Transcript Bone Development and the Vertebrae - Falcon Science

Bone Development
Unit 3, lesson 3
Bone Development
• OSTEOGENESIS (a.k.a.
ossification) is the
process of bone tissue
formation.
• In embryos this leads to
the formation of the
bony skeleton.
• In children and young
adults, ossification
occurs as part of bone
growth.
• In adults, it occurs as
part of bone
remodeling and bone
repair.
Formation of the Bony Skeleton
• Before week 8, the human
embryonic skeleton is made of
fibrous membranes and
hyaline cartilage.
• After week 8, bone tissue
begins to replace the fibrous
membranes and hyaline
cartilage.
1.
2.
The replacement of fibrous
membranes with bone is called
INTRAMEMBRANOUS
OSSIFICATION.
The replacement of hyaline
cartilage with bone is known as
ENDOCHONDRAL OSSIFICATION
Growth in Bone Length
• Epiphyseal cartilage of
the epiphyseal plate
divides to create more
cartilage
• Diaphyseal cartilage of
the epiphyseal plate is
transformed into bone.
This increases the length
of the shaft.
• And you grow!! 
At puberty, growth in bone length
is increased dramatically by the
combined activities of growth
hormone, thyroid hormone, and
the sex hormones.
As a result osteoblasts begin
producing bone faster than the
rate of epiphyseal cartilage
expansion. Thus the bone grows
while the epiphyseal plate gets
narrower and narrower and
ultimately disappears. A remnant
(epiphyseal plate) is visible on Xrays (do you see them in the
adjacent femur, tibia, and fibula?)
VERTEBRAL COLUMN
• Also called the spine, backbone, or spinal column
• Functions to:
– Protect the spinal cord
– Support the head
– Serve as a point of attachment for the ribs, pelvic girdle,
and muscles
• The vertebral column is curved to varying degrees in
different locations
– Curves increase the column strength
– Help maintain balance in the upright position
– Absorb shocks during walking, and help protect the
vertebrae from fracture
Vertebral Column
VERTEBRAE
• Composed of a series of bones called vertebrae
(Adult=26)
1.
2.
3.
4.
5.
7 cervical are in the neck (small)
12 thoracic are posterior to the chest cavity (medium)
5 lumbar support the lower back (large)
1 sacrum consists of five fused sacral vertebrae
1 coccyx consists of four fused coccygeal vertebrae
SPINE CONDITIONS
Various conditions may exaggerate the normal curves of
the vertebral column
Scoliosis – lateral imbalance of the spine (bent left or
right)
Kyphosis – arch in the upper spine (ky = high)
Lordosis – arch in the lower spine (lor = low)
INTERVERTEBRAL DISCS
• Found between the bodies of vertebrae
• Functions to:
– Form strong joints
– Permit various movements of the vertebral
column
– Absorb vertical shock
Vertebral Column
Vertebral Column (REGIONS)
• Cervical Region
– Cervical vertebrae (C1–C7)
– The atlas (C1) is the first cervical vertebra
– The axis (C2) is the second cervical vertebra
• Thoracic Region
– Thoracic vertebrae (T1–T12)
– Articulate with the ribs
• Lumbar Region
– Lumbar vertebrae (L1–L5)
– Provide for the attachment of the large back muscles
• Sacrum
– The sacrum is a triangular bone formed by the union of five
sacral vertebrae (S1–S5)
– Serves as a strong foundation for the pelvis
• Coccyx
– The coccyx, like the sacrum, is triangular in shape
– It is formed by the fusion of usually four coccygeal vertebrae
– This is the “tail bone”
Vertebral Column
So what is back pain?
Seriously…what is back pain?