Chapter 5
The Skeletal System
Pgs 152-175
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Intervertebral discs – flexible fibrocartilage
pads, act as cushion and shock absorption
In young people, these are spongy and have
a high water content (~90%)
In older people these dent to dry and weaken
along with the ligaments of the vertebral
column
◦ Predisposes elders to herniated (“slipped”) discs
◦ The protruding disc can press on the spinal cord or
nerves causing numbness and/or excruciating pain
Vertebral Column
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Abnormal curvatures of the spine may result
in musculoskeletal back, hip and shoulder
pain in adults – the number one cause for
common doctors visits in the US
There are many types of curvatures which
may result from congenital (present at birth)
abnormalities, disease, poor posture, or
unequal muscle pull on the spine
◦ Scoliosis – lateral curvature
◦ Kyphosis – upper back hunching, chin thrust
forward
◦ Lordosis – lower back curvature (sway back)
Vertebral Column II
Review: Did you get it?
1.
2.
3.
4.
5.
6.
7.
8.
9.
What are the five major regions of the vertebral
column?
How can you distinguish a lumbar vertebra from a
cervical vertebra?
What is a true rib? A false rib?
Besides the ribs and sternum, there is a third group
of bones forming the thoracic cage. What is it?
What bone class do the ribs and skull bones fall
into?
What is the single point of attachment of the
shoulder girdle to the axial skeleton?
What bone forms the skeleton of the arm?
Where are the carpals found, and what type of bone
are they?
Which bones of the upper limb have a styloid
process?
1.
2.
3.
4.
5.
What three bones form the hip bone? What
two bones form each pectoral girdle?
In what three ways does the bony pelvis of
a woman differ from that of a man?
What two bones form the skeleton of the
leg?
Bo’s longitudinal and medial arches have
suffered a collapse. What is the name of
Bo’s condition?
Which lower limb bone has an
intertrochanteric line and crest and an
intercondylar fossa?
Review: Did you get it?
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Every bone forms a joint (articulation) with at
least one other bone
◦ Exception = hyoid bone
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Functions of joints:
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Joints are classified by structure and function
Structure classes:
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Function Classes: (Based on type of tissue that
separate the bony regions at the joint
1.
2.
Hold bones together securely
Give the rigid skeleton mobility
◦ Fibrous - immovable
◦ Cartilaginous
◦ Synovial – freely movable
◦ Synarthroses – immovable joints (axial)
◦ Amphiarthroses - slightly moveable (axial)
◦ Diarthroses – freely moveable
Joints
Fibrous Joints
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Example: sutures of
the skull
◦ Bones held in place by
tight CT fibers
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In syndesmoses
joints, the fibesr are
longer allowing more
“give”
◦ Ex: distal ends of the
itbia and fibula
Joint Continued
Cartilaginous Joints
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Bone ends connected
by fibrocartilage
◦ Ex: pubic symphysis
◦ Intervertebral joints
Synovial Joints
 Bone ends are separated by a cavity containing synovial
fluid
 4 features:
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Articular cartilage
Articular capsule
Joint cavity
Reinforcing ligaments
Bursa and tendon sheaths not technically part of joint, but
closely associated
◦ Bags of lubricant which act like viscous ball bearings to reduce
friction between structures during movement
◦ Bursae are flat discs, common where structures rub together
◦ Tendon sheaths are elongated bursa that wrap around tedons like
hotdogs
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Dislocations occur when bones are moved out of their
joint cavity
◦ Reductions are used to set the bones back in place
Joints Continued
Plane (gliding) joints – short slipping/gliding
motions between bones. Motion is nonaxial
 Hinge joint – uniaxial movement. Cylinder end
of one bone fits into the trough of the other bone
 Pivot Joint – Rounded end of one bone fits into
a ring of another bone (or ligaments). Uniaxial
 Condylar joint – egg shaped arciular surface of
one bone fits into an oval cavity on the other.
Allows eliptical movement, biaxial.
 Saddle joints – each bone has a convex and
concave area, works similar to a condylar joint
 Ball and socket joint – multiaxial where
spherical head of one bone fits into a cup-shaped
socket of other bones.
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Joints based on Shape
Joints by shape
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Bursitis
Sprains
Arthritis – broad term for any joint inflammation
Osteoarthritis (OA) – chronic degenerative
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Rheumatoid arthritis (RA) – flare-ups and
remissions.
◦ Wear n’ tear arthritis. Bone spurs develop and “crepitus” may be
heard upon movement
◦ Chronic and autoimmune. The inflamed synovial membrane
thickens into “pannus” which erodes articular cartilages. The
resulting scar tissue eventually ossifies and the bone ends fuse
(ankylosis).
◦ Anti-inflammatory drugs and immunosuppressant drugs often
prescribed. Sometimes joint replacements or bone removal are
necessary
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Gouty arthritis (gout) – needle-shaped deposits
of uric acid form in the soft tissues of the joint
◦ More common in men and likely genetic. Often affects a single
joint and can be destructive if untreated.
Homeostatic imbalance of the joints