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Exercise 8
Overview of the Skeleton
Two Skeletal Divisions
 Axial skeleton
 Bones around the body’s “axis” or center of
gravity
 Skull, vertebrae, thoracic cage
 Appendicular skeleton
 Bones of the limbs or “appendages” & how
they attach to the axis (scapulae and coxal
bones)
Figure 8.1 The human skeleton.
Cranium
Skull
Facial bones
Bones of
pectoral
girdle
Clavicle
Thoracic cage
(ribs and
sternum)
Scapula
Upper
limb
Sternum
Rib
Humerus
Vertebra
Vertebral
column
Radius
Ulna
Ilium
Bones
of
pelvic
girdle
Carpals
Ischium
Pubis
Phalanges
Metacarpals
Femur
Patella
Lower
limb
Tibia
Fibula
Talus
Tarsals
Metatarsals
Phalanges
Anterior view
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Calcaneus
Posterior view
CARTILAGE LOCATIONS
 Hyaline cartilage  Elastic cartilage  Fibrocartilage



Most skeletal
cartilages
Sturdy support with
some “give”
Costal cartilage
(ribs), nose, articular
cartilage, larynx,
trachea, branches
into lungs (bronchi)
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


More flexible
Tolerates repeated
bending
External ear,
epiglottis



Very strong
Handles heavy
compression
Intervertebral discs,
pubic symphysis,
meniscus (knee)
Figure 8.2 Cartilages in the adult skeleton and body.
Epiglottis
Thyroid
cartilage
Cartilage in
external ear
Cartilages in
nose
Larynx
Cricoid
cartilage
Trachea
Lung
Articular
cartilage
of a joint
Cartilage
in intervertebral
disc
Costal
cartilage
Respiratory
tube cartilages
in neck and thorax
Bones of skeleton
Pubic
symphysis
Cartilages
Axial skeleton
Hyaline cartilages
Appendicular skeleton
Elastic cartilages
Fibrocartilages
Meniscus (padlike
cartilage in
knee joint)
Articular cartilage
of a joint
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Types of bones: Texture
 Compact bone
Looks smooth &
homogenous
 Hard, dense
 Protective
exterior of ALL
bones

Fig. 6-2
Types of bones: Texture
 Cancellous/
Spongy bone
Deep to the
compact bone
 Porous: bars
of bone and
open spaces

 Most bones
have both types
Fig. 6-2
Figure 8.3b The structure of a long bone (humerus of the arm).
Articular
cartilage
Compact bone
Spongy bone
Types of bones: Shape
 Long bones
Longer than wide
 Femur, humerus,
radius, ulna,
fibula, tibia, …
 Most of upper &
lower extremity
bones

Fig. 6-1
Types of bones: Shape
 Short bones
~cube-shaped
 Carpals, tarsals
(wrist, ankle
bones)

Fig. 6-1
Types of bones: Shape
 Flat bones
Broad surface for
muscle
attachment or
protection of
underlying organs
 Many cranial
bones, ribs,
pectoral girdle
(shoulders)

Fig. 6-1
Types of bones: Shape
 Irregular bones
Other bones
 Varied shapes
 Vertebrae, some
skull bones

Fig. 6-1
Long Bone Anatomy
 Epiphysis

ends
 Diaphysis

Shaft (middle)
 Medullary cavity

Marrow cavity,
interior of the
shaft
Fig. 6-2
Long Bone Anatomy
 Red bone marrow
In adults:
 found in porous chambers of
spongy bone, in epiphyses
 In infants:
 found in medullary cavity
 Production of WBCs, RBCs, platelets

Long Bone Anatomy
 Yellow bone marrow
Contains large amounts of yellow fat
 In medullary cavity of adults

Articular
cartilage
Long Bone Anatomy
 Articular cartilage


Thin hyaline cartilage cap to each
epiphysis
Facilitates joint movement
 Fibrous periosteum



Dense regular connective tissue
(fibrous membrane)
Covers surface of bone EXCEPT
where there’s articular cartilage
Tendon/muscle attachment
Periosteum
Microscopic Bone Structure
 Osteon

Central canal
and all the
concentric
rings
(lamellae)
surrounding
it
Osteon
Compact bone
Spongy bone
(Haversian system)
Periosteum
Central Canal
Parallel to
long axis of
bone
 Center of
osteon
 Blood
vessels,
nerves,
lymph
vessels

Central
(Haversian) canal
Lamella (plural, lamellae)
 Rings of
matrix of
the osteon
 Around
the central
canal
Circumferential
lamellae
Lamellae
Lacuna (plural, lacunae)
 Spaces within the matrix, between
the lamellae
 Contain osteocytes
Vein
Nerve
Artery
Lamellae
Canaliculus
Osteocyte
in a lacuna
Central
canal
Lacunae
Osteocytes
 Mature bone cells
 Within the lacunae
Vein
Nerve
Artery
Lamellae
Canaliculus
Osteocyte
in a lacuna
Central
canal
Lacunae
Canaliculus (pl, canaliculi)
 Tiny channels connecting lacunae
 Nutrient diffusion
Vein
Nerve
Artery
Lamellae
Canaliculus
Osteocyte
in a lacuna
Central
canal
Lacunae
Figure 8.4c Microscopic structure of compact bone.
Interstitial
lamellae
Lacuna
(with osteocyte)
Osteocyte vs Chondrocyte
 Osteocyte = “bone” “cell”
 Chondrocyte = “cartilage” “cell”
 Each type is “housed” in the lacunae
of the respective tissue (bone,
cartilage)
Figure 8.5 Growth in length of a long bone occurs at the epiphyseal plate.
Resting zone
1 Proliferation zone
Cartilage cells undergo
mitosis.
2 Hypertrophic zone
Older cartilage
cells enlarge.
Calcified
cartilage
spicule
Osteoblast
depositing
bone matrix
Osseous
tissue (bone)
covering
cartilage
spicules
3 Calcification zone
Matrix calcifies; cartilage cells die;
matrix begins deteriorating; blood
vessels invade cavity.
4 Ossification zone
New bone forms.
Table 8.1 Bone Markings
Review Figure 8.1
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Review Figure 8.1a
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Review Figure 8.1b
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Review Figure 8.1c
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Review Figure 8.2
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