Lecture 11 - Musculoskeletal System 1: Bones Flashcards
1
Q
What % of body mass does bone material make up
A
Roughly 20%
2
Q
How many bones are in humans body
A
206
3
Q
The skeletal system consists of: (4)
A
- bones
- cartilage
- joints and articulations
- ligaments
4
Q
What are 6 functions of bone
A
- Support
- Movement
- Protection
- Storage: Growth factors & Minerals
- Storage of energy
- Hematopoiesis
5
Q
How does bone provide support
A
Long bone and antigravity muscles
6
Q
How does bone provide movement
A
Acts as a lever for muscle action
7
Q
How does bone provide protection (examples)
A
Bones of cranium protect brain, vertebrae protect spinal cord, ribs protect lungs etc
8
Q
What are the growth factor and minerals stored in bones
A
Calcium and phosphate, which are essential for nervous and muscle systems
9
Q
What energy source do bones store and in what part of bone
A
They store lipids in the yellow bone marrow
10
Q
What are the types of bone tissue
A
Compact and cancellous (spongy)
11
Q
What are the 4 types of bones
A
Long, short, flat, irregular
12
Q
What is the structure of long bone
A
- longer than wide
- 1 diaphysis, epiphysis
- mostly compact, with some spongy in epiphysis
- role of support
- only type of bone that has medullary cavity
13
Q
Where are some Long bones
A
Arm, forearm, palm, finger, thigh, leg, sole, toes
14
Q
What is the structure of short bone
A
- small, almost cubic
- filled with spongy bone, covered by thin layer of compact bone
15
Q
Where might you find short bone
A
Wrist (carpals), ankles (tarsals)
16
Q
What is the structure of flat bones
A
- Thin, flat, slightly curved
- Filled with spongy bones (diploe), covered by a thick layer of compact bone
- Protection role, large surface for muscle attachment
17
Q
Where would you find flat bones
A
Cranium, sternum, ribs, scapula
18
Q
What is the structure of irregular bone
A
- Complex forms and composition varies
- Spongy bone, fine layer of compact bone
19
Q
Where would you find irregular bone
A
Vertebrae, bones of face, coxal bones
20
Q
What are Sutural bones
A
They are special irregular bones that are between sutures of cranial bones (ex. lambdoid suture at back of head)
21
Q
What are sesamoid bones
A
-Small round bone imbedded in a tendon to help reinforce and decrease stress on that tendon
22
Q
Where are sesamoid bones
A
In the knee / Patella but also in some ppls hands and feet
23
Q
What is diaphysis
A
- Body of a long bone
- Thick cylinder of compact bone with medullary cavity filled with yellow bone marrow
24
Q
What is epiphysis
A
- End of a long bone
- Filled with spongy bone and covered by thin layer of compact bone
- The part that takes part in articulation is covered in articular cartilage (hyaline)
25
What is epiphysals line
- Remnant of epiphyseal cartilage where growth takes place up until end of adolescence (metaphysis)
26
What is periosteum
- Membrane that covers the bone (lacks cartilage)
| - Contains cells important for repair and growth
27
What are 2 layers of periosteum
- Fibrous: external, dense irregular CT, neurofibers, blood and lymphatic vessels
- Osteogenic: internal, osteoblasts & osteoclasts
28
What is endosteum
A membrane that cover:
- Medullary cavity
- Trabeculae
- Canals that cross compact bone
- Osteoblast and osteoclasts
29
What is the diploe sandwiched in between in flat bone
```
An upper and lower layer of compact bone which is covered in periosteum
imagine:
periosteum
compact
diploe
compact
periosteum
```
30
What are 2 components of Bone matrix and %
- Organic 35%
| - inorganic 65%
31
What are the organic specialized cells that make up bone matrix
- osteoblasts (create the matrix)
- osteoclasts (removes deposited mineral)
- Osteocytes (bone forming cells)
32
What are the organic Osteoid (ground substance) that make up bone matrix
- proteoglycans, glycoproteins, chondroitin sulfate, collagen fibers (secreted by osteoblasts)
- leading to flexibility, resistance to pressure and adhesion
33
What is the makeup of inorganic materials that make up bone matrix (%)?
- 10% calcium carbonate
- 5% other minerals (Mg+, Na, SO42-, F-)
- 85% hydroxyapatites (crystals of calcium)
34
Function of inorganic materials in bone matrix
-The salts (hydroxyapatites) are deposited in, on and btw collagen fibers like cement around its brace, to give it hardness, solidity and rigidity
35
what % of bone is compact
80%
36
Where is compact bone
Forms external layer of bone surface and most of diaphysis
37
what is function of compact bone
Support, protection
38
what is functional unit of compact bone
Osteon
| -it is made up of 6-15 lamella/ layers (haversian system)
39
What increases compact bone solidity
Collagen fibers alternate orientation in each layer
40
What runs through central canal (Haversian) and in what direction
Blood, lymphatic vessels and nerves parallel with length of long bone
41
What runs through perforating canal (Volkmann) and in what direction
Blood, lymphatic vessels and nerves and the run perpendicular off central canals and into spongy bone
42
What is between each lamella (layer) of compact bone
A lacuna that contains an osteocyte
43
What do the osteocytes in the lacuna do
Communicate with exterior via canaliculi and btw themselves through projections
-they exchange nutrients via gap junctions
44
What is in between Osteons (osteon = Haversian canals 6-15 lamella (layers) of collagen fibers in circle pattern)
interstitial lamella which are remnants of old osteons
| -they have osteocytes and canaliculi but are not connected to central canals
45
What % of bone is spongy bone
20%
46
Do spongy bones have osteons?
no
47
What forms the trabeculae
Elongated or flattened osteocytes between irregular lamellae made lattice like structure = trabeculae
48
What dictates orientation of the trabeculae
According to the constraints that bone is subjected to and is not haphazard
- develops to be strongest and most shock absorbent it can
49
where do osteocytes in trabeculae of spongy bone get nutrients and blood
from blood that circulates between trabeculae interlinked via the canaliculi
50
what is in the spaces between trabeculae
Red bone marrow (RBM)
51
Where is there red bone marrow
exclusive to long bone epiphysis, hip, rib, thoracic cage, vertebrae, cranium
52
What are osteogenic cells
- from mesenchyme (stem cells)
| - can divide and become osteoblasts
53
What are osteoblasts
- They lose capacity to divide when they transform into osteocytes
- secrete collagen and osteoids
54
What are osteoids
- proteoglycanes
- glycoproteins
- collagen fibers
55
What are osteocytes
- Osteoblast that eventually get covered in matrix and lay down within lacunae
- they do not secrete matrix
- maintain bone tissue and exchange things like waste and nutrients with blood and other cells
56
What are osteoclasts
- Large multi-nucleated cells
- they are macrophages found at surface of bone and they destroy the matrix
- they are essential as they guarantee renewal, growth and repair
57
Bone marrow distribution in newborns
There is very little in the epiphysis of long bone
- most in medullary cavity of long bone
- only red bone marrow
58
Bone marrow distribution in adults
Main bone still contain red bone marrow but some is replaced by yellow mallow
59
What can happen if excess calcium in blood
- cardiac contraction
| - propagation of nerve impulses
60
What is homeostasis of calcium 4
1. Calcium circulation is very closely regulated
2. Calcium is important to many enzymes and blood coagulation
3. Bone serves as a calcium reserve ( release and absorb as needed)
4. Important hormones act on calcium
61
What are the 2 important hormones acting on calcium for homeostasis
```
Parathyroid hormone (PTH)
Calcitonin
```
62
What is parathyroid hormone
Hormone released from chief cells of the parathyroid gland when calcium is low
63
What does PTH do
- Stimulates activities and reproduction of osteoclasts
- increases kidney absorption of calcium from urine
- if there is an increase in vitamin D it increases absorption of calcium from intestines
64
Where does Calcitonin come from
Secreted by paraflocular cells of the thyroid
65
What does Calcitonin do
- Released when calcium concentration is high
- inhibits osteoclast activities
- stimulates calcium deposition by osteoblasts
66
What is ossification
The process of bone formation
67
Why does bone grown in width during a lifetime
1. For remodeling
| 2. consolidation of bones, making them stronger
68
When do bones stop growing
Never, it is a continuous process throughout life
69
What is the skeleton formed of at 6th week of gestation
1. Fibrous membranes
| 2. Hyaline cartilage
70
What are 2 types of ossification processes that occur at 8 weeks of gestation
1. Intramembranous ossification
| 2. Endochondral ossification
71
What is intramembranous ossification
- From fibrous membranes
- Give rise to intramembranous bone
- Most of the cranial bones, clavicles, and flat bones
72
What is endochondral ossification
- From hyaline cartilage models
- Give rise to endochondral bone
- Majority of the skeletal bones
73
What is the formation of a ossification center in intramembranous ossification
- The inside of the fibrous CT membrane
| - Mesenchymal cell aggregate and differentiate into osteoblasts
74
What is the secretion of the matrix in intramembranous ossification
- osteoblasts secrete the osteoid that is calcified in a few days
- osteoblasts become trapped in the lacunae and will become osteocytes
75
What is the formation of spongy bone in intramembranous ossification
- osteoid is deposited btw embryonic blood vessels
| - forms network of trabeculae that trap the blood vessels
76
What is the formation of periosteum in intramembranous ossification
- Mesenchymal cells join the surface of the bone and differentiate into layers:
1. External layer
2. Internal layer - osteogenic cells
77
What is formation of compact bone in intramembranous ossification
-Compact bone (external)and osteogenic layer of the periosteum (internal)
78
Why is endochondral ossification a complex process
Because hyaline cartilage must be broken down as the bone ossification process proceeds
79
The modeling of Hyaline cartilage primary center ossification
1. Primary center ossification
| - perichondrium is penetrated by blood vessels that transform it into the periosteum
80
The modeling of Hyaline cartilage formation of a bone collar
2. Formation of bone collar around the diaphysis
| - mesenchymal cells of the periosteum differentiate into osteoblasts that secrete a cylinder of osteoid
81
The modeling of Hyaline cartilage: calcification of the cartilage in the center of the diaphysis and formation of the bone cavity
- chondrocytes expand & burst, which modifies PH levels
- Calcification of the matrix
- when calcified, there are no nutrient exchange
- chondrocytes die
- Matrix disintegrates
- Bone cavity is formed
82
The modeling of Hyaline cartilage: penetration of the cavities by the periosteal bud and formation of the spongy bone
-New osteoblasts secrete osteoid on the cartilage fragment which form the trabeculae of spongy bone
83
The periosteal bud contains
The periosteal bud contains nutrient artery and vein, lymphatic connections, neurofibers, red bone marrow elements, osteoblasts, osteoclasts
84
The modeling of Hyaline cartilage: formation of medullary cavity and the initiation of secondary ossification centers in the epiphysis
- process of enlarging and shedding of ossification center
| - Osteoclasts break down the new spongy bone which forms the medullary cavity (center of the diaphysis)
85
The modeling of Hyaline cartilage: ossification of the epiphysis occurs before or right after birth
These are 2nd ossification center in the epiphysis and happens similar to diaphysis process
86
Process of ossification of epiphysis
Cartilage calcifies - matrix breaks down - obtain cavity - periosteal bud enters matrix or cavity - new osteoblasts secrete osteoid - create trabeculae with spongy bone
87
Distinction between formation of diaphysis and epiphysis
Epiphysis has no bone collar or medullary cavity
88
Final product of ossification of epiphysis
- articular cartilage at the surface of the epiphysis
| - epiphyseal plate cartilage (the junction between the epiphysis and diaphysis)
89
What is the first formed bone called and what does it develop into
Called woven bone and develops into lamellar bone
90
What are primary osteons replaced by
They are demineralized areas around blood vessel, they grow from out to in; and are eventually replaced by secondary osteons
91
Why is bone remodeling important
For homeostasis, let's bone grow in size and shape
92
what is in constant flux after bone growth complete
Ossification and reabsorption (but total size does not change)
93
Where does bone gain and loss occur
Gain from outer surface, loss from within
94
what remodels trabeculae
Mechanical stress remodels it to better withstand stress
| -higher stress = narrower tube for new osteon
95
When is ossification faster and when is reabsorption faster
Youth has more ossification
| after 40 more reabsorption
96
Bone mass is influenced by:
Stress
| -muscle tension, gravity
97
Stress on bone mass stimulates
- bone regeneration
- narrowing of osteons
- calcitonin (inhibit bone reabsorption)
- ossification
98
People who have low bone mass:
- live in weightlessness for long times
| - Are bedridden
99
What does intense exercise cause to bones
Reinforcement of bones
100
Bones of the arm
```
Scapula
humerus
radius (thumb)
ulna(elbow)
olecranon (the elbow joint)
```
101
Rib bones
7 true ribs
3 to 5 false ribs
floating ribs
total = 12 to 14 ribs
102
Bones of sternum
Manubrium (connects to clavicle)
Body
Xiphoid process (bottom of sternum)
103
Parts of spine
- intervertebral disk
- body(where bulk force goes)
- transverse process
- spinous process
104
Where are the atlas and axis in spinal column
Cervical spine c1 and c2
105
Bones of pelvic girdle
- sacrum
- coccyx
- illium
- ischium
- pubic symphysis
- acetabulum
106
Bones of the hand
- metacarpals (in palm_
- carpals (8 bones in wrist)
- phalanges (fingers)
107
Bones of wrist / carpals
- trapezium
- trapezoid
- scaphoid
- hamate
- capitate
- pisiform
- triquetrum
- lunate
108
What are 3 parts of phalanges
- distal
- middle
- proximal
109
What are 3 parts of metacarpals and what's the 1st metacarpal
-head
-shaft
-base
1st is thumb
110
bones of legs
- pelvis
- hip joint
- femur
- patella
- fibula
- tibia
111
Bones of foot
- talus (accepts weight from tib/fib)
- calcaneus (heel)
- tarsal
- metatarsals
- digits/ phalanges
112
name the tarsals (5)
```
Cuboid
Navicular
Medial cuneiform
Lateral cuneiform
intermediate cuneiform
```
113
what is first metatasal in foot
big toe
114
parts of toe digits
- proximal phalanx
- middle phalanx
- distal phalanx
