Semey medical university siw age physiology of skeletal system in child презентация

CONTENT

SKELETAL SYSTEM
Bones are made of several tissues
Primarily made of collagen and hydroxyapatite - Ca10(PO4)6(OH)2
About 206 bones in the human body

FUNCTIONS OF SKELETAL SYSTEM
SUPPORT: Hard framework that supports and anchors the soft organs of the body.
PROTECTION: Surrounds organs such as the brain and spinal cord.
MOVEMENT: Allows for muscle attachment therefore the bones are used as levers.
STORAGE: Minerals and lipids are stored within bone material.
BLOOD CELL FORMATION: The bone marrow is responsible for blood cell production

PARTS OF THE SKELETAL SYSTEM
Axial skeleton
Skull and bones that support it
Includes vertebra and ribs
80 bones
Appendicular skeleton
Limbs
126 bones

FEATURES OF A LONG BONE
Epiphysis: Ends of the bone.
Diaphysis: The shaft of the bone which surrounds the medullary cavity.
Articular Cartilage: Cushions the ends of the bones and allows for smooth movement.
Epiphyseal Plate:
Areas made of cartilage allowing for the growth of the bone.

BONE DEVELOPMENT
Initial skeleton of cartilage in infants
Replaced with bone by osteoblasts
More than 300 bones at birth – fuse to 206
Always growing and breaking down
Osteoblasts – form new bone cells
Osteoclasts – break bone cells down
Osteocytes – mature bone cells

BONE STRUCTURE
Periosteum – hard outer covering
Cells for growth and repair
Compact bone – hard strong layer
Bone cells, blood vessels, protein with Ca and P
Spongy bone – at ends of long bones
Has small open spaces to lighten weight
Marrow cavity – hollow in middle of long bones

BONE MARROW
Red marrow – produces blood cells and clotting factors
Found in humerus, femur, sternum, ribs, vertebrae, pelvis
Produces RBC 2 million per second
Yellow marrow – stores fat
Found in many bones

SKELETAL SYSTEM OF CHILD
Bone in children and toddlers is more porous than adult bone, with wider haversian canals.
A child's bones are more elastic than an adult's are. Two terms are important here: plasticity and elasticity. Bones in children permit a greater degree of deformation before they break. At times, the bone may deform but not fracture, a condition often described as a plastic deformation. At other times, the bone may simply buckle to create what is described as a torus fracture. These patterns are not seen in adults, in whom the bones' resistance and elasticity to angular deformation is significantly less

The periosteal sleeve is much thicker in children than in adults and acts as a restraint to displacement. Angular deformation of a child's bone may cause fracture of the cortices without displacement ("greenstick" fracture). The thick periosteal sleeve is important for pediatric skeletal remodeling. Subperiosteal resection of a child's bone shows the regeneration potential associated with the periosteum: the tubular bone eventually reforms inside the periosteal sleeve. Thus, the child's bone has an innate potential to heal itself.

The epiphysis is an important part of the growing skeleton. It is a secondary ossification center. Mercer Rang emphasizes the importance of using accurate terminology in relation to these parts of the growing skeleton. The physis is to the growth plate, which is a disklike structure at the end of the metaphysis; the epiphysis is a cartilaginous structure that sits atop the physis.

MICROSCOPIC ANATOMY
The epiphysis is the growing end of the long bone and is responsible for an increase in the length of the long bones
Bones are formed by 1 of the following 2 processes:
Endochondral ossification - This involves the formation of bone from a cartilaginous anlage; long bones are primarily formed by endochondral ossification
Membranous ossification - The cartilaginous phase is usually absent; ossification of flat bones and skull bones is usually via this process

Histologically, the physis consists of a number of layers that reflect the process of bone formation. The basal layer consists of resting cartilage cells. These multiply under the influence of growth factors in the zone of multiplication, and rounded cells are then seen. These rounded cells arrange themselves in rows and mature in a loose cartilaginous matrix.
Blood vessels from the metaphysis (see the image below) invade this zone to lay down minerals into the matrix, and loose woven bone is then laid down in the zone of provisional calcification. Mature bone is finally laid down in the metaphysis. A continuation of this process leads to an increase in the length of the long bone.

The epiphysis and the metaphysis are connected by mammillary processes internally and by the tough fibrous periosteum externally, both of which resist displacement forces. This attachment is not rigid and allows microscopic translation forces, and this flexibility protects the structure from injury.
Rang states that the epiphysis is periarticular and that forces typically causing dislocation in the adult are likely to cause epiphyseal or physeal injury in the child

REMODELING
Remodeling of a fracture or deformity is a process that is carried out more efficiently in the child than in the adult. A deformity corrects itself by asymmetrical appositional formation of new bone. Remodeling is influenced by a number of factors, including the following:
Age - The younger the age, the better the remodeling potential
Proximity to the physis - Fractures closer to the physis remodel better than those away from the physis
Relation to the axis of joint motion - Deformities in the axis of joint motion remodel better than deformities outside the axis of joint motion
Rotational versus nonrotational deformity - Rotational deformities do not remodel and correct themselves

An injury to a long bone can stimulate excessive growth and effectively create a temporary limb length discrepancy. The most common example is the stimulation of growth at the proximal femur after a fracture in the shaft of the femur. This phenomenon allows the surgeon to accept some shortening in the treatment of these fractures, given that they would be expected to correct with time.
In contrast, a physeal injury can cause severe growth arrest and lead to limb length discrepancies and deformities that can require years of treatment to correct. The most devastating of these injuries is seen in the aftermath of pediatric infections. Septic arthritis of the hip leads to severe limb length discrepancies and loss of function and stability.

NATURAL VARIANTS
Bone in children undergoes serial changes and adaptations to achieve its adult form over a period of years as the child reaches maturity.
The secondary ossification centers appear at various ages; these can be a guide to bone age and true skeletal age and thus are often helpful in resolving forensic and medicolegal issues. The fusion of these secondary ossification centers also follows a set pattern, which is also useful in skeletal age determination.
For example, the ossification center of the greater trochanter appears at the age of 3 in girls and 6 in boys, whereas that of the lesser trochanter appears at the age of 6 in both girls and boys. The secondary ossification centers for the pubis appears at 9-11 years in girls and at 13-16 years in boys

At birth, the sutures in the skull are unfused at the anterior and posterior fontanelles. However, whereas the posterior fontanelle fuses soon after birth, the anterior fontanelle may not close until much later (eg, 12-18 months). Delayed closure of this fontanelle is seen in malnutrition and in rickets. Premature and rigid fusion of skull bones is seen in craniosynostosis, which requires complex multidisciplinary procedures to correct.
The alignment of the lower limbs also changes as the child progresses from crawling to the unsteady bipedal gait of the toddler and, finally, to the established bipedal gait of the child.
The toddler demonstrates a varus alignment at the knee and a waddle in the gait; the foot arches are yet not developed. By about 2 years of age, knee alignment of the knee becomes neutral. Over the next few years, knee alignment progresses to a physiologic genu valgum, which spontaneously corrects itself to a normal tibiofemoral alignment by about 7 years of age. These variations are important to understand because parents often consult an orthopedist for these issues, which require nothing more than careful clinical examination and reassurance.

The varus and valgus alignments are believed to be dictated by the relative growth rates of the articular cartilage and the adjacent physeal zone. The physis grows almost 5 times faster than the articular cartilage does. This difference may control varus and valgus alignment: varus develops if the medial sides grow more slowly than the lateral sides, and valgus develops if they grow more quickly.
Gender and racial differences are well known. A number of studies have documented the evolution of the tibiofemoral angle in children by using the tibiofemoral measurement and measurements of intercondylar and intermalleolar distances. A study of European children showed that boys had a greater tendency toward varus than girls did at the end of development, with lower intermalleolar and intercondylar distances

DEFECTS
Matrix deficiencies can give rise to a myriad of conditions, the best known of which is osteogenesis imperfecta, which can lead to multiple pathologic fractures and deformities in childhood (see the image below). Deficiencies of growth hormone and thyroid dysfunction also lead to stunting of growth and dwarfism.
Infections and trauma can cause complete or partial physeal arrest, causing deformities and limb length discrepancies (see the images below). Epiphyseal dysplasias also cause stunted growth and deformities

osteogenesis imperfecta,
Epiphyseal dysplasias

BROKEN BONES
Fracture is a break of the bone
Simple or Complex fracture
Regrowth of bone:
Spongy bone forms in first few days
Blood vessels regrow and spongy bone hardens
Full healing takes 1-2 months

REFRENCE
https://emedicine.medscape.com/article/1899256-overview#a4
https://www.google.kz/search?q=skeletal+system+medscape&rlz=1C1ASRW_enKZ800KZ800&oq=skeletal+system+medscape&aqs=chrome..69i57j69i60.9086j0j4&sourceid=chrome&ie=UTF-8
Slide share
Physiology essentials book
http://www.innerbody.com/image/skelfov.html