Download 06. Bones of the trunk

Bones of the
trunk
Skeletal system
• Your bones
manufacture blood
cells.
• Our bones are held
by our muscles
• The smallest bones
are in our ears
Bones classified by shape: long, short, flat,
irregular, round
Bone enclosed in periosteum, which is continuous
with tendons and ligaments
blood vessels in periosteum
Epiphysis- ends
spongy bone contains red marrow
compact bone, articular cartilage
Diaphysis- middle
compact bone
medullary cavity- contains yellow marrow (fat)
lined with endosteum (squamous epithelium)
Compact bone
osteocytes within lacunae
arranged in concentric circles called lamellae
This surround a central canal; complex is called
Haversian system
Canaliculi connect osteocytes to central canal and
to each other
Prenatal development
skeleton is mostly cartilaginous
Cartilage cells and then osteoblasts start to
deposit minerals
Cartilaginous disk (epiphyseal disk) remains
in epiphysis
Cells eventually stop dividing
Bursae & Tendon Sheaths
• Bursae: flat, fibrous sac
w/synovial membrane
lining
• Tendon Sheaths:
elongated bursae that
wraps around tendons
• 3 Factors in Joint Stability:
– Muscle Tone
– Ligaments
– Fit of Articular Surface
pg 219
pg 224
Joint Shapes
• Hinge: cylindrical end of 1 bone
fits into trough shape of other
– angular movement-1 plane (eg)
elbow, ankle, interphalangal
• Plane: articular surface in flat
plane
– Short gliding movement
– (eg) intertarsal, articular
processes of vertebrae
pg 225
Joint Shapes
• Condyloid: egg-shape articular
surface + oval concavity
– side-to-side, back+forth movement
– (eg) metacarpophalangeal (knuckle)
• Pivot: round end fits into ring of
bone + ligament
– rotation on long axis
– (eg) prox. radius/ulna, atlas/dens
Thoracic cage
ribs
thoracic vertebrae
sternum
costal cartilages
True ribs are directly attached to the sternum
(first seven pairs)
Three false ribs are joined to the 7th rib
Two pairs of floating ribs
Clavicles and scapulae
Help brace shoulders
Attachment sites for muscles
Bones of upper limb
Humerus (upper arm)
Radius; ulna
Carpals, metacarpals, phalanges
Bones of lower limb
Femur
Patella
Tibia, fibula
Tarsals, metatarslas, phalanges
Radius and Ulna
• Radius on Top
• Ulna on Bottom
Carpals or (Wrist Bones)
Phalanges (Little Fingers)
Rib Cage
Sternum (Breastbone)
Characteristics - Ligaments
• Ligaments hold the
vertebral column in
an upright position
– The broad Anterior
Longitudinal
Ligament prevents
hyperextension and
is quite strong
– The cord like
Posterior
Longitudinal
Ligament prevents
hyperflexion and is
relatively weak
Characteristics - Ligaments
• Ligaments also
connect
specific
vertebra and
support disc
position
– Supraspinos
ligament
– Ligamentum
flavum
– Interspinous
ligament
Intervertebral Discs
• Intervertebral discs are cushion like pads
interposed between vertebra
• The discs provide elasticity and
compressibility
• Compression flattens discs
• Discs are thickest in the cervical and lumbar
to provide flexibility
Characteristics - discs
• Annulus fibrosus
surrounds the
outer margin
– Collagen fibers
• Nucleus pulposus
is the semi fluid
substance which
shifts under body
weight & pressure
• Herniation of disc
Herniation
of disk
General structure of vertebrae
• Common pattern
– Body or centrum
– Vertebral arch
• lamina
• pedicle
– Vertebral foramen
– Spinous process
• Muscles attach
– Transverse
process
• Muscles attach
General structure of vertebrae
• Interlocking pattern
– Superior and inferior
processes interlock
– The inferior from
above and the
superior from the
vertebrae below
form a movable joint
– The movement
contributes to spinal
rotation
Superior Articular
Process
General structure
• Pedicles have
notches on their
superior and
inferior borders
• Lateral openings
are called
intervertebral
foramen
– Spinal nerves
from spinal cord
exit through these
foramina
Regional Characteristic: Cervical
• Body is oval, but wide
side to side C3 - C7
• Spinous process is
short and bifid (split)
except in C7
• Vertebral foramen is
triangular
• Transverse processes
contain foramina for
blood vessels leading
to brain
Cervical Vertebrae C1
• Lateral masses articulates with the occipital
condyles of the skull
Cervical Vertebrae C1
Body of the
Vertebrae is
missing
• Inferior articular surface articulates with C2 below
Cervical Vertebrae C2
• The axis has the
odontoid process
or dens is its
unique feature
• The dens is the
missing body of
the atlas which
fuses with the
atlas during
embryonic
development
Regional Characteristic: Cervical
• Spinous processes
project directly
posteriorly
• Superior facets
directed
superoposteriorly
• Inferior facets
directed
inferoanteriorly
• Flexion/extension,
lateral flexion and
rotation
Regional Characteristic: Thoracic
• Body is larger than
cervical; heart shaped
• Spinous process is
long and sharp
• Vertebral foramen is
circular
• Transverse processes
project posteriorly
and bear facets for
ribs
Regional Characteristic: Lumbar
• Body is massive and
kidney shaped
• Spinous processes are
short and blunt
• Vertebral foramen is
triangular
• Transverse processes
are perpendicular to
spinous process but
has no special features
Regional Characteristic: Lumbar
• Spinous process
projects posteriorly
• Superior facets
directed medially
• Inferior facets directed
laterally
• Flexion/extension,
some lateral flexion,
rotation prevented
Sacral
• Ala are fused remnants
of transverse processes
that articulate with hip
bones to form the sacro
iliac joints of the pelvis
• Sacral promontory
– Center of gravity is 1 cm
posterior of this point
• Transverse line are sites
of vertebral fusion
• Sacral foramina transmit
blood vessels and nerves
Ala
Sacral
promontory
Sacral
• On the posterior aspect
median sacral crest are
fused spinous processes
• The vertebral canal
continues inside the
sacrum as the sacral
canal
• Sacral hiatus is at the
inferior end of the sacral
canal
• Superior articular surface
form a joint with the
spinal column
Coccyx
• Coccyx articulates with sacrum
Sternum
• Located on the anterior
midline of the thorax
• Consists of three fused
bones; manubrium,
body, and xiphoid
process
• Manibrium articulates
with clavicle & 2 ribs
• Body with ribs 2 - 7
• Xiphoid attachment site
for abdominal muscle
Thorax to Vertebral Column
Ribs
Ribs
• Ribs are bowed
flat bones
• Long shaft
• Tear drop shaped
with a costal
groove on inner
surface
• Head of rib has 2
facets to articulate
with its vertebrae
as well as the one
above
Ribs
• Tubercle of rib
articulates with
transverse process
• Ligaments secure
rib to transverse
process
• Note how the
transverse
processes of
thoracic vertebrae
are angled
posteriorly
Pelvis (Dancing Bone)
Femur
(Largest Bone in the Body)
The Tibia and Fibula
Metatarsals
Phalanges
Calcaneous