Skeletal System Development

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Questions and Answers

At what age does longitudinal bone growth generally cease?

21 years

23 years

20 years

25 years (correct)

What is the epiphyseal plate primarily made of?

Dense connective tissue

Hyaline cartilage (correct)

Elastic cartilage

Fibrocartilage

Which process continues even after the stop of longitudinal bone growth?

Ossification of cartilage

Formation of the epiphyseal line

Bone growth in diameter (correct)

Resorption of old bone

What happens to the chondrocytes in the epiphyseal plate when longitudinal growth stops?

They cease their proliferation Signup and view all the answers

What is the primary function of osteoblasts during bone remodeling?

Production of new bone tissue Signup and view all the answers

Which part of the skull grows the fastest during an infant's first four months of life?

Cranial bones Signup and view all the answers

How many bones are typically found in an adult skull?

22 bones Signup and view all the answers

What role does the pliable head play in a child's development?

Facilitates normal brain growth Signup and view all the answers

What is the primary function of ossification in the skeletal system?

Conversion of cartilage into bone Signup and view all the answers

When does the upper-extremity limb bud first appear compared to the lower-extremity limb bud?

Slightly before the lower-extremity limb bud Signup and view all the answers

Which structure remains as cartilage at the joint surface after the fetal skeleton is fully formed?

Articular cartilage Signup and view all the answers

What is appositional bone growth?

Increase in girth of bones Signup and view all the answers

At birth, how many bones are typically present in a baby's body?

300 Signup and view all the answers

Which of the following factors does NOT affect prenatal growth of bones?

Maternal exercise Signup and view all the answers

What are traction epiphyses?

Sites where muscles’ tendons attach to bones Signup and view all the answers

When do primary ossification centers in long bones typically appear?

During embryonic life Signup and view all the answers

Signup and view all the answers

Study Notes

Skeletal System Development

The skeletal system's structure changes throughout life, influenced by genetics and environment.
In the embryonic stage, the skeleton is a cartilage model of future bones.
Ossification centers form where bones are to be, converting cartilage or connective tissues to bone.
Ossification is the conversion of cartilage or connective tissues to bone.
Upper limb buds appear before lower limb buds, and limb development follows a proximal-distal sequence.
Primary ossification centers form in the middle of long bones during the 4th week of development.
Bone cells (osteogenesis) start forming at 2 months of fetal age.
Bone shafts ossify outward from primary centers, becoming fully ossified by birth.
Secondary ossification centers, or epiphyseal plates, allow bone growth in length.
Small bones like wrist and ankle bones ossify from the center outward.
A developing long bone comprises diaphysis, epiphyses, and metaphysis.
Growth plates are between epiphyses and metaphysis.
These regions form in mid-embryonic stage and proportionately change size until skeletal maturity.

Prenatal Development

Cartilage remains at joint surfaces (articular cartilage) and between diaphysis and epiphysis (epiphyseal plate) once the fetal skeleton is formed.
A newborn has approximately 300 bones.
Adult skeletons have 206 fused bones.
Factors affecting prenatal bone growth include genetics, maternal nutrition (calcium and vitamin D), UV-B exposure, and maternal smoking.

Postnatal Growth & Development

Long bones increase girth (appositional bone growth) alongside growth in length.
Girth increase is due to new tissue layers beneath the periosteum.
Traction epiphyses are epiphyses where tendons attach to bones.
Cartilage slowly gets replaced by bone during childhood.
Longitudinal bone growth ends at about 25 years of age.

Factors Affecting Growth

Genetic factors affect growth and development.
Maternal nutrition of the mother during pregnancy affect the fetus' development.
This means calcium, vitamin D and other nutrients are vital.
Exposure to UV-B light affects growth.
Smoking during pregnancy can damage prenatal development.

How Bones Grow in Length

The epiphyseal plate is the growth plate of long bones, made of hyaline cartilage.
Cartilage forms on the epiphyseal side of the plate.
Cartilage ossifies on the diaphysis side, increasing the diaphysis.

How Bones Grow in Diameter

Bones increase in diameter even after longitudinal growth ceases.
Osteoclasts remove old bone in the medullary cavity.
Osteoblasts create new bone beneath the periosteum, increasing bone diameter.
Modeling is the term used for bone diameter increase via osteoclasts and osteoblasts.

Bone Remodeling

Occurs in adult life and involves resorption of old or damaged bone and creation of new bone tissue in the same area.
Injury and exercise increase the rate of remodeling.
About 5-10% of skeleton is remodeled annually, regardless of whether injury or exercise occurred.

Head Growth

Infant head growth mirrors brain growth.
Fetus' skull has fibers that connect cranial bones.
Skull growth rate is fastest during first 4 months, compared to rest of life.
Fibers disappear and cranial bones fuse together a year after birth.

Head Growth - Other Points

The pliable skull allows for normal human development during first 18 months.
Skull bones fuse between 20 months and 2 years.
An adult skull is made up of 22 bones, including 8 cranial and 14 facial bones.

Head Circumference

Measuring head circumference gauges head size.
Average newborn head circumference is 35 cm.
Growth to about 38 cm by one month is considered typical.

Head Fontanelles

Specialized spaces (fontanelles) exist in the skull of infants, aiding in birth and growth.
Fontanelles gradually close as bones grow together and fuse.

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Description

Explore the fascinating journey of skeletal system development from the embryonic stage to birth. This quiz covers key concepts such as ossification, limb development, and the structure of long bones. Test your understanding of how genetics and environment influence bone formation.