Chapter 6 & 7 - Bone Tissue + Axial Skeleton Flashcards
Distinguish between **bone **as a **tissue **and as an organ
bone is composed of several different tissues working together: bone, cartilage, dense connective, epithelium, adipose & nervous tissue
therefore, each bone in your body is considered an **organ **
Functions of **Bone & Skeletal System **(6)
1) support - structural framework
2) protection - protects internal organs
3) assistance in movement - skeletal muscle contract & pull on bones to produce movement
4) mineral homeostasis (storage & release) - bone tissue stores mineral
5) blood cell production
6) **triglyceride storage **- yellow bone marrow consists of mainly adipose cells
**Structure of Bone (7) **
1) Diaphysis
2) Epiphyses
3) Metaphyses
4) articular cartilage
5) periosteum
6) medullary (marrow) cavity
7) Endosteum
1) Diaphysis
bone shaft or body
2) Epiphyses
proximal & distal ends of bone
3) Metaphyses
regions between diaphysis & epiphysis
contains epiphyseal (growth plate)
when bone stops growing in length ,cartilage in epiphyseal plate is replaced by bone - epiphyseal line
4) articular cartilage
thin layer of hyaline cartilage covering part of epiphysis where bone forms an articulation (joint) with another bone
5) periosteum
tough connective tissue sheath and its associated blood supply that surrounds bone surface wherever it is not covered by articular cartilage
outer fibrous layer & inner osteogenic layer
6) medullary (marrow) cavity
hollow, cylindrical space within diaphysis that contains fatty yellow bone marrow & humerus blood vessels in adults
7) Endosteum
thin membrane that lines medullary cavity
- contains a single layer of bone‐forming cells and small amount of connective tissue.
Like other connective tissues, **bone (osseous tissue) **congtains an abundant ..?
extracellular matrix that surronds widely separated cells
**Extracellular Matrix **
made up of?
15% water
30% collagen fibers
55% crystallized mineral salts
The most abundant mineral salt in bone is?
calcium phosphate
calcification
calcium phosphate combines with calcium hydroxide to form hydroxyapatite
as crystals form, they combine with other mineral salts (calcium carbonate, Mg, F, K & sulfate ions)
as these mineral salts are deposited & crystalzie in framework formed by collagen fibers of ECM
initiated by **osteoblasts **(bone-building cells)
Calcification is initiated by?
**osteoblasts **- bone-building cells
Bone’s flexibility depends on?
collagen fibers
(4) types of cells present in bone tissue
1) osteogenic
2) osteoblasts
3) osteocytes
osteoclasts
osteogenic cells
Undergo cell division
the resulting cells develop into **osteoblasts **
(unspecialized bone stem cells)
osteoblasts
Bone-building cells
synthesize extracellular matrix of bone tissue
become osteocytes
Osteocytes
mature bone cells
exchange nutrients & wastes with blood
(main cells in bone, maintain daily metabolism)
Osteoclasts
huge cells derived from fusion of as many as 50 **monocytes **(type of white blood cell)
Release enzymes that digest the mineral components of bone matrix (resporption)
regulate blood calcium level
(2) categories of bone
1) compact
spongy
Compact bone
resists?
components?
these consist of?
Resists the stresses produced by weight and movement Components of compact bone are arranged into repeating structural units called **osteons **(Haversian systems)
Osteons consist of a central (Haversian) canal
- run longitudinally through bone
- with concentrically arranged lamellae, lacunae, osteocytes, and canaliculi
Lamellae
part of osteon, concentric **lamallae **are around central canals
rings of calcified matrix (like rings of tree trunk)
Between the **Lamellae **are?
containing?
small spaces called **lacunae **which contain osteocytes
Canaliculi
what are they?
connect & form what?
purpose?
tiny canals radiating in all directions from **lacunae, **filled with extracellular fluid
- connect **lacunae **& forming system of interconnected canals
provides route for nutrients & oxygen to reach osteocytes
The organization of osteons changes in response to ?
the physical demands placed on the skeleton
Spongy Bone
- makes up most interior bone tissue
- lacks osteons
**lamellae **are arranged in a lattice of thin columns called **trabeculae **which contain spaces (make bones lighter)
**trabeculae **support & protect red bone marrow
- oriented around lines of stress (helps bones resist stresses without breaking)
**hematopoiesis **
blood cell production
occurs in spongy bone
**Lacunae **in spongy bone
**Lacunae **are within each trabecula
contain osteocytes that are nourished from blood circulating through trabeculae
Bone is richly supplied with blood.
Where are blood vessels found in bone?
especially abundant in portions of bone containing red bone marrow and pass into bones from periosteum.
**Periosteal **arteries
accompanied by nerves
enter diaphysis through canals
supply the periosteum and compact bone
Nutrient artery
passes through ole in compact bone **(nutrient foramen) **
upon entering **medullary cavity, **divides into proximal & distal branches that supply inner part of compact bone tissue of diaphysis & spongy bone tissue & red bone marrow
Veins that carry blood away from long bones
1) nutrient veins (exit through diaphysis)
2) epiphyseal & metaphyseal veins (exit through epiphyses)
3) periosteal veins (exit through periosteum)
Nerves accompany the blood vessels that supply bones.
The ___ _is rich in sensory nerves sensitive to tearing or tension
periosteum
process by which bone is formed
ossification (osteogenesis)
Bone formation occurs in four situations:
1) Formation of bone in an embryo
2) Growth of bones until adulthood
3) Remodeling of bone
4) Repair of fractures
Formation of Bone in an Embryo
cartilage formation and **ossification **occurs during 6th week of embryonic development
follows one of 2 patterns
(2) patterns of bone formation in an embryo
1) Intramembranous ossification
2) Endochondrial ossification
1) Intramembranous ossification
Flat bones of skull and mandible are formed in this way
- “Soft spots” that help fetal skull pass through birth canal later become ossified forming skull
1) develop ossification center - mesenchymal cells cluster at stop of bone development, differentiate into osteogenic then osteoblasts which secrete ECM
2) calcification - osteoblasts become osteocytes extend into canaliculi, mineral salts harden
3) formation of trabeculae - as ECM forms it develops into trabeculaw that fuse together around network of blood vessels in tissue (connective tissue associated with blood veseels differentiates into red bone marrow)
4) development of periosteum
2) Endochondrial ossification
The replacement of cartilage by bone
Most bones of the body are formed in this way including long bones
1) **development of cartilage model - **mesenchymal cells develop into chondroblaste that secrete cartilage ECM
2) growth of cartilage model - chondroblasts become deeply buried in ECM (chondrocytes)
3) development of primary ossification center
4) development of medullary cavity
5) development of 2ndary ossification centers
6) formation of articular cartilage & epiphyseal (growth) plate)
Bone Growth During Infancy, Childhood and Adolescence
bones throughout body grow in **thickness **by **appositional growth - **deposition of ECM on cartilage surface of model by new chondroblasts that develop from perichondrium
long bones **lengthen **by addition of bone material on diaphyseal side of epiphyseal plate by interstitial growth (endogenous)
Growth in **Length **of long bones involves (2) major events
1) interstitial growth of cartilage on epiphyseal side of epiphyseal plate
2) replacement of cartilage on diaphyseal side of epiphyseal plate by bone tissue
Growth in Length
**osteoclasts **dissolve the calcified cartilage, and **osteoblasts **invade area laying down bone matrix (replacing calcified cartilage)
activity of the **epiphyseal plate **is the way bone can increase in length
At adulthood, the epiphyseal plates close and bone replaces all cartilage leaving a bony structure called the epiphyseal line
Growth in Thickness
Bones grow in thickness at the outer surface (appositional growth)
as new bone is deposited on outer surface of bone by osteoblasts, bone tissue lining medullary cavity is destroyed by **osteoclasts **in endosteum
** Remodeling of Bone **
Bone forms before birth and continually renews itself
ongoing replacement of old bone tissue by new bone tissue
involves **bone resorption **- removal of mineral & collagen fibers from bone by osteoclasts
& **bone deposition - **addition of mineral & collagen fibers to bone by osteoblasts
The human skeleton consists of _________named bones
206
Bones of the skeleton are grouped into (2) principal divisions:
1) Axial skeleton
2) Appendicular skeleton
Axial Skeleton
Consists of bones that lie around the longitudinal axis of the human body
Skull bones, auditory ossicles (ear bones), hyoid bone, ribs, sternum (breastbone), & bones of vertebral column
Appendicular Skeleton
Consists of the bones of the upper and lower limbs (extremities), plus the bones forming the girdles that connect the limbs to the axial skeleton
Bones can be classified into (5) types based on shape
1) long
2) short
3) flat
4) irregular
5) sesamoid
Long Bones
Greater length than width and are slightly curved for strength
**Femur, tibia, fibula, humerus, ulna, radius, phalanges **
Short Bones
cube-shaped & are nearly equal in length & width
**Carpal, tarsal **
Thin Bones
Thin and composed of two nearly parallel plates of compact bone tissue enclosing a layer of spongy bone tissue
**Cranial, sternum, ribs, scapulae **
Irregular Bones
complex shapes & cannot be grouped into any of the previous categories
**Vertebrae, hip bones, some facial bones, calcaneus **
Sesamoid Bones
Protect tendons from excessive wear and tear
** Patellae, foot, hand **
Sutural Bones
classified by location rather than shape
**small bones **located in sutures of cranial bones
Bone **Surface Markings **
Structural features adapted for specific functions
(2) major types of surface markings:
1) depressions & openings
2) processes
1) depressions & openings
Allow the passage of blood vessels and nerves or form joints
2) processes
Projections or outgrowths that form joints or serve as attachment points for ligaments and tendons
Skull (cranium) consists of ___ bones
22
Bones of skull are grouped into (2) categories
1) Cranial bones
2) Facial bones
1) Cranial bones
how many?
what do they form?
what are they?
8 cranial bones form cranial cavity
frontal bone, 2 parietal bones, 2 temporal bones, occipital bone, sphenoid bone, ethmoid bone
2) Facial Bones
14 facial bones form face
2 nasal bones, 2 maxillae, 2 zygomatic, mandible, 2 lacrimal, 2 palatine, 2 inferior nasal conchae, vomer
The cranial and facial bones protect and support special sense organs and the brain.
Besides the **cranial cavity, **the skull also forms (4) small cavities
1) nasal
2) orbits
3) paranasal sinuses
4) middle ear cavities
Sutures
immovable joints that fuse most of the skull bones together
Skull and facial bones provide _______________for muscles that produce facial expressions
The facial bones form the ____ of the face and provide __ for the entrances to the ____ and ____ systems
attachment
framework
support
digestive
respiratory
Frontal Bone
forms forehead
Parietal Bones
form sides & roof of cranial cavity
Temporal Bones
Form the lateral aspects and floor of the **cranium **
Occipital Bone
Forms the posterior part and most of the base of the cranium
Sphenoid Bone
Lies at the middle part of the base of the skull
Ethmoid Bone
located?
major supporting structure of?
contains?
Located on midline in anterior part of cranial floor medial to the orbits
major superior supporting structure of the nasal cavity
Contain thin projections called conchae which are lined by mucous membranes
Increased surface area in the nasal cavity helps to humidify inhaled air trapping inhaled particles
Nasal Bones
forms bridge of nose
Maxillae
form **upper jawbone **& most of hard palate
seperates nasal cavity from oral cavity
Zygomatic Bones
cheekbones
form prominence of cheeks
Lacrimal Bones
form part of medial wall of each orbit
Palatine Bone
posterior portion of hard palate
Inferior Nasal Conchae
form part of inferior lateral wall of nasal cavity
Vomer
forms inferior portion of nasal septum
Mandible
lower jawbone
largest strongest facial bne
only movable skull bone
Nasal Septum
Divides interior of the nasal cavity into right and left sides
“Broken nose,” in most cases, refers to septal damage rather than the nasal bones themselves
Orbit
eye socket
Foramina
Openings for blood vessels , nerves , or ligaments of the skull
Unique Features of the Skull
sutures paranasal sinuses, fontanels
Paranasal Sinuses
Cavities within cranial & facial bones near nasal cavity
Secretions produced by mucous membranes which line the sinuses, drain into the nasal cavity
Serve as resonating chambers that intensify and prolong sounds
Fontanels
areas of unossified mesenchyme tissue that develops into dense connective tissue of skull
“soft spots” that link cranial bones
eventually replaced with bone to become sutures
provide flexibility to fetal skull, allowing the skull to change shape as it passes through the birth canal
Hyoid Bone
does not articulate with any other bone
supports tongue, providing attachment sites for some tongue muscles and for muscles of the neck and pharynx
helps to keep larynx (voice box) open at all times
Vertebral Column (spine, backbone, spinal column)
functions to?
Protect the spinal cord
Support the head
Serve as a point of attachment for the ribs, pelvic girdle, and muscles
vertebral column is curved to varying degrees in different locations
why?
to increase column strength
help maintain balance in upright position
absorbs shocks when walking
help protect vertebrae from fracture
(3) conditions that may exagerate normal curve of vertebral column
1) kyphosis - forward curve
2) lordosis - backward curve
3) scoliosis - sideways
**Vertebral Column **is composed of?
a series of bones called vertebrae
(26 in adults)
Components of Vertebral Column
7 cervical vertebrae in neck region
12 thoracic vertebrae posterior to thoracic cavity
5 lumbar vertebrae support lower back
1 sacrum consists of 5 fused sacral vertebrae
1 coccyx consists of 4 fused coccygeal vertebrae
Intervertebral Discs
found?
Found between the bodies of adjacent vertebrae
Intervertebral Discs
function to?
Form strong joints
Permit various **movements **of the vertebral column
Absorb vertical shock
Vertebrae typically consist of (3)
1) vertebral **body **(weight bearing)
2) vertebral **arch **(surrounds spinal cord)
3) several **processes **(points of attachment for muscles)
Regions of the Vertebral Column
1) cervical region
2) thoracic region
3) lumbar region
4) sacrum
5) coccyx
Cervical Region
Cervical Vertebrae (C1-C7)
The **atlas **(C1) is the 1st cervical vertebra
The **axis **(C2) is the 2nd cervical vertebra
Thoracic Region
Thoracic Vertebrae (T1-T12)
Articulate with the ribs
Lumbar Region
Lumbar vertebrae (L1–L5)
Provide for attachment of the large back muscles
Sacrum
a triangular bone formed by union of 5sacral vertebrae (S1–S5)
- Serves as a strong foundation for the pelvic girdle
Coccyx
like the sacrum, triangular in shape
formed by fusion of 4 coccygeal vertebrae
**Thorax **(entire chest region)
**Thoracic Cage **(skeletal part of thorax) is formed by?
sternum
ribs
costal cartilages
thoracic vertebrae
Thorax functions to?
Enclose and protect the organs in the thoracic and abdominal cavities
Provide support for the bones of the upper limbs
Play a role in breathing
Sternum
location?
consists of?
“Breastbone” located in the center of the thoracic wall
Consists of the manubrium, body, **xiphoid process **
Ribs
** 12 pairs** of ribs give structural support to the sides of thoracic cavity
Costal Cartilages
contribute to the elasticity of the thoracic cage
