Transcript File
Skeletal System
Axial Skeleton
Axial Skeleton
Includes 80 bones of the skull, vertebral
column and bony thorax
Functions:
– Supports head, neck & trunk
– Protects brain, spinal cord and thoracic
organs
Skull
Composed of flat bones
Function:
– Used for attachment of head muscles &
protects the brain
Sutures of the Skull
Sutures: interlocking joints that unite
skull bones
– Coronal: where parietal bones meet frontal
– Sagittal: where 2parietal bones meet
superiorly
– Squamos: where parietal and temporal
bones meet on lateral aspects of skull
– Lambdoidal: where parietal bones meet
occipital bones meet posteriorly
Vertebral Column aka the Spine
Location: runs from the base of the
skull to the coccyx (tailbone)
Function:
– Surrounds and protects the spinal cord
– Provides attachment sites for ribs and back
muscles
Vertebral Column
Characteristics
– 26 interconnected
irregular bones
– Provides a flexible,
curved structure
– Serves as axial
support of the trunk
Vertebral Column
Curvatures of the Spine:
–
–
–
–
S-shaped to prevent shock to head in motion
Allows for trunk flexibility
Increases resiliency & flexibility of the spine
Functions like a spring, not a rod
Cervical & Lumbar Curves: concave
posteriorly
Thoracic & Sacral Curves: convex
posteriorly
Curvatures of the Spine
Abnormal Curvatures of the
Vertebral Column
Lordosis: aka
sway back
– An accentuated
lumbar curve
Kyphosis: aka
hunchback
– An exaggerated
thoracic curve
Scoliosis: the
twisted disease
– An abnormal lateral
curvature in the
thoracic region
– Typical in girls in late
childhood
Lordosis & Kyphosis
Scoliosis
Cervical Vertebrae
7 total extending from base of skull to ~
shoulder line
Numbered C1-C7
Smallest & lightest vertebrae
Unique vertebrae
– Atlas or C1: no body; holds the occipital bone,
allows nodding motion (“yes”)
– Axis or C2: acts as a pivot for rotation; shake
head (“no”)
Thoracic Vertebrae
12 total; runs through mid-back
Numbered T1-T12
Larger than cervical
Longer, palpable spinous processes
Ribs attach here posteriorly
Lumbar Vertebrae
5 total
Numbered L1-L5
Huge bodies and
short spinous
processes
Holds most of body
weight & stress; very
sturdy
Sacrum &
Coccyx
Sacrum
– Formed from 5 fused
vertebrae
– Numbered S1-S5
– Makes up posterior
wall of pelvis
– Strengthens &
stabilizes pelvis
Coccyx
– 4 fused vertebrae
Ligaments of the Spine
There are several; only 2 you need to
know
– Anterior Longitudinal Ligament: resists
back hyperextension
– Posterior Longitudinal Ligament: resists
back flexion
Intervertebral Discs
Cushion-like pads between vertebrae
Asts as shock absorbers during motion
Makes up ~25% of length of column
Flattens during the day
Intervertebral Discs
Ribs
Flat bones
12 total pairs
Attach posteriorly to thoracic spine
Function:
– Protect thoracic organs
True Ribs: the superior 7 pairs
– Attach directly to sternum by costal cartilage
False Ribs: the inferior 5
– 8-10: join each other by cartilage and indirectly attach to
sternum
– 11& 12: the floating ribs, no anaterior attachment
Rib Cage
Pelvis
Has 2 regions: true and false pelvises
False pelvis superior to true pelvis
True pelvis dimensions are a concern
to child-bearing women
Pelvic structure differs between men
and women
Gender Difference of Pelvis
Men
– Narrow outlet
– Heavier & thicker bone
structure
– Ilia less flared, more
vertical
– Sacrum long and curved
– Ischia close together
– Less rounded pubic arch
Women
– Inlet circular & large
– Pelvis shallow, lighter &
thinner
– Ilia flare laterally
– Sacrum shorter & less
curved
– Ischia farther apart &
shorter
– Pubic arch is more
rounded
Female vs. Male Pelvis
Female vs. Male Skulls
FUNTION OF JOINTS
They hold bones together.
Allow the rigid skeleton mobility
Joints are classified in 2 ways:
1. Functionally –amount of movement
2. Structurally – type of tissue
Functionally- amount of
movement
1. Synarthrosis- immovable
Ex) sutures in skull
2. Amphiarthrosis- slightly movable
Ex) intervertebral joints
3. diarthrosis-freely movable
Ex) limbs
Structurally- tissue type between
bones
1) Fibrous- connected by fibrous tissue
- sutures skull
2) Cartilaginous- connected by cartilage
-pubic symphysis
3) Synovial- separated by a joint
containing fluid
-6 types based on articulating bone
surface
Types of Synovial Joints
1. Plane Joint-wrist
2. Hinge Joint- elbow
3. Pivot Joint- ulna & radius
4. Condyloid Joint- metacarpels
5. Saddle Joint- thumb
6. Ball & Socket- shoulder or hip
Stress Fracture of the Tibia
STAGES OF BONE REPAIR