Class Notes (Summary) for Skeletal and Muscular System
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Course
Anatomy and Physiology
Institution
University Of Santo Tomas
Book
The Skeletal and Muscular Systems
The text discusses the skeletal and muscular systems in detail. Some key points:
The skeletal system includes bones and cartilage that provide structure, support, movement, and protection. Bones have different classifications based on shape: long, short, flat, and irregular. Bones are composed o...
Skeletal System - Articular Cartilage: covers the external
surface of epiphyses, decreases friction
Functions of the Bones - Epiphyseal Plate: flat plate of hyaline
cartilage that can be seen in a young, growing
- Support: forms the internal framework that bone (allows lengthwise growth of bone)
supports the body and cradles its soft organs - Epiphyseal Line: remnant of epiphyseal plate,
- Protection: protect soft body organs marks previous location of epiphyseal plate
(lengthwise growth is done)
- Movement: skeletal muscles are attached to
bones by tendons, and use bones as levers to - Endosteum: delicate connective tissue lining
move the body and its parts that covers the inner body surface of the
shaft
- Storage: fat is stored in the internal cavities
of bones - Medullary Cavity: shaft cavity that stores o
(marrow) Adults: adipose (fat) tissue/yellow marrow o
Infants: red bone marrow
- Blood Cell Formation: hematopoiesis occurs
within the marrow - Bone Markings: reveal where muscles
tendons and ligaments were attached and
Classifications of the Bones where blood vessels and nerves passed o (T)
Processes/Projections: grow out from bone
Compact: dense, smooth, homogenous surface
Spongy: small needle-like pieces of bone o (F) Depressions/Cavities: indentation of
the
- Long: has a shaft, heads on both ends bone
- Short: cube shaped, mostly spongy bone o
Sesamoid: form within tendons (e.g. patella)
- Flat: 2 thin layers of compact, layer of spongy
bone in between
- Irregular: do not fit above categories (e.g.
vertebrae
& hip bones)
Structure of the Bone
Gross Anatomy of a Long Bone
- Diaphysis: shaft that makes up the bone’s Microscopic Anatomy
length - Osteon/Haversian System: complex
- Periosteum: fibrous connective tissue that consisting of central canal and matric rings
covers & protects the diaphysis - Central Canals: run lengthwise through the
- Sharpey’s fibers: secures periosteum to the bony matrix
underlying bone - Lamellae: made up of lacunae
- Epiphyses: ends of the long bone, thin layer - Lacunae: where osteocytes are found
of compact bone encloses area filled with - Canaliculi: radiate outward from central
spongy bone canals to lacunae, form a transportation
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, system that connects all bones cells to the Bone Remodeling
nutrient supply through the hard bone matrix - Bones are remodeled continually in response
- Volkmann’s Canals: communication pathway to 2 factors:
from the outside of the bone to its interior o Calcium levels in the blood o Pull of
gravity and muscles on the skeleton -
Hypocalcemia: parathyroid glands will
release PTH into the blood, which
activate osteoclasts to break down
bone matrix and release calcium ions to
the blood
- Hypercalcemia: calcium is deposited in bone
matrix as hard calcium salts
- Bone remodeling is essential to retain normal
proportions and strength during long bone
growth as the body increases in size and
Bone Formation, Growth, and Remodeling weight
- Bones of bedridden or physically inactive
Bone Formation & Growth people tend to lose mass and are subject to
- Ossification: bone formation o Hyaline atrophy because they are no longer subjected
cartilage is completely covered by bone to stress
matrix by osteoblasts
o Enclosed hyaline cartilage model is Homeostatic Imbalance 5.1:
digested Rickets:
away by osteoclasts, opening up a - disease in children where bones fail to calcify,
medullary cavity within the newly formed bone - bones soften, weight bearing bones of the
Appositional Growth: legs show definite bowing
o Osteoblasts in the periosteum add - due to lack of calcium in diet or lack in
bone tissue to the external face of the vitamin D
diaphysis (which is needed for calcium absorption)
o Osteoclasts remove bone from the
inner face of the diaphysis wall Bone Fractures
o Occurs at the same time!!! Fracture: break in the bone
- Closed (simple): bones breaks cleanly, does
not penetrate skin
- Open (compound): broken bone penetrates
through skin
- Comminuted: many fragments
- Compression: bone is crushed
- Depressed: broken bone is pressed inwards
- Impacted: broken bone ends are forced into
each other
- Spiral: ragged break occur when excessive
twisting forces are applied to bone
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, - Greenstick: bone breaks incompletely, much form fibrocartilage callus (contains
in the way a green twig breaks cartilage matrix, bony matrix, and
collagen fibers)
o acts to splint the broken bone, closing
the
gap
- Bony Callus Forms
o osteoblasts & osteoclasts migrate to
the area and multiply
o fibrocartilage is gradually replaced by
the
bony callus made of spongy bone
- Bone Remodeling Occurs
o over the next few weeks to months,
bony callus is remodeled in response
to the mechanical stresses place on it
o forms strong permanent patch at the
fracture site
Axial Skeleton
Skull
Reduction: realignment of broken ends - made of cranium & facial bones
- Closed Reduction: bone ends are coaxed back - connected by sutures (interlocking,
into their normal position by the physicians immovable joints)
hands - only mandible is attached by freely moving
- Open Reduction: surgery is performed, and joint
bone ends are secured together with pins or
wires
- After bone ends are reduced, it is immobilized
by a cast or traction to allow healing process
to begin
Bone Fracture Repair (Major
Events) - Hematoma Forms:
o blood vessels are ruptured when bone
breaks so blood-filled swelling forms
o bone cells deprived of nutrition die - - Cranium
Fibrocartilage Callus Forms: o encloses and protects the fragile brain
tissue o composed of 8 large flat,
o growth of new capillaries into the
clotted blood single bones except for two paired
o disposal of dead tissue through bones (parietal & temporal)
phagocytes o connective tissue cells
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