Skeletal System
internal framework of the body
strong yet light organ
provide protection and allow movement
parts of the skeletal system
bones (skeleton)
joints
cartilages
ligaments
206 bones in the body - adult
300 bones - newborn
two subdivisions of the skeleton
axial skeleton - longitudinal axis of body
appendicular skeleton - upper and lower appendages
Functions of the bones
protection — prevents injury to soft organs
skull and vertebrae protect brain and spinal cord
rib cage protects thoracic cavity organs
support — enables human to take an upright stance
attachment — provides connection to muscles during movement
storage — serves as depot for minerals and fats
calcium and phosphorus
fat in the internal marrow cavity (yellow marrow - where marrow is stored)
hematopoiesis - blood cell formation (red marrow)
is is possible for humans to be born without a skull?
Anencephaly - a serious birth defect in which a baby is born without parts of the brain and
skull.
Skeletal System 1
, Researchers estimate that about 1 in every 4,600 babies is born with anencephaly in the
United States
There is no known cure or standard treatment for anencephaly. Almost all babies born
with anencephaly will die shortly after birth.
Classification of bones
based on arrangement of osseous tissue
Compact bones
bone tissue is dense
smooth and uniform appearance
gives strength and resistance to the organ
Spongy bones
plenty of open spaces with spiky
appearance
contains small, needlelike pieces of
bone
trabeculae contains osteocytes
based on shape
long bones
Skeletal System 2
, typically longer than they are wide
shaft with enlarged ends
contain mostly compact bone; spongy
bone at ends
all of the bones of the limbs (except
wrist, ankle, and kneecap bones) are
long bones
ex
femur - long bone of the upper thigh
fibula and tibia - long bones of lower
leg
humerus - long bone of the upper
arm
radius and ulna - long bones of
forearm
short
generally cube-shaped
contain mostly spongy bone with an
outer layer of compact bone
sesamoid ones are a type of short bone
that form within tendons (patella)
ex.
carpals (wrist bones)
tarsals (ankle bones)
Skeletal System 3
, flat
thin, flattened and usually curved
two thin layers of compact bone
sandwich a layer of spongy bone
between them
ex
most bones of the skull (cranial
bones)
ribs
sternum
scapulae
irregular
irregular shape
do not fit into other bone classification
categories
ex
vertebrae
hip bones
sacrum
Skeletal System 4
internal framework of the body
strong yet light organ
provide protection and allow movement
parts of the skeletal system
bones (skeleton)
joints
cartilages
ligaments
206 bones in the body - adult
300 bones - newborn
two subdivisions of the skeleton
axial skeleton - longitudinal axis of body
appendicular skeleton - upper and lower appendages
Functions of the bones
protection — prevents injury to soft organs
skull and vertebrae protect brain and spinal cord
rib cage protects thoracic cavity organs
support — enables human to take an upright stance
attachment — provides connection to muscles during movement
storage — serves as depot for minerals and fats
calcium and phosphorus
fat in the internal marrow cavity (yellow marrow - where marrow is stored)
hematopoiesis - blood cell formation (red marrow)
is is possible for humans to be born without a skull?
Anencephaly - a serious birth defect in which a baby is born without parts of the brain and
skull.
Skeletal System 1
, Researchers estimate that about 1 in every 4,600 babies is born with anencephaly in the
United States
There is no known cure or standard treatment for anencephaly. Almost all babies born
with anencephaly will die shortly after birth.
Classification of bones
based on arrangement of osseous tissue
Compact bones
bone tissue is dense
smooth and uniform appearance
gives strength and resistance to the organ
Spongy bones
plenty of open spaces with spiky
appearance
contains small, needlelike pieces of
bone
trabeculae contains osteocytes
based on shape
long bones
Skeletal System 2
, typically longer than they are wide
shaft with enlarged ends
contain mostly compact bone; spongy
bone at ends
all of the bones of the limbs (except
wrist, ankle, and kneecap bones) are
long bones
ex
femur - long bone of the upper thigh
fibula and tibia - long bones of lower
leg
humerus - long bone of the upper
arm
radius and ulna - long bones of
forearm
short
generally cube-shaped
contain mostly spongy bone with an
outer layer of compact bone
sesamoid ones are a type of short bone
that form within tendons (patella)
ex.
carpals (wrist bones)
tarsals (ankle bones)
Skeletal System 3
, flat
thin, flattened and usually curved
two thin layers of compact bone
sandwich a layer of spongy bone
between them
ex
most bones of the skull (cranial
bones)
ribs
sternum
scapulae
irregular
irregular shape
do not fit into other bone classification
categories
ex
vertebrae
hip bones
sacrum
Skeletal System 4
