Anatomy Flashcards
What is the upper respiratory system made of?
Nose Nasal cavities Paranasal sinuses Pharynx - naso, oral, laryngo Larynx
What is the functions of the nose and nasal cavities?
- Olfaction: olfactory receptors in mucosa of upper 1/3 medial and lateral nasal walls
- Airways for respiration
- Filter inspired air
- Warm and moisten inspired air
- Resonance chambers for speech
- Reception of secretions from the nasal cavities and nasolacrimal ducts
Describe what the external nose is composed of.
Nasal bone
Nasal cartilages - septal, greater and lesser alar cartilage
Fibrous fatty tissue
What cartilage makes up the medial wall of the nasal cavity?
Septal cartilage
What makes up the medial wall of the nasal cavitiy?
Septal cartilage
Vomer
Ethmoid bone
What makes up the roof of the nasal cavity?
Nasal bone
Frontal bone
Ethmoid bone (cribriform plate)
Sphenoid bone
What makes up the floor of the nasal cavity?
Maxilla and palatine bone
What makes up the lateral wall of the nasal cavity?
Maxilla Lacrimal bone Ethmoid bone (superior and middle nasal concha) Inferior nasal concha - separate bone Palatine bone
What is the function of the upper 1/3rd of the medial and lateral walls of the nasal cavities?
Olfaction
Describe the pathway of olfactory exons.
Olfactory receptor axons pass through the cribriform plate of the ethmoid bone to connect with the olfactory bulb situated on the upper surface of the cribriform plate.
Which part of the nasal cavity is responsible for respiratory functions?
Lower 2/3rd medial and lateral walls
What type of epithelium is the respiratory part of the nasal cavity and what are its functions?
Pseudostratified ciliated columnar epithelium with goblet cells
Goblet cells = mucus secretion
Cilia beat to move the mucus towards the nasopharynx
Mucus picks up particulate matter and moistens the air
What warms the inhaled air?
Nasal blood temperature
What are nasal concha?
Projections from the lateral wall of the nasal cavity
What are nasal concha covered by?
Respiratory type mucosa
What are the differences between the superior/middle nasal concha and inferior concha?
Superior/middle nasal concha are part of the ethmoid bone
Inferior nasal concha is a separate bone
What are nasal meatuses?
Air passages below the concha.
Where is the superior nasal meatus located?
Superior to middle nasal concha
Where is the middle nasal meatus located?
Inferior to middle nasal concha, but superior to the inferior nasal concha
Where is the inferior nasal meatus located?
Inferior to the inferior nasal concha
What is the space called superior/above the superior nasal concha or superior to the nasal meatus?
Sphenoethmoidal recess
Name the paranasal sinuses.
Frontal sinuses
Sphenoidal sinuses
Ethmoidal sinuses/ethmoidal cells - anterior, middle, posterior
Maxillary sinuses (largest)
What lines the paranasal sinuses?
Respiratory type mucosa
What are the functions of the paranasal sinuses?
Decrease the weight of the bones
Resonance chambers for speech/voice production
What are paranasal sinuses?
Air-filled extensions of the nasal cavities into adjacent bones
What does the sphenoid sinus drain into?
Sphenoethmoidal recess
What drains into the middle nasal meatus?
Maxillary sinuses
Frontal sinuses
Anterior and middle ethmoidal cells
Where do the posterior ethmoidal cells drain?
Superior nasal meatus
What opening is found in the inferior nasal meatus?
Nasolacrimal duct opening
Which paranasal sinus is used as a pathway in pituitary gland tumours?
Sphenoidal sinus
What is the pharynx?
Common pathway for air and food.
What is the wall of the pharynx composed of?
Mainly skeletal muscle
What lines the upper part of the pharynx?
Resp-type epithelium
What lines the lower part of the pharynx?
Stratified squamous epithelium (protection from food)
How does the nasopharynx connect with the nasal cavities?
By nasal apertures called choanae (posterior nares)
What are the posterior nares called?
Choanae
What opens onto the lateral wall of the nasopharynx?
Auditory (Eustachian tube)
What are tonsils?
Lymphoid aggregations/masses
Name the two tonsils found in the nasopharynx.
Pharyngeal tonsils (adenoids in children) Tubal tonsils (paired)
Describe the position of the pharyngeal tonsils in the nasopharynx.
Localized in the roof and posterior wall of the nasopharynx
State the position of the tubal tonsils in the nasopharynx.
Lateral wall behind the opening of the auditory tube.
How does the oropharynx connect with the oral cavity?
Via the oropharyngeal isthmus
Describe the length of the oropharynx.
Expands from the soft palate to the upper border of epiglottic cartilage of the larynx
Name the two tonsils found in the oropharynx.
Lingual tonsils
Palatine tonsils
Where are the lingual tonsils found?
Posterior end of tongue in oropharynx
Where are the palatine tonsils (paired) found?
Between the palatoglossal and palatopharyngeal arches at the lateral wall of the pharynx
How does the laryngopharynx connect with the larynx?
Via the laryngeal inlet
What is another name for the laryngopharynx?
Hypopharynx
Which tonsils are paired?
Tubal tonsils
Palatine tonsils
Where does the larynx extend from?
Extends from the laryngopharynx to the trachea
What levels does the larynx extend from?
C3 to C6
What are the functions of the larynx?
Airway protection
Respiration: maintain the airway
Phonation: voice production
What is the larynx made up of?
3 paired cartilages (smaller)
3 unpaired cartilages
Fibro-elastic membrane
Intrinsic muscles
What forms synovial joints with the cricoid cartilage?
Inferior horn of the thyroid
Arytenoid cartilage
What is the largest laryngeal cartilage?
Thyroid cartilage.
Where is the laryngeal prominence (Adam’s apple) found?
Thyroid cartilage where the two lamina join together
What is the epiglottic cartilage attached to?
The laryngeal prominence from the posterior aspect
What part of the thyroid cartilage attaches to the cricoid cartilage?
Inferior horn
What is embedded in the aryepiglottic fold?
Cuneiform and corniculate cartilages
Name the two external membranes of the larynx.
Thyrohyoid membrane Cricothyroid membrane (median cricothyroid ligament)
What does the thyrohyoid membrane attach to?
Superiorly to hyoid bone
Inferiorly to thyroid cartilage
What is important to remember about the thyrohyoid membrane?
Thyroidal notch
Lateral aspect - internal branch of superior laryngeal artery/nerve penetrate this
What does the cricothyroid membrane attach to?
AKA median cricothyroid ligament
Attaches superiorly to the thyroid cartilage
Attaches inferiorly to the cricoid cartilage
What is important to remember about the cricothyroid membrane?
Artificial penetration in emergency situations can provide access to the lower airways when there is blockage above the level of the vocal folds
Name the two internal membranes of the larynx.
Quadrangular membrane Cricothyroid membrane (lateral aspect)
Name the attachments of the quadrangular membrane.
Superiorly to the epiglottic cartilage
Inferiorly to the vestibular fold
Anteriorly to the laryngeal prominence of the thyroid cartilage
Posteriorly to the aryepiglottic fold
Name the attachments of the cricothyroid internal membrane (lateral aspect).
Superiorly to the vocal fold
Inferiorly to the arch of the cricoid cartilage
Anteriorly to the laryngeal prominence (posterior aspect)
Posteriorly to the arytenoid cartilage
What forms the vocal folds?
Mucosal coating of the vocal cords
Where do the vocal cords extend from?
Artytenoid cartilage to thyroid cartilage
What varies the position and tension of the vocal folds?
Muscles of the larynx
What is the rima glottidis and how is its size changed?
Rima glottidis is the interval between the vocal folds. Abduction and adduction of the vocal folds alters its size.
Gap between the vocal ligaments
Name two ligaments found near the vocal folds.
Vocal ligaments Vestibular ligaments (superior)
Which muscles are responsible for the abduction of the vocal cords resulting in opening of the rima glottidis.
Posterior cricoarythenoid muscles
What is the purpose of an open rima glottidis?
Phonation
Respiration - allows airflow in during inspiration
Which muscles are responsible for adduction of the vocal cords resulting in the closure of the rima glottidis.
Lateral cricoarythenoid muscles
What is the purpose of the closure of the rima glottidis?
Block foreign objects from entering
Needed for an increase in intrathoracic pressure (coughing)
Needed for an increase in intra-abdominal pressure (defaecation)
What modulates the pitch of sound and how?
Cricothyroid muscle
Tenses the vocal cords by pulling the thyroid cartilage anteroinferiorly
Name the three parts of the larynx.
Vestibule
Laryngeal Ventricles
Infraglottic Cavity
Describe the location of the vestibule of the larynx.
From the laryngeal inlet to the vestibular folds
Describe the location of the laryngeal ventricles.
From the vestibular folds to the vocal folds (rima glottidis) below
Describe the position of the infraglottic cavity.
From the vocal folds (rima glottidis) to the trachea
Describe the sensory innervation of the larynx.
Above the laryngeal ventricle - internal branch of the superior laryngeal nerve (Vagus nerve)
Below the laryngeal ventricle - recurrent laryngeal nerve (Vagus nerve)
Describe the motor innervation of the larynx.
All muscles are innervated by the recurrent laryngeal nerve except for the cricothyroid muscle which is innervated by the external branch of the superior laryngeal nerve.
Which space allows a pharyngeal infection to spread to the thorax?
Retropharyngeal space
Name the air conducting parts of the LRT.
Trachea Bronchi - primary (main) - secondary (lobar) - tertiary (segmental) Bronchioles - terminating bronchioles
Name the respiration parts of the LRT.
Respiratory bronchioles
Alveolar units
What is the characteristic feature of the trachea in transverse section?
D-shaped lumen
What is the trachea made of?
15-20 tracheal cartilages (maintain airway patency)
What is the trachealis muscle and where is it found?
Posteriorly in gaps between C-shaped cartilage
Bundles of smooth muscle fibres
What fills the narrow gaps between adjacent bars of cartilage of the trachea?
Annular ligaments (elastic fibres to give elasticity to its wall)
Where is the jugular notch found?
Sternum, between two ends of clavicle
What is the importance of the sternal angle and what level is it at?
T4
This is where the trachea terminates/bifurcates.
What level does the trachea begin?
Level C6
What is the tracheal length on inspiration and expiration/post mortem?
Inspiration = 15cm
Expiration/post mortem = 10cm
Name the divisions of bronchi.
2 main/primary bronchi (left/right) 3 right secondary/lobular bronchi 2 left secondary/lobular bonchi Tertiary/segmental bronchi (one for each bronchopulmonary segment in the lobes) Bronchioles
Name the extrapulmonary bronchi.
Right main bronchus
Left main bronchus
Right superior lobular bronchus
What do the extrapulmonary bronchi resemble?
Trachea
List the characteristics of the extrapulmonary bronchi.
Incomplete cartilage rings
Posterior deficiency is occupied by smooth muscle
D-shaped lumen
What are the intrapulmonary bronchi?
All the other bronchi excluding the extrapulmonary bronchi
What are the features of intrapulmonary bronchi?
Spherical in outline
No posterior flattening or C-shaped cartilage rings
Irregular plates of cartilages and smooth muscle fibres arranged in spirals around the bronchus with elastic fibres
Define bronchioles.
Conducting tubes of less than 1mm.
Why is it important that cilia extend further down in the resp tract than goblet cells and submucosal glands?
Prevent the resp tissue from waterclogging/occluded by mucus.
What is present for drainage in the smallest bronchioles where cilia are absent?
Macrophages
What is the narrowest part of the air conducting system?
Terminal Bronchioles
What is the composition of terminal bronchioles?
Cuboidal epithelium
No goblet cells
Ciliated
Surrounded by resp tissue
What is the first component of the resp system?
Respiratory bronchioles
Alveoli on their wall
What are alveolar ducts?
Thin walled tubes that connect the resp bronchioles to the alveolar sacs
What do alveolar sacs contain?
A collection of alveoli
What are alveoli?
Small pouches made of flattened epithelial cells that allow gas exchange
What is the pulmonary acinus?
Respiratory bronchioles, alveolar ducts and alveoli
What is another name for the blood air barrier?
Respiratory membrane
Describe the process of gas exchange.
Carbon dioxide in blood diffuses across the blood capillary wall into the alveoli. Oxygen from the air diffuses across the blood capillary wall into the pulmonary veins to be taken back to the left atrium of the heart.
What are layers of tissue that constitute gas exchange called?
Air-blood barrier
What are the lungs attached to?
Lie free in thoracic cavity except where they are attached to the heart by their roots and trachea
What shape are the lungs?
Conical shape
What is the apex of the lungs?
Upper tapered part (lies in plane of thoracic inlet)
What is the base of the lungs?
Concave lower part (overlies dome of the diaphragm)
Name the surfaces of the lungs.
Costal
Diaphragmatic
Medial
Explain the costal surface of the lungs.
Convex, fits wall formed by sternum, ribs and costal cartilages
Describe the diaphragmatic surface of the lungs.
Concave
Fits the dome of the diaphragm
What is the medial surface of the lungs split into?
Mediastinal and vertebral part
Describe the mediastinal part of the medial surface.
Has concavity caused by the heart and praecordium = CARDIAC IMPRESSION
Describe the vertebral part of the medial surface of the lungs.
Comes into contact with the sides of thoracic vertebrae.
List the borders of the lungs and the surfaces they separate.
Anterior border: separates medial and costal surfaces
Inferior border: separates diaphragmatic surface from the costal and medial surfaces
Posterior border: separates the costal and (vertebral part) of the medial surface
Where is the hilum found?
On the medial surface of the lung above and behind the cardiac impression
What does the hilum contain?
It is a depression containing blood vessels, lymphatic vessels, nerves, bronchi.
These enter/leave the lung
What is the root of the lung?
Hilum containing its structures
What is an important ligament to remember?
Pulmonary ligament
Where do the bronchial arteries end?
At the level of the respiratory bronchioles (travel and branch with bronchi)
What is blood mainly returned by?
Pulmonary veins rather than bronchial veins
Where is blood from the first few divisions of the bronchi carried?
In the bronchial veins to veins of the posterior thoracic wall
What is the difference between pulmonary arteries and bronchial arteries?
Pulmonary arteries carry deoxygenated blood from the right ventricle. They are part of the pulmonary circulation. Large.
Bronchial arteries carry oxygenated blood from the left ventricle. They are part of the systemic circulation. Small.
Describe the pathway of lymph drainage.
Pulmonary nodes (within lungs) to bronchopulmonary nodes (hilum) to inferior tracheobronchial nodes (angle of division of trachea) to superior tracheobronchial nodes (alongside the trachea). Then into the right and left bronchomediastinal trunks into the right lymphatic trunk and then into the thoracic duct and into the systemic venous system.
What divides the lung into the upper and lower lobes?
Oblique fissure
What are importance characteristics of the left lung?
Cardiac notch
Lingula
How do we tell the difference between the left lung and right lung at the hilum?
Pulmonary artery is superior to the bronchus at the hilum in the left lung.
Pulmonary artery is anterior to the bronchus at the hilum in the right lung.
Name the fissures dividing the right lung lobes.
Oblique fissure separates the upper and middle lobe from the lower lobe.
Horizontal fissure separates the upper and middle lobes.
What is a segment of the lung?
Each lobe is further divided into a number of segments (pulmonary and bronchopulmonary segments)
What supplies each segment?
Branch of bronchial artery
Branch of pulmonary artery
Segmental bronchus
What drains each segment?
Tributary of a pulmonary vein
Tributary of a bronchial vein
Lymphatic vessels
What is the smallest functionally independent region of a lung which is surgically resectable?
Bronchopulmonary segment
What are the pulmonary plexuses in close proximity to?
The roots of the lungs
Describe the sympathetic fibres of the lungs.
Postsynaptic sympathetic fibres arise from the upper 4/5 thoracic sympathetic ganglia and reach the pulmonary plexuses.
Describe the parasympathetic fibres of the lung.
Presynaptic parasympathetic fibres (carried in Vagus nerve) synapse with parasympathetic ganglion cells present in the pulmonary plexuses and along the bronchial tree.
What do sympathetic efferent fibres do?
Inhibitory to smooth muscle of bronci and bronchioles (bronchodilator)
Inhibitory to glands of the bronchial tree
Causes contraction of smooth muscles of pulmonary vessels = vasoconstrictor
What do the parasympathetic efferent fibres do?
Causes contraction of smooth muscle of bronchi and bronchioles = bronchoconstrictor
Increases secretion by glands of bronchial tree = secretomotor
Inhibitory to smooth muscle of the pulmonary vessels = vasodilator
Name the two visceral afferent fibres of the pulmonary plexuses.
Nociceptive
Reflexive
Describe the nociceptive visceral afferent fibres of the pulmonary plexuses.
Conducting pain impulses generated in response to painful of injurious stimuli e.g. chemical irritants, ischaemia or excessive stretching.
Describe the reflexive visceral afferent fibres of pulmonary plexuses.
Coughing, ability of lungs to regulate oxygen and carbon dioxide levels
List the structures involved in the mechanics of breathing.
Pleura
Thoracic bones
Muscles of Resp
What are the two serous membranes covering the lung?
Visceral and serous membranes
What covers the lung surface?
Visceral pleura
What is the outer membrane?
Parietal pleura
What is the parietal pleura attached to?
Thoracic wall (costal pleura)
Mediastinum (mediastinal pleura)
Diaphragm (diaphragmatic pleura)
The cupula (cervical pleura)
Where are the visceral and parietal pleura continuous with one another?
At the root of the lung
What is the potential space between the visceral and parietal pleura called?
Pleural cavity
What is the function of the small amounts of fluid secreted by the pleura?
Reduce friction
Facilitate inflation and deflation of the lungs in respiration.
Name the borders of the visceral and parietal pleura in the anterior, lateral and posterior planes.
Anterior: visceral - rib 6, parietal - rib 8
Lateral: visceral - rib 8, parietal - rib 10
Posterior: visceral - rib 10, parietal - rib 12
Where does pleural fluid drainage occur? Where do you insert the needle?
In the costodiaphragmatic recess
Laterally between ribs 8 and 10
Name the two pleural recesses.
Costomediastinal
Costodiaphragmatic
Where is the costomediastinal recess found?
Angle of reflection of the costal pleura and mediastinal pleural at the anterior border of the pleura
Where is the costodiaphragmatic recess found?
Angle of reflection between the costal and diaphragmatic pleura at the inferior border of pleura
What is the function of the pleura?
The lung expands into these recesses during forced inspiration.
Describe the innervation of the visceral pleura.
Visceral pleura is insensitive to pain as it receives no nerves of general sensation
Describe the innervation of parietal pleura.
Parietal pleura is extremely sensitive to pain
Innervated by the nerves innervating the thoracic wall
Intercostal nerves innervate the costal pleura
Rest of the pleura is innervated by the phrenic nerve
Name the parts making up the thoracic skeleton.
Sternum
Ribs and costal cartilages
Thoracic vertebrae
Name the three parts of the sternum.
Manubrium
Body
Xiphoid process
Which ribs are the true ribs and why?
Ribs 1-7
Articulate directly with the sternum
Which are the false ribs and why?
Ribs 8-10
They articulate with the costal cartilage of the rib immediately above
They form the costal margin
Which ribs are the floating/free ribs and why?
Ribs 11 and 12
Do not reach the sternum
Name the parts of a typical rib.
Head
Neck
Body (shaft)
Tubercle
What does the rib attach to posteriorly?
Vertebra
What is the name of the joint - head of rib articulates with the body of its own vertebra and that of the above vertebra?
Costovertebral joint –> synovial
What is the costotransverse joint?
Tubercle articulates with the transverse process of its own vertebra.
Synovial joint
What are the ribs anteriorly attached to?
Sternum
Describe sternocostal/chondrosternal joints.
Unossified part of rib (i.e. costal cartilage) articulates with sternum
Only ribs 1-7
Synovial joint
Name the diameters of the thoracic cavity.
Anteroposterior diameter
Transverse
Vertical
What causes an increase in the vertical diameter?
Contraction of the diaphragm
What causes an increase in the anteroposterior diameter?
Elevation of the ribs by inspiratory muscles
What causes an increase in the transverse diameter?
Elevation of the ribs by the inspiratory muscles
Name the two movements of the ribs
Pump handle
Bucket handle
Describe the pump handle movement.
Ribs and sternum act as single structure
Sternum is elevated and carried forwards
Ribs are lifted and AP diameter is increased
Ribs also spread out laterally
Which joints are involved in the pump handle movement?
Costovertebral and costotransverse joints allowing rotation
Why do the upper ribs undergo more movement than the lower ribs in the pump handle movement?
The articular surfaces of the costotransverse joint in the upper ribs are curved more allowing more rotation
Which joints are involved in the bucket handle movements?
Sternocostal and costovertebral joints
What is the bucket handle movement?
Mostly at the lower ribs
Lower ribs spread laterally and transverse diameter increases
Mainly by the diaphragm
Describe the borders of the superior thoracic aperture.
Anteriorly - manubrium of sternum
Laterally - 1st ribs
Posteriorly - body of T1 vertebra
What is the function of the superior aperture?
Allows structures to pass between the neck and thorax
What structures pass through the superior aperture?
Trachea Oesophagus Brachiocephalic artery Left subclavian artery and vein Vagus and phrenic nerve Internal jugular vein Common carotid artery Apex of right lung
Name the borders of the inferior thoracic aperture.
Anteriorly - xiphoid process of sternum
Laterally - costal margin, 11th/12th ribs
Posteriorly - T12 vertebrae
What is the function of the inferior thoracic aperture?
Allows structures to pass between the thorax and abdomen
What structures pass through the inferior thoracic aperture?
Aorta
Oesophagus
IVC
What closes the inferior thoracic aperture?
Diaphragm
Name the three parts of the diaphragm.
Sternal
Costal
Lumbar
Where do all 3 parts of the diaphragm join?
Central tendon
Describe where each part of the diaphragm comes from.
Sternal part arises from narrow slips at the back of the xiphoid process.
Costal part arises from the inner surface of the 6 lower costal cartilages and 4 lower ribs. Forms the right and left dome of diaphragm.
Lumbar part arises from the lumbar vertebrae& forms two muscular crura. Right crus comes from the upper 3 vertebrae, left crus comes from lower 2 vertebrae
Name the ligaments near the diaphragm.
Lateral arcuate ligament
Medial arcuate ligament
Median arcuate ligament
What diameter does contraction of the diaphragm increase?
Vertical diameter
Name the diaphragms highest position.
Trendelenburg position
What do the muscles of inspiration do?
Cause an increase in the diameters of the thoracic cavity
Describe what happens in inspiration.
Increase in volume of thoracic cavity (diameters increased)
Intrathoracic pressure is decreased
Air is sucked in and lungs become inflated (air inside is lower than air outside)
What do the muscles of expiration do to the diameters of the thoracic cavity?
Decrease the diameters (contraction)
Explain what happens in expiration.
Volume of thoracic cavity decreases (decrease in diameter)
Intrathoracic pressure is increased
Air is forced out of the lungs and lungs become deflated (pressure inside is greater than pressure outside)
Name the classification of the muscles of respiration.
Primary muscles - active in quiet and assist in forced respiration
Secondary muscles - active in forced respiration
Name the primary muscles of resp.
Diaphragm
Intercostal muscles
What do the intercostal muscles fill?
Fill an intercostal space
Name the 3 planes of intercostal muscles.
Superficial layer: External intercostal muscles
Intermediate layer: Internal intercostal muscles
Deep layer: Innermost intercostal muscles, subcostalis muscle, transversus thoracis muscle
What do the muscle fibres in the intercostal space attach to?
The rib above and the rib below
How do we determine the actions of the intercostal muscles?
Direction of their fibres
List the direction of fibres and movements of the intercostal muscles.
External intercostal muscles = downwards and forwards (elevate the ribs - inspiration)
Internal intercostal muscles = upwards and forwards (depress the ribs - expiration)
Innermost intercostal muscles = upwards and forwards (depress the ribs - expiration) N
Name the rib depressors.
Internal intercostal muscles
Innermost internal intercostal muscles, transversus thoracis, subcostalis muscle
Name the rib elevators
External intercostal muscles
Name the layers which the needle will pass through to enter the intercostal space.
Skin Superficial fascia Serratus anterior muscle External intercostal muscle Internal intercostal muscle Innermost internal intercostal muscle Parietal pleura
Name the muscles involved in active forced respiration (secondary muscles)
Scalane muscles Quadratus Lumborum Psoas Major and Psoas Minor Rhomboid muscles Pectoralis Minor Serratus anterior Serratus posterior Abdominal muscles
Who performs forced inspiration?
Those who have chronic obstructive pulmonary disease (COPD).
What is the function of the scalene muscles?
Lift the upper ribs higher as they can and increase their lung capacity
What is the function of the rhomboid and pectoralis minor in forced inspiration?
Shift the scapula medially and lift the upper ribs and increase their lung capacity
What do the psoas major and quadratus lumborum do in forced inspiration?
Stabilize and pull the floating ribs downwards to increase lung capacity
What do the abdominal muscles do in forced expiration?
Increase intraabdominal pressure and push the diaphragm up in forced expiration
