The human skeleton is the internal framework of the body. It is composed of 270 bones at birth[1][2][3] - this total decreases to 206 bones by adulthood after some bones have fused together. The bone mass in the skeleton reaches maximum density around age 30. The human skeleton can be divided into the axial skeleton and the appendicular skeleton. The axial skeleton is formed by the vertebral column, the rib cage and the skull. The appendicular skeleton, which is attached to the axial skeleton, is formed by the pectoral girdles, the pelvic girdle and the bones of the upper and lower limbs.
The human skeleton serves six major functions; support, movement, protection, production of blood cells, storage of ions and endocrine regulation.
The human skeleton is not as sexually dimorphic as that of many other primate species, but subtle differences between sexes in the morphology of the skull, dentition, long bones, and pelves exist. In general, female skeletal elements tend to be smaller and less robust than corresponding male elements within a given population. The pelvis in female skeletons is also different from that of males in order to facilitate child birth.
Contents[hide]The axial skeleton (80 bones) is formed by the vertebral column (32-34 bones; the number of the vertebrae differs from human to human as the lower 2 parts, sacral and coccygeal bone may vary in length), the rib cage (12 pairs of ribs and the sternum), and the skull (22 bones and 7 associated bones).
The upright posture of humans is maintained by the axial skeleton, which transmits the weight from the head, the trunk, and the upper extremities down to the lower extremities at the hip joints. The bones of the spine are supported by many ligaments. The erectors spinae muscles are also supporting and are useful for balance.
A human is able to survive with just the axial portion of their skeleton.
Appendicular skeletonMain article: Appendicular skeletonThe appendicular skeleton (126 bones) is formed by the pectoral girdles, the upper limbs, the pelvic girdle or pelvis, and the lower limbs. Their functions are to make locomotion possible and to protect the major organs of digestion, excretion and reproduction.
FunctionsA human skeleton on exhibit at The Museum of Osteology, Oklahoma City, OklahomaThe skeleton serves six major functions; support, movement, protection, production of blood cells, storage of minerals and endocrine regulation.
SupportThe skeleton provides the framework which supports the body and maintains its shape. The pelvis, associated ligaments and muscles provide a floor for the pelvic structures. Without the rib cages, costal cartilages, and intercostal muscles, the lungs would collapse. MovementThe joints between bones allow movement, some allowing a wider range of movement than others, e.g. the ball and socket joint allows a greater range of movement than the pivot joint at the neck. Movement is powered by skeletal muscles, which are attached to the skeleton at various sites on bones. Muscles, bones, and joints provide the principal mechanics for movement, all coordinated by the nervous system. ProtectionThe skeleton protects many vital organs:There are many classified skeletal disorders. One of the most common is osteoporosis. Also common is scoliosis, a side-to-side curve in the back or spine, often creating a pronounced "C" or "S" shape when viewed on an x-ray of the spine. This condition is most apparent during adolescence, and is most common with females.
OsteoporosisMain article: OsteoporosisOsteoporosis is a disease of bone, which leads to an increased risk of fracture. In osteoporosis, the bone mineral density (BMD) is reduced, bone microarchitecture is disrupted, and the amount and variety of non-collagenous proteins in bone is altered. Osteoporosis is defined by the World Health Organization (WHO) in women as a bone mineral density 2.5 standard deviations below peak bone mass (20-year-old sex-matched healthy person average) as measured by DXA; the term "established osteoporosis" includes the presence of a fragility fracture.[8] Osteoporosis is most common in women after the menopause, when it is called postmenopausal osteoporosis, but may develop in men and premenopausal women in the presence of particular hormonal disorders and other chronic diseases or as a result of smoking and medications, specifically glucocorticoids, when the disease is craned steroid- or glucocorticoid-induced osteoporosis (SIOP or GIOP).
Osteoporosis can be prevented with lifestyle advice and medication, and preventing falls in people with known or suspected osteoporosis is an established way to prevent fractures. Osteoporosis can also be prevented with having a good source of calcium and vitamin D. Osteoporosis can be treated with bisphosphonates and various other medical treatments.
ReferencesLibrary resources aboutSkeletal system
[show]
Human systems and organsTA 2-4:
MSSkeletal system
Joints
Muscular system
TA 5-11:
splanchnic/
viscusmostly
Thoracic
Respiratory system
mostly
Abdominopelvic
Digestive system+
adnexa
GU: Urinary system
GU: Reproductive system
Endocrine system
TA 12-16Circulatory system
Cardiovascular system
Lymphatic system
Nervous system
Integumentary system
Blood
(Non-TA)Myeloid
Lymphoid
General anatomy: systems and organs, regional anatomy, planes and lines, superficial axial anatomy, superficial anatomy of limbs[show]
Bones (TA A02, GA 2)AxialVertebral column
Thoracic skeleton
Skull
Neurocranium
Facial bones
Ossicles
AppendicularUpper
Lower
M: BON/CAR
anat (c/f/k/f, u, t/p, l)/phys/devp/cell
noco/cong/tumr, sysi/epon, injr
proc, drug (M5)
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Bones of head and neck: the facial skeleton of the skull (TA A02.1.08-15, GA 2.156-177)MaxillaSurfaces
Processes
Other
Zygomatic
PalatineFossae
Plates
Processes
MandibleBody
Ramus
Minor/
nose
M: BON/CAR
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Bones of head and neck: the neurocranium of the skull (TA A02.1.01-07, GA 2.129-155)OccipitalSquama
Lateral parts
Basilar part
Other
Parietal
FrontalSquama
Orbital part
TemporalSquama
Mastoid part
Petrous part
Tympanic part
SphenoidSurfaces
Great wings
Small wings
Pterygoid
processes
Other
EthmoidPlates
Surfaces
Labyrinth
M: BON/CAR
anat (c/f/k/f, u, t/p, l)/phys/devp/cell
noco/cong/tumr, sysi/epon, injr
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Bones of head and neck: compound structures of skull (TA A02.1.00.002-052, GA 2.178-199)Neurocranium
Facial skeleton
Both
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Bones of upper limbs (TA A02.4, GA 2.200-230)Pectoral girdle, clavicle
Scapula
Humerus
Forearm
Hand
M: BON/CAR
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Bones of torso (TA A02.2,3, GA 2.96-128)VertebraGeneral structures
Cervical vertebrae
Thoracic vertebrae
Lumbar vertebrae
Sacrum
Coccyx
Thoracic skeletonRib
Sternum
Thoracic cage
M: BON/CAR
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Bones of lower limbs (TA A02.5.04-18, GA 2.242-277)Femurupper extremity
body
lower extremity
CrusTibia
upper extremity
body
lower extremity
Fibula
Other
FootTarsus
Metatarsus
Other
phalanges of the foot
M: BON/CAR
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noco/cong/tumr, sysi/epon, injr
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Bones of pelvis / pelvic cavity (TA A02.5.01-03, GA 2.231-241)General
Iliumbody
winggluteal lines
iliac spines
other:
Ischiumbody
superior ramus
inferior ramus
Pubisbody
superior ramus
inferior ramus
Compound
M: BON/CAR
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When you cross your arms, you may observe protraction and retraction movements at the sternoclavicular joint as the clavicles move forward or backward. At the acromioclavicular joint, there can be elevation and depression movements as the clavicles move up or down slightly.
The joint that allows you to move your heel is the subtalar joint, located between the talus and calcaneus bones in the foot. This joint enables the foot to perform inversion and eversion movements, which are essential for walking and balancing. Additionally, the ankle joint (talocrural joint) also contributes to heel movement by allowing the foot to flex and extend. Together, these joints facilitate various movements of the heel and foot.
Muscular tissue enables the fingers to move when playing a piano.
The knee joint primarily allows flexion and extension, enabling the leg to bend and straighten. The hip joint facilitates a wider range of motion, including flexion, extension, abduction, adduction, and rotation. The shoulder joint, being a ball-and-socket joint, allows for extensive movement in multiple directions, including flexion, extension, abduction, adduction, and rotation. The elbow joint predominantly permits flexion and extension, allowing the forearm to move towards and away from the upper arm. The ankle joint enables dorsiflexion and plantarflexion, allowing the foot to move up and down.
this is because the partially movable joint wont move as easy r quickly as that of the elbow joint.
joint
ball and socket joint
it is a mobile joint! It is a mobile joint because it allows the door to move through the hinges!! Are arms are also mobile joints because are arms also move
it is a mobile joint! It is a mobile joint because it allows the door to move through the hinges!! Are arms are also mobile joints because are arms also move
ball-and-socket joint
in pin joint the linkages are free to move relative to one another angularly, whereas in hinge joint, one linkage is fixed and the other is free to move in angular direction.
it is a mobile joint! It is a mobile joint because it allows the door to move through the hinges!! Are arms are also mobile joints because are arms also move
Moving our arms in a circular motion is possible due to the structure and range of motion of our shoulder joints. The knee joint, however, is a hinge joint designed primarily for flexion and extension, limiting its ability to move in a circular motion. The ligaments and tendons surrounding the knee joint also restrict its range of motion compared to the shoulder joint.
When you cross your arms, you may observe protraction and retraction movements at the sternoclavicular joint as the clavicles move forward or backward. At the acromioclavicular joint, there can be elevation and depression movements as the clavicles move up or down slightly.
Several organizations offer free on-line advice about joint health. Examples of these are Arthritis Research, Move free and Meridian Health which all offer free advice for this subject.
A joint in which the opposing bony surfaces are covered with a layer of hyaline cartilage or fibrocartilage and in which some degree of free movement is possible.
A joint that doesn't move.