Cardiopulmonary Anatomy and Physiology

1
Cardiopulmonary Anatomy and Physiology

• Respiratory Care Program
• Indian River Community College

2
Anatomy of theRespiratory Tract

• The respiratory tract is divided into an upper
  and a lower airway.
• The upper airway includes
• the nose
• the oral cavity
• the pharynx
• The lower airway includes
• the larynx
• the tracheobronchial tree
• the lung parenchyma

3
The Upper Airway

• The upper airway consists of the nose, oral
  cavity, and pharynx.
• The primary functions of the upper airway are
• act as a conductor of air
• prevent foreign materials from entering the
  tracheobronchial tree
• serve as an important area involved in speech and
  smell.
• heat and humidify inspired air

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The Nose

• Top third is bony lower two thirds is cartilage.
• Nasal septum is cartilage in its anterior portion
  and divides the nose into two nasal fossae or
  nares.
• The anterior portion of the nasal cavity is lined
  with skin and contains hair follicles.
• Three major turbinates arise from the lateral
  nasal walls increasing surface area and allowing
  very close contact between inspired air and nasal
  mucosa.

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The Nose

• Anterior third is lined with squamous,
  nonciliated epithelium.
• Posterior two thirds is covered with ciliated,
  pseudostratified, columnar epithelium containing
  many serous and mucous glands.
• Olfactory region facilitates smell.
• The primary functions of the nose are to
  humidify, heat, and filter the inspired air.
• Two secondary functions are the sense of smell
  and a resonance chamber for phonation.

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The Oral Cavity

• The oral cavity is involved in digestion, speech
  and respiration.
• The palate separates the nasal cavity from the
  oral cavity.
• The anterior 2/3 has a bony skeleton and is
  called the hard palate.
• The posterior third is composed of cartilage and
  is called the soft palate.
• The oral cavity also houses tonsils that serve
  certain protective functions.

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The Pharynx

• The pharynx is the space behind the oral and
  nasal cavities and is subdivided into the
  nasopharynx, oropharynx and laryngopharynx.
• The nasopharynx is the area above the soft palate
  lined with ciliated, pseudostratified, columnar
  epithelium. It houses the eustachian tubes and
  adenoids.

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The Pharynx

• The oropharynx extends from the soft palate to
  the base of the tongue and houses lymphoid tissue
  called faucial tonsils, the tonsils. It also
  houses the lingual tonsils and together play an
  important role in the pulmonary defense system.
• The laryngopharynx extends from the base of the
  tongue to the opening of the esophagus and houses
  many of the important landmarks for intubation.

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The Lower Airway

• The lower airway starts at the level of the vocal
  cords.
• Divided into tthree sections
• The larynx
• Tracheobronchial Tree
• Lung Parenchyma

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The Larynx

• Lies between the upper and lower airways at the
  level of the fourth-sixth vertebrae.
• The opening to the larynx is the glottis.
• Composed of cartilage connected to one another by
  muscles and membranes.
• The largest laryngeal cartilage is the V-shaped
  thyroid cartilage Adams apple.
• Below the thyroid cartilage is the ringlike
  cricoid cartilage.

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The Larynx

• The cricothyroid membrane connects the thyroid
  and cricoid cartilage.
• The cricoid cartilage is the only complete ring
  in the trachea and is the narrowest portion of
  the upper airway in infants and small children.
• The laryngeal mucosa is composed of stratified,
  squamous epithelium above the vocal cords and
  pseudostrafied, columnar epithelium below.(no
  cilia)

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4 Functions of the Larynx

• To act as a gas-conducting channel connecting the
  upper and lower airways.
• To protect the lower airway from foreign
  substances.
• To participate in the cough mechanism.
• To participate in speech.

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The Tracheobronchial Tree

• Functions as a system of conducting tubes,
  allowing passage of gas to and from the lung
  parenchyma, where gas exchange occurs.
• Subdivided into two portions central airways
  (bronchi) and peripheral airways (bronchioles).
• Composed of three major layers an epithelial
  lining, the lamina propria and cartilaginous
  layer.

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Tracheobronchial Tree

• The epithelial layer is composed of
  pseudostratified, ciliated, columnar epithelium
  with numerous mucous and serous glands.
• The lamina propria is composed of loose, fibrous
  tissue containing many small blood vessels,
  lymphatic vessels and nerves. It also contains
  bronchial smooth muscle which may contract,
  resulting in an acute increase in airway
  resistance.

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Tracheobronchial Tree

• The cartilaginous layer provides structure for
  the airways and progressively diminishes until it
  essentially disappears in tubes of less than 1 mm
  in diameter.
• The contents and functional significance of these
  layers change as the diameters of the tubes
  become smaller.

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The Trachea

• Generation 0
• In the adult, the trachea is a tube 11 to 13 cm
  in length and 1.5 to 2.5 cm in diameter.
• It extends from the larynx to its bifurcation
  (the carina) at the level of the the second
  costal cartilage or fifth thoracic vertebra.
• Supported by 16 to 20 C-shaped cartilage.
• Posterior wall is made up of muscle and sits
  anterior to the esophagus.

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Main Stem Bronchi

• First generation.
• Structurally similar to the trachea.
• The right main stem bronchus forms an
  approximately 25 degree angle with the vertical
  axis and is wider and shorter than the left.
• The left main stem bronchus forms a 40 to 60
  degree angle.
• In the infant, both main stem bronchi form equal
  angles of approximately 55 degrees.

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Lobar Bronchi

• 2nd Generation.
• The right main stem bronchus divides into three
  lobar branches upper, middle and lower.
• The left main stem bronchus divides into a upper
  and lower lobar bronchi.
• The cartilage lose the characteristic horseshoe
  shape but still provide rigidity under most
  circumstances.

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Segmental Bronchi

• 3rd Generation.
• The lobar bronchi give rise to various branches
  called segmental bronchi that are named according
  to the lung segments they supply.
• Ten on the right and eight on the left.
• Important to the application of postural drainage
  and other chest physical therapy techniques.

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Subsegmental Bronchi

• Generations 4-9.
• Each generation of segmental bronchi give rise to
  a number of generations of subsegmental bronchi.
• The total cross-sectional area increases with
  each generation.
• The diameter decreases from about 4 mm to 1 mm.

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Subsegmental Bronchi

• The bronchi are surrounded by connective tissue
  containing arteries, lymphatics and nerves until
  the diameter becomes 1mm or less.
• Tubes greater than 1 mm diameter with connective
  tissue are called bronchi and are responsible for
  80 of normal airway resistance below the
  glottis.

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Bronchioles

• Generation 10-15
• Tubes less than 1 mm without connective tissue
  are called brochioles.
• Account for the other 20 of normal total airway
  resistance below the glottis.
• The tracheobronchial tree ends at approximately
  the 16th generation from the trachea.

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Terminal Bronchioles

• Generation 16-19.
• Average diameter is approximately 0.5 mm.
• Epithelium becomes flattened.
• Mucous glands and cilia are scant.
• Unique secretory cells called clara cells may
  produce some mucous.
• Very important surfactant is found at the level
  of the terminal brochioles.

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Lung Parenchyma

• Lung parenchyma is composed of
• Respiratory Bronchioles
• Alveolar Ducts
• Alveolar Sacs
• Primary Lobules

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Respiratory Bronchioles

• Generation 20-23.
• The terminal bronchioles give rise to respiratory
  bronchioles which serve as a transition to pure
  alveolar epithelium possessing maximum gas
  exchange capability.
• Lack cilia, mucous and serous glands.

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Alveolar Ducts

• Generation 24-27.
• Alveolar ducts arise from the respiratory
  bronchiole.
• About half of lung alveoli arise directly from
  the alveolar ducts and are responsible for 35 of
  alveolar gas exchange.

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Alveolar Sacs

• Generation 28.
• Alveolar sacs, also known as primary lobules, are
  the last generation of the airways and are
  functionally the same as alveolar ducts.
• The lung parenchyma is actually composed of
  numerous primary lobules or functional units,
  approximately 130,000.
• Each lobule has a diameter of 3.5 mm and contains
  approximately 2,200 alveoli responsible for
  approximately 65 of gas exchange.

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Alveolar Epithelium

• Alveolar type I cell squamous pneumocyte
• makes up 80-95 of alveolar surface
• play integumentary role in the maintenance of the
  air-blood barrier
• broad, thin cells provide the surface area for
  gas diffusion
• junctions between cells are very tight and
  usually impermeable to water except for areas
  called pores of Kohn located in alveolar septa
• extremely susceptible to injury

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Alveolar Epithelium

• Alveolar Type II cells granular pneumocyte
• cuboidal cell responsible for considerable
  metabolic and enzymatic activity
• primary source of pulmonary surfactant which
  decreases surface tension of fluid that lines the
  alveoli
• also may secrete other substances for clearance
  and degradation of pulmonary secretions and
  cellular debris

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Alveolar Epithelium

• Alveolar Macrophages Type III cells
• mononuclear phagocytes
• originate in bone marrow and migrate to lung
  where they mature
• does not function in gas exchange but is an
  important aspect in lung defense removing
  bacteria and other foreign particles

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Interstitium

• The interstitial space is composed of a
  threadlike network of collagen fibers surrounded
  by a gel like matrix which function to surround
  and support alveolar clusters.
• Composed of tight and loose space
• Tight space is the area between alveolar and
  capillary vessels where gas exchange takes place.
• Loose space is the area that surrounds the
  bronchioles, alveolar ducts and alveolar sacs.

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Pulmonary Lymphatics

• Pulmonary lymphatic capillaries arise in the
  loose space.
• The lymphatic channels contain smooth muscle and
  eventually become the larger collecting vessels
  located in the areas of alveolar ducts and
  respiratory bronchioles.

33
Endothelium

• Pulmonary endothelial cells are usually very
  leaky depending on variations in capillary
  pressure.
• Metabolic functions of pulmonary endothelial
• catabolic
• anabolic
• conversion

34
Normal Pulmonary Defense Mechanisms

• The mucous blanket is created by a number of
  serous and mucous glands at a rate of 100ml/day.
• Normal mucous is composed of 95 water, 2
  glycoprotien, 1 carbohydrate and trace amounts
  of lipid and DNA.
• Forms two layers
• sol
• gel

35
Defense Function

• There are about 200 cilia per cell which lie
  almost entirely within the fluid sol layer.
• Cilia movement makes the upper end of the
  hairlike projection extend into the viscous gel
  layer and pulls it forward.
• The mucous blanket moves at an average rate of 2
  cm/min.
• Cough mechanism also mobilizes the mucous blanket.

36
Factors That Effect Mucociliary Clearance

• Smoking
• Positive pressure ventilation
• Dehydration
• Anesthesia
• High FIO2s
• Disease processes

37
Cough Mechanism

• A cough is a pulmonary defense mechanism that
  attempts to maintain adequate bronchial hygiene
  in spite of inadequate normal mechanisms.
• It functions in the presence of abnormalities
  such as copious, dry or thick mucous as well as
  poor ciliary activity.
• The cough is the major defense against retained
  secretions and is often destroyed in pulmonary
  disease.

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Cough Mechanics

• Cough consists of five separate mechanical
  components
• a deep breath
• an inspiratory pause
• glottic closure
• increased intrathoracic pressure
• glottic opening
• No matter how effective the cough may be
  mechanically, it must have an intact mucous
  blanket.

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Clinical Manifestations

• Common manifestations of retained secretions are
• increased work of breathing
• mucous plugging
• hypoxemia
• inadequate cough
• atelectasis
• pneumonia

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Causes of Retained Secretions

• Dehydration
• Pulmonary Disease
• Tracheal Foreign Body
• Muscular Weakness
• Bulbar Malfunction
• Abdominal Musculature Limitations

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Pulmonary Vascular System

• The pulmonary vascular system can be viewed as an
  independent vascular network with the purpose of
  delivering blood to and from the lungs for gas
  exchange.
• The pulmonary vascular system is composed of
• arteries -venules
• arterioles -veins
• capillaries

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Arteries

• The right ventricle of the heart pumps
  deoxygenated blood into the pulmonary artery.
• Pulmonary arteries divide into the right and left
  branches, penetrating their respective lung
  through a region called the hilum.
• The hilum is the part of the lung where the main
  stem bronchi, vessels, and nerves enter.

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Arterioles

• The arterioles progressively get smaller and
  smaller as they reach the pulmonary capillaries.
• The pulmonary arteries supply nutrients to the
  respiratory bronchioles, alveolar ducts, and
  alveoli.
• The arterioles play an important role in the
  distribution and regulation of blood and are
  called the resistance vessels.

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Capillaries

• The pulmonary arterioles give rise to a complex
  network of capillaries that surround the alveoli.
  (p. 33)
• The capillaries are essentially an extension of
  the inner lining of the larger vessels.
• The capillaries are where gas exchange occurs and
  also have a selective permeability to water,
  electrolytes, and sugars.

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Venules

• After blood moves from the pulmonary capillaries,
  it enters the pulmonary venules.
• The venules are actually tiny veins continuous
  with the capillaries.
• The venules empty into the veins, which carry
  blood back to the heart.

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Veins

• Veins contain one-way, flaplike valves that aid
  blood flow back to the heart.
• The valves open as long as the flow is toward the
  heart, but close if flow moves away from the
  heart. (p. 35)
• Veins are capable of collecting a large amount of
  blood with very little pressure change and are
  also called capacitance vessels.
• The pulmonary veins then empty into the left
  atrium of the heart.

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The Lymphatic System

• Lymphatic vessels are found superficially around
  the lungs just beneath the visceral pleura.
• The primary function of the lymphatic vessels is
  to remove excess fluid and protein molecules that
  leak out of the pulmonary capillaries.
• Deep within the lungs, the lymphatic vessels
  arise from the loose space of the interstitium.

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The Lymphatic System

• Lymphatic vessels are similar to veins in that
  they also have one-way valves that direct fluid
  toward the hilum.
• The vessels end in the pulmonary and
  bronchopulmonary lymph nodes.
• Lymph nodes act as filters, keeping particulate
  matter and bacteria from gaining entrance to the
  bloodstream.
• Lymph nodes produce lymphocytes and monocytes.

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Neural Control of the Lungs

• The balance, or tone, of the bronchial and
  arteriolar smooth muscle of the lungs is
  controlled by the ANS.
• The ANS has two divisions (1) the sympathetic
  nervous system, which accelerates the HR,
  constricts blood vessels, relaxes bronchial
  smooth muscle and raises blood pressure and (2)
  the parasympathetic nervous system, which has the
  opposite effects.

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Sympathetic Nervous System

• When activated, neural transmitters, such
  epinephrine and norepinephrine, are released.
• These agents stimulate beta2 receptors in the
  bronchial smooth muscles, causing relaxation of
  the airways.
• They also stimulate alpha receptors in bronchial
  smooth muscles causing the pulmonary vascular
  system to constrict.

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Parasympathetic Nervous System

• When the parasympathetic nervous system is
  activated, the neural transmitter acetylcholine
  is released, causing constriction of the
  bronchial smooth muscle.
• Inactivity of either systems allows for the
  action of the other to dominate the bronchial
  smooth muscle response.

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The Lungs

• The apex of each lung is somewhat pointed and the
  base is broad and concave to accommodate the
  convex diaphragm.
• The mediastinal border of each lung is concave to
  fit the heart.
• At the center of the mediastinal border is the
  hilum, where the mainstem bronchi, blood vessels,
  lymph vessels and nerves enter and exit the lungs.

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Right and Left Lungs

• The right lung is larger and heavier than the
  left.
• It is divided into the upper, middle and lower
  lobes by fissures.
• The right lung is shorter than the left due to
  the liver occupying the space directly below it.
• The left lung is divided into an upper and a
  lower lobe.

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Mediastinum

• The mediastinum is a cavity that contains organs
  and tissues in the center of the thoracic cage
  between the right and left lungs.
• It is bordered anteriorly by the sternum and
  posteriorly by the thoracic vertebrae.
• The mediastinum houses the trachea, heart, major
  blood vessels, various nerves, esophagus, thymus
  gland and lymph nodes.

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Pleural Membranes

• Two moist, slick-surfaced membranes, called the
  visceral and parietal pleurae, are closely
  associated with the lungs.
• The visceral pleura is firmly attached to the
  outer surface of each lung.
• The parietal pleura lines the inside of the
  thoracic surface of the diaphragm, and the
  lateral portion of the mediastinum.

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Pleural Membrane

• The potential space between the visceral and
  parietal pleura is called the pleural cavity.
• The pleural layers are held together by a thin
  film of serous fluid.
• This fluid allows the two membranes to glide over
  each other during inspiration and expiration.
• The potential space between the two membranes has
  a subatmospheric pressure causing the two
  membranes to adhere.

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Thorax

• The thorax houses and protects the organs of the
  cardiopulmonary system.
• Twelve thoracic vertebrae form the posterior
  midline border of the thoracic cage.
• The sternum forms the anterior burder of the
  chest.
• The sternum is composed of the manubrium, body,
  and xiphoid process.

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Thorax

• The twelve pairs of ribs form the lateral
  boundary of the thorax.
• The ribs attach directly to the thoracic
  vertebrae posteriorly and anteriorly to the
  sternum by way of the costal cartilage.
• The first seven ribs are true ribs, since they
  are attached directly to the sternum.
• Ribs 8-10 are called false ribs since they attach
  to the cartilage of the ribs above.
• Ribs 11 and 12 are called floating ribs since
  they float freely anteriorly.

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Diaphragm

• The diaphragm is the major muscle of ventilation.
• It is a dome-shaped muscle located between the
  thoracic cavity and the abdominal cavity.
• The diaphragm is composed of two separate muscles
  known as the right and left hemidiaphragms.
• The diaphragm is pierced by the esophagus, aorta,
  nerves and inferior vena cava.

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Diaphragm

• The phrenic nerve leaves the spinal cord between
  the 3rd and 5th cervical vertebrae and supply the
  primary motor innervation to the diaphragm.
• The lower thoracic nerves also contribute to the
  motor innervation of each hemidiaphragm.
• When stimulated to contract, the diaphragm moves
  downward and the lower ribs move upward and
  outward.

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Accessory Muscles of Ventilation

• During normal breathing in healthy individuals,
  the diaphragm alone can manage the task of moving
  gas in and out of the lungs.
• During vigorous exercise and during advanced
  stages of COPD, the accessory muscles are
  activated to assist the diaphragm.

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Accessory Muscles of Inspiration

• The accessory muscles of inspiration are those
  muscles that are recruited to assist the
  diaphragm in creating a subatmospheric pressure
  in the lungs.
• Major accessory muscles of inspiration include
• scalene muscles
• sternocleidomastoid muscles
• pectoralis major muscles
• trapezius muscles
• external intercostal muscles

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Scalene Muscles

• The scalene muscles are three separate muscles
  that function as a unit.
• They originate from the 2nd - 6th cervical
  vertebrae and insert into the 1st and 2nd ribs.
• When used as accessory muscles for inspiration,
  they elevate the first and second ribs.

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Sternocleidomastoid Muscles

• The sternocleidomastoid muscles are located on
  each side of the neck.
• They originate from the sternum and clavicle and
  insert into the mastoid process.
• When functioning as an accessory inspiratory
  muscle, it elevates the sternum increasing the
  A/P diameter of the chest.

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Pectoralis Major Muscles

• The pectoralis major muscles are powerful,
  fan-shaped muscles located on each side of the
  upper chest.
• They originate from the clavicle and sternum and
  insert into the upper part of the humerus.
• When functioning as an accessory inspiratory
  muscle, they elevate the chest, resulting in an
  increased A/P diameter.

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Trapezius Muscles

• The trapezius muscles are large, flat, triangular
  muscles that are situated superficially in the
  upper back and neck.
• When used as accessory inspiratory muscles of
  inspiration, they help to elevate the thoracic
  cage.

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External Intercostal Muscles

• The external intercostal muscles arise from the
  lower border of each rib and insert into the
  upper border of the rib below.
• The external intercostals contract during
  inspiration and pull the ribs upward and outward,
  increasing both lateral and a/p diameters of the
  thorax.

68
Accessory Muscles of Expiration

• The accesory muscles of expiration are those
  muscles that are recruited to assist in
  exhalation when airway resistance increases.
• When these muscles contract, they increase
  intrapleural pressure and offset the increased
  airway resistance.
• Accessory muscles of expiration include
• abdominal muscles
• internal intercostal muscles

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Abdominal Muscles

• The abdominal muscles used as accessory muscles
  of expiration include
• rectus abdominis
• external abdominis oblique
• internal abdominis oblique
• tranverse abdominis
• When these muscles contract, they compress the
  abdominal cavity, in turn, pushing the diaphragm
  into the thoracic cage.

70
Internal Intercostal Muscles

• The internal intercostal muscles run between the
  ribs immediately beneath the external intercostal
  muscles.
• The muscles arise from the inferior border of
  each rib and insert into the superior border of
  the rib below.
• These muscles contract during expiration and pull
  the ribs downward and inward, decreasing both the
  lateral and A/P diameter of the thorax.

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• TEST TIME!!!!
• Any Questions???????