Characteristics of Skin, Muscles, and Bones in Children

Characteristics of Skin, Muscles, and Bones in Children

# Skin

Characteristics:

• Soft, watery, thin and porous, smooth like velvet, with many capillaries, poorly developed muscle fibers and elastic fibers, well-developed sebaceous glands from birth.

• Sweat glands develop within the first 3-4 months but do not function yet due to the incomplete development of the nervous system.

• Vernix caseosa: This is a waxy, cheese-like substance that covers the skin of a newborn.

• Functions of vernix caseosa:

• Protects the skin from injury.

• Helps to prevent heat loss.

• Has immune properties.

• Serves as a nutrient for the skin.

• Physiological Erythema:

• After cleaning the vernix caseosa from the skin, the skin appears slightly edematous, pale, then turns reddish-pink, with mild bluish discoloration.

• This is most prominent in premature infants 1-2 days after birth.

• Subsequently, the skin gradually becomes white and flakes off, coinciding with physiological jaundice.

• Subcutaneous fat layer formation: During the 7th-8th month of pregnancy.

• Development and location of subcutaneous fat:

• Full-term infants develop subcutaneous fat well from birth.

• In the first 6 months, fat development is most prominent in the face and less in the abdomen.

• Chemical composition of subcutaneous fat in children: Contains high levels of saturated fatty acids (palmitic and stearic acids) and lower levels of unsaturated fatty acids (oleic acid) compared to adults.

• Reason for edema in children during winter: High levels of saturated fatty acids (palmitic and stearic acids) and lower levels of unsaturated fatty acids (oleic acid) compared to adults -> higher melting point -> unable to generate enough heat to keep the body warm in winter.

• Why should some oil-soluble drugs like camphor be avoided in children? High levels of saturated fatty acids (palmitic and stearic acids) and lower levels of unsaturated fatty acids (oleic acid) compared to adults -> children’s skin easily stiffens when these drugs are injected, and the oil dissolves slowly, leading to abscesses.

• Premature infants who are poorly nourished have more lanugo hair than full-term infants who are well-nourished? True.

• The skin surface area of children is higher than that of adults relative to their body weight? True.

• Formula for calculating skin surface area in children: 1/10 x P^2/3 (P: weight).

• Functional characteristics of the skin in children:

• Protection: Easily susceptible to injury and infection.

• Excretion: Sweat glands do not function in the first few months -> skin excretes sweat.

• Temperature regulation: Not yet perfected.

• Metabolism: Synthesis of enzymes, immune substances, and vitamin D.

# Muscles

• Percentage of muscle weight to body weight in newborns: 23%.

• Characteristics:

• Lighter and more watery than in adults.

• Muscle fiber thickness = 1/5 of adults, interstitial tissue development is abundant and rapid, muscle cells have multiple nuclei.

• High water content, low protein, fat, and inorganic salts.

• Why do children lose weight quickly when severely dehydrated? Because children’s muscles are high in water and low in protein, fat, and salts.

• Characteristics of muscle development: Uneven muscle development: Larger muscles develop first, smaller muscles develop until the age of 6.

• Upper limb hypertonia ends when: 2 – 2.5 months.

• Lower limb hypertonia ends when: 3 – 4 months.

# Bones

• Characteristics in newborns:

• Large head.

• Long trunk.

• Short limbs.

• Spinal column is almost straight.

• Rounded, soft rib cage, easily deformed.

• Chemical composition characteristics: High water content and low mineral salts. Similar to adults by the age of 12.

• Histological characteristics:

• Fibrous mesh-like tissue, few bone lamellae and uneven distribution.

• Haversian canals are large and have many blood vessels.

• Bone formation and resorption processes are rapid.

• Thick periosteum -> prone to “green stick” fractures.

• Appearance of ossification centers in 3-6 month old children: Capitate bone, hamate bone.

• Appearance of ossification centers in 3 year old children: Scaphoid bone.

• Appearance of ossification centers in 4-6 year old children: Lunate bone, trapezium bone.

• Appearance of ossification centers in 5-7 year old children: Triquetrum bone.

• Appearance of ossification centers in 10-13 year old children: Pisiform bone.

• Anterior fontanelle closes when: 12 months, at the latest 18 months.

• Posterior fontanelle closes when: 3 months.

• Maxilla and mandible formation: At birth.

• Frontal sinus formation: At 3 years old.

• Key milestones of spinal column changes in children:

• Head lifting (1.5 – 2 months): Spinal column axis rotates forward.

• Sitting at 6 months: Rotates backward.

• Walking at 1 year: Thoracic region curves forward.

• 7 years old: Two permanent curves: cervical and thoracic.

• Puberty: Lumbar curve becomes permanent.

• Children are prone to scoliosis due to: The spinal column is composed of a lot of cartilage and the curves are not yet firm.

• The two iliac bones, sacrum, and coccyx start fusing together when and are completed when? 7 years old. 20 – 21 years old.

• Physiological bowing of the limbs ends when: 1 month after birth.

• Wrist formation: 7 years old.

• Wrist bone formation complete: 10 – 13 years old.

• Children start teething when: 6 months old.

• How many deciduous teeth erupt each year? 8.

• Deciduous teeth eruption period ends when? How many deciduous teeth? 2 years old. 20 teeth.

• Formula for calculating the number of teeth: Age in months – 4.

• Children erupt molars when: 5 – 7 years old.

• When do children replace deciduous teeth with permanent teeth? How many permanent teeth? After 5-7 years old. 32.

• Do children with rickets have delayed tooth eruption? True.