Infant Development & Brain Anatomy – Quick Reference

Infants are very helpless early on but develop rapidly; neck muscles cannot support the head at birth.
First year milestones: sit, stand, climb, walk; bend head up/down (stooping).
Second year focuses more on motor skills (grabbing/manipulating objects, clapping).

Cephalocaudal growth: growth starts at the head and proceeds downward to the trunk and limbs.
Proximodistal growth: growth starts at the center (torso) and moves outward to the limbs.

Average newborn weight: $7.6\,\text{lb}$ ; length: $20\,\text{in}$ .
First year growth: about $1\,\text{inch}$ per month.
By age 2: weight approximately $26\text{-}32\,\text{lb}$ ; height about $2.5\,\text{ft}$ (≈ $30\,\text{in}$ ).
Brain at birth weighs about $25\%$ of adult brain weight.

Brain is highly vulnerable and malleable; protection from head trauma is crucial.
Shaken Baby Syndrome: violent shaking causing brain trauma, hemorrhage, swelling; cognitive/physical problems; can be fatal.
Signs include pale/blue top of head and lethargic eyes; perpetrated most often by male caregiver (father or mother's boyfriend).

Two hemispheres: Left (language, logic, semantic skills) controls the right side of the body; Right (spatial skills, perception, creativity) controls the left side.
Corpus callosum: thick bundle of nerves connecting the hemispheres; severing can stop seizures but may cause communication, memory, or feeling issues.
Left-brain/right-brain myth: both hemispheres are used; widespread connectivity.
People with more left-side activity tend to be happier on average (simplified observation).

Neocortex: outer, front portion; thinking, language, cognition, higher-level skills.
Limbic system: emotions, intuition.
Brainstem / Basal ganglia (reptilian brain): basic survival functions, instincts, respiration, nourishment signals.

Frontal lobes: voluntary movement, personality, morality, sense of purpose.
Occipital lobes: vision.
Temporal lobes: hearing, language processing, memory.
Parietal lobes: spatial perception, attention, hand-eye coordination.
Brain plasticity: can reallocate functions to other regions if one area is underactive or damaged (e.g., occipital involvement shifting in blind individuals).

Protect the front of the head; injuries here are linked to cognitive and physical health problems.
The brain operates as an integrated network; no fixed “left vs right” personality type.