© Goodheart-Willcox Co., Inc.. 8 Physical Development of the Infant.

© Goodheart-Willcox Co., Inc.


8Physical Development

of the Infant


Key Terms

• skeletal system• failure to thrive• body proportions• ossification• deciduous teeth• motor

development• gross-motor skills

• fine-motor skills• age norm• crawl• creeping• cruising• voluntary grasping


Objective

• Describe how an infant develops physically during the first year.


Skeletal Growth

• Skeletal system is made up of bones and teeth

• Length– increase birth length by 30% during first

five months– reach 1.5 times their birth length during

first year– boys are usually ¾ inch longer than girls

by one year of age

continued


Skeletal Growth

• Weight– around 9 months, babies are rather

chubby as fat tissues increase– boys are usually 1½ pounds heavier

than girls by one year of age • boys have more muscle mass than girls• girls have more fat than boys

continued


Skeletal Growth

• Average length and weight during first year

continued

Age in Months

Length Weight

Birth 20 in. 7½ lbs.

3 23¾ in. 12½ lbs.

6 26 in. 26¾ lbs.

9 28 in. 20 lbs.

12 29½ in. 22¼ lbs.


Skeletal Growth

• Failure to thrive is a condition in which a child fails to grow at a healthy rate

• Possible causes– disease preventing nutrient absorption– food not providing enough nutrients– feedings offered too infrequently or last

too short of a time– baby abused or neglected

continued


Skeletal Growth

• Body proportions (relative size of body parts) differ from those of adults– infant’s head one-fourth of total length;

adult’s head one-eighth of total height

• Head larger than chest• “Pot-bellied” abdomen and short legs• Center of gravity high on baby’s body

continued


Skeletal Growth

• Infant skeleton is mainly made of cartilage– large spaces between “bones” to help

the joints bend easily without breaking– skeletons are not sturdy, which makes

sitting and standing impossible– bones can easily become misshapen

continued


Skeletal Growth

• Babies need to change position often– tummy time encourages

rolling over, reaching, crawling

continued


Skeletal Growth

• During the first year, three changes occur in a baby’s bones– length increases– ossification (depositing of the minerals,

calcium, and phosphorus) begins– number of bones changes

• few bones in hand differentiate into many• parts of skull become one large bone

continued


Skeletal Growth

• Deciduous teeth (nonpermanent) appear in a predictable manner, but timing varies greatly– most babies begin

cutting teeth during second half of first year


What Do You Think?

• How should families care for an infant’s deciduous teeth?

• Why is it important to practice healthy dental hygiene for teeth that will be replaced by permanent teeth at a later date?


Objective

• Describe the order in which an infant’s motor skills develop.


Motor Development

• Motor development is the use and control of muscles that direct body movements

• Gross-motor skills use large muscles– trunk, arms, legs

• Fine-motor skills use small muscles– hands, fingers

continued


Motor Development

• Baby’s motor skills develop in three main patterns– movements are slow because babies

must think as they move– reactions develop from general to specific– development occurs in two directions

• head-to-foot• center-to-extremities


Head-to-Foot Development

• Begins before birth• Milestones are sequenced steps

– order of steps more constant than timing

• Age norm is a typical time when a developmental milestone occurs– can be expressed as an average age or

age range

continued



continued



• Crawl means to move by pulling with arms, not lifting abdomen from floor– about seven months

• Creeping means to move by using hands and knees or feet– between six and eight months

• Cruising means to walk by holding something for support– between 12 and 14 months


Center-to-Extremities Development

continued


Center-to-Extremities Development

• Control of arms, hands, fingers develop in stages– born with Palmar reflex– at two months, begin to swipe at

objects in an attempt to grasp them– about four months, grasping reflex is

replaced by voluntary grasping• well developed between five to six months

– at eight or nine months, pincer grasp is developed


What Do You Think?

• How can adult caregivers support head-to-foot development and center-to-extremities development of infants? Describe some specific activities that can be incorporated into the infant’s daily schedule.


• age norm. Typical time when a developmental milestone, such as walking or talking, occurs; an age norm can be expressed as an average age or an age range.

• body proportions. Relative size of body parts.

• crawl. Moving by pulling with the arms, but not lifting the abdomen from the floor.

Glossary of Key Terms


• creeping. Moving by using the hands and knees or the hands and feet with the abdomen off the floor.

• cruising. Walking by holding something for support.

• deciduous teeth. First set of teeth, which will later be replaced by permanent teeth; also called nonpermanent or baby teeth.



• failure to thrive. Condition in which a child fails to grow at a healthy rate.

• fine-motor skills. Being able to use and control the small muscles, especially those in the fingers and hands.

• gross-motor skills. Being able to use the large muscles to roll over, sit, crawl, stand, and walk.



• motor development. Use and control of muscles that direct body movements.

• ossification. Hardening of bones caused by the depositing of the minerals calcium and phosphorus.

• skeletal system. Body system that includes the bones and teeth.

• voluntary grasping. Intentional grasping of objects.


© Goodheart-Willcox Co., Inc.. 8 Physical Development of the Infant.

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