Skeletal System Flashcards
1
Q
Why is the skeletal system important?
A
Provides a strong framework for the protection and support of the remainder of the systems, organs, and tissues.
2
Q
How are bird bones different from the bones of other animals?
A
They are evolved to enhance the ability of the birds to fly.
3
Q
What modifications have been made that allow the birds to fly?
A
- Pneumatic bones where the air sacs are connected with cavities in some of the long bones.
- Fusion of some vertebral sections to provide rigidity.
- Sternum provides a large surface area for strong attachment of the main muscles used for flight.
- Significant reduction in the size of the head.
- Long neck.
4
Q
What does a long neck allow for?
A
- Protection of delicate tissues of the brain from too much jarring when landing. Neck acts as a shock absorber.
- The bird can reach food located on the ground. Rigid body makes this difficult.
- Allows the bird to adjust its center of gravity when changing from walking/perching to flying.
5
Q
What is the tail of a bird called and why?
A
- Pygostyle.
- It is a short section of fused vertebrae.
6
Q
How many pairs of ribs do birds have?
A
7.
7
Q
How many pairs of ribs reach the sternum?
A
2-3, depends*.
*Sometimes the seventh pair does not reach the sternum.
8
Q
What are the 2 segments in the third through sixth pair of ribs?
A
- Sternal segment.
- Vertebral segment.
9
Q
How have the ribs been modified to strengthen them?
A
The inclusion of a uncinate process.
10
Q
What is the uncinate process?
A
A rearward projection of bone, with the process projecting over the outer surface of the next rib through a connection by a ligament.
*Strengthens the thoracic cavity
11
Q
Which rib pairs have uncinate processes?
A
Second through fifth.
12
Q
How many separate bones are in the vertebral column of birds?
A
39 bones divided into 5 sections.
13
Q
How many bones are in the cervical section?
A
13.
14
Q
How many bones are in the thoracic section?
A
7.
15
Q
What do all thoracic vertebrae except the last one have?
A
Large ventral process for the attachment of muscles.
16
Q
How many bones are in the lumbar and sacral sections COMBINED?
A
14.
17
Q
Which lumbar vertebrae are fused?
A
Second through fifth.
18
Q
How many bones are in the coccygeal section?
A
5.
19
Q
What bones are difficult to separate?
A
T7, All of L, All of S, and C1 because of their fusion for strength.
20
Q
What is the atlas?
A
The first bone in the cervical vertebrae.
21
Q
How is the atlas described?
A
- Ring-like.
- Small.
- Has a deep cavity for articulating with a condyle (projection) at the base of the skull.
22
Q
What is the atlas/epistropheus?
A
The second bone in the cervical vertebrae.
23
Q
How is the axis described?
A
- Short.
- Projects cranially into the atlas.
- Possesses the dens, a small process that allows for articulation with the occipital condyle.
24
Q
What motion does the axis allow for?
A
The head to turn on the neck or side-to-side.
25
What is the shape of the sternum/breastbone?
Quadrilateral, curved plate.
*Processes project from each angle.
26
What is the metasternum/caudal medial projection/keel bone?
The longest sternum projection that carries the sternal crest that runs from front to back on the ventral surface.
27
What muscles are attached to the keel bone?
1. Subcontractors.
2. Pectoralis.
28
What are the two regions of the skull?
1. Conical facial region.
2. Rounded cranium.
29
What does the conical facial region possess?
2 large orbitals, where the eyes would be.
30
What two bones separate the orbitals?
1. Ethmoid.
2. Sphenoid.
*Form the septum.
31
Why does the cranium's external appearance suggest that the brain is larger than it actually is?
Due to being formed by 2 layers of dense bone separated by a layer of very spongy bone.
32
What does the spongy bone contain?
Pockets of air derived from eustachian tubes that connect the inner ear to upper respiratory tract.
33
Where are the eardrums located?
In large, hemispherical cavities at the rear of the skull called tympanic cavities.
34
How does the spinal cord directly connect with the brain?
Through an opening at the base of the cranium.
35
How do the carotid arteries and jugular veins enter the skull?
Through openings in each lateral part of the occipital bone.
36
Where do the optic nerves enter the cranial cavity?
One common opening.
37
Where is the hyoid bone found?
Beneath the skull, floating bone.
38
What does the hyoid bone form the framework for?
The tongue.
39
What are the 3 major sections of the tongue?
1. Entoglossal.
2. Basi-hyal.
3.
40
Where is the entoglossal found?
Within the tongue.
41
How is the entoglossal connected to the basi-hyal?
Through a moveable joint.
42
What type of animals have similar forelimbs to birds?
Theropod dinosaurs.
43
What types of limbs do birds have?
Pentadactyl limbs modified for the purpose of specialized feeding and flight.
44
What are the two parts of the wing skeleton divided into?
1. Shoulder girdle.
2. Wing.
45
What are the 3 parts of the shoulder girdle?
1. Scapula.
2. Clavicle.
3. Coracoid.
46
What are the 3 parts of the wing?
1. Upper arm or humerus.
2. Forearm or radius and ulna.
3. The hand or manus (carpus, metacarpus, digits).
47
How is the scapula described?
1. Narrow.
2. Thin.
3. Slightly curved.
48
What is located at the cranial end of the scapula-coracoid cavity?
The head of the humerus.
49
What is the strongest bone of the shoulder girdle?
The coracoid.
50
What does the medial end of the coracoid have?
A flattened articular surface that fits into the sternum and a foramen for the connection of the clavicular air sac.
51
What is located at the lateral end of the coracoid?
A connection with the clavicle.
52
What is the clavicle described as?
1. Thin.
2. Rod-like.
3. Bent.
53
What parts of the clavicle are connected to the coracoid bone?
The dorsal portion.
54
What does the opposite end of clavicle attach to?
The one from the other wing to form the wishbone.
55
What are the combined clavicles called?
The furcula.
56
What does the furcula act as?
A spring and a firm base of support for the wing.
57
What does the opening formed by the scapula, clavicle, and coracoid provide a passage for?
The tendon that connect the humerus to the supracoracoideus muscle.
58
What is the humerus described as?
1. Large.
2. Long.
3. Ovid head.
4. Pneumatic bone.
59
What does the ovid head of the humerus allow for?
Articulation with the scapula, coracoid, and clavicle.
60
What air sac is the humerus connected to?
The clavicular.
61
Which bone of the forearm is longer and thicker?
The ulna.
62
Where does the radius lay relative to the ulna?
Lateral.
63
What is the large space between the radius and ulna called?
The interosseous space.
64
What two bones make up the carpus?
1. Radial.
2. Ulnar.
*Represent the mammalian row of carpal bones.
65
Where did the distal row disappear to?
It fused with the metacarpus in the embryo. Now are cartilaginous nodules.
66
How many bones make up the metacarpus?
1 bone (Fusion of 3 in theropod limbs).
67
What has the fusion of metacarpals led to?
A reduced number of digits (5 to 3).
68
What is unique about the hipbone in birds?
1. They are fused to the vertebral column.
2. No ventral union between the two hipbones.
3. No independent tarsus.
69
What are the two major parts of the leg?
1. Pelvic girdle or hip bone.
2. The leg.
70
What are the 3 parts of the pelvic girdle or hip bone?
1. Ilium.
2. Ischium.
3. Pubis.
71
What are the 3 parts of the leg?
1. Thighbone or femur.
2. Pes or foot (tarsus, metatarsus, and digits or toes).
3. Tibia and fibula.
72
What is the deep concavity formed by the joining of the ilium, ischium, and pubis?
The acetabulum, which the head of the femur fits into.
73
What is the ileum fused to?
The last sacral, lumbar, and thoracic vertebrae.
74
Why is the ileum fused to those vertebrae?
To provide strength and rigidity.
75
What bone is the ischium continuous with?
The ileum.
76
What is the pubis?
A narrow strip of bone running along the border of the ischium (briefly).
77
What structure does the pubis form?
The pins via the projection of its free posterior end slightly backwards beyond the ischium.
78
What nerve runs through the area formed by the ileum, ischium, and pubis?
The sciatic nerve.
79
How is the femur described?
1. Long.
2. Thick.
80
What does the proximal end of the femur possess?
A prominent head that articulates loosely with the acetabulum.
81
What does the distal end of the femur possess?
A deep, pulley-shaped surface with two convex condyles that articulate with the patella and lower leg bones to form the knee joint.
82
Which bone is longer: the tibia or the fibula?
The tibia.
83
Which end of the tibia is thicker: the proximal or distal end?
The proximal end.
84
What fused to the distal end of the tibia?
The proximal row of tarsal bones.
85
How is the fibula described?
A slender spicule with a flattened proximal head that attaches to the proximal head of the tibia.
86
What is the metatarsus bone a fusion of?
The second, third, and fourth metatarsal bones.
87
What do male chickens have on their feet that females do not?
A small conical projection on the medial side that supports the spur.
88
What is the digit arrangement on the feet of fowl?
3 facing forward, 1 facing backward.
*Some have 5.
89
What is the synsacrum?
The collective name for the fused 7 sacral and 6 caudal vertebrae.
90
What is bone structure affected by?
The stress put on it.
91
What does bone mainly consist of?
Phosphorous and calcium in the form of hydroxy-apatite crystals in a matrix.
92
What cells are responsible for depositing new bone?
Osteoblasts.
93
What cells are responsible for resorbing existing bone?
Osteoclasts.
94
What cells help maintain bone structure?
Osteocytes.
95
What percentage of the calcium in the body is stored in the skeleton?
99%.
96
What percentage of the phosphorous in the body is stored in the skeleton?
80%.
97
Other than changes in the amount of phosphorus and calcium, what other factors change the microstructure of bone?
1. The level of vitamin D in the diet.
2. The level of PTH, GH, estrogenic hormone, androgenic hormone, and calcitonin.
98
At what two stage are poultry most susceptible to vitamin D deficiency?
When young and if they lay eggs.
99
What is vitamin D deficiency typically seen as and why?
A calcium deficiency, because vitamin D is need for the absorption and utilization of calcium.
100
What 2 forms is vitamin D found in?
1. D2-Ergocalciferol.
2. D3-Cholecalciferol.
101
Which form of vitamin D is more active?
D3, 10 times more active.
102
What is ergosterol?
A compound under the skin of animal that is converted to Vitamin D by sunlight.
103
What is the first stage of bone development?
Prechondral or membranous.
104
What is the second stage of bone development?
Chondral or cartilaginous.
105
What is the third stage of bone development?
Ossification.
106
When does the membranous stage take place in poultry?
In the egg during the embryo stage.
107
What cells bring about cartilage formation?
Chondroblasts.
108
What is the main mineral taken up during ossification?
Calcium carbonate.
109
What bones increase in length during ossification?
Long bones.
110
How are bones formed in birds?
Successive layers that form dense, compact bone covered by the periosteum.
111
What is unique about long bones in birds?
They act as connections of the air sacs.
112
What do Haversian canals carry?
Blood vessels and nerve fibers.
113
What surrounds Haversian canals?
Bone plates that contain lacunae in between them.
114
What is found in each lacunae?
Osteocytes.
115
How do nutrients reach the osteocytes?
Nutrients from the blood vessels diffuses into canaliculi that connect lacunae.
116
What is unique about the bone structure of female poultry?
They lay down highly unstable secondary bone in marrow cavities during reproduction called medullary bone.
117
What purpose does medullary bone serve?
It acts as a ready supply of calcium for eggshells.
118
Why is medullary bone formed?
Laying hens cannot absorb enough calcium through their intestinal wall in one day to meet the requirement for producing an egg shell.
119
When does medullary bone start to form?
10-14 days before the first egg is laid due to estrogen and androgen levels from sexual maturation.
120
What happens to the egg shell if the calcium requirement is not met?
The egg shell is weak and thin.
121
When should a pullet flock be changed from a grower diet to a layer diet?
2 weeks before egg production starts.
122
What happens if pullets enter production too young?
1. Depleted body reserves of calcium.
2. Thinner egg shells/drop in production.
123
What condition is associated with layers housed in laying cages?
Cage layer fatigue, a form of paralysis accompanied by osteoporosis.
124
How is cage layer fatigue corrected?
Placing them on the floor for a short period.
125
What is a weaker egg shell in an older hen a result of?
Loss of shell gland efficiency.
