Thorax
Thoracic Cavity
3 parts: 2 pleural cavities and the mediastinum
parietal pleurae line inside of thoracic cavity
visceral pleurae cover exterior of lung
pleural cavity is potential space between the 2 pleurae
right and left pleural cavities do not communicate
3 surfaces to each lung: diaphragmatic, costal, mediastinum
internal jugular vein and subclavian vein Þ brachiocephalic right and left Þ superior vena cava
Lung Morphology
tracheal buds Þ right lung and left lung
- right lung
- 3 lobes: superior, middle, inferior
- horizontal and oblique fissure
- PA and bronchus are side by side
- left lung
- 2 lobes: superior, inferior
- oblique fissure
- PA is superior to bronchus
- hilus: area in space where things are entering and leaving lung
- root of lung: anything entering or leaving the lung
trachea Þ right and left primary bronchi Þ lobar bronchi Þ segmental bronchi (10 segments each with own vascularization)
bronchial arteries and veins vascularize lungs
veins are anterior and inferior to arteries
Autonomic Innervation
sympathetic
- from T1-T4
- cause vasoconstriction and dilation of bronchioles
parasympathetic
- from vagus nerve
- opposite effect of above
Miscellaneous
objects preferentially lodge in the right primary bronchi
° off the vertical and longer
right is 20° off the vertical and wider
carina (cartilaginous) also directs it right
Thoracic Structures
body - weight bearing portion
pedicle - two roots attach to flat plates (laminae)
lamina - flat plate; two
transverse process - two, from pedicle lamina joint; point laterally
articular processes - point superiorly and inferiorly; attach adjacent vertebral arches
spinous process - projects posteriorly in medial plane
vertebral foramen - hole; forms vertebral canal
vertebral canal - canal where spinal cord runs
intervertebral foramen - between pedicles of adjacent vertabrae
Rib
head - joint with vertebrae (i.e. rib five with T4 and T5)
neck
tubercle - articulates with transverse process of vertabra with same number
body
costal groove - runs on inferior edge for nerve and vessels
Sternum
manubrium - superior part, junction of first rib
body - middle part; junction of ribs 2-7; 7-10 through cartilage; 11,12 floating
xyphoid process - inferior part
jugular notch - at superior end of manubrium
sternal angle - joint of manubrium and body; junction of second rib
Other surface features
clavicle
acromion - point of shoulder
caracoid process
Skin
epidermis
dermis
superficial fascia - contains fat, blood vessels, superficial nerves
deep fascia - covers muscle, same as epimyseum
reticula cutis - connective tissue connects skin and deep fascia
Breast
- modified sweat glands; lie in superficial fascia
retromammary space - loose connective tissue space between deep fascia and mammary glands
- allows mammary gland to move freely (i.e. no attachment between deep fascia and gland
suspensory ligaments - pass from deep fascia to skin; boundaries of fat containing compartments
nipple
areola - pink area around nipple
lactiferous ducts - 15-20; drain glandular lobules, open on nipple via lactiferous sinuses
platysma - muscle of facial expression
seratus anterior
origin: upper 8 ribs
insertion: costal surface of scapula at medial border
innervation: long thoracic nerve
action: draws scapula forward (when pushing); rotates scapula (during abduction)
cutaneous branches of spinal nerves: innervate subcutaneous tissue
- anterior cutaneous twigs - emerge just lateral to sternal margin and run laterally
- lateral cutaneous branches (anterior and posterior) - emerge from intercostal space and pass between digitations of seratus anterior; run anteriorly and posteriorly
- intercostobrachial nerve - lateral cutaneous nerve of T2; innervates subcutaneous tissue of back and medial side of arm
pectoralis major
- origins: sternocostal head and clavicular head
- insertion: intertubercular groove of humerus
- innervation: lateral pectoral nerve and medial pectoral nerve
- action: adduction and medial rotation of arm
deltopectoral triangle - junction of pectoralis major and deltoid
cephalic vein - runs along deltapectoral triangle; drains into axillary vein
lateral pectoral nerve - medial to pectoralis minor
medial pectoral nerve - pierces pectoralis minor; is lateral to lateral pectoral nerve
clavipectoral fascia - covers the pectoralis minor
pectoralis minor
- origin: ribs 3,4,5
- insertion: coracoid process of scapula
- innervation: medial pectoral nerve
- action: draws scapula forward and downward as in adduction
subclavius - slender muscle immediately inferior to the clavicle
axillary vein
thoracoacromial artery - a branch of the axillary artery
lateral throacic artery - lateral to pectoralis minor, runs on outside of lateral throracic wall intercostals
intercostal muscles
- external - direction is ‘hands in pockets’; turn into external intercostal membranes near sternum
- origin: inferior border of rib
- nsertion: superior border of rib
- action: elevate ribs during inspiration
- internal - oriented 90 degrees to externals
- origin: superior border of rib
- insertion: inferior border of rib
- action: draw adjacent ribs together during forced expiration
- innermost
intercostal nerves, intercostal vessels - supply intercostal muscles; run between internal and innermost intercostal muscles
parietal pleura
anterior thoracic wall
- internal thoracic artery - runs lateral to internal thoracic vein
- internal thoracic vein - runs medial to internal thoracic artery
- anterior intercostal branches - branches of internal thoracic vessels
- transversus thoracis - on posterior surface of anterior wall
- sternocostal joints
- synovial cavity - in sternocostal joint