Muscle Histology

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Myology 1 (HS 113)
Lecture 5 Bony Anatomy of the Vertebral Column
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Gross Anatomy
Osteology of the Spine
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Spinal Anatomy

• Spine is made up of 24 small bones (vertebrae)
  that are stacked on top of each other to create
  the spinal column.
• Between each vertebra is a soft, gel-like
  intervertebral disc that helps absorb pressure
  and keeps the bones from rubbing against each
  other.
• Each vertebra is held to the others by groups of
  ligaments (connect bones to bones)
• Tendons connect muscles to bones. There are also
  tendons that fasten muscles to the vertebrae.
• The spinal column also has real joints (just like
  the knee or elbow or any other joints) called
  facet joints. The facet joints link the vertebrae
  together and give them the flexibility to move
  against each other.

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• The spine itself has three main segments
• Cervical spine
• Thoracic spine
• Lumbar spine
• The cervical is the upper part of the spine, made
  up of seven vertebrae.
• The thoracic is the center portion of the spine,
  consisting of 12 vertebrae.
• The lower portion of the spine is called the
  lumbar spine, consisting of five vertebrae.

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Intervertebral Discs

• Between adjacent vertebrae absorbs vertical shock
• Permit various movements of the vertebral column
• Fibrocartilagenous ring (Annulus fibrosis) with a
  pulpy center (Nucleus pulposus)

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Normal Curves of the Vertebral Column

• Curves in vertebral column function to
• Increase strength
• Maintain balance in the upright position
• Absorb shock during walking and running
• Protect spinal column from fracture
• Primary curves
• Thoracic and sacral are formed during fetal
  development
• Secondary curves
• Cervical is formed when infant raises head at 4
  months
• Lumbar forms when infant sits up begins to walk
  at 1 year

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Anatomy of a typical vertebrae

• Body
• Large, round portion of bone
• Superior and inferior surfaces are roughened for
  attachment of intervertebral disc.
• Neural Arch attached to the vertebral body
  consists of several parts
• Pedicle two thick processes which project
  posteriorly from the body, uniting with the
  laminae.
• Vertebral notches upper and lower indentations
  on the pedical
• Intervertebral Foramen Opening formed between
  adjacent vertebrae (when stacked) for the exiting
  of a single spinal nerve.
• Laminae flat pieces of bone forming the
  posterior portion of the vertebral arch

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• Vertebral Foramen space between the vertebral
  arch and body containing the spinal cord,
  adipose, and areolar connective tissue
• Vertebral (Spinal) Canal formed by all vertebral
  foramina of all vertebrae together.
• Processes a total of 7 processes
• Transverse process (2) extends laterally from
  the lamina pedicle junction functions for muscle
  attachment
• Spinous process (1) extends posteriorly from the
  junction of the lamina functions for muscle
  attachment
• Superior articulating process (2) articular
  processes that form joints with the vertebrae
  above
• Inferior articulating process (2) articular
  processes that form joints with the vertebrae
  below
• Facet the articulating surface of the articular
  process.

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Cervical Spine

• The cervical spine is made up of the first seven
  vertebrae in the spine.
• It starts just below the skull and ends just
  above the thoracic spine.
• The cervical spine has a lordotic curve (a
  backward C-shape)
• The cervical spine is much more mobile than both
  of the other spinal regions.
• Unlike the rest of the spine, there are special
  openings in each transverse process in the
  vertebra in the cervical spine for the arteries
  supplying the brain.
• All of the cervical vertebrae with the exception
  of C1 and C7 have a bifid spinous process.

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• Atypical Vertebrae C1, C2, and C7
• Two vertebrae in the cervical spine, the atlas
  and the axis, differ from the other vertebrae
  because they are designed specifically for
  rotation. The 7th cervical vertebrae differs as
  it is marked by its large spinous process.
• First cervical vertebra (Atlas)
• Sits between the skull and the rest of spine.
• Arches atlas does not have a vertebral body,
  but does have a thick forward (anterior) arch and
  a thin back (posterior) arch.
• Spinous process atlas has no spinous process
• Lateral masses in place of a vertebral body, the
  atlas has two lateral masses which support the
  skull.
• Superior articular facets located on superior
  aspect of the facet articulating with the
  occipital condyles. This joint allows for
  movement as in nodding the head yes

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• Second cervical vertebra (Axis)
• Odontoid process bony projection projecting
  upward from the body through the front of the
  ring of the atlas.
• Allows rotation to the left and right
• 7th Cervical vertebra (Vertebra prominens)
• C7 has a large non-bifid spinous process

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Atlas and Axis
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C3 through C6 Vertebrae

• The remaining vertebrae (C3-C7) have the features
  of a more typical vertebrae (bodies, spinous
  processes, transverse processes, lamina, and
  pedicles).

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Thoracic Spine

• The thoracic spine is made up of the middle 12
  vertebra of the spine.
• These vertebrae connect to the ribs and form part
  of the back wall of the thorax (the ribcage area
  between the neck and the diaphragm).
• The thoracic spine has very narrow, thin
  intervertebral discs, so there is much less
  movement allowed between vertebrae than in the
  lumbar or cervical parts of the spine.
• The thoracic spine's curve is called kyphotic
  because of its shape, which is a regular
  "C"-shaped curve with the opening of the "C" in
  the front.

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• Body
• Larger and stronger bodies than in the cervical
  spine
• Processes
• Longer transverse spinous processes
• Spinous processes are directed more inferior, so
  that they overlap
• Facets or demifacets on body articulating
  surfaces for the articulation with the head of
  rib
• Facet full indentation on the body of the
  thoracic vertebrae
• Demifacet half facet on the body of a thoracic
  vertebrae
• Facets on transverse processes (T1-T10) for
  articulation with the tubercle of rib

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Lumbar Spine

• The lowest part of the spine
• This area has five vertebrae.
• Strongest largest vertebrae
• Short thick spinous transverse processes
• Serves as attachment points for back musculature

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Sacrum

• Triangular bone which curves anteriorly, formed
  by the union of five sacral vertebrae, serving as
  a foundation for the pelvic girdle
• Anatomy
• Sacral foramen Anterior and posterior sacral
  foramen, allow passage of the sacral nerves
• Sacral Ala (Wings) upper lateral portion of the
  sacrum formed by the fusion of transverse
  processes.
• Median sacral crest posterior ridge formed by
  the fusion of sacral spinous processes
• Sacral canal continuation of the vertebral
  canal. Ends as the sacral hiatus which is an
  opening for the last spinal nerve.
• Articular surface on both lateral surfaces for
  articulation with the ilium of the pelvis.
• In the female, the sacrum is shorter, wider, and
  more curved between S2-S3

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Coccyx

• Also a triangular bone form by the fusion of four
  coccygeal vertebrae.
• In the female the coccyx points inferiorly while
  in the male is points more anteriorly.

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Palpation of the Spine
Spinous process of the vertebrae (general)
Seated have your partner flex their head and
trunk slightly. Place your fingers along the
centerline of the back and locate the long line
of processes. Slide your fingers slowly up and
down the spine noting the different sizes,
prominences, and spaces between the process a.
Cervical spinous processes Supine locate the
EOP and then slide your fingers inferior onto the
neck. The first palpable spinous process will be
C2 (recall, C1 has a posterior tubercle).
Continue palpating inferiorly gently until you
reach the C7 spinous (the most prominent of the
cervical spinous processes). Verify C7 by
flexing your partners neck, C7 will move
superiorly while T1 will remain fixed. Inferior
angle and T7 Prone, locate the inferior angle
of the scapula slide your finger medially to the
vertebral column. The spinous of T7 is in line
with the inferior angle. Superior angle and T2
Prone, locate the superior angle of the scapula
slide your finger medially to the vertebral
column. The spinous of T2 is in line with the
superior angle.
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Top of iliac crest and L4 Prone using the
knife edge portion of your hand place your
hands on the tops of the iliac crests. Then
slide your thumbs medially meeting at the spine,
the spinous process of L4 can be felt as a large
knob. Twelfth rib and T12 Prone locate the
lowest rib (12th) and palpate the shaft of the
rib back to the spinal column. The 12th rib may
be lost as it passes under the large erector
spinae musculature. Transverse processes of
cervical vertebrae Supine place your fingers on
the side of the neck below the ear lobes. Using
the flat thumbpads, slide anteriorly and
posteriorly to feel the ridge of the transverse
processes. Note, the tips of the individual TPs
are not usually palpable as the pass anterior and
inferior. Thoracic transverse process Prone
locate a portion of the thoracic spinous
processes. Move about 1 laterally and palpate
through the thick erector spinae group for the
knobby shaped transverse processes. Lumbar
transverse processes Prone locate the lumbar
spinous processes and slide about 2 laterally.
Slowly sink your fingers through the thick
erector spinae muscle, directing your pressure at
a medial angle. Because of the thick muscle, the
individual process may not be palpable, try to
sense the solid ridge they form.
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• Cervical laminar groove Supine support the
  head with one hand and locate the cervical
  transverse process with the other hand. Slide
  posteriorly off the transverse processes,
  palpating the space between the transverse and
  the spinous processes which is the laminar
  groove.
• Thoracic and lumbar laminar groove Prone
  locate the spinous processes of the thoracic
  vertebrae. With the other hand locate the
  transverse processes of the thoracic vertebrae.
  Using firm pressure palpate the area between
  these two landmarks. Work your way down the
  laminar groove to the lumbar spine. Note the
  thick muscle of the transversospinalis group.
• Sternum Supine place your fingers on the
  center of the chest. Then slide superiorly
  toward the jugular notch at the top. Then move
  your fingers slightly lateral and palpate the
  sternoclavicular joints (confirm by having your
  partner move their upper extremity). Return to
  the sternum and palpate inferiorly onto the
  manubrium and body. Finally, slide your fingers
  down onto the xiphoid process feeling the tip
  between the costal cartilages.
• Ribs Supine slide laterally from the sternum
  onto the costal cartilages. Roll off the
  cartilage into the spaces between. Follow the
  costal cartilages laterally on to the ribs.