The Skeletal System

The skeletal system includes connective tissues such as
bone, cartilage, tendons, and ligaments. These tissues
are combined with the various types of muscle tissue to
form the Musculo-Skeletal System.
The Musculo-Skeletal System
Osteology
Articular System
Myology
Osteology – a study of the skeleton
The human skeleton
Functions of the Skeletal
System
A. Support
- a framework and structural support for the
whole body
Functions of the Skeletal
System
B. Protection
- enclose delicate and vital organs
Functions of the Skeletal
System
C. Movement
1.
Muscles are attached to bones
2.
Muscles pull bones to produce movement
Functions of the Skeletal
System
 D. Storage
1. Calcium is stored in the bones
2. The skeletal system has an important role in the
homeostatic maintaince of blood calcium levels.
Functions of the Skeletal
System
 E. Hemopoiesis
1. Definition: The process of blood cell formation.
2. Occurs in red bone marrow
Types of Bones

A.


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Long bones
1.
2.
Femur
Humerus
B. Short bones


1.
2.
Tarsals
Carpals
- provide levers for movement
- develop by replacement of
hyaline cartilage
- have structurally distinct
regions
Types of Bones
C. Flat bones
(squamous)
1.
2.
Frontal
Scapula
- generally serve
protective or
reinforcement
functions
- develop by
replacement of
connective tissue
- Diploe – spongy
bone structure
between two plates
of compact bone
(lamina vitrea)
Types of Bones

D.
Irregular bones
- Vertebrae (26 bones)
Types of Bones
• F. Sesamoid bones
o Patella
o Pisiform bone
- develop within
tendon
- change the attrition
of the tendon
- increase the
volume of the
movement
Types of Bones

G.
Pneumatic bones
-bones which contain air
spaces lined with mucous
membrane
-typically skull bones
-make the skull light
-impart resonance to voice
-act as conditioning
chambers for inspired air
Chemical Composition of the
Bones
Osteogenesis imperfecta (OI)
(brittle bone disease, Lobstein syndrome)

deficiency of type I collagen - defective connective tissue (or without
the ability to make it)
Long Bone Structure

1. Diaphysis


2. Medullary
cavity



a. Shaft: made of
hard compact
bone
3.


a. Hollow area
inside diaphysis
b. Contains yellow
bone marrow
(inactive, fatty
marrow)
Epiphyses
a. Ends of long
bone
b. Inside contains
red, spongy bone
marrow
Long Bone Structure

4. Articular Cartilage



5. Periosteum


a. Thin layer of cartilage
cover each epiphyses
(bone ends)
b. Act as a cushion at
the joint
a. Fibrous membrane
covering a long bone
(except the ends)
6. Endosteum

a. Fibrous membrane
lining medullary cavity
Microscopic Structures




1. Compact bone
a.Outer layer of
bone that is hard
and dense
2. Spongy
(trabecular) bone
a. Porous bone in
the end of a long
bone
Compact bone:




Matrix composed of
Osteons or
Haversian systems
Calcium matrix
arranged in rings
Each ring =
concentric lamella
Central canal
contain blood
vessels

Osteocytes = bone cells that lie between lamellae in
space called lacunae
Canaliculi= passageways that connect the lacunae with
each other and the central canal

Blood vessels from
the outer periosteum
enter bone and pass
through the central
canal of an Osteon
(or Haversian Canal).
Nutrients pass from
the blood vessel
through the canaliculi
to the osteocytes.
Bone Growth

Bone begins as cartilage and fibrous
structures in the fetus.



a. Primary center (Punctum ossificatum primum) - middle of long bone
b. Secondary centers (Punctum ossificatum secundum) - in both
epiphyses at ends of long bone
c. Epiphyseal plate - cartilage between epiphysis and diaphysis

Growth will continue
to occur as long as
any cartilage in
epiphyseal plate
remains. An x-ray will
show if any remains.

Epiphyseal line is all
that is left after
growth ceases and
the epiphyseal plate
disappears.
Equilibrium lever
(First Class)
Power lever
(Second Class)
Speed lever
(Third Class)
Anatomic planes
Lateral
Posterior
Medial
Anterior
Lateral
Superior
Inferior
Divisions of the Human Skeleton

Axial division

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
Skull bones
Vertebral column
Appendicular division


Pectoral girdle
Pelvic girdle
Skull bones
Skull bones


a. Cranial bones (7
bones):



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Frontal ( 1 )
Parietals ( 2 )
Temporals ( 2 )
Occipital ( 1 )
Sphenoid ( 1)
Face bones (14
bones):

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
Maxilla ( 2 )
Mandible ( 1 )
Zygomatic ( 2 )
Nasal ( 2 )
Palatine ( 2 )
Lacrimal ( 2 )
Vomer ( 1 )
Inferior choncha ( 2 )
Vertebral column


a. Cervical vertebrae (7)
b. Thoraic vertebrae (12)



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c. Lumbar vertebrae (5 )
d. Sacrum

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True ribs (first 7 pairs of ribs
attached to T-1 through T-7)
False ribs (last 5 pairsof ribs
attached to T-8 through T-12)
Note: True ribs are directly
attached to the sternum and
false ribs are not directly
attached.
(5 bones fused into 1 bone)
e. Coccyx

( found as 3 to 5 separate
vertebrae in a child while in
the adult they are fused into 1
bone)
Pectoral girdle
Pelvic girdle

In a young
child each
coxal bone
consists of
three bones:
ilium,
ischium and
pubis. In
adults they
grow together
into 1 bone.
Endochondral ossification


Punctum ossificatum primum
Punctum ossificatum secundum