Anatomy Exam #2

Internal intercostals

Lie deep to the external intercostal muscles

function: work to retract the rib cage

Innermost Intercostals

The deepest of the intercostal muscles

• Run parallel to the internal intercostals

function: assist in retraction of the rib cage

Transversus Thoraci

Exists on the inside surface of the rib cage

function: retracts the rib cage and resists elevation of the rib cage

Subcostals

Deep to the internal intercostals on the inferior interior surface of the posterior thorax

• The length and number of subcostals vary from person to person

function: retract the rib cage

Serratus Posterior Inferior

Quadrilateral shaped muscle of the lower back

• Has extensions that give the muscle its serrated appearance

Primary function: Stabilizes the trunk

Secondary function: assists in retracting the rib cage

Points of attachment for abdominal muscles

Abdominal aponeurosis: large flat tendinous structure

• Forms the anterior wall of the abdomen

• Deep to it are the abdominal muscles

Very few skeletal points of attachment for muscles in the abdomen

Instead, connect via tendinous aponeuroses:

o Linea alba

o Linea semilunaris

o Abdominal aponeurosis

o Lumbodorsal fascia

Transversus Abdominis

Deepest of the abdominal muscles

• The fibers course horizontally, as is implied by the word transversus

Function: Compresses the abdomen, which stretches the diaphragm, reducing vertical thoracic volume

Internal Oblique Abdominis

Located between the external oblique abdominis and transverse abdominis

• Smaller and thinner than external oblique abdominis

• Pulls in the opposite direction to the external oblique abdominis

Function: Bilateral: Pulls the lower ribs down and compresses the abdomen

Unilateral: Assists in rotation and bending of the trunk towards the side of contraction.

External Oblique Abdominis

Most superficial and largest abdominal muscles

Function:

Bilateral contraction pulls the thorax down and compresses the abdomen

Unilateral contraction facilitates contralateral rotation of the trunk and ipsilateral bending of

the trunk

Rectus Abdominis

Paired flat muscle across the anterior of the abdomen

• Divided into its paired right and left divisions at midline by the linea alba and laterally by other tendinous connective tissue

Functions:

To bend the torso anteriorly

To pull the thorax towards the pelvis as in the action performed during sit-ups

To compress the abdomen

Quadratus Lumborum

Deep posterior muscle of the abdomen

Roughly quadrilateral in shape

Function: Bilateral contraction pulls inferiorly on the last rib, retracting the rib cage

Vegetative Respiration

occurs automatically; Neural signals originate from the brainstem

Respiratory center receives information from the body and brain about oxygen and carbon

dioxide levels

• This information is used to manage the rhythm, rate, and depth of respiration

• Ensures homeostasis (balance) of oxygen and carbon dioxide in the body

If not enough oxygen during quiet respiration

Respiratory center signals to increase the speed and volume of respiration to take

in larger amounts of air faster and acquire greater levels of oxygen (more muscles - hyperpnea)

Speech Breathing

Forced respiration pattern that is used to volitionally commandeer the respiratory system

to produce speech sounds

• Adduction of the vocal folds during expiration to generate phonation

• Varying constriction of the vocal tract for articulation of phonemes

During speech breathing

10% inspiration/ 90% expiration

The inspiratory phase for speech breathing

shorter duration and greater inspiratory volumes

Inspiratory Checking

– Controlled, slowed rebound of thorax

■ During quiet respiration the thorax rebounds quickly

and unopposed by muscle activation

– Allows airstream to be controlled for speaking

■ Slows the airstream & maintains pressure beneath

vocal folds

■ Controlled contraction of expiratory muscles to

slowly push air out

Thorax expands and retracts in three dimensions

Anterior-posterior,Vertical,Transverse

Active force of muscular contraction

mostly involved in inspiration (diaphragm & accessory)

Passive forces that contribute

mostly to expiration

Passive Forces – Gravity (Standing)

Standing: gravity pulls base of the lungs and abdominal viscera inferiorly

– Increases the ease of inferior expansion of the thorax by the diaphragm, assists

inspiration

– Works against superior retraction of the lungs and diaphragm, against expiration

– For active respiration, works against elevation of the thorax for inspiration but facilitates

inferior retraction of the thorax during expiration

Passive Forces – Gravity (Supine)

Supine: gravity pulls down on ribcage and flattens abdominal viscera

– Pushes viscera towards the head against the base of the diaphragm

■ Makes expansion of the thorax for inspiration more difficult

■ Facilitates retraction of the thorax for expiration

Tissue Recoil/Elasticity

Degree to which the fibers of the body are able to passively retract to their original position

– Tissue elasticity is associated with the retraction of the thorax

Atmospheric pressure

Air pressure on the surface of the earth; consistent during respiration

Intraoral pressure

Air pressure within the oral cavity

Subglottal pressure

Air pressure below the glottis between vocal folds; responsible for phonation

Alveolar pressure

Air pressure within the alveoli of the lungs

Intrapleural pressure

Air pressure within pleural linkage

Brownian Motion

• Within a closed container, molecules exhibit:

– Random, high speed, and constant motion

– Constant collisions with each other and walls

of the container

• More frequent collisions = greater air pressure

• Less frequent collisions = lower air pressure

Boyle’s Law

• Relationship between volume and air pressure within a closed container

• Container volume decrease = air pressure increase

• Container volume increase = air pressure decrease

Respiratory Cycle

Thorax expands → lungs expand (increases lung volume) → pressure differential → air rushes in → gas exchange in alveoli → thorax shrinks → lungs shrink (reduce lung volume) → pressure differential → air rushes out of lungs → cycle repeats

Tidal Volume (TV)

the volume of air that is inspired and expired during a cycle of quiet respiration

Inspiratory Reserve Volume (IRV)

The maximal amount of air that can be inspired beyond a tidal inspiration

Expiratory Reserve Volume (ERV)

The maximal amount of air that can be expired beyond a tidal expiration

Residual Volume (RV)

Amount of air remaining in the lungs after maximal exhalation

• Cannot be used to generate breath to speak on

Total lung capacity (TLC)

TLC= TV+ERV+IRV+RV

Functional residual capacity (FRC)

FRV= RV + ERV

Inspiratory Capacity (IC)

IC= TV+ IRV

Vital Capacity (VC)

VC= IRV+TV+ERV

Developmental differences

Children and infants have faster rates of quiet respiration

– Smaller lungs = faster air exchange to

maintain appropriate oxygenation

■ TV and rate of respiration during quiet respiration changes as the body grows and ages

lungs fully mature

20-25 (declines after do not impair functional respiration in healthy adults)

Four primary changes with age

• Lung elasticity decreases (less dilated = less airflow; airways may collapse)

• Thorax stiffens (increases energy needed)

• Muscles weaken (increases energy needed)

• Gas exchange becomes less efficient (reduced SA for exchange, capillaries weaken)

Changes in Lung Volumes & Capacity During Aging

• Expiratory reserve volume (ERV) declines

• Residual volume (RV) increases

• Vital Capacity (VC) progressively declines after early 20s

• Total lung capacity (TLC) declines slightly with normal age but does not impair respiration

Respiration is usually measured along three parameters:

• Rate

• Cycles of respiration (inhale + exhale) per minute; breaths per minute; BPM

• Pressure

• Volume

Manometer

Measures expiratory pressure

● Simplest form: U-tube manometer

● Expiration pushes water upward

● Harder expiration = more water displaced

● Measured in cm H2O

● ~5 cmH2O needed to drive vocal folds for phonation

Wet Spirometer

Measures most lung volumes and vital capacity

• Person expires through the tube, air moves into the first container  displaces water, causing it to rise

• Amount of displacement is measured to generate lung volumes and capacities

• Must calculate residual volume and total lung volume

• Measures tidal volume, inspiratory reserve volume, and expiratory reserve volume

ALSO HANDHELD AND INCENTIVE

Pulse Oximeter

● O2 sat = oxygen-saturated Hgb ÷ total Hgb

● Normal: 95–100% (can drop to 80%)

● Too low = hypoxia

● can occur w/ normal HR/RR

● causes reversible cognitive/motor slowing

● Pulse oximeter uses infrared and red light

● Measure differences in oxygenated vs deoxygenated blood

● SLP relevance: monitor during feeding/swallowing (e.g., NICU, COPD therapy)

Laryngeal function

Protect the airway (e.g., during swallowing)

– Adduct (close) the vocal folds

– Cough/throat clearing mechanism

• Breathing

– Abduct (open) the vocal folds so air can move in and out

Secondary biological function

• Phonation

– Build up air pressure below the closed vocal folds so they can vibrate

– Convert air from the lungs into acoustic energy (sound)

False vocal folds (ventricular folds/vestibular folds)

not responsible for sound production

True vocal folds

sound production; close off glottis to protect airway

Sex differences

male larynx grows larger (about 23 mm vs. 18 mm)

Branches of CN X (vagus) supply the larynx:

Superior laryngeal nerve (SLN)

– Internal branch: sensation above the vocal folds

– External branch: motor to the cricothyroid muscle

Recurrent laryngeal nerve (RLN)

– Motor to all other intrinsic laryngeal muscles

– Sensation below the vocal folds

The left RLN loops under the aortic arch, so its path is longer

unpaired cartilages

epiglottis, cricoid, thyroid

paired

arytenoids, corniculates, cuneiform

cricoid cartilage

Hyaline cartilage; the only complete ring of cartilage in the airway

• Located inferior to the thyroid cartilage and articulates with inferior horns

• Superior to the trachea (about C6); attaches to first tracheal cartilage

Attachment site for multiple muscles, ligaments, and cartilages

Thyroid cartilage

Largest cartilage in the larynx

• At front of larynx, superior to the thyroid gland

– Shaped like a shield; its two laminae protect the front and sides of the larynx

• Superior thyroid notch: superior to the laryngeal prominence

• Cricothyroid joint: the inferior horns of the thyroid articulate with the sides of the cricoid cartilage

Epiglottis

Elastic cartilage - resembles a large spoon or leaf

• Attached to the hyoid bone

The sides of the epiglottis are connected to the arytenoid cartilages via the aryepiglottic folds

• The stem (bottom) of the epiglottis is attached to the anterior thyroid cartilage

valleculae

small pockets between base of tongue and epiglottis; space that SLPs observe during modified barium swallow studies

Pyriform sinuses

pockets on each side, between the aryepiglottic folds and the thyroid cartilage

– Together, the valleculae and pyriform sinuses are the pharyngeal recesses

Sensory nerves of the epiglottis

– CN IX (glossopharyngeal) → upper epiglottis → sensory side of the gag reflex

– CN X (internal branch of the superior laryngeal nerve) → lower epiglottis → sensory

side of the cough reflex

Arytenoids

Triangular (hyaline)

Located at the posterior-superior border of the cricoid cartilage

● Muscular process: projects laterally; attachment site for muscles that open

and close the vocal folds

● Vocal process: projects anteriorly; attachment site for the vocal ligament (the

vocal fold)

● Attached to the vocal folds and allow for movement of the folds

● Adjust tension/relaxation and position of the vocal folds

Corniculate Cartilages

Horn-shaped elastic cartilages

● Derived from the Latin root “cornu” which means “horn-like

projection”

● Located at the tip of each arytenoid cartilage

● Posterior to the aryepiglottic folds

● Provides structural support to the aryepiglottic folds