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The Skeleton
Part C
Human Anatomy & Physiology, Sixth Edition
Elaine N. Marieb
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7
Cervical Vertebrae
 Seven vertebrae (C1-C7) are the smallest, lightest
vertebrae
 C3-C7 are distinguished with an small oval body,
short bifid spinous processes (except C7), and large,
triangular vertebral foramina.
 Each transverse process contains a transverse
foramen
 Superior facets directed superoposteriorly foramina
 Inferior facets directed inferoanteriorly
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Cervical Vertebrae: Anatomical characteristics
Movement’s allowed:
 Flexion and extension
 Rotation (greatest
range of movement)
Table 7.2
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Cervical Vertebrae: The Atlas (C1)
 The first two cervical vertebrae, the atlas and the axis
have no intervertebral disc between them, and they are
highly modified, reflecting their special functions.
 The atlas is a ring bone, 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 , thus “ They carry the skull, just
as Atlas supported the heavens in Greek mythology”.
This joint allow you to nod “yes”. The inferior articular
surfaces form joints with the axis.
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Cervical Vertebrae: The Atlas (C1)
Figure 7.16a, b
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Cervical Vertebrae: The Axis (C2)
 The axis has a body, spine, and vertebral arches as
do other cervical vertebrae. It is not as specialized
as atlas
 Unique to the axis is the dens, or odontoid process,
which projects superiorly from the body and is
cradled in the anterior arch of the atlas
 The dens is a pivot for the rotation of the atlas
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Cervical Vertebrae: The Axis (C2)
Figure 7.16c
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Cervical Vertebrae: Anatomical view
The spinous p. of C7 is much larger than those of other cervical
vertebrae. Because it is visible through the skin C7 can be used as a
landmark for counting the vertebrae and it is called “v. prominent”
Figure 7.17a
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Thoracic Vertebrae
 There are twelve vertebrae (T1-T12) all of which
articulate with ribs. The first looks much like C7 and
the last four like the lumbar vertebral structure.
Increase in size from the first to the last
 Major markings include: two facets and two
demifacets on the heart-shaped body (except T10T12, have only a single facet), the circular vertebral
foramen, transverse processes, and a long spinous
process (points sharply downward)
 The location of the articulate facets prevents flexion
and extension, but allows rotation of this area of the
spine
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Thoracic Vertebrae
With the exception of T11 and
T12, the transverse process
have facet that articulate with
the tubercles of the ribs
Figure 7.17b
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Lumbar Vertebrae
 The five lumbar vertebrae (L1-L5) are located in the
small of the back and have an enhanced weightbearing function. This region receives the most
stress
 They have short, thick pedicles and laminae, flat
hatchet-shaped spinous processes, and a triangularshaped vertebral foramen
 Orientation of articular facets locks the lumbar
vertebrae together to provide stability
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Lumbar Vertebrae
Figure 7.17c
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Sacrum
 Sacrum (triangular)
 Consists of five fused vertebrae (S1-S5), which
shape the posterior wall of the pelvis
 It articulates with L5 superiorly, and laterally with
the auricular surfaces of the two hip bones to form
the sacroiliac joints of the pelvis
 Major markings include the sacral promontory,
transverse lines, alae, dorsal sacral foramina, sacral
canal, and sacral hiatus
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Coccyx
 Coccyx (Tailbone)
 The coccyx is made up of four (in some cases three
to five) fused vertebrae that articulate superiorly
with the sacrum
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Sacrum and Coccyx: Anterior View
Figure 7.18a
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Sacrum and Coccyx: Posterior View
Figure 7.18b
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Characteristics of Cervical,Thoracic and Lumbar Vertebrae
(Table 7.2,and Fig, Pag 222)
Characteristics Cervical (3-7)
Thoracic
Lumbar
Body
Small, wide side to
side
Larger than cervical,
heart shaped, bears
two costal demifacets
Massive, kidney
shaped
Spinous
process
Short bifid, projects
directly posteriorly
Long, sharp, projects
inferiorly
Short, blunt,
projects directly
posteriorly
Vertebral
foramen
Transverse
process
Sup. and inf.
art. process
Triangular
Circular
Triangular
Contain foramina
Bear facets for ribs
(except T11-T12)
Thin and tapered
Inf facet → inf-ant
Inf. facets → anterior
Movements
Flex and extension,
lateral flex, rotation
Rotation, limited
Flex and ext, some
lateral flex (ribs), flex lat flexion, rotation
& ext prevented
prevented
Sup facet→ sup-pos Sup facets→ posterior Sup facet→ posmed
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Inf. facet → ant-lat
Homeostatic Imbalance
 Herniated (prolapsed) disc.
Severe or sudden physical trauma to the spine, may
result in hernation of one or more discs. A herniated
disc (slipped disc) usually involves rupture of the
annulus fibrosus followed by protrusion of the
spongy nucleus pulposus through the annulus (Fig
7.14). If the protrusion presses on the spinal cord or
on spinal nerves exiting from the cord, numbness or
excruciating pay result.
Treatments: moderated exercise, massage, heat ther.
and painkillers if this fail→ surgery
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Bony Thorax (Thoracic Cage)
 The thoracic cage is composed of the thoracic
vertebrae dorsally, the ribs laterally, and the sternum
and costal cartilages anteriorly
 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
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Bony Thorax (Thoracic Cage)
Figure 7.19a
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Bony Thorax (Thoracic Cage)
Figure 7.19b
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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
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Ribs
 There are twelve pair of ribs forming the flaring
sides of the thoracic cage
 All ribs attach posteriorly to the thoracic vertebrae
 The superior 7 pair (true, or vertebrosternal ribs)
attach directly to the sternum via costal cartilages
 Ribs 8-10 (false, or vertebrocondral ribs) attach
indirectly to the sternum via costal cartilage
 Ribs 11-12 (floating, or vertebral ribs) have no
anterior attachment
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Ribs
Figure 7.19a
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Structure of a Typical True Rib
 Bowed, flat bone
consisting of a
head, neck,
tubercle, and shaft
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Figure 7.20
Appendicular Skeleton
 Although the bones of upper and lower limbs differ
in their functions and mobility, they have the same
fundamental plan: each limb is composed of three
major segments connected by movable joints.
 The appendicular skeleton is made up of the bones
of the limbs and their girdles
 Pectoral girdles attach the upper limbs to the body
trunk
 Pelvic girdle secures the lower limbs
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Pectoral Girdles (Shoulder Girdles)
 The pectoral girdles consist of the anterior clavicles
and the posterior scapulae
 They attach the upper limbs to the axial skeleton in a
manner that allows for maximum movement
 They provide attachment points for muscles that
move the upper limbs
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Pectoral Girdles (Shoulder Girdles)
Figure 7.22a
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Clavicles (Collarbones) “ Little keys”
 The clavicles are slender, doubly curved long bones
lying across the superior thorax
 The acromial (lateral) end articulates with the
scapula, and the sternal (medial) end articulates with
the sternum
 They provide attachment points for numerous
muscles, and act as braces to hold the scapulae and
arms out laterally away from the body
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Clavicles (Collarbones)
Each clavicle is cone
shaped at its medial
sternal end, which
attaches to the sternal
manubrium, and flattened
at its lateral acromail end
in which articulate with
scapula
Figure 7.22b, c
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Scapulae (Shoulder Blades)
 The scapulae are thin triangular, flat bones lying on
the dorsal surface of the rib cage, between the
second and seventh ribs
 Scapulae have three borders and three angles:
1.- superior (shortest, sharpest), 2.- medial (borders
parallels to the vertebra col, 3.- lateral or axillary
(were articulates with humerus)
 Major markings include the suprascapular notch, the
supraspinous and infraspinous fossae, the spine, the
acromion, and the coracoid process
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Scapulae (Shoulder Blades)
Figure 7.22d, e
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