Lab 3
SKELETAL SYSTEM
rev 7-11
• Bone or Osseous Tissue
– consists primarily of nonliving extracellular
crystals of calcium minerals
– contains several types of living bone cells,
nerves, and blood vessels
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SKELETAL SYSTEM
Lab 3
Bones perform 5 important functions:
• support-provides a hard framework that supports
the body, attaches the skeletal muscles and cradles
the body’s organs
• movement-supports muscles to allow us to move
• protection-because they are hard and surround
our internal organs, they protect our organs
• formation of blood cells within the marrow cavity
• mineral storage-bones store minerals that are important
to body metabolism and function
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SKELETAL SYSTEM
Lab 3
Bones can be classified into 4 categories based on
shape
• Long--bones of the limbs and fingers
– are longer than they are wide
– consist of a hollow, cylindrical shaft called the
diaphysis and
– an enlarged knob at each end called the
epiphysis
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SKELETAL SYSTEM
Lab 3
• Short--bones of the wrists
– are approximately as wide as they are long
• Flat--including the cranial bones, sternum and ribs
– are thin, flattened and sometimes curved, with a small
amount of spongy bone between 2 layers of compact
bone
• Irregular--hip bones and vertebrae
• include a variety of shapes that don’t fit into the
other categories
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SKELETAL SYSTEM
Lab 3
• All bones contain 2 types of osseous tissue
– a solid, compact tissue which forms the
external layer of bone
– a spongy tissue
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SKELETAL SYSTEM
Lab 3
• Periosteum covers the outer surface of all bones
• is a tough connective tissue consisting of 2 layers
• the outermost layer is dense irregular connective
tissue
– is richly supplied with nerve fibers, lymphatic
vessels and blood vessels which enter the bone
through openings called nutrient foramen
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SKELETAL SYSTEM
Lab 3
– provides insertion or anchoring points for the
tendons and ligaments
– contains specialized bone forming cells
– if the end of a long bone forms a movable joint,
the joint surface is covered by a thin layer of
articular or hyaline cartilage that reduces
friction, cushions the bone ends during joint
movement, and absorbs mechanical stress
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SKELETAL SYSTEM
Lab 3
• The internal part of the bone surface is covered by
endosteum (a delicate connective tissue
membrane)
– this covers the trabeculae in the marrow
cavities of the spongy bone
– lines the canals that pass through compact bone
– contains osteoblasts (bone forming cells) and
osteoclasts (bone resorption cells)
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Long bones
• Compact bone forms the external layer
• central cavity of the shaft of long bones is called
the medullary cavity
– this cavity is filled with red marrow in children
(for RBC production), and with yellow bone
marrow in adults
• yellow marrow is primarily fat which can be
utilized for energy
• Compact bone consists of calcium phosphate laid
in a pattern around the central cavity
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SKELETAL SYSTEM
Lab 3
• Structural Unit of Compact bone is the
– Osteon (or Haversian system) this forms a
pattern of hollow tubes like the growth rings of
a tree trunk
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SKELETAL SYSTEM
Lab 3
• Parts of the Haversian system:
– each ring of bone tissue in the hollow tube is
called a lamellae
– Haversian or Central canal: middle cavity in
a Haversian system. Contains the blood
vessels and nerve fibers
– lacunae: found at the junctions of the lamellae
and is filled with bone cells called osteocytes
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SKELETAL SYSTEM
Lab 3
• canaliculi: thin canals in bone tissue which
connect the lacunae to each other and to the
central canal
– provide a path for nutrients to travel to the osteocytes
and for wastes to be removed
• Volkmann’s canals lie at right angles to the long
axis of the bone and connect the blood and nerve
supply of the periosteum to those in the central
canals and the medullary cavity
– this allows all osteocytes to get nutrients even
though they aren’t near a blood vessel
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Spongy bone
– Is found inside the epiphysis
• spongy bone is less dense than compact bone
allowing the bones to be light but strong
– this helps the bone to withstand mechanical stress
• spongy bone is a honeycomb of hard, strong pieces
called trabeculae
– helps the bone to resist mechanical stress
– the open spaces of the trabeculae are filled with red or
yellow bone marrow
• blood cell formation (hemopoiesis) takes place in
the spongy bone
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SKELETAL SYSTEM
Lab 3
– Contains the epiphyseal plate: line of cartilage where
bone lengthening takes place in childhood
• When bone length growth is completed, the
epiphyseal plate becomes ossified (hardened) and
leaves an epiphyseal line
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SKELETAL SYSTEM
• Skeleton
–
–
–
–
–
–
provides support
protects internal organs
produces blood cells
stores minerals (calcium and phosphate)
stores energy
provides levers to make movement easier
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SKELETAL SYSTEM Lab 3
Skeletal system contains 3 types of connective
tissue
• bone--hard elements of the skeleton
• ligaments--dense fibrous connective tissue that
binds the bones to each other
• cartilage--specialized connective tissue consisting
primarily of fibers of collagen and elastic in a gellike fluid called ground substance
The Skeleton is organized into the (page 39)
• Axial skeleton and the Appendicular skeleton
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SKELETAL SYSTEM
Lab 3
• Axial skeleton
– forms the long axis of the body which supports
the head, neck and trunk
–
–
–
–
–
consists of the
skull,
vertebral column,
ribs and
sternum
**bones of the ear
**hyoid bone (in the throat)
**these bones are also parts of the axial skeleton
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SKELETAL SYSTEM
Lab 3
• The Skull (page 41) includes the bones of the
face, the cranial bones and the jaws
• Frontal bone (forehead)
• Parietal bones (behind the frontal bone, on the top
rear part of the skull)
• Occipital bone (forms the back of the skull)
near the base of this bone is an opening called the foramen
magnum. This is where the vertebral column connects to
the skull and the spinal cord enters the skull to
communicate with the brain
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SKELETAL SYSTEM
Lab 3
• Occipital condyles--2 rounded bumps at the base of
the skull which pivot on the 1st vertebrae (as in
nodding the head to say “yes”)
• Temporal bones (on the lateral [left and right side]
of the skull under the parietal bone)
– each temporal bone has an opening into the ear canal
which allows sound to travel to the eardrum
• Sphenoid bone which forms the back of the eye
sockets
• Ethmoid bone which helps support the nose and
part of the eye socket
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SKELETAL SYSTEM
Lab 3
• Facial bones and jaws-comprise the front of the
skull
– zygomatic bones form the cheeks and the outer part of the
eye sockets
– nasal bones (including the ethmoid) underlie only the
upper bridge of the nose (the rest of the nose is made up of
cartilage and other connective tissue)
– lacrimal bones are the inner part of the eye sockets
» each is pierced by a tiny opening through which the
tear ducts drain
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SKELETAL SYSTEM
Lab 3
– maxillary bones form part of the eye sockets, anchors the
upper row of teeth, and forms part of the upper palate
» upper, immovable, jaw bone is called the maxilla
– Mandible or lower jaw anchors the lower teeth
• Hyoid bone: not really part of the skull; lies inferiorly to the
mandible in the anterior neck
– is the only bone in the body which doesn’t articulate with
another bone
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SKELETAL SYSTEM
Lab 3
• Ear bones
– present in the middle ear and move when air vibrations
bend the eardrum inward
» called the malleus (hammer), incus (anvil) and stapes
(stirrup)
– Several of the cranial and facial bones contain air
spaces which form the sinuses and make the skull
lighter
• Vertebral column or spine
– supports the head, protects the spinal cord and serves as
the attachment for each of our arms and legs and the
body’s muscles
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SKELETAL SYSTEM
Lab 3
– Is a column of 33 vertebrae (irregular bones)
which extends from the skull to the pelvis
– is classified into 5 anatomical regions
•
•
•
•
cervical (neck)-7 vertebrae
thoracic (chest or thorax)- 12 vertebrae
lumbar (lower back)-5 vertebrae
sacral (sacrum/upper pelvic region)- 5 vertebrae
which have fused
• coccygeal (coccyx or tailbone)- 4 fused vertebrae
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SKELETAL SYSTEM Lab 3
– The first cervical vertebrae is called the Atlas
• it articulates with the occipital condyles
– The second cervical vertebrae is called the Axis
• you need to know these names
– vertebrae share 2 points of contact called
articulations
• The spinal cord passes through a canal between the
articulations
– vertebral bodies are separated from each other
by intervertebral disks which serve as shock
absorbers and permit a limited amount of
movement
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SKELETAL SYSTEM
Lab 3
• Ribs and sternum (breastbone)
– protect the chest cavity
– we have 12 pairs of ribs
• the upper 7 pairs, called “true” ribs, attach via
cartilage to the sternum
• “False ribs:
– pairs 8-10 are joined to the 7th rib by cartilage and are
thus indirectly attached to the sternum
– pairs 11 and 12 are called floating ribs because they don’t
attach to the sternum at all.
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SKELETAL SYSTEM
Lab 3
• Appendicular skeleton
• bones which help get us from place to place (locomotion)
and enable us to manipulate our environment
– includes the:
– Pectoral Girdle is a supportive frame for the
upper limbs
• consists of the clavicles and scapulas
– Arms (the humerus, ulna, radius, wrist bones,
the palm [metacarpal bones], and the fingers
[the phalanges])
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SKELETAL SYSTEM Lab 3
– The Pelvic Girdle consists of the 2 pelvic (hip)
bones and the sacrum and coccyx of the
vertebral column
• they meet in front at the pubic symphysis where
cartilage joins the 2 bones
• primary purpose is to support the weight of the
upper body against the force of gravity
• in adult women, the pelvic girdle is
– broader and shallower than in men and
– the pelvic opening is wider/rounder--to allow for
childbirth
– the sacrum is flatter
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SKELETAL SYSTEM
Lab 3
– The leg bones:
•
•
•
•
•
•
•
Femur
Patella
Tibia
Fibula
Tarsals
Metatarsals
Phalanges (toes)
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SKELETAL SYSTEM
Lab 3
• Joints or Articulations
– are sites where 2 or more bones meet
– give our skeleton mobility
– hold the skeleton together
– are the weakest parts of the skeleton
• ligaments and tendons are connective tissues that
stabilize each joint
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SKELETAL SYSTEM
Lab 3
• Joint types
– freely movable, diarthrosis, or synovial -bones are separated by a thin fluid filled
synovial cavity (this type joint is seen in the limbs)
– Types of synovial joints:
• ball and socket--the ball end of one bone fits into
the socket of another bone: shoulder and hip joints
• ovoid--an egg shaped surface of bone fits into a
matching shaped surface on another bone: wrist
joint and forearm bones
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SKELETAL SYSTEM
Lab 3
• Hinge--freely movable: knee and elbow joint
• Pivot--joint spins around an axis: between the atlas
and axis (vertebrae)
• Gliding--nearly flat bone surfaces allow side to side
and back and forth motion: carpals of the wrist and
the tarsals of the ankle
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SKELETAL SYSTEM
Lab 3
• Slightly Movable, Cartilaginous or
Amphiarthrosis Joint --has no synovial cavity
and permit only slight movement (this type joint is mainly
found in the axial skeleton)
– have a pad of fibrocartilage between 2 bones
• Pubic Symphysis (is only moveable during
childbirth)
• intervertebral discs
• sacroiliac
• joint connecting the lower ribs to the sternum
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SKELETAL SYSTEM
Lab 3
• Immovable, Synarthrosis or Fibrous Joints
– flat bones in a baby’s skull
• at birth these bones are separated by space filled
with fibrous connective tissue. These “soft spots”
are called fontanels
– allow the baby’s head to squeeze through the birth canal
– allow for brain growth and development
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REMINDER,
page 1 of 2
:
1. Learn the major bones of the human skeleton(in
bold print in your lab manual and identified in the
diagram, except for the middle ear bones).
– Use the large models as well as those on your
lab desks
2. Look at the adult and infant skull
– You need know what a fontanelle is but you
don’t need to know the individual names
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REMINDER,
page 2 of 2
:
3. Learn the parts of a typical long bone
– study the long bone model which is cut in half
4. Study the male and female pelvis and know their
differences
5. Learn the basic joints on page 45 of your lab
manual.
6. Learn the microscopic structures of bone from the
models not the microscope slides
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