4 - thoracic cavity grays

7/30/2019 4 - Thoracic Cavity Grays

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The Thoracic Cavity

Boundaries of and Structures Within


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Body Cavities

Dorsal body cavity

Ventral body cavity

Thoracic

2 Pleural

Mediastinum

Divided by Diaphragm

Abdominopelvic

Abdominal

Pelvic

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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


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Pleural Cavities

Surround the lungs

Pleural fluid secreted by pleural

membranes

Holds layers together

Reduces friction of organs

Benefit of Compartmentalization

pg 159


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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


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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


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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, trachea, bronchi,

nerves, caudal vena cava,

MiddleContains: heart + pericardium

pg 177


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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


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Respiratory Tract

Upper Respiratory Tract

Superior to Larynx

Lower Respiratory Tract Larynx

Trachea

Primary Bronchi

Secondary Bronchi

Rest of Bronchial Tree

Lungspg 168

pg 992


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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

Adventitiamade of connective tissue, contains cartilage rings

pg 966


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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 divisionspg 168


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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 ofAlveoli

Respiratory exchange chamber

Among alveoli are blood vessels, nerves, lymphatics

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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 exchangeOxygen into blood

Carbon Dioxide into alveoli


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Throughout Bronchial Tree

Psuedostratified columnar changes to simple columnar to

simple cuboidal

Cartilage rings replaced by cartilage plates once bronchienter 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)


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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


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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


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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


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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 CTpg 212


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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

Innervated by right + left PHRENIC Nervespg 136


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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 (highlow 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


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Thoracic Cavity Capacity is Increased by:

Contraction of diaphragm

Intercostal muscles elevate ribs

Rib elevation causes the sternum to move

anteriorly

pg 135


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Openings of Diaphragm

PosteriorAnterior

Aortic Hiatus

Aorta

Azygos vein Thoracic duct

Esophageal Hiatus

Esophagus

Vagus nerves Caval Opening

Inferior Vena Cava

Right Phrenic Nerve pg 157


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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 + LftCommon Iliac Veins

Empties into Right Atrium

Widest blood vessel in body


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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 hemiazygosthat drain left side

pg 153


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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

Capsule

Cortex

Medulla

pg 206

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