cavity

potential space between the pleuras

pneuomothorax

entry if aur into the pleural cavity from either penetrating trauma or rupture of pulmonary lesion

this will cause the lung to collapse

atelectasis

collapsed lung

where do you insert the chest tube

4th to 5th ICS in anterior axillary or midaxillary line

also must be upper border of rib

hemothorax

shown with blood in costodiaphragmatic recess

different parts of parietal pleura

costal

mediastinal

diaphragmatic

the suprapleural membrane (Sibsons fascia)

is an extension of the endothoracic fascia

it covers the superior surface of the cervical pleura

provides apical support for the pleura in the root of the neck

endothoracic fascia

is a loose connective tissue layer separating the parietal pleura from the internal surface of the thoracic wall

provides a cleavage plane during thoracic surgery

parietal pleura is innervated by

somatic afferent fibers and may produce local pain or referred pain

the costal pleura is innervated

branches from the intercostal nerves

pain would be felt in relation to dermatomes of thoracic and abdominal walls

the diaphragmatic pleura and mediastinal pleura are innervated by

phrenic nerve

pain would refer to C3,4,5 dermatomes which would be lateral neck and supraclavicular region

visceral pleura is believed to be insensitive to

pain

afferent detect stretch

pleuritis inflammation of pleura will cause

sharp stabbing pain of the chest wall upon inspiration

a friction rub can be auscultated

adhesion between parietal and visceral pleura may form

mid clavicular line lung and visceral pleura and parietal pleura

lung and visceral: 6th rib

parietal pleura: 8th rib

mid axillary line lung/visceral pleura and parietal pleura

lung and visceral: 8th

parietal: 10th

scapular line lung and visceral pleura and parietal pleura

lung and visceral: 10th rib

parietal pleura: 12th rib

visceral and parietal pleura are separated in regions that

are not occupied by lungs during quiet respiration, resulting in recesses or potential spaces

these allow for lung expansion during forced inspiration

the costomediastinal recess is located

anteriorly where the costal pleura and mediastinal pleura meet

clinically the most important recess is the

costodiaphragmatic recess. this enlarges during expiration

fluid can pool here

what can become injured during thoracentesis in costdiaphragmatic recess

diaphragm and liver on the right

diaphragm and liver on the left

how many lobes does the right lung have

3 lobes which are separated by horizontal and oblique fissures

the left lung has

2 lobes and is separated by oblique fissure

the lingula is an

extension of the superior lobe of left lung

the oblique fissure begins at level of

the spine of T2/T4 passes 5th ICS at midaxillary line then follows contour of rib 6 anteriorly

the horizontal fissure extends from the

oblique fissure crosses rib 5 MAL then follows the contour of rib 4 anteriorly

the oblique fissure also follows the contour of the

medial border of scapula in the abducted position and can be used as a guide for identifying superior vs inferior lobes