Transcript Bones -part 2 spine

Chapter 7 Part B
The Skeleton
© Annie Leibovitz/Contact Press Images
© 2016 Pearson Education, Inc.
PowerPoint® Lecture Slides
prepared by
Karen Dunbar Kareiva
Ivy Tech Community College
7.2 The Vertebral Column
General Characteristics
• Extends from skull to pelvis
• Also called spine or spinal column
• Functions to transmit weight of trunk to lower
limbs, surround and protect spinal cord, provide
attachment points for ribs and muscles
• Flexible curved structure contains 26 irregular
bones called vertebrae in five major regions
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General Characteristics (cont.)
• Regions and curvatures
– Regions: ~28 long vertebral column broken into
five major regions:
1. Cervical: consists of 7 vertebrae
2. Thoracic: 12 vertebrae
3. Lumbar: 5 vertebrae
– Remember meal times: 7 am, 12 noon, and 5 pm
4. Sacrum: one bone, formed from fusion of several
bones, articulates with hip
5. Coccyx: also fused bones that form terminus of
column
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General Characteristics (cont.)
– Curvatures: four main curves in the column help
to increase resilience and flexibility of spine
• Cervical and lumbar curvatures
– Concave posteriorly
• Thoracic and sacral curvatures
– Convex posteriorly
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Figure 7.16 The vertebral column.
C1
2
3
4
5
6
7
Cervical curvature (concave)
7 vertebrae, C1: C7
T1
Spinous
process
2
3
Transverse
processes
4
5
6
7
8
Thoracic curvature
(convex)
12 vertebrae,
T1: T12
9
10
11
Intervertebral
discs
Intervertebral
foramen
12
L1
2
3
4
Lumbar curvature
(concave)
5 vertebrae, L1: L5
5
Sacral curvature
(convex)
5 fused vertebrae
sacrum
Coccyx
4 fused vertebrae
Anterior view
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Right lateral view
General Characteristics (cont.)
• Ligaments: along with trunk muscles, help
support vertebral column
– Anterior and posterior longitudinal
ligaments: continuous bands from neck to
sacrum that run down front and back of spine
• Support and prevent hyperextension (backward) or
hyperflexion (forward) bending
– Ligamentum flavum: connects adjacent
vertebrae
– Short ligaments: connect each vertebra to those
above and below
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Figure 7.17a Ligaments and fibrocartilage discs uniting the vertebrae.
Supraspinous ligament
Transverse process
Sectioned
spinous process
Intervertebral
disc
Anterior
longitudinal
ligament
Intervertebral foramen
Ligamentum flavum
Posterior longitudinal
ligament
Interspinous
ligament
Anulus fibrosus
Inferior articular process
Median section of three vertebrae
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Nucleus pulposus
Sectioned body
of vertebra
Figure 7.17b Ligaments and fibrocartilage discs uniting the vertebrae.
Posterior longitudinal
ligament
Anterior longitudinal
ligament
Body of a vertebra
Intervertebral disc
Anterior view of part of the spinal column
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General Characteristics (cont.)
• Intervertebral discs
– Cushionlike pad sandwiched between vertebrae
that act as shock absorbers
– Composed of two parts
• Nucleus pulposus
– Inner gelatinous nucleus
– Gives disc its elasticity and compressibility
• Anulus fibrosus
– Outer collar composed of collagen and fibrocartilage
– Limits expansion of nucleus pulposus when
compressed
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Figure 7.17c Ligaments and fibrocartilage discs uniting the vertebrae.
Vertebral spinous process
(posterior aspect of vertebra)
Spinal cord
Spinal nerve root
Transverse
process
Herniated portion
of disc
Anulus fibrosus
of disc
Nucleus
pulposus
of disc
Superior view of a herniated intervertebral disc
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Figure 7.17d Ligaments and fibrocartilage discs uniting the vertebrae.
Nucleus
pulposus of
intact disc
Herniated
nucleus
pulposus
MRI of lumbar region of vertebral column in
sagittal section showing herniated disc
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Clinical – Homeostatic Imbalance 7.2
• Severe physical trauma to spine may result in one
or more herniated (prolapsed) discs
• Usually involves rupture of anulus fibrosus,
resulting in protrusion of nucleus pulposus, which
can press on spinal cord or nerves, causing
numbness or excruciating pain
• Treatment: exercise, massage, heat, painkillers, or
surgical intervention involving bone grafting to fuse
adjoining vertebrae
• Percutaneous laser disc decompression vaporizes
part of disc; tears can be sealed electrothermally
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Clinical – Homeostatic Imbalance 7.2
• Abnormal spinal curvatures can be congenital or
result from disease, poor posture, or unequal pull of
muscles on spine
• Scoliosis: abnormal lateral rotation of spine, most
often in thoracic region, which may lead to
breathing difficulties
• Kyphosis (hunchback): is abnormal dorsal thoracic
curvature common in people with osteoporosis,
tuberculosis of spine, rickets, or osteomalacia
• Lordosis (swayback): is accentuated lumbar
curvature that can result from disease but is also
seen in men with pot bellies and in pregnant women
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Figure 7.18 Abnormal spinal curvatures.
Scoliosis
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Kyphosis
Lordosis
General Structure of Vertebrae
• All have common structural pattern consisting of:
– Body (centrum), the anterior weight-bearing
region
– Vertebral arch composed of:
• Two pedicles: short pillars form sides of arch
• Two laminae: fused, flattened plates form posterior
arch
– Vertebral foramen: enclosure formed by body
and vertebral arch coming together
– Vertebral canal: series of vertebral foramina
– Intervertebral foramina: lateral openings
between vertebrae for passage of spinal nerves
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Figure 7.19 Typical vertebral structures.
Posterior
Spinous
process
Transverse
process
Superior
articular
facet
and
process
Vertebral
arch
• Lamina
• Pedicle
Vertebral
foramen
Body
Anterior
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General Structure of Vertebrae (cont.)
• Vertebrae have seven processes:
– Spinous process: projects posteriorly
– Transverse processes (2): project laterally
– Superior articular processes (2): protrude
superiorly
– Inferior articular processes (2): protrude inferiorly
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Animation: Rotatable Spine (Horizontal)
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Animation: Rotatable Spine (Vertical)
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Regional Vertebral Characteristics
• Cervical vertebrae
– C1 to C7: smallest, lightest vertebrae
– C3 to C7 share following features:
•
•
•
•
Oval-shaped body
Exception: C7 spinous processes are split (bifid)
Large, triangular vertebral foramen
Transverse foramen found in each transverse
process for artery passageways
• C7 is vertebra prominens; large and can be felt
through skin, so used as a landmark
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Table 7.2-1 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae
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Table 7.2-2 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae (continued)
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Table 7.2-3 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae (continued)
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Figure 7.21a Posterolateral views of articulated vertebrae.
Dens of axis
Transverse ligament
of atlas
C1 (atlas)
C2 (axis)
C3
Inferior articular
process
Bifid spinous
process
Transverse processes
C7 (vertebra
prominens)
Cervical vertebrae
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Regional Vertebral Characteristics (cont.)
• Cervical vertebrae (cont.)
– C1 (atlas) and C2 (axis) have unique features
– Atlas (C1)
• No body or spinous process
• Consists of anterior and posterior arches, and two
lateral masses
• Superior surfaces of lateral masses articulate with
occipital condyles
– Occipital condyles “carry” skull
• Movement for nodding head “Yes”
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Figure 7.20a The first and second cervical vertebrae.
Posterior
C1
Posterior tubercle
Posterior arch
Transverse foramen
Lateral
masses
Superior articular
facet
Anterior arch
Anterior tubercle
Superior view of atlas (C1)
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Figure 7.20b The first and second cervical vertebrae.
Posterior
Posterior tubercle
Posterior arch
Inferior
articular
facet
Transverse
process
Lateral
masses
Transverse foramen
Facet for dens
Inferior view of atlas (C1)
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Anterior arch
Anterior tubercle
Regional Vertebral Characteristics (cont.)
– Axis (C2)
• Has body and processes like other vertebrae
• Major feature is knoblike dens that projects superiorly
into anterior arch of atlas
– Dens is the “missing” body of atlas
• Dens is a pivot for rotation of atlas
• Movement allows side to side rotation for saying “No”
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Figure 7.20c The first and second cervical vertebrae.
Posterior
C2
Spinous process
Inferior
articular
process
Lamina
Pedicle
Transverse
process
Superior
articular
facet
Dens
Body
Superior view of axis (C2)
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Figure 7.20d The first and second cervical vertebrae.
Posterior
Transverse
foramen in
transverse
process
Spinous process
Superior
articular
facet
Dens
Body
Photo of axis (C2), superior view
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Figure 7.21a Posterolateral views of articulated vertebrae.
Dens of axis
Transverse ligament
of atlas
C1 (atlas)
C2 (axis)
C3
Inferior articular
process
Bifid spinous
process
Transverse processes
C7 (vertebra
prominens)
Cervical vertebrae
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Regional Vertebral Characteristics (cont.)
• Thoracic vertebrae
– T1 to T12 increase in size and articulate with ribs
– Unique characteristics:
• Body is heart shaped with two small demifacets that
articulate with ribs
– T10 to T12 have only single facet, not two
• Vertebral foramen is circular
• Long, sharp spinous process points inferiorly
• Transverse processes have transverse costal facets
that articulate with ribs (except T11, T12)
• Location of articular facets allows rotation of this area
of spine
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Table 7.2-1 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae
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Table 7.2-2 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae (continued)
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Table 7.2-3 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae (continued)
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Figure 7.21b Posterolateral views of articulated vertebrae.
Transverse
process
Superior articular
process
Transverse
costal facet (for
tubercle of rib)
Intervertebral
disc
Body
Spinous
process
Thoracic vertebrae
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Inferior costal
facet (for head
of rib)
Inferior articular
process
Regional Vertebral Characteristics (cont.)
• Lumbar vertebrae
– L1 to L5 “small of back”; receives most stress, so
bodies are massive
– Other characteristics:
• Short, thick pedicles and laminae
• Flat, hatchet-shaped spinous processes point
posteriorly
• Vertebral foramen is triangular
• Orientation of articular facets locks lumbar vertebrae
together to prevent rotation
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Table 7.2-1 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae
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Table 7.2-2 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae (continued)
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Table 7.2-3 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae (continued)
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Figure 7.21c Posterolateral views of articulated vertebrae.
Superior
articular
process
Transverse
process
Body
Intervertebral
disc
Inferior
articular
process
Spinous
process
Lumbar vertebrae
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Regional Vertebral Characteristics (cont.)
• Sacrum: triangular bone shapes posterior wall of
pelvis; made from five fused vertebrae (S1–S5)
– Superior articular process articulates with L5
– Articulates inferiorly with coccyx and laterally with hip
bones via its auricular surfaces, forming sacroiliac
joints
– Sacral promontory: anterosuperior margin
– Transverse ridges mark lines of fusion
– Anterior sacral foramina: lie at lateral ends of
ridges; act as openings for nerves and vessels
– Alae: winglike expansions
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Regional Vertebral Characteristics (cont.)
• Sacrum (cont.)
– Median sacral crest: roughened bumps on posterior
midline and lateral sacral crest; roughened area
seen laterally on posterior side
– Posterior sacral foramina: large openings for
sacral spinal nerves
– Sacral canal: continuation of vertebral canal
– Sacral hiatus: large opening at end of canal
• Coccyx: tailbone formed from three to five fused
vertebrae; articulates superiorly with sacrum
– Very little function
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Figure 7.22a The sacrum and coccyx.
Sacral promontory
Ala
Body of
first
sacral
vertebra
Transverse ridges
(sites of vertebral
fusion)
Apex
Anterior
sacral
foramina
Coccyx
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Anterior view
Figure 7.22b The sacrum and coccyx.
Sacral
canal
Ala
Body
Facet of superior
articular process
Auricular
surface
Lateral
sacral
crest
Median
sacral
crest
Posterior
sacral
foramina
Coccyx
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Posterior view
Sacral
hiatus
7.3 Thoracic Cage
• Composed of:
– Thoracic vertebrae posteriorly
– Sternum and costal cartilages anteriorly
– Ribs laterally
• Functions
– Protects vital organs of thoracic cavity
– Supports shoulder girdles and upper limbs
– Provides attachment sites for muscles of neck,
back, chest, and shoulders
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Figure 7.23a The thoracic cage.
Jugular notch
Clavicular notch
Sternum
True
ribs
(1–7)
• Manubrium
• Sternal angle
• Body
• Xiphisternal
joint
• Xiphoid
process
False
ribs
(8–12)
Intercostal
spaces
L1
Floating Vertebra
ribs (11, 12)
Skeleton of the thoracic cage, anterior view
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Costal cartilage
Costal margin
Sternum
• Also called the breastbone; consists of three
fused bones:
– Manubrium: superior portion that articulates with
clavicular notches and ribs 1 and 2
– Body: midportion that articulates with costal
cartilages of ribs 2 through 7
– Xiphoid process: inferior end that is site of
muscle attachment
• Not ossified until ~age 40
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Sternum (cont.)
• Sternum has three important anatomical
landmarks:
– Jugular notch
• Central indentation in superior border of manubrium
– Sternal angle
• Horizontal ridge across front of sternum
– Xiphisternal joint
• Point where sternal body and xiphoid process fuse
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Figure 7.23b The thoracic cage.
T2
Jugular notch
T3
T4
Sternal angle
Heart
T9
Xiphisternal
joint
Midsagittal section through the thorax, showing
the relationship of surface anatomical landmarks
of the thorax to the vertebral column
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Clinical – Homeostatic Imbalance 7.4
• Xiphoid process projects posteriorly in some
people
• A blow to the chest (chest trauma) at the level
of the xiphoid process can push process into
underlying liver or heart
• Can cause massive hemorrhaging
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Ribs
• 12 pairs form sides of thoracic cage
• All attach posteriorly to bodies and transverse
processes of thoracic vertebrae
• True (vertebrosternal) ribs (pairs 1–7)
– Attach directly to sternum by individual costal
cartilages
• False (vertebrochondral) ribs (pairs 8–10)
– Attach indirectly to sternum by joining costal
cartilage of rib above
• Vertebral (floating) ribs (pairs 11–12)
– No attachment to sternum
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Figure 7.23a The thoracic cage.
Jugular notch
Clavicular notch
Sternum
True
ribs
(1–7)
• Manubrium
• Sternal angle
• Body
• Xiphisternal
joint
• Xiphoid
process
False
ribs
(8–12)
Intercostal
spaces
L1
Floating Vertebra
ribs (11, 12)
Skeleton of the thoracic cage, anterior view
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Costal cartilage
Costal margin
Ribs (cont.)
• Main parts of rib:
– Shaft: flat bone that makes up most of rib
• Costal groove: houses nerves and vessels
– Head (posterior end)
• Articulates with facets (demifacets) on bodies of two
adjacent vertebrae
– Neck: constricted portion beyond head
– Tubercle: knoblike structure lateral to neck
• Articulates posteriorly with transverse costal facet of
same-numbered thoracic vertebra
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Figure 7.24a Ribs.
Transverse costal facet
(for tubercle of rib)
Angle
of rib
Superior costal facet
(for head of rib)
Body of vertebra
Head of rib
Intervertebral disc
Neck of rib
Tubercle of rib
Shaft
Crosssection
of rib
Sternum
Costal groove Costal cartilage
Vertebral and sternal articulations of a typical true rib
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Figure 7.24b Ribs.
Articular facet
on tubercle of rib
Spinous process
Shaft
Ligaments
Neck of rib
Head of rib
Superior costal facet
(for head of rib)
Transverse
costal facet
(for tubercle
of rib)
Body of
thoracic
vertebra
Superior view of the articulation between a rib and a
thoracic vertebra
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Figure 7.24c Ribs.
Shaft
Facets for articulation
with vertebrae
Junction with
costal cartilage
Head
Neck
Costal groove
A typical rib (rib 6, right), posterior view
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Articular facet
on tubercle
Angle of rib