pt 2. anatomy, emryology, physiology, and typical development

pharyngeal swallow rate in infants awake vs asleep

~6×/min (awake), ~6×/hr (asleep)

what are keys to safety for pharyngeal swallow in infants

Cessation of breath (stop breathing) & sustained laryngeal closure

Preterm infants at higher risk:

• Immature timing → swallow during inhalation

• Leads to oxygen desaturation, possible penetration, aspiration

Cough Reflex

• Triggered by __________

• Glottis closes with _______

• laryngeal/subglottic receptors

• explosive cough

cough reflex is rare for preterm infants!

esophageal swallow function

Automatic peristaltic wave carries bolus to stomach

triggered by pharyngeal swallow, travels UES → LES

primary peristalsis

initiated by esophageal provocation and is independent of the swallow; can occur during swallowing or reflux

secondary peristalsis

In infants, An inactive, distended esophagus and continuous LES relaxation may result from _________ seen during feeding and increase the risk of ____________.

rapid sequence swallowing; gastroesophageal reflux (GER)

what is used to hep increase likelihood of full peristaltic wave to help with reflux

solid boluses (increase weight of bolus)

Esophageal ____ and esophageal and gastric ______ are necessary for a healthy upper digestive tract.

motility; competence

Mechanisms involved in normal acid clearance include ______, ______, and _______. All may be significantly impaired in patients with swallowing disorders

salivation, swallowing, and peristalsis

Stomach function is influenced by neural and hormonal factors. Food volume, physical state (solid or liquid), and specific food content all affect gastric emptying.

• The stomach empties ____ faster than ______

• Increased _______ and ______ slow gastric emptying

• ____________ affects the rate of gastric emptying

• breast milk ; formula

• carbohydrates and proteins

• Body positioning (left side and elevated manner)

The lower esophageal sphincter (LES) at the distal end of the esophagus normally prevents free reflux of gastric contents into the esophagus.

• During swallowing, a momentary _______ of the LES allows swallowed food to enter the stomach

• In the first few weeks after a term birth, the LES at the gastroesophageal junction ________ and contributes to the prevention of reflux.

• relaxation

• matures rapidly

what is essential for survival and safe oral feeding?

Proper oxygenation (getting enough oxygen)

In newborns, especially preterm infants, _______ and _______ are not yet perfectly coordinated

breathing and sucking/swallowing

When infants suck to feed, they often do what to their breathing?

• Slow down breathing (decreased respiratory rate and tidal volume).

• Temporarily stop breathing (brief breath holds)

When infants suck to feed, they often:

• Slow down breathing (decreased respiratory rate and tidal volume).

• Temporarily stop breathing (brief breath holds).

This is usually well-tolerated in full-term infants, but preterm infants or those with lung issues (like bronchopulmonary dysplasia or BPD) may:

• Experience hypoxia (low oxygen).

• Be at higher risk for aspiration (food or liquid entering the airway)

Young infants may have anatomical and muscular issues that compromise their airway, such as:

• Weak throat muscles (hypotonia),

• Flexed neck posture,

• Posterior jaw position

• Compressed hyoid bone

what is important to maintain airway safety?

Proper positioning (neutral head/neck/shoulder/hips)

what taste stimulates suck-and-swallow reflexes in neonates and increases fluid intake over time

Sweet taste (e.g., sucrose)

_______ and ______ influence newborn feeding behavior and recognition, supported by early arousal systems like the locus coeruleus

Breast odor and maternal scent

Infants have sensitive periods during early infancy when ______ influences future preferences

flavor exposure

Although subjective, infant _____ responses to food are informative behavioral indicators of acceptance or rejection

These responses are _____ and can be modified through repeated exposure and positive feeding experiences

facial

malleable

• _____________ early—especially vegetables—can help children accept more foods as they start eating solids.

• Paying attention to ___ and ___ in feeding therapy can help improve results, especially for kids with feeding challenges.

• A ___ approach that looks at movement, senses, and behavior is key to understanding and treating feeding problems effectively.

• Introducing a variety of flavors

• taste and smell

• team

reflexes related to swallowing

• rooting reflex

• phasic bite

• tongue

• gag reflex

rooting reflex

touch the cheek or the corner of the mouth, their reflex is to turn to look for food

phasic bite

pressure on the gum and they close their mouth

tongue reflex

• transverse: put a finger on either side of the mouth, the tongue goes towards that side like bolus manipulation on the sides (reflex becomes a skill)

• protrusion: touch the tongue or lips, and the tongue comes forward

The presence, strength, or absence of these reflexes can aid in neurological assessment and guide _______

feeding readiness

Their timing of disappearance aligns with developmental feeding transitions—such as spoon feeding and introduction of solids

reflexes

Overactive or underactive reflexes may be signs of ______ or ______, but should be interpreted in the context of overall function, especially in the case of the gag reflex.

neurological dysfunction or feeding disorders

Anatomic and Physiologic Changes Supporting Transition:

• ________ As the mandible grows downward and forward, the oral cavity elongates vertically, increasing intraoral space.

Oral cavity expansion

Anatomic and Physiologic Changes Supporting Transition:

• The ______ and ____ shift downward, altering the coordination of breathing and swallowing, which begin to function more reciprocally.

hyoid bone and larynx

Anatomic and Physiologic Changes Supporting Transition:

• ______, initially used for structural support in suckling, begin to resorb during early infancy.

Sucking pads

Anatomic and Physiologic Changes Supporting Transition:

• _______ begins around 6–8 months (typically mandibular incisors first), continuing through 24 months until all 20 deciduous teeth are present.

Tooth eruption

Anatomic and Physiologic Changes Supporting Transition:

• _____ provide sensory input more than motor function during this stage, supporting CNS control of feeding.

teeth

Anatomic and Physiologic Changes Supporting Transition:

• _______ increases as sucking pads diminish, allowing for food to be moved between the tongue and the buccal wal

Buccal space

Anatomic and Physiologic Changes Supporting Transition:

• Crushing and grinding of food is aided by ____ when present, or the ____ if not.

molars; gums

Anatomic and Physiologic Changes Supporting Transition:

• __________ are crucial for food manipulation—moving food from the midline to lateral buccal walls

lateral tongue movements

Anatomic and Physiologic Changes Supporting Transition:

• Early spoon feeding elicits _______ tongue movements, often pushing food out due to anteroposterior motion that mimics tongue thrusting

suckling

Anatomic and Physiologic Changes Supporting Transition:

• With time, the infant demonstrates ______ movements in coordination with ______ action, which are essential for efficient oral phase feeding

lateral tongue; rotary jaw

Key Domains of Feeding Development

• oral sensorimotor skills

• posture and muscle tone

• psychosocial development

• cultural influence

Improve alongside CNS maturation and general muscle control. Feeding begins with reflexive actions and becomes increasingly voluntary and coordinated.
which Domains of Feeding Development?

Oral Sensorimotor Skills

Essential for head/trunk stability to support safe, efficient feeding

Domains of Feeding Development?

Posture and Muscle Tone

Feeding supports bonding, social interaction, and emotional regulation

Domains of Feeding Development?

Psychosocial Development

Techniques, timing, and expectations around feeding vary by culture and must be respected in clinical care.

Domains of Feeding Development?

Cultural Influence