Transcript The Thoracic Cavity

The Thoracic Cavity
Boundaries of and Structures Within
Cavities
• Dorsal body cavity
• Ventral body cavity
– Abdominopelvic
• Abdominal
• Pelvic
– Divided by Diaphragm
– Thoracic
• 2 Pleural
• Mediastinum
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Serous membrane = Serosa
• Simple squamous epithelium + areolar connective tissue
• 2 Layers
– Outer layer = PARIETAL serosa
– Inner layer = VISCERAL serosa
• Between them = Serous Cavity containing Serous Fluid
– Serous fluid is blood filtrate + secretions by 2 layers of membrane
– Allows movement of organs with reduced friction
• Types of Serous Membranes
– Pleural = surrounds lungs
– Pericardium = surrounds heart, slightly modified
– Peritoneal = surrounds some abdominal organs
Pleural Cavities
• Surround the lungs
• Pleural fluid secreted by
pleural membranes
• Holds layers together
• Reduces friction of organs
• Compartmentalization
pg 136
Pleural Cavities
• 2 Layers
– Parietal pleura (outer)
• inner surface of
thoracic wall
• superior surface of
diaphragm
• lateral surface of
mediastinum
– Visceral pleura (inner)
• root of lungs marks
transition
• external surface of
lungs
pg 137
Pleural Abnormalities
www.rcjournal.com
• Pleural Effusion
– Excess fluid in the
pleural cavity
– More than 20X
• Usually less than 1 ml
of fluid
• Pneumothorax
– Air located in pleural
space
Pg 210
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Divisions of Mediastinum
•Superior (to heart)
•Contains: thymus, cranial vena
cava, trachea, esophagus
•Inferior
•Anterior (to heart)
•Contains: thymus
•Posterior (to heart)
•Contains: aorta, esophagus,
trachea, bronchi,
caudal vena cava
•Middle
•Contains: heart
pg 153
Boundaries of Mediastinum
• Lateral
– parietal pleura of lungs
• Anterior
– ventral parietal pleura
• Posterior
– dorsal parietal pleura
• Superior
– dome of the neck
• Inferior
– diaphragmatic pleura
pg 136
Respiratory Tract
• Upper Respiratory Tract
– Superior to Larynx
• Lower Respiratory Tract
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Larynx
Trachea
Primary Bronchi
Secondary Bronchi
Rest of Bronchial Tree
Lungs
pg 944
Trachea = windpipe
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Starts at Larynx and travels through mediastinum
Located Anterior to Esophagus
Trachea terminates into 2 primary bronchi entering lungs
Walls contain 16-20 “C” shaped rings Hyaline Cartilage
Trachealis Muscle (smooth muscle and soft CT)
Layers (deep to superficial)
– Mucosa = Ciliated Psuedostratified Epithelium
– Submucosa- contains seromucous glands
– Adventitia – made of connective tissue, contains cartilage rings
Pg 917
Bronchial Tree
• Primary (main) Bronchi
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Bifurcation of trachea
Basically the same structure
Cartilage plates replace rings
Posterior to pulmonary vessels
Right is wider, vertical, shorter
• Secondary (lobar) Bronchi
– Each primary bronchi divides
– Same structure as primary bronchi
– Right lung has 3, Left has 2
• Tertiary (segmental) Bronchi
• Up to 23 divisions
pg 145
Bronchial Tree (continued)
• Bronchioles
– further divisions, < 1 mm diameter
• Terminal Bronchioles
– further divisions, 0.5 mm diameter
• Respiratory Zone
– Respiratory Bronchioles
– Alveolar Ducts
– Alveolar Sacs
• Terminal bunches of Alveoli
• Respiratory exchange chamber
Respiratory Zone (continued)
• Lining the Walls of Alveoli
– Respiratory Membrane
• Type I cells = simple squamous
epithelial cells
• Basal lamina and fine areolar CT
• Covered with capillaries and elastic
fibers
– Gas exchange
• Oxygen into blood
• Carbon Dioxide into alveoli
– Type II cells = cuboidal epithelial
cells
• Secrete fluid containing surfactant
Throughout Bronchial Tree
• Psuedostratified columnar changes to simple columnar to
simple cuboidal
• Cartilage rings replaced by cartilage plates once bronchi
enter the lungs
• Smooth muscle and Elastic fibers remain important
• In Bronchioles
– Ciliated mucosa disappears, replaced by macrophages in alveoli
– Cartilage disappears
– Smooth muscle forms bands around smallest bronchi and
bronchioles (not found around alveoli)
LUNGS (continued)
• Located in Pleural Compartments
• Lateral to Mediastinum
• Location
– Apex posterior to clavicle
– Base lays on Diaphragm
– Costal Surface = Ant, Lat, Post
surfaces contact ribs
• Left Lung = 2 lobes
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Upper
Lower
Oblique Fissure
Cardiac Notch
• Right Lung = 3 lobes
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Upper
Middle
Lower
Oblique fissure
Horizontal fissure
pg 145
LUNGS
• Hilus- medial indentation
• Root of Lung = structures
enter each lung
– 2 Pulmonary Veins =
carries O2-rich blood from
each lung to heart
– 1 Pulmonary Artery =
carries O2-poor blood to
each lung
– Primary Bronchus
– Nerves
– Lymph Vessels
pg 141
Specific Location of Lungs
• Right Lung
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1” above Rib 1
Crosses Costal Cartilage 6
Midclavicular at Rib 6
Midaxillary at Rib 8
Vertebral Border at Rib 10
Inferior border 2 rib widths
above diaphragm
• Left Lung
– 1” above Rib 1
– Deep to Manubroclavicular
joint
– Midsternally to Rib 4
– Jogs to left, continues to
Rib 6
– Midaxillary Rib 8
– Vertebral Border at Rib 10
Lung Lobes
• Lobes are anatomically +
functionally separate
• Lung lobes divided into
Lobules
– Functionally separate
– Separated by dense CT
– Vary in size
• Stroma = lung tissue
– CT
– Many elastic fibers
pg 155
Esophagus
• Esophagus
– Pharynx to Stomach
– Passes thru diaphragm at esophageal hiatus
– Anterior to vertebrae, Posterior to trachea
• Layers of Esophagus (deep to superficial)
– Mucosa
• Stratified squamous epithelium
• Lamina propria (loose CT)
• Muscularis mucosae
– Submucosa
• Loose connective tissue
• Secretes mucus
– Muscularis Externa
• Circular/Longitudinal layers
• Skeletal m, Mix, then Smooth m
– Adventitia
• Fibrous CT
pg 139
The Diaphragm
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Skeletal Muscle
Dome-shaped (relaxed)
Flattens (contracts)
Divides thoracic &
abdominopelvic cavities
• Attachments
– O: Inferior Internal rib cage,
Lumbar vertebrae (by crura)
– I: Central tendon
• Innervated by right + left
PHRENIC Nerves
pg 114
Action of the Diaphragm
• Primary muscle of respiration
(involuntary)
– Contraction during inspiration
• Increases volume of thoracic cavity
• Decreases pressure of thoracic cavity
• Air moves into lungs (highlow
pressure)
• Forced contraction (voluntary)
– Used for defecation, urination, labor
• Decreases volume of abdominal
cavity
• Increases pressure in abdominal cavity
• Pushes on abdominal organs to move
contents out
pg 114
Thoracic Cavity Capacity is Increased by:
• Contraction of
diaphragm
• Intercostal muscles
elevate ribs
• Rib elevation
causes the sternum
to move anteriorly
pg 113
Openings of Diaphragm
• PosteriorAnterior
• Aortic Hiatus
– Aorta
– Azygos vein
– Thoracic duct
• Esophageal Hiatus
– Esophagus
– Vagus nerve
• Caval Opening
– Inferior Vena Cava
– Right Phrenic Nerves
pg 134
Vena Cava
• Superior Vena Cava
– in Superior mediastinum,
right side
– Receives blood from regions
above diaphragm
– Formed from Rt + Lft
Brachiocephalic Veins
cranially
– Azygos Vein empties into it
just superior to heart
– Empties into Right Atrium
• Inferior Vena Cava
– in Inferior mediastinum
(right side), runs through
abdomen
– Returns blood to heart from
regions below diaphragm
– Formed from Rt + Lft
Common Iliac Veins
– Empties into Right Atrium
– Widest blood vessel in body
Veins of Thoracic Cavity
• Vena Cavae
• Azygos Vein
– “unpaired”
– right side of vertebral
bodies (at level of T12)
– runs superiorly
– empties into Sup. Vena
Cava
– drains right posterior
intercostal veins
– Connects to hemiazygos
and accessory
hemiazygos that drain
left side
pg 131
The Lymphatic Vessels
• Function: to collect excess tissue fluid collecting at
arteriole end of capillary beds, and return leaked blood
proteins to blood (maintain osmotic pressure needed to
take up water into bloodstream)
• Lymph is moved through vessels
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Pulse of nearby arteries
Contraction of surrounding skeletal muscle
Regular movement of body (wiggling legs)
Muscle in Tunica Media
• Lacteals-lymphatic capillaries w/unique function
– In mucosa of small intestine, receive digested fat from intestine
– Fatty lymph becomes milky = Chyle
– Chyle goes to bloodstream
Lymphatic System…The Players:
• Lymph- clear fluid from loose CT at capillaries
– Contains small molecules of blood plasma, water, various
ions, nutrient molecules, respiratory gases
• Lymphatic capillaries (near blood capillaries) 
• Lymph collecting vessels (small, 3 tunicas, #
valves)
• Lymph nodes (sit along collecting vessels)-clean
lymph of pathogens, they are NOT glands
• Lymphatic trunks (convergence large collecting
vessels)
• Lymphatic ducts  empty into veins of neck
Lymphatic Ducts
• Thoracic Duct
– Receives lymph from large
trunks in abdomen and
thorax
– Receives lymph from ducts
of thoracic lymph nodes
– Along vertebral bodies
– Contain valves to ensure 1way flow of lymph to
lymph nodes
– Drains into left
Brachiocephalic Vein (or
subclavian or int. jugular
veins)
pg 132, 150
Thymus Gland
• Lymphatic Organ
• 2-lobed w/lobules
• Sits on heart and great
vessels
• Immature lymphocytes
mature into T-lymphocytes
• Secretes Thymic Hormones:
help T-lymphocytes gain
immunocompetence
• Decreases in size w/age
• Functional tissue is replaced
with fatty tissue
pg 183
Thymus Gland
• Increases in size
during childhood
• Decreases in size
during adulthood
• Contains lobes and
lobules
– Capsule
– Cortex
– Medulla