SKELETAL SYSTEM ▪ Short bones
p 160, 164, 170, 171, 174, 175, 185, 187, 192 ▪ Cube shaped
Intro ▪ Contain mostly spongy bone
• Skeleton: dried up body ▪ Bones of wrist and ankle
• For protection and motion ▪ Patella
• Axial skeleton: longitudinal axis of the body ▪ Sesamoid bones: form tendons
• Appendicular skeleton: bones of the limbs and girdles are appended (attached) to axial skeleton ▪ Flat bones
• Includes joints, cartilages, ligaments ▪ Thin, flatted, and usually curved
• Joints give body flexibility ▪ Two thin layers of compact bone sandwiching a layer of spongy b
Bones: Overview ▪ Skull (cranium), scapula, sternum
▪ Irregular bones
• Functions
o Support ▪ Do not fit any of the categories
▪ Form internal framework that supports body and cradles organs ▪ Vertebrae, which make up the spinal column
▪ Bones of legs support body runk ▪ Pelvis
▪ Rib cage supports thoracic wall ▪ Sacrum, mandible, facial bones, rib bones
o Protection • Structure of Bone
▪ Protect soft body organs o Long bone or diaphysis or shaft makes up most of bone’s length and is composed of
▪ Fused skull bones provide snug enclosure for the brain ▪ Covered by fibrous connective tissue membrane or periosteum
▪ Vertebrae surrounds spinal cord ▪ Perforating or Sharpey’s fiber secure periosteum to the underlying bone
▪ Rib cage protects organs of thorax o Epiphyses are the ends of the long bones
o Movement ▪ Consists of a thin layer of compact bone enclosing an area filled with spongy
▪ Skeletal muscles are attached to bones by tendons spongy bone.
▪ Bones are used as lever to move body ▪ Articular cartilage covers external surface of epiphyses (permanent)
o Storage ▪ It is glassy hyaline cartilage
▪ Fat is stored in internal (marrow) cavities of bones. ▪ Provides smooth slippery surface
▪ Storehouse for minerals (Ca and P) ▪ decrease friction at joint surface (between bones)
▪ Most of body’s Ca is stored as Ca2+ ▪ Epipyseal line (permanent) is a remnant of the epipyseal plate (flat hyaline
▪ Must be present in blood for the nervous system to transmit messages for muscles young, growing bone
to contract ▪ The plates cause lengthwise growth of a long bone
o Blood cell formation ▪ By the end of puberty, when hormones inhibit long bone growth, e
▪ Hematopoiesis occurs within the cavities of certain bones have been completely replaced by bone, leaving only the epiphys
o Endosteum covers inner bony surafce of the shaft
• Classification of bones
o Adult skeleton is composed of 206 bones ▪ Delicate connective tissue lining
o Pisiform bone: size and shape of a pea ▪ Shaft is a storage area of adipose tissue
o Femur/thigh bone: 2 ft long and has a large, ball-shaped head ▪ Called the yellow marrow or medullary cavity— where hematop
o Osseous ▪ Cavity inside the shaft
▪ Compact bone (cortical) ▪ In infants, this forms RBCs and red marrow is found here
▪ Dense, smooth, homogenous ▪ In adults, red marrow is confined to cavities in the spongy bone o
▪ Spongy bone (cancellous, trabecular) epiphysis of some long bones
▪ Composed of small needlelike pieces of bone and open spaces o Bone markings
▪ Long bones ▪ Bone surfaces are not smooth
▪ Longer than they are wide ▪ Scarred with bumps, holes, and ridges
▪ Have a shaft with heads at both ends ▪ Reveal where musles, tendons, and ligaments wereattached
▪ Mostly compact bone ▪ Where blood vessels and nerves passed
▪ All bones of the limbs (except patella, wrist, and ankle bones) are long bones ▪ Projections/processes: grow out from bone surface
▪ Humerus, femur, tibia, fibula, radius, ulna, clavicle, metatarsals, metacarpals, ▪ Terms often begin in T
phallenges ▪ Depressions/cavities: indentations in the bones
▪ Necessary weight bearing ▪ Terms often begin with F
, ▪ Microscopic Anatomy ▪ These processes occur simuntaneously, ensuring that
▪ Spongy bone: spiky, open appearance circumference of the long bone expands and widens
▪ Compact bone: dense ▪ Appositional growth: process by which bones grow i
▪ Osteocytes: mature bone cells. Found within the matrix in lacunae Controlled by hormones—growth hormone (anterior pi
▪ Lacunae: tiny cavities. Aranged in cocentric circles called lamellae around gland) and sex hormones. Ends during adolescence,
central (Harvesian) canals. plated are completely converted to bone.
▪ Osteon/ Harvesian system: each complex consisting of central canal and matrix ▪ Bone growth and remodeling happen alternatively
ring. Run lengthwise through bony matrix. Carry blood vessels and nerves to all ▪ Epiphyseal plates are converted to bone during adolescence
areas of the bone ▪ Growth in length ends
▪ Canaliculi: tiny canals. Radiate outward from central canal to all lacunae. Form a o Bone Remodeling
transportation system that connects all the bone cells to nutrient supply through ▪ Regulate bone marow in producing RBC
hard bone matrix. ▪ Bone is an active and dynamic tissue
▪ Bone cells are well noursihed in spite of hardness of matrix ▪ Bones are remodelled in response to changes in:
▪ Bone injuries heal quickly and well ▪ Ca levels in the blood
▪ The communication pathway from outside of the bone to its interior is completed ▪ When blood Ca levels drop, the parathyroid galnds are
by perforating (Volkmann’s) canals which run in the compact bone at right release parathyroid hormone (PTH) into the blood.
angles to the shaft ▪ PTH activates osteoclasts, bone-destroying cells, to b
o Bone is one of the hardest materials in the body matrix and release Ca ions into blood
o It is relatively light but has a remarkable ability to resist tension and other forces acting on it ▪ When blood Ca levels are too high (hypercalcemia) Ca
o The calcium salts deposited in the matrix give bone its hardness, which resist compression bone matrix as hard Ca salts
o The organic parts (collagen fibers) provide for bone;s flexibility and great tensile strength ▪ Pull of gravity and muscles on the skeleton
• Bone Formation, Growth, and Remodeling ▪ Essential if bones are to retain normal proportions and strength during long-b
o Bone Formation and Growth ▪ Accounts for the fact that bones become thicker and form large projections to
▪ The skeleton is formed from cartilage and bone, the strongest and most supportive tissues in strength in areas where bulky muscles are attached.
the body. ▪ At such sites, osteoblasts lay down new matrix and become tra
▪ In embryos, the skeleton is made of hyaline cartilage. Replaced by bone in the young child. it. (Once they are trapped, they become osteocytes, or mature b
▪ Occurs on hyaline cartilage models or fibrous membranes ▪ In contrast, the bones of bedridden or physically inactive people tend to lose
▪ Cartilage remians in bridge of nose, parts of ribs, joints. atrophy because they are no longer subjected to stress.
▪ Except for flats bones, which form on fibrous membranes, most bones develop using hyaline ▪ Ca uptake and release and bone remodeling work together
cartilage structures as their models. ▪ PTH determines when bone is to be broken down or formed in res
▪ Bone formation or ossification involves two major phases levels in blood
▪ Osteoblast ▪ The stresses of muscle pull and gravity determine where bone ma
▪ The hyaline cartilage model in covered with bone matrix (bone collar) by broken down or fomed
osteoblasts, bone forming cells. ▪ Ensures that skeleton can remain as strong and vital a
▪ The fetus has cartilage bones encodlosed the bony bones ▪ Rickets: disease of children which the bones fail to calcify. Bones dogten and
▪ The enclosed hyaline cartilage model is digested away, opening up a medullary bones of legs show definite bowing. Due to lack of Ca or vit. D. Milk, bread, a
cavity within the newly formed bone food to avoid. Can happen to infants nursed by mothers who are vit. D defici
▪ By birth, most hyaline cartilage models have been converted to bone except for • Bone Fractures
the articular cartilages (cover bone ends) and epiphyseal plates o Low mass but strong
▪ New cartilage is formed continuously on the external face of the articular cartilage o Susceptible to fractures
and on the epiphyseal plate surface that faces the bone end (is farther away from ▪ During youth, most fractures results from exceptional trauma that twists or s
the medullary cavity). bones. In old age, bones thin and weaken, and fractures occur more often.
▪ Enclosed hyaline cartilage is digested, opening up a medullary cavity ▪ Closed/simple fracture: when the bone breaks cleanly but does not penetrate
▪ The old cartilage abutting the internal face of the articular cartilage and the ▪ Open/compoud fracture: when the broken bone ends penetrate through the s
medullary cavity is broken down and replaced by bony matrix o A fracture is treated by reduction, the realignment of the broken bone ends
▪ Growing bones also widen as they lengthen ▪ Closed reduction: bone ends are coaxed back into their normal position by p
▪ Osteoblasts in the periosteum add bone tissue to the external face of Non-invasive.
the diaphysis ▪ Open reduction: surgery is performed. Bone ends are secured together with
▪ cells called osteoclasts in the endosteum remove bones from inner face Invasive.
of diaphysis wall
p 160, 164, 170, 171, 174, 175, 185, 187, 192 ▪ Cube shaped
Intro ▪ Contain mostly spongy bone
• Skeleton: dried up body ▪ Bones of wrist and ankle
• For protection and motion ▪ Patella
• Axial skeleton: longitudinal axis of the body ▪ Sesamoid bones: form tendons
• Appendicular skeleton: bones of the limbs and girdles are appended (attached) to axial skeleton ▪ Flat bones
• Includes joints, cartilages, ligaments ▪ Thin, flatted, and usually curved
• Joints give body flexibility ▪ Two thin layers of compact bone sandwiching a layer of spongy b
Bones: Overview ▪ Skull (cranium), scapula, sternum
▪ Irregular bones
• Functions
o Support ▪ Do not fit any of the categories
▪ Form internal framework that supports body and cradles organs ▪ Vertebrae, which make up the spinal column
▪ Bones of legs support body runk ▪ Pelvis
▪ Rib cage supports thoracic wall ▪ Sacrum, mandible, facial bones, rib bones
o Protection • Structure of Bone
▪ Protect soft body organs o Long bone or diaphysis or shaft makes up most of bone’s length and is composed of
▪ Fused skull bones provide snug enclosure for the brain ▪ Covered by fibrous connective tissue membrane or periosteum
▪ Vertebrae surrounds spinal cord ▪ Perforating or Sharpey’s fiber secure periosteum to the underlying bone
▪ Rib cage protects organs of thorax o Epiphyses are the ends of the long bones
o Movement ▪ Consists of a thin layer of compact bone enclosing an area filled with spongy
▪ Skeletal muscles are attached to bones by tendons spongy bone.
▪ Bones are used as lever to move body ▪ Articular cartilage covers external surface of epiphyses (permanent)
o Storage ▪ It is glassy hyaline cartilage
▪ Fat is stored in internal (marrow) cavities of bones. ▪ Provides smooth slippery surface
▪ Storehouse for minerals (Ca and P) ▪ decrease friction at joint surface (between bones)
▪ Most of body’s Ca is stored as Ca2+ ▪ Epipyseal line (permanent) is a remnant of the epipyseal plate (flat hyaline
▪ Must be present in blood for the nervous system to transmit messages for muscles young, growing bone
to contract ▪ The plates cause lengthwise growth of a long bone
o Blood cell formation ▪ By the end of puberty, when hormones inhibit long bone growth, e
▪ Hematopoiesis occurs within the cavities of certain bones have been completely replaced by bone, leaving only the epiphys
o Endosteum covers inner bony surafce of the shaft
• Classification of bones
o Adult skeleton is composed of 206 bones ▪ Delicate connective tissue lining
o Pisiform bone: size and shape of a pea ▪ Shaft is a storage area of adipose tissue
o Femur/thigh bone: 2 ft long and has a large, ball-shaped head ▪ Called the yellow marrow or medullary cavity— where hematop
o Osseous ▪ Cavity inside the shaft
▪ Compact bone (cortical) ▪ In infants, this forms RBCs and red marrow is found here
▪ Dense, smooth, homogenous ▪ In adults, red marrow is confined to cavities in the spongy bone o
▪ Spongy bone (cancellous, trabecular) epiphysis of some long bones
▪ Composed of small needlelike pieces of bone and open spaces o Bone markings
▪ Long bones ▪ Bone surfaces are not smooth
▪ Longer than they are wide ▪ Scarred with bumps, holes, and ridges
▪ Have a shaft with heads at both ends ▪ Reveal where musles, tendons, and ligaments wereattached
▪ Mostly compact bone ▪ Where blood vessels and nerves passed
▪ All bones of the limbs (except patella, wrist, and ankle bones) are long bones ▪ Projections/processes: grow out from bone surface
▪ Humerus, femur, tibia, fibula, radius, ulna, clavicle, metatarsals, metacarpals, ▪ Terms often begin in T
phallenges ▪ Depressions/cavities: indentations in the bones
▪ Necessary weight bearing ▪ Terms often begin with F
, ▪ Microscopic Anatomy ▪ These processes occur simuntaneously, ensuring that
▪ Spongy bone: spiky, open appearance circumference of the long bone expands and widens
▪ Compact bone: dense ▪ Appositional growth: process by which bones grow i
▪ Osteocytes: mature bone cells. Found within the matrix in lacunae Controlled by hormones—growth hormone (anterior pi
▪ Lacunae: tiny cavities. Aranged in cocentric circles called lamellae around gland) and sex hormones. Ends during adolescence,
central (Harvesian) canals. plated are completely converted to bone.
▪ Osteon/ Harvesian system: each complex consisting of central canal and matrix ▪ Bone growth and remodeling happen alternatively
ring. Run lengthwise through bony matrix. Carry blood vessels and nerves to all ▪ Epiphyseal plates are converted to bone during adolescence
areas of the bone ▪ Growth in length ends
▪ Canaliculi: tiny canals. Radiate outward from central canal to all lacunae. Form a o Bone Remodeling
transportation system that connects all the bone cells to nutrient supply through ▪ Regulate bone marow in producing RBC
hard bone matrix. ▪ Bone is an active and dynamic tissue
▪ Bone cells are well noursihed in spite of hardness of matrix ▪ Bones are remodelled in response to changes in:
▪ Bone injuries heal quickly and well ▪ Ca levels in the blood
▪ The communication pathway from outside of the bone to its interior is completed ▪ When blood Ca levels drop, the parathyroid galnds are
by perforating (Volkmann’s) canals which run in the compact bone at right release parathyroid hormone (PTH) into the blood.
angles to the shaft ▪ PTH activates osteoclasts, bone-destroying cells, to b
o Bone is one of the hardest materials in the body matrix and release Ca ions into blood
o It is relatively light but has a remarkable ability to resist tension and other forces acting on it ▪ When blood Ca levels are too high (hypercalcemia) Ca
o The calcium salts deposited in the matrix give bone its hardness, which resist compression bone matrix as hard Ca salts
o The organic parts (collagen fibers) provide for bone;s flexibility and great tensile strength ▪ Pull of gravity and muscles on the skeleton
• Bone Formation, Growth, and Remodeling ▪ Essential if bones are to retain normal proportions and strength during long-b
o Bone Formation and Growth ▪ Accounts for the fact that bones become thicker and form large projections to
▪ The skeleton is formed from cartilage and bone, the strongest and most supportive tissues in strength in areas where bulky muscles are attached.
the body. ▪ At such sites, osteoblasts lay down new matrix and become tra
▪ In embryos, the skeleton is made of hyaline cartilage. Replaced by bone in the young child. it. (Once they are trapped, they become osteocytes, or mature b
▪ Occurs on hyaline cartilage models or fibrous membranes ▪ In contrast, the bones of bedridden or physically inactive people tend to lose
▪ Cartilage remians in bridge of nose, parts of ribs, joints. atrophy because they are no longer subjected to stress.
▪ Except for flats bones, which form on fibrous membranes, most bones develop using hyaline ▪ Ca uptake and release and bone remodeling work together
cartilage structures as their models. ▪ PTH determines when bone is to be broken down or formed in res
▪ Bone formation or ossification involves two major phases levels in blood
▪ Osteoblast ▪ The stresses of muscle pull and gravity determine where bone ma
▪ The hyaline cartilage model in covered with bone matrix (bone collar) by broken down or fomed
osteoblasts, bone forming cells. ▪ Ensures that skeleton can remain as strong and vital a
▪ The fetus has cartilage bones encodlosed the bony bones ▪ Rickets: disease of children which the bones fail to calcify. Bones dogten and
▪ The enclosed hyaline cartilage model is digested away, opening up a medullary bones of legs show definite bowing. Due to lack of Ca or vit. D. Milk, bread, a
cavity within the newly formed bone food to avoid. Can happen to infants nursed by mothers who are vit. D defici
▪ By birth, most hyaline cartilage models have been converted to bone except for • Bone Fractures
the articular cartilages (cover bone ends) and epiphyseal plates o Low mass but strong
▪ New cartilage is formed continuously on the external face of the articular cartilage o Susceptible to fractures
and on the epiphyseal plate surface that faces the bone end (is farther away from ▪ During youth, most fractures results from exceptional trauma that twists or s
the medullary cavity). bones. In old age, bones thin and weaken, and fractures occur more often.
▪ Enclosed hyaline cartilage is digested, opening up a medullary cavity ▪ Closed/simple fracture: when the bone breaks cleanly but does not penetrate
▪ The old cartilage abutting the internal face of the articular cartilage and the ▪ Open/compoud fracture: when the broken bone ends penetrate through the s
medullary cavity is broken down and replaced by bony matrix o A fracture is treated by reduction, the realignment of the broken bone ends
▪ Growing bones also widen as they lengthen ▪ Closed reduction: bone ends are coaxed back into their normal position by p
▪ Osteoblasts in the periosteum add bone tissue to the external face of Non-invasive.
the diaphysis ▪ Open reduction: surgery is performed. Bone ends are secured together with
▪ cells called osteoclasts in the endosteum remove bones from inner face Invasive.
of diaphysis wall
