CH 6/7 A&P
Describe bone remodeling.
-Bone remodeling refers to the process whereby old bone is continuously being destroyed by osteoclasts while new bone is being constructed by osteoblasts. -turnover rate of bone is high: in young adults almost 1/5 of the skeleton is recycled and replaced each year
bone structure
-Epiphysis- end of a long bone -Metaphysis- neck of the bone, region between epiphysis and diaphysis, narrow zone -Diaphysis-shaft of long bone (long part)
openings:
-Sinus: Chamber within a bone, normally filled with air -Foramen: Rounded passageway for blood vessels and/or nerves -Fissure: Deep furrow, cleft, or slit -Meatus: Passage or channel, especially the opening of a canal -Canal: Duct or channel
characteristics of bone:
-The matrix of bone is very dense due to deposits of calcium salts around the protein fibers. -The matrix contains bone cells, or osteocytes, within pockets called lacunae. (The same term is used for the spaces that chondrocytes occupy in cartilage p. 136. The lacunae of bone are typically organized around blood vessels that branch through the bony matrix. -Canaliculi, narrow passageways through the matrix, extend between the lacunae and nearby blood vessels, forming a branching network through which osteocytes exchange nutrients, wastes, and gases. -Except at joints, a periosteum covers the outer surfaces of bones. It consists of an outer fibrous layer and an inner cellular layer.
manubrium
-articulates with the clavicles (collarbones) and the cartilages of the first pair of ribs. -broad, triangular
the vertebral column
-cervical (c1-c7) -thoracic (t1-t12) -lumbar (l1-l5) -sacrum, fused area (s1-s5) -coccyx
axial skeleton: the skull and functions
-cranial bones: protect brain -facial bones: protect entrances to digestive and respiratory tract
thoracic cage
-function: protect heart and lungs, attaches to skeletal muscles -sternum: jugular notch, manubrium, sternal angle, body of sternum, xiphoid process -rib cage: 1-7 true ribs (attached directly to sternum. 8-12 false ribs (attached to 7 rib so indirectly attached to the sternum) 11 and 12 are floating ribs +remember: all floating ribs are false ribs but not all false ribs are floating ribs
sacrum
-fused area -very strong, connects your upper to lower body -can identify a skeletons sex by the curvature, more curved=male
coccyx
-makes up last portion of the vertebral column -controls your ability to voluntarily defecate
ossification
-process of bone formation -occurs in two ways: endochondral and intramembranous. In endochondral ossification, bone replaces existing cartilage. Then bone growth occurs through interstitial growth (in length) and appositional growth (in width). In intramembranous ossification, bone develops directly from mesenchyme (loosely organized embryonic connective tissue) or fibrous connective tissue.
projections
-process: projection or bump -ramus: part of a bone that forms an angle with the rest of the structure
sacrum
-protects the reproductive, digestive, and urinary organs. -fused vertebrae
cervical vertebrae
-support skull, stabilize relative positions of brain and spinal cord, and allow controlled head movement
thoracic vertebrae
-support weight of head, neck, upper limbs, and chest; articulate with ribs to allow changes in volume and thoracic cage
lumbar vertebrae
-support weight of head, neck, upper limbs, and trunk
Bone shape categories
-sutural bones: or Wormian bones, are small, flat, irregularly shaped bones between the flat bones of the skull -irregular bones: compex shapes ex. vertebrae and bones of the pelvis -short bones: boxy with equal dimensions -flat bones: thin parallel surfaces which produce a flattened shape -long bones: relatively long and slender, consisting of a shaft with two ends that are wider that the shaft -sesamoid bones: usually small, round and flat and shaped somewhat like a sesame seed. Tend to develop with tendons
cervical vertebrae
-thin and small -contain many areas for protecting blood vessels that travel to and from the brain -c1: atlas -c2: axis
Projections where muscles, tendons and ligaments attach
-trochanter: large, rough projection -crest: prominent ridge -spine: pointed process -line: low ridge -tubercle: small, rounded projection -tuberosity: rough projection
Define fontanelle, and identify the major fontanelles
A fontanelle is a relatively soft, flexible, fibrous region between two flat bones in the developing skull. The major fontanelles are the anterior fontanelle, posterior fontanelle, sphenoidal fontanelles, and mastoid fontanelles.
At which point in fracture repair would you find an external callus?
An external callus forms early in the healing process, when cells from the endosteum and periosteum migrate to the area of the fracture. These cells form an enlarged collar (external callus) that encircles the bone in the area of the fracture.
Which three types of bone cells are developmentally related and what is their progression from the earliest to the latest stage?
An osteogenic cell divides to produce osteoblasts. Osteoblasts become osteocytes when they are completely surrounded by bone matrix.
If the activity of osteoclasts exceeds the activity of osteoblasts in a bone, how will the mass of the bone be affected?
Because osteoclasts break down or demineralize bone, the bone would have a decreased mineral content (less mass); as a result, it would also be weaker.
What purpose does a fontanelle serve?
Because they are not ossified at birth, fontanelles permit the skull to change shape during childbirth, and they allow for enlargement of the brain during infancy and early childhood.
Define bone markings.
Bone markings (surface features) are characteristics of a bone's surface that have specific functions, such as joint formation, muscle attachment, or the passage of nerves and blood vessels.
Compare the structures and functions of compact bone and spongy bone.
Compact bone consists of osteons (Haversian systems) with little space between them. Compact bone lies over spongy bone and makes up most of the diaphysis. It functions to protect, support, and resist stress. Spongy bone consists of trabeculae with numerous red marrow-filled spaces. Spongy bone makes up most of the structure of short, flat, and irregular bones and is also found at the epiphyses of long bones. Spongy bone functions in storing marrow and providing some support.
During intramembranous ossification, which type of tissue is replaced by bone?
During intramembranous ossification, fibrous connective tissue is replaced by bone.
Describe false ribs.
False ribs (ribs 8-12) are the five lower ribs on either side that do not articulate with the sternum directly.
A child who enters puberty several years later than the average age is generally taller than average as an adult. Why?
Growth continues throughout childhood. At puberty, a growth spurt takes place and is followed by the closure of the epiphyseal cartilages. The later puberty begins, the taller the child will be when the growth spurt begins, so the taller the person will be when growth is completed.
compact bone
Hard and dense, but not solid, bone tissue that is beneath the outer membrane of a bone. forms a sturdy protective layer that surrounds a central space called the medullary cavity (medulla, innermost part), or marrow cavity.
How would the compressive strength of a bone be affected if its ratio of collagen to hydroxyapatite increased?
If the ratio of collagen to hydroxyapatite in a bone increased, the bone would become less strong (as well as more flexible).
List the four steps involved in fracture repair, beginning at the onset of the bone break
Immediately following a fracture, extensive bleeding occurs at the injury site. After several hours, a large blood clot called a fracture hematoma develops. Next, an internal callus forms as a network of spongy bone unites the inner edges, and an external callus of cartilage and bone stabilizes the outer edges. The cartilaginous external callus is eventually replaced by bone, and the struts of new spongy bone now unite the broken ends. With time, the swelling that initially marks the location of the fracture is remodeled, new compact bone is formed, and there is little evidence that a break occurred.
Improper administration of cardiopulmonary resuscitation (CPR) can result in a fracture of which bones?
Improper compression of the chest during CPR can—and commonly does—result in a fracture of the xiphoid process of the sternum or the ribs.
In endochondral ossification, what is the original source of osteoblasts?
In endochondral ossification, cells of the inner layer of the perichondrium differentiate into osteoblasts, and a cartilage model is gradually replaced by bone.
Where is spongy bone found in long bones? Where is spongy bone found in flat bones?
In long bones, spongy bone is found in the epiphyses. In flat bones, spongy bone is found between two layers of compact bone.
A 7-year-old child has a pituitary gland tumor involving the cells that secrete growth hormone (GH), resulting in an increased level of GH. How will this condition affect the child's growth?
Increased levels of growth hormone prior to puberty will result in excessive bone growth, making the child taller.
What are the three ways in which lamellae are organized in compact bone?
Lamellae are organized concentrically around an osteon, interstitially between osteons, and circumferentially around the entire bone.
spongy bone
Layer of bone tissue having many small spaces and found just inside the layer of compact bone. consists of an open network of struts and plates that resembles a three-dimensional garden lattice.
How could x-rays of the femur be used to determine whether a person has reached full height?
Long bones of the body, such as the femur, have an epiphyseal cartilage, a plate of cartilage that separates the epiphysis from the diaphysis so long as the bone is still growing lengthwise. An x-ray would indicate whether the epiphyseal cartilage is still present. If it is, growth is still occurring. If it is not, the bone has reached its adult length and, thus, the person has reached full height.
Name the major functions of the skeletal system
Major functions of the skeletal system are support, storage of minerals and lipids, blood cell production, protection, and leverage
Mature bone cells are known as ___, bone-building cells are called ___, and ___ are bone-resorbing cells.
Mature bone cells are known as osteocytes, bone-building cells are called osteoblasts, and osteoclasts are bone-resorbing cells.
Explain the role of PTH and the interaction between PTH and calcitriol on blood calcium ion level.
Parathyroid hormone (PTH) indirectly stimulates osteoclasts to release calcium ions from bone and enhances calcitriol's effect on the intestinalabsorption of calcium. Increased PTH secretion would result in an increase in the level of calcium ions in the blood.
Identify the facial bones.
The 14 facial bones include 2 inferior nasal conchae, 2 lacrimal bones, 1 mandible, 2 maxillae (maxillary bones), 2 nasal bones, 2 palatine bones, 1 vomer, and 2 zygomatic bones.
List the components of the vertebral column
The adult vertebral column consists of 26 bones: the vertebrae (24), the sacrum (1), and the coccyx
Why does the vertebral column of an adult have fewer vertebrae than that of a newborn?
The adult vertebral column has fewer vertebrae than a newborn because, in an adult, the five sacral vertebrae fuse to form a single sacrum, and the four coccygeal vertebrae fuse to form a single coccyx.
Identify the bones of the axial skeleton.
The axial skeleton includes the skull (8 cranial bones and 14 facial bones), the bones associated with the skull (6 auditory ossicles and the hyoid bone), the thoracic cage (the sternum and 24 ribs), and the vertebral column (24 vertebrae, the sacrum, and the coccyx).
List the primary functions of the axial skeleton
The axial skeleton serves as a framework that supports and protects organs, provides an extensive surface area for muscle attachment, and stabilizes and positions parts of the appendicular skeleton that support the limbs.
Joe suffered a hairline fracture (fracture without separation of the fragments) at the base of the dens. Which bone is fractured, and where is it located?
The axis is fractured. The dens is a tooth-like process projecting upward from the body of the axis, or second cervical vertebra, which is located in the neck (cervical region).
Why are the bodies of the lumbar vertebrae larger than those of the cervical and thoracic vertebrae?
The bodies of the lumbar vertebrae are larger because they must support a great deal more weight than do vertebrae that are more superior in the spinal column. The larger vertebral bodies allow the weight to be distributed over a larger area.
Identify the bones of the nasal complex
The bones forming the nasal complex are the frontal, ethmoid, nasal, maxilla, palatine, and sphenoid.
Identify the bones of the orbital complex
The bones forming the orbital complex are the frontal, sphenoid, zygomatic, palatine, maxilla, lacrimal, and ethmoid
Why does a child who has rickets have difficulty walking?
The bones of children who have rickets are poorly mineralized and as a result are quite flexible. Under the weight of the body, the leg bones bend. The instability makes walking difficult and can lead to other problems of the legs and feet.
Identify the categories used for classifying a bone according to shape.
The different broad categories for classifying bones according to shape are sutural bones, irregular bones, short bones, flat bones, long bones, and sesamoid bones.
In which bone is the foramen magnum located?
The foramen magnum is located in the base of the occipital bone.
Name the foramina found in the ethmoid bone.
The foramina in the ethmoid are the olfactory foramina.
Name the fontanelles found on the infant skull. Why aren't they labeled on the adult skull?
The infant skull has six fontanelles: sphenoidal (paired), mastoid (paired), anterior, and posterior. As the skull develops, bones ossify and fuse. In an adult skull, all of the bones are complete and fused, so there aren't any fontanelles on the adult skull
Why would you expect the arm bones of a weight lifter to be thicker and heavier than those of a jogger?
The larger arm muscles of the weight lifter would apply more mechanical stress to the bones of the upper limbs. In response to that stress, the bones would grow thicker.
Which two pairs of ribs are the floating ribs? What distinguishes them from the other false ribs?
The last two pairs of ribs (11 and 12) are the floating ribs and do not attach to the sternum. The other false ribs are indirectly attached to the sternum by costal cartilage.
Identify the bone containing the mental foramen, and list the structures using this passageway.
The mental foramen is found in the mandible. Structures passing through this opening include the mental nerve, which carries sensory information to the brain, and mental vessels, which supply the chin and lips.
Identify the bone containing the optic canal, and cite the structures using this passageway.
The optic canal is found in the sphenoid. The optic nerve and ophthalmic artery pass through this structure.
What gland responds when the blood calcium level is too low?
The parathyroid gland secretes parathyroid hormone when the blood calcium level is too low.
The (endosteum/periosteum) covers the superficial layer of compact bone and is made up of (the fibrous and cellular layers/osteoblasts, osteoclasts, and osteocytes).
The periosteum covers the superficial layer of compact bone and is made up of the fibrous and cellular layers.
A sample of long bone has lamellae, which are not arranged in osteons. Is the sample most likely taken from the epiphysis or diaphysis?
The presence of lamellae that are not arranged in osteons is indicative of spongy bone, which is located in an epiphysis.
Examining a human vertebra, you notice that, in addition to the large foramen for the spinal cord, two smaller foramina are on either side of the bone in the region of the transverse processes. From which region of the vertebral column is this vertebra?
The presence of transverse foramina indicates that this vertebra is from the cervical region of the vertebral column. These foramina are passageways for important blood vessels that supply the brain.
What is the importance of the secondary curves of the spine?
The secondary curves of the spine allow us to balance our body weight on our lower limbs with minimal muscular effort. Without the secondary curves, we would not be able to stand upright for extended periods.
Looking at all the views of the skull, name the major sutures.
The skull contains four major sutures: the sagittal suture, the lambdoid suture, the squamous suture, and the coronal suture.
Which bone contains the depression called the sella turcica? What is located in this depression?
The sphenoid contains the sella turcica, which in turn contains the pituitary gland.
Identify the bones containing the paranasal sinuses
The sphenoid, ethmoid, frontal, and paired palatine and maxillary bones contain the paranasal sinuses
Which two regions of the spine form primary curves?
The thoracic and the sacral regions of the spine form primary curves.
axis
This joint permits rotation (as when you shake your head to indicate "no"). C2
collagen fibers to bone matrix
To understand the relationship of collagen fibers to bone matrix, think about the reinforcing steel rods (rebar) in concrete. Like the rebar in concrete, collagen adds tensional strength and flexibility to bone.
tomás suffers a hit to the skull that fractures the right superior lateral surface of his cranium. Which bone is fractured?
Tomás has fractured his right parietal bone.
What are the main differences between true ribs and floating ribs?
True ribs (ribs 1-7) attach directly to the sternum by separate costal cartilages; floating ribs (ribs 11-12) are the two lower ribs on either side that are not attached anteriorly to the sternum.
bone tissue
a supporting connective tissue with a solid matrix and is ensheathed by a periosteum.
medullary cavity
cavity within the shaft of the long bones filled with bone marrow
atlas
cervical vertebra C1, holds up the head. It articulates with the occipital condyles of the skull.
foramen magnum
connects the cranial cavity with the vertebral canal, which is enclosed by the vertebral column. This foramen surrounds the connection between the brain and spinal cord.
why do bones have bumps?
for muscle attachment
why do bones have holes?
for nerves and blood vessels to pass through
Explain how heavy-metal ions could be incorporated into bone matrix.
he biochemistry of some heavy-metal ions, such as strontium, cobalt, uranium, and plutonium, is very similar to that of calcium. Osteoblasts cannot differentiate these heavy-metal ions from normal calcium ions, so the heavy-metal ions become incorporated into the bone matrix. Over time, these dangerous ions can be released into the bloodstream during normal bone remodeling.
jugular foramen
lies between the occipital bone and the temporal bone. The internal jugular vein passes through this foramen, carrying venous blood from the brain.
calcification
process that hardens bones by adding calcium phosphate and collagen
components of the axial skeleton
skull, vertebral column, thoracic cage (sternum and ribs)
function of axial skeleton
supports body, protects organs, provides a skeletal muscle attachment
the vertebral column function
supports entire body, allows for muscle attachment, protect the within spinal cord
hyoid bone
supports the larynx (voicebox) and is the attachment site for muscles of the larynx, pharynx, and tongue
the temple and the mandible create _____?
temporomandibular joint
lumbar vertebrae
the largest vertebrae, support majority of your weight
occipital condyles
the sites of articulation between the skull and the first vertebra of the neck
hypoglossal canals
begin at the lateral base of each occipital condyle and end on the inner surface of the occipital bone near the foramen magnum. The hypoglossal nerves, cranial nerves that control the tongue muscles, pass through these canals