*
Chapter 7: Part II
*
*At birth, fusion is ongoing, there are still 2 frontal,
4 occipital, a number of sphenoid, and temporal
bone elements
- the cranial bones are connected by areas of fibrous CT
- CT connections are flexible and the skull can be distorted
without damage
*Fontanels, are the largest fibrous regions between
the cranial bones. They include the:
- Anterior, Posterior, Sphenoidal, and Mastoid
*By age 5 the brain stops growing and the cranial
sutures develop
*
Fig 6.18
*
*Consists of 26 bones:
- 24 vertebra, 1 sacrum, and 1 coccyx
*Performs several functions:
- provides a column of support
- bears the weight of the head, neck, and trunk
- transfers weight to the lower limbs
- encloses and protects the spinal cord
- provides a passageway for spinal nerves
- helps maintain the upright position of the body
*
From superior to inferior, they are
*Cervical (7)
*Thoracic (12)
*Lumbar (5)
*Sacral (1) composed of 5 fused vertebrae
*Coccygeal (1) composed of 3-5 fused vertebrae
*
*Weight-transferring spinal curves are named for
the region of the vertebral column they occur in
*Primary curves/accommodation curves appear
during late fetal development
- sacral curve and thoracic curve
- allow room for the abdominopelvic viscera
*Secondary curves/compensation curves appear
several months after birth
- lumbar curve and cervical curve
- develop as an infant learns to hold up its head and begins
to walk
*Curves are fully developed by the time a child is 10
*
Fig 6.19
*
Fig 6.19
When standing, body weight must be transmitted through the
column to the hips and lower limbs. But most of the body weight
Lies in front of the column - various curves bring the weight of
the body in line with the body axis and its center of gravity
*
*
Fig 6.21
*
*
*7 total – smallest, most superior vertebrae
*Spinous processes are relatively stumpy and may
be split, resulting in a bifid process
*Costal processes are extra extensions of bone
from the ventrolateral body that attach to the
transverse processes
*Transverse foamina result from the hole between
the costal process and the transverse
*
Fig 6.22
*
Fig 6.22
*
*The atlas has no body and
articulates cranially with the
occipital condyles
- these articulations allow one to nod ‘yes’
but prevent twisting
*The atlas has 2 arches – the anterior
and posterior vertebral arches
*Superior and inferior articular facets
do not extend beyond the arches
*
*
*The body of the atlas fuses with the body of the
axis during development to form the dens (odontoid
process)
- because of the dens, there is no intervertebral disc
*The articulation between the atlas and axis allows
one to shake their head ‘no’
*
Fig 6.23
*
Fig 6.23
*
*The last cervical vertebrae, and therefore
resembles the thoracic vertebra in structure
- has a long, slender spinous process
- enlarged transverse processes that may or may not
contain a transverse foramen
*An elastic ligament called the ligamentum
nuchae extends from the spinous process
cranially to the occipital crest
*
*12 total thoracic vertebrae make up the
posterior of the rib cage
*The bodies have a heart shape
*The spinous process is long and slender and
points on a posterocaudal angle
*The transverse processes point dorsolateral
*The thoracic vertebrae articulate with ribs and
contain extra facets
*
Fig 6.24
*
*The largest vertebrae (5) make up
the lower back region – weight
bearing
*The body is very thick and oval
shaped
*Relatively small vertebral foramina
are triangular
*The transverse processes point more
laterally
*The spinous process resembles a tail
fin of a fish, stumpy and flattened
*
*
*Is curved with a convex dorsal surface, consists
of the fused components of 5 sacral vertebrae
- fuse shortly after puberty (25 – 30)
*Protects reproductive, digestive, and excretory
organs
*Broad surface area provides an extensive area
for attachment of muscles
- especially those involved in thigh movement
*Sacral apex – narrow caudal portion
*Broad superior surface forms the base
*
*Consists of 3 – 5 fused coccygeal vertebrae
- begin fusing by age 26
*Provides an attachment site for ligaments and a
muscle that constricts the anal opening
*Coccygeal cornua – laminae of the 1st vertebra
curve to meet the cornua of the sacrum
*In males, the adult coccyx points anteriorly while
in females it points inferiorly
*In the very elderly the coccyx may fuse with the
sacrum
*
*
Has 2 functions:
*Protects the heart, lungs, thymus, and other
structures within the cavity
*Serves as the attachment site for muscles
involved in:
- Respiration
- Positioning the vertebral column
- Movements of the pectoral girdle and upper limb
*
Fig 6.27
Fig 6.27
Fig 6.27
*
*Chest tube
*Craniostenosis
*Deviated nasal septum
*Hemothorax
*Microcephaly
*Pneumothorax
*Spina bifida