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THE RESPIRATORY SYSTEM

WALTHAUSER H. VIAJE, M. D.

Department of Surgery

Riverside Medical Center

 

 

 

 

Division of the Respiratory System

 

Upper Respiratory tract

-          Nose

-          Oropharynx

-          Nasal cavities

-          Nasopharynx

 

Lower Respiratory tract

-          Larynx

-          Bronchi

-          Trachea

-          Lungs

 

Primary respiratory role:

     -  Gaseous exchange & ventilation

 

Secondary function:

     -  Phonation

     -  Olfaction

     -  Mechanical stabilization of the thorax

     -  Biochemical functions

 

External Nose

 

-          Apex

-          External nares ( nostrils )

-          Dorsum nasi

-          Alae nasi

 

Skeleton of the external nose

 

Bony framework

-          Nasal bones

-          Frontal processes of maxilla

-          Nasal part of frontal bone

 

Cartilaginous framework

-          septal & lateral cartilages

-          Major/minor alar nasal cartilages

 

Nasal cavity

 

-          Divided into R & L halves by nasal septum

-          Each half has floor, roof, lateral & medial ( septal ) walls

-          Extends from the nostrils in front to choanae behind walls

     

Floor

-          Formed by palatine process of maxilla & horizontal plate of the hard palate.

Roof

-          Body of sphenoid, cribriform plate of ethmoid, frontal & nasal bones, & the nasal cartilages.

Lateral wall

-          Marked by 3 projections --- superior, middle & inferior nasal concha with its corresponding meatuses.

Medial wall (nasal septum)

-          Upper part – vertical plate of ethmoid posterior part formed by the vomer.

3 regions of the nasal cavity

-          Nasal vestibule

-          Respiratory region

-          Chemosensory / olfactory area

 

Nasal vestibule

 

-          Forms the beginning of NC anteriorly.

-          Lumen lined with skin; inferior region bearing sebaceous & sweat glands, coarse hairs (vibrissae)—arrests passage of particles in inspired air.

 

Respiratory region

 

This region encompasses the lateral & medial walls, the nasal roof, floor & conchae.

 

Nasal Conchae

-          Enlarges surface area of NC

-          Warms, moistens, & cleans the inspired air

-          Inspired dust particles are removed from the air by the moist, sticky surface of mucus membrane.

-          Contaminated mucus is moved backward by ciliary action of the columnar ciliated epithelium.

 

Meatus

 

-  Located inferolateral to each concha.

 

Supreme nasal meatus

-          Passage beneath highest nasal concha.

-          Sometimes displaying an opening of post ethmoidal sinus.

 

Superior meatus

-          Receives opening of post ethmoidal sinus.

 

Middle meatus

-          Receives opening of maxillary sinus via the hiatus semilunares.

 

Inferior meatus

-          Contains the opening of nasolacrimal duct.

 

Chemosensory / Olfactory area

 

-          Limited to the superior nasal concha.

-          Contains sensory terminals of olfactory nerve.

 

Microstructure of the Nasal Lining

 

Anterior part of NC & vestibule

-          Continuous with skin.

-          Keratinized stratified squamous epith.

 

Posterior

-          Transition from non-keratinizing stratified squamous epith to pseudostratified ciliated (respiratory) epithelium.

 

Respiratory epithelium

 

-          Ciliated columnar or cuboidal epith cells.

-          Non-ciliated columnar cells w/ microvilli.

-          Basal cells.

-          Muscular walls of arterioles are under endocrine & neural control.

-          Local vascular changes, due to vasomotor autonomic innervation alter thickness & contours of mucosal surfaces, resulting alterations in rate of inflow through the passageways.

-          Fibrous layer is infiltrated w/ lymphocytes forming diffuse lymphoid tissue.

-          Secretions of nasal mucosa contain bacteriocides lysozymes, lactoferrin, & IgA. 

 

Respiratory mucosa is continuous with:

-          Nasopharyngeal mucosa thro’ post nasal apertures.

-          Conjunctiva thro’ nasolacrimal duct & lacrimal canaliculi.

-          mucosae of sphenoidal, ethmoidal, frontal & maxillary sinuses thro’ their respective openings.

 

Arterial supply

 

-          Ant & post ethmoidal branches of ophthalmic aa ethmoidal & frontal sinuses; nasal roof.

-          Sphenopalatine branch of maxillary aa mucosa of conchae, meatuses & septum.

-          Septal branch of sup labial ramus of facial aa vestibular septum anastomose with sphenopalatine aa common site of bleeding from the nose (epistaxis).

-          Infraorbital, sup., ant., & post alveolar branches of maxillary aa mucosa of maxillary sinus.

-          Pharyngeal branch of maxillary aa sphenoidal sinus.

 

Venous drainage

-          sphenopalatine vein

-          facial vein

-          ophthalmic vein

 

Lymph drainage

-          submandibular nodes

-          parotid nodes

-          upper deep cervical nodes

-          retropharyngeal nodes

 

Innervation

                           

-          Nerves of ordinary sensation

-          Olfactory nerves

-          Autonomic nerves

 

Nerves of ordinary sensation

-          Mediate sensations of pain, touch & temp.

-          Trigeminal fibers sensitive to noxious chem.

-          Derived from maxillary nn & nasociliary branch of ophthalmic nn.

 

1.       Ant ethmoidal br of nasociliary nn

-          Ant & upper parts of septum.

2.       Infraorbital nn

-          Nasal vestibule.

3.       Ant sup alveolar nn

-          Part of septum & ant part of lateral wall.

4.       Lat post sup nasal & med post sup nasal nn nasopalatine nn post inf nasal br of ant palatine nn

-          Post 3 quarters of lateral wall, roof, floor & septum.

5.       Br from nerve to pterygoid canal

-          Upper & post part of roof & septum.

 

Olfactory nn

-          from sensory cells of area olfactoria, passing into cranial cavity via foramina of cribriform plate

 

Autonomic nn

-          Sympa postganglionic vasomotor fibers to the.

-          Nasal blood vessels.

-          Postganglionic parasympa fibers providing.

-          secretomotor supply to nasal glands.

 

Paranasal sinuses

 

Frontal

Ethmoidal

Sphenoidal

Maxillary

 

-          Rudimentary or absent at birth

-          Enlarge during eruption of permanent teeth & after puberty

-          Open into lateral wall of NC via small apertures

-          Found in interior of their respective bones

-          Lined w/ mucoperiosteum & filled w/ air

-          Act as resonators to the voice

-          When apertures of sinuses are blocked, or become filled w/ fluid, quality of voice is markedly changed

 

Function of the sinuses

-          Add some resonance to the voice

-          Impt in contouring the head for identification  of gender, sexual maturity, & group identity

-          Uncertain

 

Frontal sinus

-          Contained w/in frontal bone posterior to superciliary arches

-          Roughly triangular in shape

-          Extends upward above medial end of eyebrow & backward into medial part of roof of orbit

-          Aperture opens into middle meatus via the ethmoidal infundibulum or thro’ the frontonasal duct

-          3.2 cm x 2.6 cm x 1.8 cm

-          Well-developed between 7th & 8th years, reach full size after puberty

-          More prominent in males

 

Vessels & nerve supply

Arterial supply

-          supraorbital aa; ant ethmoidal aa

Venous drainage

-          supraorbital vv; sup ophthalmic vv

Lymph drainage

-          submandibular nodes

Nerve supply

-          supraorbital nerve

 

Ethmoidal sinus

-          Lie between upper part of NC & the orbit

-          Separated by the paper thin orbital plate of ethmoid ( poor barrier to infection )

-          Small thin-walled cavities, formed by frontal, maxillary, lacrimal, sphenoid & palatine bones

 

Anterior group (infundibular sinus)

       -  opens into ethmoidal infundibulum or frontonasal duct

Middle group (bullar sinus)

       -  opens into middle meatus

Posterior group

       -  opens into sup meatus, highest meatus & sphenoidal sinus

 

Vessels & nerve supply

Arterial supply

-          sphenopalatine aa; ant & post ethmoidal aa

Venous drainage

-          Via corresponding veins

Lymphatics

-          Submandibular nodes

Innervation

-          Ant & post ethmoidal nerves (sensory); orbital branches of pterygo-palatine ganglion (parasympasecretomotor fibers

 

Sphenoidal sinuses

                         

-          Situated post to upper part of NC, w/in the sphenoid bone

-          Each sinus opens into the sphenoethmoidal recess above sup concha

 

Vessels & nerves

Arterial supply

-          post ethmoidal aa

Venous drainage

-          thro’  its corresponding vein

Lymphatics

-          retropharyngeal nodes

Nerve supply

-          post ethmoidal nn (sensory) orbital branch of pterygopalatine ganglion (parasympa secretomotor)

 

Maxillary sinus

 

-          Largest air sinus of the nose

-          Pyramidal in shape

Roof – floor of orbit

Floor – alveolar process of maxilla

Apex - zygomatic process

Base - lateral wall of nose

-          Sinus opens into middle meatus thro’ the hiatus semilunares

-          Roots of 1st  &  2nd premolars, 3rd molar, & root of canine project up into the sinus

-          Occasionally, thin layer of compact bone enclosing roots of teeth is absent

§          tooth extraction may result in fistula

§          an infected tooth may produce sinusitis

 

Vessels & nerve supply

Blood supply

-          facial, infraorbital; greater palatine aa & vv

Lymph

-          submandibular nodes

Nerve supply

-          infraorbital; ant, middle, & post sup; alveolar nn

Clinical anatomy

     

-          Congenital nasal deformities

-          Traumatic injury

-          Infection

-          Surgical procedures

 

 

 

The larynx

 

-          A specialized organ that provides a protective sphincter at the inlet of air passages.

-          Responsible for voice production.

-          Above, it opens into the laryngopharynx.

-          Below, is continuous w/ the trachea.

-          In adult males, lies opposite 3rd to 6th CV; higher in children & adult females.

-          In males, continues to grow till 40 yrs of age w/ thyroid cartilage projecting in anterior midline of the neck.

 

Skeleton of the larynx

-          Cartilages form the skeletal framework.

-          Interconnected by ligaments & fibrous membrane.

-          Moved by a number of muscles.

-          Lined by mucous membrane.

 

Thyroid cartilage

-          Largest of the laryngeal cartilages.

-          2 laminae of hyaline cartilage meeting in the midline forming the prominent V angle of the Adam’s apple.

-          Laryngeal prominence well marked in men, scarcely visible in women.

-          Line of fusion is 90 degrees in males,  120 degrees in females.

-          The shallower angle in males is asso w/ the prominence, greater length of vocal cords & the deeper pitch of voice.

-          Superior cornu

-          Inferior cornu

-          Oblique line  -  for attachment of the ff muscles : sternothyroid, thyrohyoid, inf. constrictor mm

 

Cricoid cartilage

-          Formed from a complete ring of hyaline cartilage.

-          Skeletal foundation of the larynx.

-          Forms a complete ring around the airway.

-          Articulated by synovial joints to thyroid cartilage & the 2 arytenoids.

 

Arytenoid cartilage

-          Pyramidal in shape.

-          Situated @ the back of the larynx, on the lateral part of upper border of cricoid’s lamina.

-          3 surfaces, 2 processes, base, & an apex.

-          Apex supports the corniculate cartilage.

-          Base articulates w/ cricoid cartilage.

-          Vocal process – gives attachment to the vocal ligament.

-          Muscular process – gives attachment to posterior & lateral cricoarytenoid mm.

 

Corniculate cartilage

-          2 small nodules that articulate w/ apices of arytenoid cartilages.

-          Gives attachment to the aryepiglottic folds.

 

Cuneiform cartilage

-          2 small rod-shaped pieces of cartilages.

-          Serves as support for the aryepiglottic folds.

 

Epiglottic cartilage

-          Leaf-shaped elastic cartilage, situated behind the root of the tongue.

-          Connected in front to body of hyoid bone, & by its stalk (petiolus) to the back of thyroid cartilage.

 

Classification of laryngeal cartilage

-          Elastic fibrocartilage

-          little tendency to ossify or calcify

-          corniculate, epiglottis, cuneiform, apices of arytenoids, tritiate

-          Hyaline cartilage

-          calcifies as age advances

-          thyroid, greater part of arytenoids, cricoid

 

Membranes & ligaments of the Larynx

-          Extrinsic ligaments

-          thyrohyoid membrane

-          median & lateral thyrohyoid ligament

-          cricotracheal ligament

-          Intrinsic ligaments

-          fibroelastic membrane of the larynx

-          quadrangular memb

-          cricothyroid ligament

 

Cavity of the Larynx

-          Extends from inlet to lower border of the cricoid carilage

-          Divided into 3 parts, the upper, middle & lower part

 

Inlet of the Larynx (aditus laryngis)

-          Bounded in front by upper margin of epiglottis

-          Lateral – aryepiglottic fold of mucous membrane

-          Posterior – mucous memb between arytenoid cartilages

-          Aperture between larynx & pharynx

 

Upper part of LC

-          The vestibule of the larynx  extends from the inlet to vestibular folds

Anterior wall – post epiglottic surface

Lateral wall - aryepiglottic folds

Posterior wall – arytenoid cartilage

 

Middle part of LC

-          Smallest

-          Extends from level of vestibular folds to level of vocal folds

 

Rima glottidis (glottis)

-          Fissure between vocal folds anteriorly & arytenoid cartilage posteriorly

-          2 regions :

intermembranous part

intercartilaginous part

-          Narrowest part of the larynx

-          Ave sagittal diam in adult males = 23 mm, females = 17 mm

-          Its width & shape vary w/ movements of vocal folds & arytenoid cartilages during respiration & phonation

 

Lower part of LC

-          Extends from level of vocal folds to lower border of cricoid cartilage

-          Continuous w/ the trachea

 

 

 

 

Muscles of the larynx

 

Extrinsic muscles

-          connect the larynx to neighbouring structures

-          responsible for moving larynx vertically during phonation & swallowing

-          Thyrohyoid  & thyrosternoid muscles

-          Thyropharyngeus & cricopharyngeus components of inf pharyngeal constrictor mm

 

Elevators of the larynx

-          Digastric

-          Stylohyoid

-          Mylohyoid

-          Geniohyoid

-          Stylopharyngeus

-          Salpingopharyngeus

-          Palatopharyngeus

 

Depressors of the larynx

-          Sternothyroid

-          Sternohyoid

-          Omohyoid

 

Intrinsic muscles

-          confined to larynx in their attachments

-          divided into 3 groups

-          mm that vary the glottis

-          mm regulating tension of vocal ligaments

-          mm controlling laryngeal inlet

 

Muscles that vary the glottis

-          post & lat crico-arytenoids

-          oblique & transverse arytenoids

 

Muscles regulating tension of vocal ligaments     

-          cricothyroids

-          post crico-arytenoids

-          thyro-arytenoids & vocalis

 

Muscles controlling laryngeal inlet  

-          oblique arytenoids, aryepiglottics, & thyro-epiglottics

 

Posterior cricoarytenoid (abductor)

O    : back of the lamina of cricoid cartilage

I     : muscular process of arytenoid cartilage

N    : recurrent laryngeal nerve

A    : abducts vocal fold

 

Lateral cricoarytenoid (adductor)

O    : upper border of arch of cricoid cartilage

I     : muscular process of arytenoid cartilage

N    : recurrent laryngeal nerve

A    : adducts vocal fold       

 

Transverse arytenoid muscle

O    : back & medial surface of arytenoid cartilage

I     : back & medial surface of the opposite arytenoid cartilage

N    : recurrent laryngeal nerve

A    : closes the post part of glottis

 

Cricothyroid (tensor)

O    : side of cricoid cartilage

I     : upper fibers

§          lower border of lamina of

§          thyroid cartilage

§          lower fibers  -  ant border of inferior cornu of thyroid cartilage

N    : external laryngeal nerve

A    : tenses & elongates the vocal ligaments

 

Thyroarytenoid (relaxor)

O    : inner surface of angle of thyroid cartilage

I     : anterolateral surface of arytenoid cartilage

N    : recurrent laryngeal nerve

A    : shortens & relaxes vocal ligament

 

Vocalis muscle (relaxor)

O    : inner surface of angle of thyroid cartilage

I     : vocal process of arytenoid cartilage

N    : recurrent laryngeal nerve

A    : shortens & relaxes vocal ligament

 

Oblique arytenoid muscle

O    : muscular process of arytenoid cartilage

I     : apex of opposite arytenoid cartilage

N    : recurrent laryngeal nerve

A    : act as sphincter to laryngeal inlet

 

Aryepiglottic muscles

O    : muscular process of arytenoid cartilage

I     : aryepiglottic fold

N    : recurrent laryngeal nerve

A    : acts as sphincter to the laryngeal inlet

 

Thyro-epiglotticus muscle

O    : inner surface of angle of thyroid cartilage

I     : epiglottic margin

N    : recurrent laryngeal nerve

A    : widens laryngeal inlet

 

Microstructure of Laryngeal mucosa

 

-          Continuous w/ that of pharynx & trachea

-          Ciliated pseudostratified epithelium

-          Non-keratinized stratified squamous epithelium covering the vocal folds

-          Replete w/ numerous mucous glands

 

Sphincteric Function of the Larynx

 

-          2 sphincters in the larynx

a.       @ the inlet

b.       @ the rima glottidis

-          The sphincter @ the inlet is used only during swallowing

-          As the bolus of food is passed backward, the larynx is pulled up beneath the back of the tongue.

-          Inlet is narrowed by the pull of oblique arytenoid & aryepiglottic mm.

-          Epiglottis is pushed backward by the tongue & serves as a cap over the inlet.

-          The bolus of food or fluids enters the esophagus by passing over the epiglottis & on either side of the inlet, the pyriform fossae.

 

Coughing / sneezing

-          After inspiration, vocal folds are adducted.  As intrathoracic pressure rises, vocal folds are abruptly abducted.

-          The sudden release of compressed air often dislodges foreign particles or mucus up into the pharynx --- either swallowed expectorated.

 

Abdominal straining

-          defecation, micturition, childbirth

§          After deep inspiration, air is held in the RT by closure of the glottis

§          Upward movement of diaphragm prevented by compressed air w/in the RT

§          Opening of the glottis releases air

 

Anatomy of Speech

-          Involves the intermittent release of expired air between adducted vocal folds

 

Frequency / pitch

§          det by changes in length & tension of the vocal ligaments

Quality

§          depends on resonators eg., pharynx, mouth & the sinuses

§          controlled by mm of the soft palate, tongue, floor of mouth, cheeks & the lips

Normal speech

§          depends on modification of sound into recognizable consonants & vowels

Singing

§          needs a more prolonged release of expired air bet adducted vocal folds

Whispering

§          Vocal folds are adducted, but arytenoids cartilages are separated

 

Vessels & nerve supply

Arterial supply

§          upper half  -  sup laryngeal br of sup thyroid aa

§          lower half  -  inf laryngeal br of inf thyroid aa

Venous drainage

§          sup thyroid vv into the int jugular vein

§          inf thyroid vv into the L brachiocephalic

Lymphatics

§          deep cervical nodes              

Sensory nerve supply

§          above VF  -  int laryngeal br of sup laryngeal br of the vagus nn

§          below VF  -  recurrent laryngeal nerve

Motor nerve supply

§          Recurrent laryngeal nn supplies intrinsic mm except cricothyroid mm

§          cricothyroid mm supplied by ext laryng br of sup laryngeal br of the vagus nn

 

 

 

Clinical anatomy

-          Obstruction & trauma

-          Recurrent laryngeal nerve palsy

-          Vocal cord nodes

-          Tracheostomy

 

Trachea

 

-          U-shaped bars of hyaline cartilage interconnected by fibromuscular membrane

-          10 – 11 cm. long

-          From level of 6th CV to upper border of 5th TV, where it divides into R  &  L  principal bronchi

-          Pt of bifurcation is usually a little to the  R

-          Mobile & can rapidly alter in length

-          In deep inspiration, the bifurcation descends to level of 6th TV

-          Ext transverse diameter is 2cm in adult males, 1.5cm in adult females, smaller in children

-          Later childhood – diameter in mm is equal to age in yrs

 

Right Principal Bronchus

 

-          Wider, shorter, & more vertical than the  L

-          About 2.5 cm long

-          Enters  R  lung @ the hilus where it divides into secondary branches

-          Greater width & more vertical course explain why FB enters it more often than the  L

 

Left Principal Bronchus

 

-          Narrower, & less vertical than the  R

-          About 5 cm long

-          Enters hilum of  L  lung @ level of 6th TV, where it divides into secondary branches

 

Bronchopulmonary segmentation

 

-          Primary br of the  R  &  L  lobar bronchi are called segmental bronchi

-          Each enters in a structurally separate & functionally independent unit of lung tissue

-          Each segment is surrounded by connective tissue continuous w/ the visceral pleura

 

Right Lung

 

-          Superior lobe

apical

posterior

anterior

-          Middle lobe

lateral

medial

-          Inferior lobe

superior (apical)

medial basal

anterior basal

lateral basal

posterior basal

 

Left Lung

 

-          Superior lobe

apical

posterior

anterior

sup lingular

inf lingular

 

-          Inferior lobe

superior (apical)

medial basal

anterior basal

lateral basal

posterior basal

                              

Microstructure of the Trachea & Bronchi

 

-          Framework of incomplete rings of hyaline cartilage

-          United by fibrous tissue & smooth mm

-          Lined internally by mucosa

 

Cartilage skeleton

-          Tracheal cartilage

§          16 – 20 in number

§          forms an incomplete ring surrounding ant 2/3 of tracheal circumference

§          posteriorly, it is completed by fibro-elastic tissue & smooth mm

§          may become calcified in the aged

-          Bronchial cartilage

§          in intrapulmonary bronchi, plates of cartilage become progressively lesser, disappearing where the bronchioles begin.

 

Fibrous membrane

-          Perichondrium & membrane mainly composed of collagen & elastin fibers

-          Fibers cross each other diagonally, allowing changes in luminal diameter

-          Smooth mm are located posteriorly 

 

Mucosa

-          Pseudostratified ciliated columnar epith w/ goblet cells

-          Continuous w/ larynx above & intrapulm bronchi below

-          Large no. of lymphocytes deep in the epith

 

Vessels & nerves

-          Arterial supply

§          inferior thyroid aa

§          bronchial aa

-          Venous drainage

§          inferior thyroid venous plexus

-          Lymphatics

§          pretracheal & paratracheal LN

-          Nerve supply

§          tracheal br of vagus

§          rec laryngeal nn

§          sympathetic trunks

§          Sympa nerve endings causes bronchodilatation by releasing catecholamines

§          Parasympa activity w/c is cholinergic causes bronchoconstriction