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Transcript
The Thoracic Cavity
Boundaries of and Structures Within
Remove frame
Body Cavities
• Dorsal body cavity
• Ventral body cavity
– Thoracic
• 2 Pleural
• Mediastinum
– Divided by Diaphragm
– Abdominopelvic
• Abdominal
• Pelvic
www.newworldencyclopedia.org/entry/Body_cavity
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
• Benefit of Compartmentalization
pg 159
Pleural Cavities
• 2 Layers
– Visceral pleura (inner)
• root of lungs marks transition
• external surface of lungs
– Parietal pleura (outer)
• inner surface of thoracic wall
• superior surface of diaphragm
• lateral surface of mediastinum
pg 161
Pleural Abnormalities
• 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 238
Divisions of Mediastinum
•Superior (to heart)
•Contains: thymus, cranial vena cava, trachea,
esophagus, nerves
•Inferior
•Anterior (to heart)
•Contains: thymus
•Posterior (to heart)
•Contains: aorta, esophagus,
nerves, caudal vena cava,
•Middle
•Contains: heart + pericardium
pg 177
trachea, bronchi,
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 159
Respiratory Tract
• Upper Respiratory Tract
– Superior to Larynx
• Lower Respiratory Tract
–
–
–
–
–
–
Larynx
Trachea
Primary Bronchi
Secondary Bronchi
Rest of Bronchial Tree
Lungs
pg 992
pg 168
Trachea = windpipe
•
•
•
•
•
•
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 966
Bronchial Tree
• Primary (main) Bronchi
–
–
–
–
–
Bifurcation of trachea
Basically the same structure
Cartilage 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 168
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
• Among alveoli are blood vessels, nerves, lymphatics
www.nlm.nih.gov/.../ency/imagepages/1103.htm
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
– Type II cells = cuboidal epithelial cells
• Secrete fluid containing surfactant
– Dust Cells (macrophages)
• Gas exchange
– Oxygen into blood
– Carbon Dioxide into alveoli
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
–
–
–
–
Upper
Lower
Oblique Fissure
Cardiac Notch
• Right Lung = 3 lobes
–
–
–
–
–
Upper
Middle
Lower
Oblique fissure
Horizontal fissure
pg 168
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
– Nerve plexus
– Lymph Vessels
pg 164
Lung Lobes
• Lobes are anatomically + functionally separate
• Lung lobes divided into Lobules
– Functionally separate
– Separated by dense CT
– Vary in size
• Stroma = lung tissue
– Areolar CT
– Many elastic fibers
pg 178
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 212
The Diaphragm
•
•
•
•
•
Skeletal Muscle
Dome-shaped (relaxed)
Flattens (contracts)
Divides thoracic & abdominopelvic cavities
Attachments
– O: Inferior Internal rib cage, Lumbar vertebrae (by
crura)
– I: Central tendon
pg 136
• Innervated by right + left PHRENIC Nerves
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 136
Thoracic Cavity Capacity is Increased by:
• Contraction of diaphragm
• Intercostal muscles elevate ribs
• Rib elevation causes the sternum to move
anteriorly
pg 135
Openings of Diaphragm
• PosteriorAnterior
• Aortic Hiatus
– Aorta
– Azygos vein
– Thoracic duct
• Esophageal Hiatus
– Esophagus
– Vagus nerves
• Caval Opening
– Inferior Vena Cava
– Right Phrenic Nerve
pg 157
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 153
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
• Contains lobes and lobules
pg 206
– Capsule
– Cortex
– Medulla