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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 continuouswith tendons and ligamentsblood vessels in periosteum
Epiphysis- endsspongy bone contains red marrowcompact bone, articular cartilage
Diaphysis- middlecompact bonemedullary cavity- contains yellow marrow (fat)lined with endosteum (squamous epithelium)
Compact boneosteocytes within lacunaearranged in concentric circles called lamellae
This surround a central canal; complex is calledHaversian system
Canaliculi connect osteocytes to central canal andto each other
Prenatal developmentskeleton is mostly cartilaginous
Cartilage cells and then osteoblasts start todeposit minerals
Cartilaginous disk (epiphyseal disk) remainsin 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
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 224
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
pg 225
Thoracic cageribsthoracic vertebraesternumcostal cartilages
True ribs are directly attached to the sternum(first seven pairs)Three false ribs are joined to the 7th ribTwo pairs of floating ribs
Clavicles and scapulae
Help brace shouldersAttachment sites for muscles
Bones of upper limb
Humerus (upper arm)Radius; ulnaCarpals, metacarpals, phalanges
Bones of lower limb
FemurPatellaTibia, fibulaTarsals, metatarslas, phalanges
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 discHerniation Herniation
of diskof 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 ArticularSuperior ArticularProcessProcess
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
• Inferior articular surface articulates with C2 below
Body of the Body of the Vertebrae is Vertebrae is
missing missing
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
SacralSacralpromontorypromontory
AlaAla
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