FUNCTIONS FUNCTIONS
SUPPORT SUPPORT - - organs and tissues of the body are organs and tissues of the body are held in place by the skeleton. held in place by the skeleton.
PROTECTION PROTECTION – provides a rigid surface for – provides a rigid surface for protection of vital organs. cranium protects the protection of vital organs. cranium protects the brainbrain
MOVEMENT MOVEMENT – bones provide a base for muscle – bones provide a base for muscle attachment. It allows movement of the body attachment. It allows movement of the body through using the bones as levers.through using the bones as levers.
PRODUCTION & STORAGE PRODUCTION & STORAGE – bones provide – bones provide a site for manufacture of red & white blood cells a site for manufacture of red & white blood cells and storage of minerals. Ie.calcium and storage of minerals. Ie.calcium
STRUCTURE OF SKELETONSTRUCTURE OF SKELETON There are about 206 bones found in an adult There are about 206 bones found in an adult
skeleton.skeleton.
The bones are divided into two main groupsThe bones are divided into two main groups
(1)(1) AXIAL SKELETON AXIAL SKELETON
(2) (2) APPENDICULAR SKELETON APPENDICULAR SKELETON
AXIAL SKELETONAXIAL SKELETON
• The axial skeleton The axial skeleton forms the basic forms the basic structure structure supporting the rest supporting the rest of the skeleton.of the skeleton.
• It consists of:It consists of:– SkullSkull– Vertebral columnVertebral column– Rib cageRib cage
AXIAL SKELETONAXIAL SKELETON
SKULLSKULL
CraniumCranium consists of 8 consists of 8 bones fused together.bones fused together.
FaceFace has 14 bones. has 14 bones. Most are fused, Most are fused, whilst others like the whilst others like the mandible (lower jaw mandible (lower jaw bone) can move bone) can move independently independently
AXIAL SKELETONAXIAL SKELETONVERTEBRAL COLUMNVERTEBRAL COLUMN
Divided into 5 main regionsDivided into 5 main regions
(1)(1) Cervical spine (7)Cervical spine (7)
(2)(2) Thoracic spine (12)Thoracic spine (12)
(3)(3) Lumbar spine (5) Lumbar spine (5)
(4)(4) Sacrum (5)Sacrum (5)
(5)(5) Coccyx (4)Coccyx (4)
The 5 sacrum vertebrae The 5 sacrum vertebrae and 4 coccyx vertebrae and 4 coccyx vertebrae are fused to form one are fused to form one solid bone.solid bone.
AXIAL SKELETONAXIAL SKELETON• ATLAS – first cervical ATLAS – first cervical
vertebravertebra• AXIS – second cervical AXIS – second cervical
vertebravertebra• Spinal chord runs down the Spinal chord runs down the
canal formed by the canal formed by the vertebra being stacked on vertebra being stacked on top of one another.top of one another.
• Intervertebral Discs are Intervertebral Discs are found between each found between each vertebrae and keep spine vertebrae and keep spine flexible and they absorb flexible and they absorb shockshock
• Coccyx remnance of a tailCoccyx remnance of a tail
AXIAL SKELETONAXIAL SKELETON
THORAXTHORAX• 12 pairs of ribs12 pairs of ribs• Joined to thoracic Joined to thoracic
vertebraevertebrae• Top 10 ribs joined Top 10 ribs joined
to sternumto sternum• Remaining two have Remaining two have
“free” ends – “free” ends – ‘floating’‘floating’
APPENDICULAR SKELETONAPPENDICULAR SKELETON
• Forms mainly the Forms mainly the extremities of the extremities of the body and their body and their connections to the connections to the axial skeletonaxial skeleton
• Consists ofConsists of
- limbs (arms & legs)- limbs (arms & legs)
- shoulder and pelvic - shoulder and pelvic girdlesgirdles
TYPES OF BONE TISSUETYPES OF BONE TISSUE
(1)(1) COMPACT BONE TISSUECOMPACT BONE TISSUE Heavy, dense, strong Heavy, dense, strong
bone tissuebone tissue Consist of closely packed Consist of closely packed
osteon.osteon. Osteon consist of a Osteon consist of a
central canal called central canal called osteonic canal. osteonic canal.
It surrounded by It surrounded by concentric ring called concentric ring called lamella lamella
Thickest at the centre of Thickest at the centre of the shaftthe shaft
TYPES OF BONE TISSUETYPES OF BONE TISSUE
(2) CANCELLOUS BONE (2) CANCELLOUS BONE TISSUETISSUEor “spongy bone”or “spongy bone”
It consist of Plates It consist of Plates (Trabecule)(Trabecule)
Strong, hard & less Strong, hard & less dense than compact dense than compact bonebone
Found mainly ends of Found mainly ends of bones bones
Bone Development and GrowthBone Development and Growth
The terms osteogenesis and ossification are often used synonymously to indicate the process of bone formation. Parts of the skeleton form during the first few weeks after conception. By the end of the eighth week after conception, the skeletal pattern is formed in cartilage and connective tissue membranes and ossification begins.
Intramembranous Intramembranous
Intramembranous ossification involves the Intramembranous ossification involves the replacement of sheet-like connective tissue replacement of sheet-like connective tissue membranes with bony tissue. Bones formed in this membranes with bony tissue. Bones formed in this manner are called intramembranous bones. They manner are called intramembranous bones. They include certain flat bones of the skull and some of include certain flat bones of the skull and some of the irregular bones. The future bones are first the irregular bones. The future bones are first formed as connective tissue membranes. formed as connective tissue membranes. Osteoblasts migrate to the membranes and Osteoblasts migrate to the membranes and deposit bony matrix around themselves. When the deposit bony matrix around themselves. When the osteoblasts are surrounded by matrix they are osteoblasts are surrounded by matrix they are called osteocytes. called osteocytes.
Endochondral Ossification Endochondral Ossification Endochondral ossification involves the replacement of
hyaline cartilage with bony tissue. Most of the bones of the skeleton are formed in this manner. These bones are called endochondral bones.
In this process, the future bones are first formed as hyaline cartilage models. During the third month after conception, the perichondrium that surrounds the hyaline cartilage "models" becomes infiltrated with blood vessels and osteoblasts and changes into a periosteum.
The osteoblasts form a collar of compact bone around the diaphysis. At the same time, the cartilage in the center of the diaphysis begins to disintegrate. Osteoblasts penetrate the disintegrating cartilage and replace it with spongy bone. This forms a primary ossification center. Ossification continues from this center toward the ends of the bones. After spongy bone is formed in the diaphysis, osteoclasts break down the newly formed bone to open up the medullary cavity.
Bone Growth Bone Growth Bones grow in length at the epiphyseal plate by a
process that is similar to endochondral ossification. The cartilage in the region of the epiphyseal plate next to the epiphysis continues to grow by mitosis.
The chondrocytes, in the region next to the diaphysis, age and degenerate. Osteoblasts move in and ossify the matrix to form bone. This process continues throughout childhood and the adolescent years until the cartilage growth slows and finally stops.
When cartilage growth ceases, usually in the early twenties, the epiphyseal plate completely ossifies so that only a thin epiphyseal line remains and the bones can no longer grow in length. Bone growth is under the influence of growth hormone from the anterior pituitary gland and sex hormones from the ovaries and testes.
TYPES OF BONESTYPES OF BONES
Bones are classified into 5 groups according to their shape:Bones are classified into 5 groups according to their shape: LONG BONESLONG BONES – – are longer than they are wide are called long bones. are longer than they are wide are called long bones.
They consist of a long shaft with two bulky ends or They consist of a long shaft with two bulky ends or extremities. They are primarily compact bone but may extremities. They are primarily compact bone but may have a large amount of spongy bone at the ends or have a large amount of spongy bone at the ends or extremities. Long bones include bones of the thigh, leg, extremities. Long bones include bones of the thigh, leg, arm, and forearm. arm, and forearm.
incl. humerus, radius, tibia and phalangesincl. humerus, radius, tibia and phalanges
TYPES OF BONESTYPES OF BONES
SHORT BONESSHORT BONES – – Short bones are roughly cube shaped with Short bones are roughly cube shaped with
vertical and horizontal dimensions approximately vertical and horizontal dimensions approximately equal. They consist primarily of spongy bone, equal. They consist primarily of spongy bone, which is covered by a thin layer of compact which is covered by a thin layer of compact bone. Short bones include the bones of the wrist bone. Short bones include the bones of the wrist and ankle. and ankle.
incl. carpals and tarsalsincl. carpals and tarsals
TYPES OF BONESTYPES OF BONES
FLAT BONESFLAT BONES – – Flat bones are thin, flattened, and usually Flat bones are thin, flattened, and usually
curved. Most of the bones of the cranium curved. Most of the bones of the cranium are flat bones. are flat bones.
incl. skull, pelvis, ribs and shoulder blades incl. skull, pelvis, ribs and shoulder blades (Flat bones protect vital organs and (Flat bones protect vital organs and provide sites for muscle attachment)provide sites for muscle attachment)
TYPES OF BONESTYPES OF BONES
IRREGULAR BONESIRREGULAR BONES – – Bones that are not in any of the above
three categories are classified as irregular bones. They are primarily spongy bone that is covered with a thin layer of compact bone. The vertebrae and some of the bones in the skull are irregular bones .
incl. facial and vertebrae
ANATOMICAL TERMINOLOGYANATOMICAL TERMINOLOGY
TERMTERM DEFINITIONDEFINITION
SuperiorSuperior Toward the HeadToward the Head
InferiorInferior Toward the feetToward the feet
Anterior (ventral)Anterior (ventral) FrontFront
Posterior (dorsal)Posterior (dorsal) BackBack
MedialMedial Toward the midline (inside)Toward the midline (inside)
LateralLateral Toward the side (outside)Toward the side (outside)
ProximalProximal Nearer the trunkNearer the trunk
DistalDistal Further from the trunkFurther from the trunk
ProneProne Face down (on stomach)Face down (on stomach)
SupineSupine Face up (on back)Face up (on back)
BODY GROWTHBODY GROWTH
Changing rate of growth to the body is affected by two Changing rate of growth to the body is affected by two things – height and weight.things – height and weight.
Differs from time to time during life and differs for various Differs from time to time during life and differs for various body parts.body parts.
Adolescent Growth SpurtAdolescent Growth Spurt Most rapid gains in height within first 1 to 2 years of lifeMost rapid gains in height within first 1 to 2 years of life By 2 years of age – an individual has reached half their By 2 years of age – an individual has reached half their
adult height.adult height. Pubertal growth spurt is the next major increase in Pubertal growth spurt is the next major increase in
height. (11-12 years for girls and 13-14 years for boys height. (11-12 years for girls and 13-14 years for boys approximately)approximately)
Body changes length in the following patternBody changes length in the following pattern(1)(1) Feet and hands develop first (increase in size)Feet and hands develop first (increase in size)(2)(2) Lower legs and forearms grow rapidlyLower legs and forearms grow rapidly(3)(3) Thighs and upper arms increase in lengthThighs and upper arms increase in length(4)(4) Finally trunk develops in lengthFinally trunk develops in lengthThe width of the body develops next, as the shoulders and The width of the body develops next, as the shoulders and
pelvis widens pelvis widens
SHORT BONE GROWTHSHORT BONE GROWTH The outside of a short bone is formed by The outside of a short bone is formed by cartilagecartilage. The . The
cartilage grows until the final shape of the bone is cartilage grows until the final shape of the bone is formed.formed.
Meanwhile the bone Meanwhile the bone ossifiesossifies (hardens into bone) from (hardens into bone) from the inside outwards. Eventually all cartilage is ossified, the inside outwards. Eventually all cartilage is ossified, and growth is complete.and growth is complete.
LONG BONE GROWTHLONG BONE GROWTHTwo growth processes responsible for done development.Two growth processes responsible for done development.First process:First process: OSTEOBLASTSOSTEOBLASTS (bone builders) – add bone to the (bone builders) – add bone to the
outside surface, enlarging and elongating the bone.outside surface, enlarging and elongating the bone. OSTEOCLASTS OSTEOCLASTS (bone eaters) – tunnel out the marrow (bone eaters) – tunnel out the marrow
cavity and internal spaces (these work at the same time cavity and internal spaces (these work at the same time as osteoblasts.)as osteoblasts.)
Second processSecond process (greatest growth occurs): (greatest growth occurs): EPIPHYSEAL PLATESEPIPHYSEAL PLATES (growth plates) found at either (growth plates) found at either
end of the bone where the shaft (diaphysis) meets the end of the bone where the shaft (diaphysis) meets the head or base (epiphysis). These growth plates are made head or base (epiphysis). These growth plates are made of cartilage cells which multiply rapidly and the outside of cartilage cells which multiply rapidly and the outside cells ossify, increasing the length of the shaft. cells ossify, increasing the length of the shaft.
GROWTH HORMONE (GH)GROWTH HORMONE (GH)
GH - Responsible for most growth changes occurring.GH - Responsible for most growth changes occurring.
Produced by the Produced by the pituitary glandpituitary gland, at the base of the , at the base of the brain.brain.
Growth Hormone:Growth Hormone:
(1)(1) stimulates the epiphyseal plates to expand and stimulates the epiphyseal plates to expand and form boneform bone
(2)(2) increase protein uptake by the muscles, therefore increase protein uptake by the muscles, therefore increasing muscle growthincreasing muscle growth
FACTORS AFFECTING GROWTHFACTORS AFFECTING GROWTH
Basic control of growth is Basic control of growth is geneticgenetic
Starvation and Malnutrition can Starvation and Malnutrition can delay growth spurtdelay growth spurt
Major illness slow down growth Major illness slow down growth Regular exercise has many Regular exercise has many
growth benefitsgrowth benefits Aerobic exercise also Aerobic exercise also
increases the size and increases the size and efficiency of the heart, blood efficiency of the heart, blood and lungs. However, repetitive and lungs. However, repetitive long distance training for long distance training for marathons or triathlons may marathons or triathlons may damage epiphyseal plates. damage epiphyseal plates.