Anatomy Exam #2

What is the organ of the skeletal system?

Bones

What kind of tissues are bones composed of?

Bone tissue, cartilage, dense connective tissue, blood and nervous tissue

What are some functions of bones?

Support and protect softer tissues

Provide points of attachment for muscles

House blood-producing cells

Store inorganic salts

What is the structure of skeletal cartilages?

All contain chondrocytes in lacunae and extracellular matrix

What do bones vary in?

Size and shape

What are features all bones have in common?

Structure (gross anatomy, microscopic, chem comp)

Development

Function

What are the four types of bone shapes?

Long, short, flat, irregular

What are the two types of bone textures?

Compact and spongey

What is the function and composition of compact bone?

Protects and shields

Dense outer layer; smooth and solid

What is the function and structure of spongy bone?

Allows flexibility, allows space for blood vessels, bone marrow, etc, makes skeleton lighter

Honeycomb of flat pieces of bone deep to compact

What are trabeculae?

Branching plates in spongy bone

True or false: spongy bones contain osteons

False

What are diploë?

Holes in spongy bone

What covers the epiphysis?

Articular (hyaline) cartilage

What separates the epiphyses and diaphysis? And what is it a remnant of?

The epiphyseal line, a remnant of the growth plate

What is periosteum?

White, double layered membrane that covers external long bone surfaces EXCEPT joint surfaces

What s the difference between the outer and inner layer of periosteum?

Outer fibrous layer of dense irregular connective tissue

Inner osteogenic layer helps repair bones

What are the functions of the periosteum?

Inner layer contains stem cells - osteogenic cells to help with bone repair

Provides anchoring points for tendons and ligaments

Where is the endosteum found? What does it contain?

Covering internal bone surface, lines canals that pass through compact bone

Contains osteogenic cells that can differentiate into other bone cells

Where is red marrow found?

Found within trabecular cavities of spongy bone and diploë of flat bones

Where is red marrow fond in adult long bones?

Heads of femur and humerus only

Where is red marrow most active in adults?

Pelvis

True or false: Yellow marrow can convert to red marrow if needed

True

What kind of tissue is the forerunner of long bones in the embryo?

Hyaline cartilage

How is the periosteum secured to the underlying bone? What kind of tissue is it?

Sharpays fibers (dense connective tissue)

What are osteocytes?

Mature bone cells in lacunae that monitor and maintain bone matrix. Act as stress or strain stressors

How do osteocytes exchange nutrients and waste?

Cell processes within tiny passageways called canaliculi, connected via a gap junction

What are osteogenic cells?

Mitotically active stem cells, when stimulated differentiate into osteoblasts or bone lining cells

What are osteoblasts?

Bone forming cells, secrete non-mineralized bone matrix, are actively mitotic

What is osteoid?

Organic gooey non-mineralized bone matrix that includes collagen and calcium-binding proteins

What percent of bone protein is collagen?

90%

What are osteoclasts?

Giant, multinucleate cells for bone reabsorbtion

Have a ruffled border to increase surface area for enzyme degradation of bone and seals off area from surrounding matrix

What would be a reason for bone breakdown?

Damage, calcium redirection

What join adjacent central canals?

Perforating canal

Why do collagen fibers run in different directions?

To resist twisting and withstand stress

How much of organic bone matrix is osteoid?

1/3

What are hydroxyapatites?

Mineral salts, mainly of tiny phosphate crystals in and around collagen fibers

What percent of a bone by mass are hydroxyapatites?

65%

Why are bones too bendy? Too brittle?

Too bendy is too much organic material and too brittle is too much inorganic material

What is a disease of the bone is which bone reabsorption outpaces bone deposit, leaving a person with thin and often very fragile bones?

Osteoporosis

What do bones grow in our lifetime?

Development, growth/remodeling, repair

What are the two ways bone tissues replace existing connective tissues?

Intramembranous bones and endochondral bones

What bones are formed via intramembranous ossification?

Sternum, skull, clavicle

What is endochondral ossification?

Process of replacing hyaline cartilage to form an endochondral bone

What are the steps of endochondral ossification?

Begin as hyaline cartilage models

Chondrocytes (cartilage cells) enlarge, lacunae grow

Matrix breaks down, chondrocytes die

Osteoblasts invade area, deposit bone matrix (osteoid)

Osteoblasts form spongy, then compact bone

Once encased by matrix, osteoblasts are now osteocytes

Where is the primary ossification center? The secondary?

The primary ossification center is the diaphysis. The secondary is the epiphysis

What are the 4 layers of the epiphyseal plate

Zone of resting cartilage

Zone of proliferating cartilage

Zone of hypertrophic cartilage

Zone of calcified cartilage

What is the zone of resting cartilage?

Layer closest to end of epiphysis, resting cells

What is the zone of proliferating cartilage?

Rows of young cells, undergoing mitosis

What is the zone of hypertrophic cartilage?

Rows of older cells left behind when new cells appear, thicken epiphyseal plate, lengthening bone, matrix calcifies, chondrocytes die

What is the zone of calcified cartilage?

Thin layer of dead cartilage cells and calcified matrix

How long can bones continue to grow in length?

As long as the cartilage cells of epiphyseal plate ossifies

How can bone thicken?

By depositing compact bone on outside, under periosteum

What causes gigantism?

An excess in human growth hormone

How can GH disorders be treated?

Surgery/radiation if pituitary tumor

A gh-receptor blocking agent, less invasive

What is acromegaly?

Increased GH in adults. Growth plates are closed so long bones don't grow but facial hand and feet bones may grow

What two processes make up bone remodeling? What do they consist of?

Bone resorption: removal of bone, action of osteoclasts

Bone deposition: formation of bone, action of osteoblast

How much of the skeleton is replaced each year?

10% - 20%

Why do older bones become more brittle?

Calcium salt starts to crystallize, fractures more easily

How do osteoclasts perform bone resorption?

Secrete lysosomal enzymes that digest proteins and matrix

Acidity converts calcium to soluble forms.

What roles do osteoclasts have outside of bone reabsorption?

Phagocytize demineralized matrix and dead osteocytes

What is para thyroid hormone and where is it produced?

Produced by parathyroid glands. Removes calcium from bone regardless of bone integrity​

What is calcitonin and where is it produced?

Produced by thyroid gland. in high doses lowers blood calcium temporarily

Where is the bone thickest on long bones and why?

Midway along diaphysis where bending stresses greatest

What is a reduction? Open vs. Closed?

• Realignment of broken bone ends​

• Closed reduction – physician manipulates to correct position​

• Open reduction – surgical pins or wires secure ends​

Steps in fracture repair

A. Hematoma → large blood clot

B. Cartilaginous callus → phagocytes remove debris, fibrocartilage invades

C. Bony callus → osteoblasts invade, hard callus fills space

D. Remodeling → bone restored close to original shape

What is rickets?

Osteomalacia of children, causes bowed legs, bones ends enlarged and abnormally long. Caused by poor nutrition

What is osteomalacia?

Bones are poorly mineralized, calcium salts not adequate, soft, week bones

What are risk factors for osteoporosis?

Most often postmenopausal women, because sex hormones maintain normal bone health and density, so as secretion wanes with age, osteoporosis can develop

What are some examples of extra bones that people can have?

Spiritual bones in sutures between major skull bones and small sesamoid in tendons

How many bones in axial skeleton? Appendicular?

Axial - 80

Appendicular - 126

How many bones are in the skull?

22

What suture connects the frontal and parietal bone?

Coronal suture

What suture connects the parietal and temporal bones?

Squamous suture

What suture connects the parietal bone and the occipital bone?

Lambdoid suture

When do skull cranial bones fully fuse?

Between 3-24 months

What are fontanels? Why are they present?

Soft spots where intarmembranous ossification is complete. Are present to help fit through the birth canal

Where does the spinal cord exit the skull?

Foramen Magnum

What two structures articulate between the vertebral column and the occipital bone?

Occipital condyles and atlas (1st vertabra)

Where do many ligaments and neck and back muscles attach to the cranium?

External occipital protuberance and external occipital crest

What sits in the posterior cranial fossa?

Cerabellum

What is matoiditis?

Infection of the mastoid bone that causes branch the ear swelling

What goes through the carotid canal? What does it bring?

The carotid artery and it brings oxygen rich blood to the brain

What bone is the base of the beacon and forms the central wedge that articulates with all other cranial bones?

Sphenoid

What does the sella turcica contain?

Pituitary gland

What bone contains the crista gall and cribiform plate? What do these structures do?

Ethmoid bone

Crista galli - dura attachment

Cribiform plate - olfactory nerves

What happens when the palatine process has problems with fusing?

Cleft palate

What bones form the cheekbones?

Zygomatic bones

What bone contains the tear ducts?

Lacrimal bones

What process on which bones anchors chewing muscles?

Coronoid process on the mandible

What connects with the mandibular fossa of the temporal bone?

Mandibular condyle

What contains the sockets for teeth?

Alveolar margin

What contains the nerves and blood vessels for chin and lower lip?

Mental foramina

What is the only bone ion the body that doesn’t articulate with another bone and is the site of attachment for muscles of swallowing and speech?

Hyoid bone

What are the functions of the vertebral column?

Forms vertical axis of skeleton

Supports head and trunk, permits different types of movements

Protects spinal cord in vertebral canal

How many bones are in the adult vertebral column and how are they spilt up?

26

7 cervical

12 thoracic

5 lumbar

Sacrum

Coccyx

Where does the spinal cord stop and start free nerves?

L1-L2

What are the 4 curvatures of the vertebral column and are they primary or secondary?

Cervical (secondary)

Thoracic (primary)

Lumbar (secondary)

Sacral (primary)

What is scoliosis?

Abnormal lateral curve of the spine

What is kyphosis?

AKA hunchback - exaggerated thoracic curvature