General Structure of Vertebrae

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The Vertebral Column
• Flexible curved structure
• Extends from Skull to Pelvis
• 26 irregular bones in adults
• 33 separate bones in the fetus
and infants
• 9 of the 33 fuse to form the
sacrum and coccyx
The Vertebral Column
• Transmits weight from trunk to
lower limbs
• Surrounds and protects the spinal
cord
• Provides attachment points for
ribs and muscles of the back and
neck
The Vertebral Column
• Vertebrae separated by
intervertebral discs
(fibrocartilage)
• Each vertebrae is given a name
according to its location
The Vertebral Column
• Has five major
divisions
– Cervical vertebrae
•7 bones in neck
– Thoracic vertebrae
•12 bones in torso
– Lumbar vertebrae
•5 bones in lower
back
The Vertebral Column
• Has five major
divisions
– Sacrum
•Bone inferior to
the lumbar
•Articulates with
hip bones
The Vertebral Column
• Has five major
divisions
– Coccyx
•4 (sometimes 3 to
5) fused bones
– Everyone has same
number of cervical
vertebrae, but
other areas vary in
number in 5% of
people
• All mammals
have 7 cervical
vertebrae
The Vertebral Column
• Vertebrae has four
curvatures
– Sinusoid shaped (Sshaped)
• Cervical and lumbar
curvatures are Concave
• Thoracic and Sacral
curvatures are Convex
The Vertebral Column
• Abnormal
spine
curvatures
Abnormal spine curvatures
• Scoliosis
– Abnormal lateral
curve
Abnormal spine curvatures
• Kyphosis
– hunchback
Abnormal spine curvatures
• Lordosis
– swayback
Vertebral Column
Major Supporting Ligaments
• Anterior and posterior
longitudinal ligaments
– continuous bands down the
front and back of the spine
from the neck to the sacrum
• Short ligaments connect
adjoining vertebrae together
Vertebral Column: Ligaments
Figure 714a
Intervertebral Discs
• Cushionlike pad composed of two
parts
– Nucleus pulposus – inner gelatinous
nucleus that gives the disc its
elasticity and compressibility
– Annulus fibrosus – surrounds the
nucleus pulposus with a collar
composed of collagen and
fibrocartilage
Vertebral Column:
Intervertebral Discs
Nucleus pulposus
Figure 7.14b
Vertebral Column:
Intervertebral Discs
Annulus fibrosus
Figure 7.14b
Intervertebral Discs
• Acts as shock absobers
• Thickest in the lumbar and cervical
regions
– Enhances the flexibility of these
regions
Intervertebral Discs
• Account for about 25% of the
height of the vertebral column
• Flatten some during the day
– We are always a few centimeters
shorter at night
Intervertebral Discs
• Herniated
(prolapsed)
disc
• Commonly
called
‘slipped disc’
Intervertebral Discs
Slipped discs
• Usually involves rupture of the
annulus fibrousus followed by
protrusions of the spongy nucleus
pulposus
• If protrusion presses on spinal cord
or on spinal nerves, numbness or
excruciating pain may result
General Structure of Vertebrae
• Spinous processes project posteriorly, and
transverse processes project laterally
• Superior and inferior articular processes –
protrude superiorly and inferiorly from the
pedicle-lamina junctions
• Intervertebral foramina – lateral openings
formed from notched areas on the superior
and inferior borders of adjacent pedicles
General Structure of
Vertebrae
• Body or centrum – disc-shaped,
weight-bearing region
Figure 7.15
General Structure of Vertebrae
• Vertebral arch – composed of
pedicles and laminae that, along
with the centrum, enclose the
vertebral foramen
Figure 7.15
General Structure of Vertebrae
• Vertebral foramina – make up
the vertebral canal through
which the spinal cord passes
Figure 7.15
General Structure of Vertebrae
• Spinous
processes
project
posteriorly
Attachment sites for muscles
that move the vertebral column
and for ligaments that stabilize it
Figure 7.15
General Structure of Vertebrae
• Transverse
processes
project
laterally
Figure 7.15
General Structure of
Vertebrae
• Spinous and transverse
processes are attachment sites
for muscles that move the
vertebral column and for
ligaments that stabilize it
General Structure of
Vertebrae
• Superior and inferior articular
processes
– Protrude superiorly and
inferiorly from the pediclelamina junctions
General Structure of
Vertebrae
• Intervertebral foramina
– Lateral openings formed from
notches areas on the superior
and inferior borders of
adjacent pedicles
– Spinal nerves from spinal cord
pass through
Structure of a Typical Vertebrae
Figure 5.16
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.29
Regional Characteristics of
Vertebrae
Figure 5.17a, b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.30a
Cervical Vertebrae
• Seven vertebrae (C1-C7) are the
smallest, lightest vertebrae
• C3-C7 are distinguished with an
oval body, short spinous
processes, and large, triangular
vertebral foramina
• Each transverse process
contains a transverse foramen
Regional Characteristics of
Vertebrae
Figure 5.17a, b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.30a
Cervical Vertebrae: The Atlas
(C1)
• The atlas has no body and no
spinous process
• It consists of anterior and
posterior arches, and two lateral
masses
• The superior surfaces of lateral
masses articulate with the
occipital condyles
Cervical Vertebrae: The Atlas
(C1)
Figure 7.16a, b
Cervical Vertebrae: The Atlas
(C1)
Figure 7.17a
Cervical Vertebrae: The Axis
(C2)
• The axis has a body, spine, and
vertebral arches as do other
cervical vertebrae
• Unique to the axis is the dens
• The dens is a pivot for the
rotation of the atlas
The Axis (C2)
• The dens projects superiorly from
the body and is cradled in the
anterior arch of the atlas
Cervical Vertebrae: The Axis
(C2)
Dens
Figure 7.17a
Cervical
Vertebrae
C3 through C7
Table 7.2
Regional Characteristics of
Vertebrae
Thoracic
Figure 5.17c, d
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.30b
Thoracic
Vertebrae
• There are
twelve
vertebrae
(T1-T12) all
of which
articulate
with ribs
Figure 7.17b
Thoracic
Vertebrae
• Major markings
include two facets and
two demifacets on the
heart-shaped body,
the circular vertebral
foramen, transverse
processes, and a long
spinous process
Figure 7.17b
Thoracic
Vertebrae
• The location of the
articulate facets
prevents flexion and
extension, but
allows rotation of
this area of the
spine
Figure 7.17b
Regional Characteristics of
Vertebrae
Lumbar
Figure 5.17c, d
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.30b
Lumbar Vertebrae
• The five lumbar
vertebrae (L1-L5)
are located in the
small of the back
and have an
enhanced weightbearing function
Figure 7.17c
Lumbar Vertebrae
• They have short,
thick pedicles and
laminae, flat
hatchet-shaped
spinous processes,
and a triangularshaped vertebral
foramen
Figure 7.17c
Lumbar Vertebrae
• Orientation of
articular facets
locks the lumbar
vertebrae
together to
provide stability
Figure 7.17c
Sacrum
• Consists of five
fused
vertebrae (S1S5), which
shape the
posterior wall
of the pelvis
Figure 7.18a
Sacrum
– It articulates
with L5
superiorly,
and with the
auricular
surfaces of
the hip bones
Figure 7.18a
Sacrum
– Major markings
include the sacral
promontory,
transverse lines,
alae, dorsal sacral
foramina, sacral
canal, and sacral
hiatus
Figure 7.18a
Coccyx - Tailbone
– The coccyx is
made up of four
(in some cases
three to five)
fused vertebrae
that articulate
superiorly with
the sacrum
Figure 7.18a
Sacrum and Coccyx
Anterior view
Sacrum and Coccyx
Posterior View
Figure 7.18b
The Bony Thorax
• Made up of
three parts
– Sternum
– Ribs
– Thoracic
vertebrae
The Bony Thorax
• The thoracic cage
is composed of
the thoracic
vertebrae
dorsally, the ribs
laterally, and the
sternum and
costal cartilages
anteriorly
Bony Thorax (Thoracic Cage)
• Functions
– Forms a protective cage around the
heart, lungs, and great blood vessels
– Supports the shoulder girdles and
upper limbs
– Provides attachment for many neck,
back, chest, and shoulder muscles
– Uses intercostal muscles to lift and
depress the thorax during breathing
Bony Thorax (Thoracic Cage)
Figure 7.19a
Bony Thorax (Thoracic Cage)
Figure 7.19b
Sternum (Breastbone)
• A dagger-shaped, flat bone that lies in
the anterior midline of the thorax
• Results from the fusion of three bones
– the superior manubrium, the body, and
the inferior xiphoid process
• Anatomical landmarks include the
jugular (suprasternal) notch, the sternal
angle, and the xiphisternal joint
Ribs
• There are twelve pair of ribs
forming the flaring sides of the
thoracic cage
• All ribs attach posteriorly to
the thoracic vertebrae
Ribs
• The superior 7
pair (true, or
vertebrosternal
ribs) attach
directly to the
sternum via
costal cartilages
Ribs
• Ribs 8-10 (false,
or
vertebrocondral
ribs) attach
indirectly to the
sternum via
costal cartilage
Ribs
• Ribs 11-12
(floating, or
vertebral ribs)
have no
anterior
attachment
Ribs
Figure 7.19a
Structure of a Typical True Rib
• Bowed, flat
bone
consisting
of a head,
neck,
tubercle,
and shaft
Figure 7.20
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