Exam 1 Part Three Flashcards
The flat bone of skull is formed by
Intramembranous ossification
Contains concentric lamallae
Osteon
Spongy bone is formed by
Trabeculae
End of a long bone
Epiphysis
Organic components of bone matrix
Osteoid
The parathyroid hormone stimulates
Osteoclasts to become active
The endosteum lines
The medullary cavity
Osteoclasts are responsible for
Bone resorption
Vitamin D increases
Calcium absorption in intestine
Hydroxyapatite is
Calcium phosphate/ hydroxide crystals
The immature cells that produce osteoid are called
Osteoblasts
Hyaline cartilage is found in these places
Trachea, layrnx, fetal skeleton
A small space within compact bone housing an osteocyte is termed a
Lacuna
Endochondral ossification begins with a _____ model of bone
Hyaline cartilage
Production of new bone _______as a result of increased sex hormone production at puberty.
Increases rapidly
An epiphyseal line appears when
Epiphyseal plate growth as ended
The condition of inadequate ossification that may accompany aging and is a result of reduced calcification is called
Osteopenia
The femur is an example of a?
Long bone
A large, rough projection of a bone is termed a
Tuberosity
Identify the three types of cartilage, describing the extracellular matrix of each type
1) Hyaline
2) Elastic
3) Fibrocartilage
A matrix of protein fibers embedded within a gel-like ground substance. Chondroblasts are the cells that produce the matrix of cartilage. Once they become encased w/in the matrix they have produced and secreted, the cells are called chondrocytes & occupy small spaces called lacunae. These mature cartilage cells maintain the matrix & ensure that it remains healthy & viable
Describe the structure of the periosteum, & list its functions
It is a tough sheath that covers the outer surface of bone, except for the areas covered by articular cartilage. Made of dense irregular connective tissue & consists of an outer fibrous layer & an inner cellular layer.
Its functions are:
*Protects the bone from surrounding structures
*Anchors blood vessels & nerves to the surface of bone
*Provides stem cells (osteoprogenitor cells & osteoblasts) for bone width growth & fracture repair
What are the types of bones?
Long bones, short bones, flat bones, irregular bones
What are the functions of the skeletal system?
1) Support: Provides structural support & serve as the framework for the entire body
2) Protection: surrounds soft tissue- ex. ribs and sternum protect the heart and lungs, - skull protects the brain
3) Movement: skeletal muscle is attached to bone so it pulls on the bone when it contracts
4) Hemopoiesis: The process of blood cell production. Red bone marrow produces red blood cells, white blood cells and other blood elements
5) Storage of mineral & energy reserves: storage of minerals and lipids(fats)—yellow marrow stores fat –(found in long bones) stores calcium and phosphate–minerals are released into the blood when needed
Endochondral ossification basic steps
1) A hyaline cartilage model of bone forms
2) Bone first replaces hyaline cartilage in the diaphysis
3) Later, bone replaces hyaline cartilage in the epiphyses
4) Eventually, bone replaces hyaline cartilage everywhere, except the epiphyseal plates & articular cartilage
5) By a persons late 20s, the epiphyseal plates have ossified, & lengthwise bone growth is complete
Osteoporosis is
In which bone mass becomes reduced enough to compromise normal function. A large number of older women & a smaller number of older men suffer from this.
Name the steps of appositional growth
1) Stem cells at the internal edge of the perichondrium begin to divide, forming new stem cells & committed cells
2) The committed cells differentiate into chondroblasts
3) These chondroblasts begin to produce & secrete new cartilage matrix. As a result, they push apart & become chondrocytes, each occupying its own lacuna
4) The new matrix has been produced peripherally, & thus appositional growth as occurred
Describe the microscopic anatomy of compact bone
Organized structure when viewed under the microscope. A cylindrical osteon is the basic functional & structural unit of mature compact bone. Osteons run parallel to the diaphysis of the long bone.
An osteon is a three-dimensional structure that has several components
- The central canal
- Concentric lamellae
- Osteocytes
- Canaliculi
Simple fracture=
(Closed) Bone does not break through the skin
Compound fracture=
(Open) Broken ends of the bone protrude through the skin
Complet fracture=
Bone is broken into two or more pieces
What are the steps to fracture repair in bones
1) A fracture hematoma forms
2) A fibrocartilage (soft) callus forms
3) A hard (bony) callus forms
4) The bone is remodeled
comminuted fracture is
Bone is splintered into several small pieces between the main parts
Incomplete fracture=
Fracture extends only partway across the bone
Greenstick fracture=
Partial fracture; convex side of bone breaks-the other side is bent
Transverse fracture=
Fracture at right angles to the long axis of the bone
Spiral fracture=
Fracture spirals around axis of long bone; results from twisting stress
What kind of secretion does the sebaceous glands secrete?
Holocrine
Sesamoid bones are
small round & flat bones that form within tendons, highly variable from individual to individual except for the patella
Flat bones
have two parallel plates of compact bone with a thin layer of spongy bone sandwiched in between them
Mesenchyme are
Star shaped cells- They are stem cells that give rise to all connective tissue
Osteoprogenitor is
From mesenchyme (usually in the endosteum) Can divide & differentiate into osteoblasts Differentiate during bone formation and after bone fracture...
Fibroblast
- Produce all connective tissue fibers
* Collagen, reticular & elastic fibers
Cartilage forming cells
Chondroblast
Encased chondroblasts
Chondrocytes
Bone forming cells
Osteoblast
Osteocytes are
Encased osteoblasts
*mature bone cells occupying lacuna (maintains bone)
Osteoclasts are
Bone destroying cells
- Giant multinucleate (fused bone marrow stem cells)
- contain lysosomes
- secret HCI
- dissolve bone matrix (osteolysis)
- frees Ca++ into the blood
What are the 3 types of cell secretion?
Merocrine (eccrine), apocrine, holocrine
What is the mature cell of cartilage?
Chondrocyte
What kind of bone is the patella?
Sesamoid bone
What is one unit of compact bone called?
Osteon
What causes skin color?
Melanin, carotene, blood
Where are melanocytes located?
Stratum Basale
What is the waterproof protein of skin & hair?
Keratin
What is the band of cartilage between diaphysis and epiphysis?
Epiphyseal plate..
Bone matrix composition
Organic framework: collagen fibers
*Secreted by osteoblasts, roughly 1/3 the weight of bone.
*Due to its toughness & flexibility, provides bone its tensile strength (acting like rebar)
Inorganic salts: Ca3(PO4)2-Calcium Phosphate
• Hardest matrix material
• Tooth enamel!
• Rigid
• Brittle
• Small plates of Ca3(PO4)2 lie alongside the collagen fibers (like cement with rebar)
Trabeculae
form a lattice-like network of struts.
- Significantly decrease the weight
- Keeps strength
“Direct” ossification
Intramembranous Ossification
Describe Intramembranous Ossification
- Eight weeks of development- 8 weeks
- Osteoblasts form within connective tissue (“dermal bones”).
- Only about 10% of your bones form this way: many in the skull, clavicle, scapula, os coxae & all sesamoid bones (including patella)
What are the steps to Intramembranous Ossification
Step 1 – Mesenchyme cell clusters become osteoprogenitor cells that become osteoblasts.
Osteoblasts produce osteoid. Osteoid begins to mineralize as the ossification center…
Step 2 – Bony spicules (trabeculae) begin to radiate out from the ossification center. Any trapped osteoblasts become osteocytes; blood vessels branch & grow.
Step 3 – Over time, this bone assumes the structure of spongy bone with blood vessels trapped in trabeculae
Step 4- Bone remodeling results in two layers of
compact bone with spongy bone and small marrow cavities in between. A sandwich!
Endochondral Ossification is
- “Indirect” ossification via cartilage
- A hyaline cartilage skeleton model is made first, then that cartilage is converted into bone.
- Most bones form this way…
Summary of Endochondral Bone-
- Hyaline cartilage model develops (in fetus via chondroblasts).
- Cartilage calcifies and periosteal collar forms.
- Primary ossification center (osteoblasts in diaphysis.
- Secondary ossification centers (epiphysis).
- Replacement of cartilage w/ bone (except epiphyseal plates.
- Complete ossification (epiphyseal line)
Appositional bone growth
- proceeds as periosteal cells differentiate into new osteoblasts which lay down bone on the bone’s exterior.
- New osteons will organize over time.
- Osteoclasts on the endostium will dissolve bone enlarging the marrow cavity…
Hormones influence what in bones?
Ca++ balance, as well as the timing of growth spurts & the end of growth
Calcitonin from the thyroid & parathyroid hormone from the parathyroid glands control
homeostasis of Ca++
Human Growth Hormone & Thyroxine maintain
epiphyseal cartilages until growth is done
Estrogen & testosterone accelerate
bone growth & the “closure” of epiphyseal plates

Ligaments join
bone to bone
Tendons join
Muscle to bone
Bursa
small pockets of synovial membrane, filled with synovial fluid, eases motion & cushions friction
Tendon sheaths are
Tubular bursae that surround tendons with bony friction
Articular discs are
Articular discs: fibrocartilage pads that limit movement, also called menisci
Name the different knee injuries
- Meniscus tear
- ACL tear
- Medial colateral tear
- Patellar ligament tear
Rotator cuff injury
- Shoulder- greatest range of movement!
* Muscles (with tendons) hold head of humerus in glenoid fossa
Carpal tunnel syndrom
Any compression of either the median nerve or the tendons in the tunnel results in carpal tunnel syndrome.
Tennis elbow
Also called lateral epicondylitis is a painful condition resulting from trauma or overuse of the common extensor tendon of the posterior forearm muscles. It arises from the lateral epicondyle of the humerus, the attachment site of the common extensor tendon
What are the indications that bone is alive?
It grows, repairs, thickens and undergoes atrophy
Osteocytes communicate through?
Canaliculi
Describe the characteristics of articular cartilage
A thin layer of hyaline cartilage covering the epiphysis at a joint surface. It helps reduce friction & absorb shock in movable joints
What are the characteristics of the medullary cavity
The hollow, cylindrical space within the diaphysis. In adults it contains yellow bone marrow
The characteristics of the endosteum are
An incomplete layer of cells that covers all internal surfaces of the bone, such as the medullary cavity. Contains osteoprogenitor cells, osteoblasts, & osteoclasts, & is active during bone growth, repair, & remodeling
Why is spongy bone able to withstand stress in an area such as the expanded end of a long bone?
Spongy bone is lighter & able to withstand stresses applied from many directions.
What is ossification?
The developmental process of bone formation
What are the effects of exercise on bone mass
- Bone has the ability to increase its strenght over a period of time by increasing the amounts of mineral salts deposited & collagen fibers synthesized
- Bones of athletes become thicker
- Weight lifting or walking help build and retain bone mass
- lack of exercise weakens bone
What is the difference between intramembranous ossification and endochondral ossification?
Intramembranous ossification [flat bones] & endochondral ossification [long bones].The essential between them is the presence or absence of cartilaginous phase
Bones growth in length is called?
Interstitial growth
Bones growth in diameter or thickness is called?
Appositional growth
Interstitial growth occurs
Within the epiphyseal plate as chondrocytes undergo mitotic cell division in zone 2 & chondrocytes hypertrophy in zone 3
*these activities combine to push the zone of resting cartilage toward the epiphysis, while the new bone is being produced at the same rate in zone 5, resulting in increased bone length.
Appositional growth occurs
Within the periosteum. Osteoblasts in the inner cellular layer of the periosteum lay down bone matrix in layers parallel to the surface. As these lamellae increase in number, the structure widens. As new bone is being laid down the osteoclasts along the medullary cavity resorb bone matrix, creating an expanding medullary cavity
List the four types of arteries that are found in a long bone and what portion of each bone does the artery supply
1) Nutrient artery-Diaphysis
2) Metaphyseal arteries & metaphyseal veins-Diaphyseal side of the epiphyseal plate
3) Epiphyseal arteries & epiphyseal veins-Epiphyses
4) Periosteal arteries & periosteal veins-External circumferential lamellae & the superficial osteos within the compact bone at the external edge of the bone
Supraorbital forearm
Frontal bone
Foremen magnum
Occipital bone
Sella turcica
Sphenoid bone
Cribriform plate
Ethmoid bone
Transverse foramina
Cervical vertebrae
Costal demifacets
Thoracic vertebrae
Xiphoid process
Sternum
Upper Jaw
Maxillae
Which bones form the hard palate?
Palatine bones & maxillae
The bony portion of the nasal septum is formed by the?
Perpendicular plate of the ethmoid bone and vomer
The mandible articulates with the_____bone.
Temporal
Some muscles that control the tongue and larynx are attached to the?
Hyoid bone
The frontal and parietal bones articulate at the ___ suture
Coronal
The compression of an infant’s skull bones at birth is facilitated by spaces between unfused cranial bones called
Fontanelles
What are the openings in the sphenoid
Foramen rotundum, foramen spinosum, optic canal
Each temporal bone articulates with the
Occipital, zygomatic, sphenoid, & parietal bones, and the mandible
Most____vertebrae have a long spinous process that is angled inferiorly
Thoracic
The clavicles articulate with the _____ of the sternum
Manubrium
What are sutures, & how do they affect skull shape & growth?
Immovable joints that form the boundaries between the cranial bones. (coronal, lambdoid, sagittal, & squamous)
They allow the cranium to grow & expand during childhood. In adulthood, when cranial growth as stopped, the sutures fuse and are obliterated.
Identify the first two cervical vertebrae
C1-Atlas-supports the head via its articulation with the occipital condyles of the occipital bone
C2-Axis-during development the body of the atlas fuses to the body of the axis
The fusion produces the most distinctive feature of the axis, the prominent dens
The dens acts as a pivot for the rotation of both the atlas & the skull
Identify the region of the vertebral column that is most likely to experience a herniated disc, & discuss the causes of this problem
The cervical and lumbar intervertebral discs are the most common discs to be injured, because the vertebral column has a great deal of mobility in these regions, and the lumbar regions bears increased weight.
It occurs when the gelatinous nucleus pulposus protrudes into or through the anulus fibrosus.
What are the 5 regions of the vertebral column
1) Cervical vertebrae
2) Thoracic vertebrae
3) Lumbar vertebrae
4) Sacrum
5) Coccyx
Describe the similarities and differences among true, false and floating ribs
Ribs 1-7-true ribs which connect individually to the sternum by separate cartilaginous extensions called costal cartilages
Ribs 8-12-false ribs their costal cartilages do not attach directly to sternum, instead they fuse to the costal cartilage of rib 7
Ribs 11-12-floating ribs because they have no connection with the sternum
Lateral malleolus
Fibula
Supraspinous fossa
Scapula
Tarsal bone
Talus
Capitulum
Humerus
Radial notch
Ulna
Acetabulum
Os coxae
Lesser trochanter
Femur
Medial malleolus
Tibia
Sternal end
Clavicle
The female pelvis typically has which characteristics?
Wide subpubic angle, greater than 100 degrees
The posterior surface depression at the distal end of the humerus is the
Olecranon fossa
The spine of the scapula separates which two fossae?
Infraspinous, supraspinous
The femur articulates with the tibia at the femur’s
Medial & lateral condyles
The bony feature palpated on the dorsolateral side of the wrist is the
Styloid process of radius
Identify the bone that articulates with the os coxae at the acetebulum
Femur
When sitting upright, you are resting on your
Ischial tuberosities
The two prominent bumps you can palpate on the sides of your ankle are the
Medial malleolus & lateral malleolus
The glenoid cavity articulates with which bone or bone features?
Head of the humerus
Compare the anatomic and functional features of the pectoral & pelvic girdles
Pelvic:
- Deep, secure socket for limb attachment
- Lightweight
- Weight-Bearing
Pectoral:
- Shallow socket for limb attachment
- Massive
- Flexibility
How do the glenoid cavity & the acetabulum differ?
Compared to the acetabulum (hip-joint) the glenoid cavity is relatively shallow
The glenoid cavity is found in the upper body, where the humerus joins the scapula and is referred to as the shoulder socket. It is not very deep and allows for a great range of motion.
The acetabulum is in the lower body, where the ilium joins the femur. It is a deep socket and is very secure for the support and ability to bear the weight of our bodies
