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The Skeletal System's functions are:
- -Support
- -Calcium & Phosphorus Storage
- -Marrow Cavities- blood cell production
- -Protection
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Has 2 Bone Forms:
1. Compact Bone
2. Spongy Bone
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Compact Bone:
- -Osteon (ring structures)
- -Central canal- parallel to bone
- -Lamellae rings
- -Lacuna with osteocytes inside them
- -Canaliculi
- -Perforating canals- running perpendicular to bone
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Spongy Bone:
- -Also formed from Lamellae
- -Found at the end of the bone- Epiphysis (head of the bone)
- -Shaft of the bone is called- Diaphysis
- -Red Marrow is where blood cell production occurs
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Facts about the bone:
- -Prior to 6 weeks, there's no bone- its cartilage. Continues to age 25yr
- -Loss of bone mass at age 30
- -Bone loss in women can be up to 8% per decade
- -Men lose up to 3% per decade
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Bone is classified based on shape:
- 1. Long Bones- longer in length then width
- 2. Flat Bones- thin; narrow; flat
- 3. Sutural Bones/Wormian Bones- sutures
- 4. Irregular Bones- random odd shapes; vertebra
- 5. Short Bones- cuboidal shaped; make up carpals/tarsal bones, like the wrist/ankle
- 6. Sesamoid Bone- form where you have joints; small/round; example is the patella-almost everyone has, but also can be found in some in the ankles and wrist
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AXIAL Skeleton:
- -80 Bones
- -Found along midline of body
- -Make up skull-cranium & facial
- -Vertebral column
- -Thoracic cage
- -Hyoid Bone- found in the neck (ligament); not connected to any other bone
- -Ear ossicles- malleus, incus, stapes--these are the smallest in the body, found in the ear structure
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APPENDICULAR Skeleton:
- -Remaining 126 bones
- -Associated with appendages
- -Includes:
- 1. Pectoral Girdle-or shoulder girdle; consists of S shaped clavicle, and broad flat scapula-shoulder blade.
- 2. Pelvic Girdle- support and protect the lower viscera, including reproductive organs; bones are more massive then Pectoral Girdle due to the stress in weight bearing and locomotion.
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Structures in Skull:
-8 Bones make up the cranium
- -Has 4 Suture Lines:
- 1. Sagittal Suture- between parietals
2. Coronal Suture- separates frontal from parietal
3. Lambdoid Suture- separates occip. from parietals
4. Squamous Suture- separates parietal from temperal
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Sphenoid Bone
- -Butterfly shaped
- -Contacts all other Cranial Bones
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Sella Turcica Bone:
-(Saddle- looking) pituitary gland--aka the master gland
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Ethmoid Bone:
- -Most secretive
- -Hard to see
- -Tucked away
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How many bones make up the Eye Socket?
- 7 Bones
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How many bones make up the Vertebral Column?
- 26 Bones
- -Protects spinal cord
- -Broken up into different regions
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How many Bones make up the Cervical Region (neck)?
- 7
- -C1- Atlas; holds up; flat; allows to move head in the "yes" motion (aka. the YES bone)
- -C2- Axis; allows head to move in the "no" position (aka. the NO bone)
- -C7- vertebra prominens; sticks out; can feel it on the back of neck; ligamentum nuchae
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How many Bones make up the Thoracic Region? (main back)
- - 12 vertebra
- - Rib artiulations
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How many Bones make up the Lumbar Region? ( lower back)
- 5
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How many Bones make up the Sacrum Region?
- 1 single bone-- actually 5 bones fussed together, only counted as 1
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How many Bones in the Coccyx?
- 1 bone; actually 3-5 bones fussed together, only counted as 1
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How many Rib Bones?
-12
- -1 to 7- are true ribs
- -8 to 10- are false ribs
- -11 to 12- are floating ribs; not connected to sternum
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Clavicle Bone:
-the Clavicle (collarbone) is the ONLY direct connection between the Axil skeleton, and the Pectoral Girdle.
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