lab practical 2

classification of bones; what are the four type and how are they determined

the four classes of bone are determined by shape

• long bones: greater in length than width; ex: femur, humerus

• short bones: length nearly equal to width; ex: carpals and tarsals 

• flat bones: flat, thin surfaces, may be slightly curved; ex: cranial bones

• irregular bones: elaborate, sometimes complex shapes; ex: vertebrae

axial skeleton

composed of bones along central body axis; form the longitudinal axis of the body from skull to the end of the vertebral column

• skull, vertebral column, and thoracic cage

appendicular skeleton

bones of upper and lower limbs & girdles of bones attach limbs to axial skeleton

what are bone landmarks? what are they used for?

they are the bumps, grooves, and hole on bones

landmarks (markings) are used for muscle attachment, passageways for blood vessel and nerves, support, and movement (joints)

cells of bone

• osteoprogenitor cells: stem cells that mature to become osteoblast

• osteoblasts: immature bone cell that secretes osteoid, the organic component of bone matrix

• osteocytes: mature bone cell; maintains the bone matrix

• osteoclasts: multinucleate cell; secretes acids and enzymes to dissolve bone matrix

osteon components for compact bone

• central canal

• concentric lamellae

• osteocytes

• canaliculi

bone: supporting connective tissue

structure: calcified extracellular matrix containing osteocytes trapped in lacunae

• compact bone: arranged in osteons (concentric lamellae arranged around a central canal)

• spongy bone: a meshwork that has a different organization from compact bone

function: provides levers for body movement, supports soft structures, protects organs, stores calcium + phosphorus

• spongy bone: contains hemopoietic tissue & is the site for hemopoietic

location: bones of the body

spongy (cancellous) bone

locations: flat bones of the skull, ribs, sternum, mandible 

• Head (epiphysis) of long bones

composed of: trabeculae, parallel lamellae 

endochondral ossification: 6 steps

1. A hyaline cartilage model of bone forms

2. cartilage calcifies, a periosteal bone collar forms

3. Primary ossification center forms in diaphysis (shaft)

4. Secondary ossification centers form in epiphyses

5. Bone replaces cartilage, except articular cartilage & epiphyseal plates

6. Epiphyseal plates ossify & form epiphyseal lines

• forms most bones in the body, long bones, & end bones of clavicle & replaces cartilage w/ bone

• cartilage is formed first, then bone is laid down on it

• replaces cartilage w/ bone

• begins in embryological/ as a fetus

intramembranous ossification: 4 steps

1. ossification centers form within mesenchyme

2. osteoid undergoes calcification

3. woven bone & periosteum form

4. Lamellar bone replaces woven bone, compact & spongy bone form

• forms the flat bones of skull, face, jaw, center of clavicle

• incomplete ossification at birth can be seen as the “soft spot” on a baby’s head

• bone is directly formed on meserichymal tissue]does not form an intermediate cartilage

• bone growth in membrane; osteoblasts help synthesize the bones

developing membrane bone (developing spongy bone)

hemopoiesis

blood cell production

ossification

formation and development of bone

osteons

basic functional & structural unit of mature compact bone

trabeculae

highly porous form of bone tissue that is organized into a network of interconnected rods & plates which surround pores that are filled with bone marrow

articulating surfaces

depressions

projections for tendon & ligament attachment

openings & spaces

pelvis

femur

skull, anterior view

skull, sagittal view

humerus

bone markings

bumps, holes, and ridges on bones where muscles, tendons, and ligaments are attached and where blood vessels  and nerves pass through

articulation

a joint; where two bones meet

fontaneis

spaces between bones in an infant skull

canaliculi

tiny canals that radiate outward from the Haversian canal to lacunae to supply the bone cells with nutrients

diaphysis

shaft of a long bone; composed of compact bone

epiphysis

end of a long bone; composed mostly of spongy bone

epiphyseal line

marking left on the bone from growth at the epiphyseal plate

remodeling

process of breaking down and reforming bone that occurs throughout life to maintain proportion and strength and well as healthy calcium levels

fracture

broken bone

rickets

soft bones caused by lack of vitaminD, calcium, or phosphorus

cranial bones

fun fact

part of the axial skeleton (skull is a part of it), contains 8 cranial bones that form the brain case and 14 facial bones that protect and support the entrances of: the digestive and respiratory tracts

• the hyoid bone is the only bone in humans that does not articulate with any other bone

whats the function of the axial skeleton

to support and protect the organs in body cavities and attach to the muscles of the head, neck, trunk, and muscles for respiration

function of the appendicular skeleton

to attach the limbs to the axial skeleton and functions the upper and lower limbs of the body

cranial sutures

• coronal suture

• sagittal suture

• lambdoid suture

• squamous suture

8 cranial bones

• occipital bone (1)

• parietal bone (2)

• frontal bone (1)

• temporal bones (2)

• sphenoid (1)

• ethmoid (1)

occipital bone

parietal bones

frontal bone

temporal bones

sphenoid bone

ethmoid bone

facial bones

-Maxillae (2)
-Palatine Bones (2)
-Nasal Bones (2)
-Vomer
-Inferior Nasal Conchae (2)
-Zygomatic Bones (2)
-Lacrimal Bones (2)
-Mandible

maxillae (2)

palatine bones (2)

nasal bones (2)

vomer

inferior nasal conchae (2)

zygomatic bones (2)

lacrimal bones (2)

mandible

hyoid bone

sinuses of the head

vertebral column

• 24 individual vertebrae and fused the sacrum and coccyx

Vertebral column divisions
• 5 divisions or regions
• Identified by capital letter for region followed by numerical subscript
- Indicates sequence from superior to inferior locations

• Cervical vertebrae
• 7 vertebrae, C1–C7
• Thoracic vertebrae
• 12 vertebrae, T1–T12
• Lumbar vertebrae
• 5 vertebrae, L1–L5
• Sacrum
• Formed from 5 sacral vertebrae, S1–S5
• Coccyx (tailbone)
• Formed from 4 coccygeal vertebrae: Co1–Co4

vertebral anatomy

• Body
  ➢ Vertebral arch
  ➢ Vertebral foramen
  ➢ Vertebral canal
  ➢ Intervertebral foramina
  ➢ Pedicles
  ➢ Laminae
  ➢ Spinous process
  ➢ Transverse process
  ➢ Superior and Inferior articular processes
  ➢ Intervertebral discs

regions: cervical vertebrae

The Cervical Vertebrae (C1-C7)
• Transverse processes
➢ Are fused to costal processes
➢ Fusion creates transverse foramen (protect arteries and veins)
• Also contain long spinous processes with bifid tip

cervical vertebrae atlas (c1) and axis (c2)

Atlas
• Articulates with occipital condyles of skull at superior articular facet (or surface)
• Articulates with axis at the inferior articular facets
• Lacks body or spinous process
• Has a large, round foramen within anterior and posterior arches
• anterior tubercle serves as site of attachment for cervical ligaments and muscles
Axis
• Supports the atlas at the Superior Articular Facet
• Has heavy spinous process
• To attach muscles of head and Neck
Axis and atlas bodies fuse during development to form the dens
             - dens disassociates from atlas to allow rotation

regions: (T1-T12) thoracic vertebrae

Have heart-shaped bodies
Larger bodies than in C1–C7
Smaller vertebral foramen than in C1–C7
Long, slender spinous processes
Inferior vertebral notch is the lower concavity of the pedicle
(forms ½ of the border of the intervertebral foramen)
Have costal facets:
• articulate with heads of ribs
• T1 - T8 have 2 sets of costal facets (1 superior, 1inferior)
on each side (allows for articulation with 2 ribs)
• T9 – T10 have a single superior costal facet

regions (L1-L5) lumbar vertebrae

Thickened vertebral body, pedicles and lamina
Have narrow vertebral foramen
Contain superior and inferior articular processes and
facets for articulation with adjacent vertebrae
Transverse processes
• Slender
• Project dorsolaterally
Spinous process
• Short, heavy
• For attachment of lower back muscles

sacrum

Anteriorly curved, triangular bone: forms posterior wall of pelvic cavity
5 fused vertebrae, fused by age 20-30
Apex pointed bone projecting inferiorly
Base broad superior surface
Articulates with L5 superiorly via pair of superior articular processes
Sacral canal Continuation of vertebral canal
• Continues through sacrum on posterior side, allows for passage of sacral roots of spinal nerves
• Terminates in inferior opening, sacral hiatus
Median sacral crest Dorsal ridge formed by fusion of spinous processes: Four pairs of sacral foramina open to either side
Lateral sacral crest fused transverse processes
Ala broad lateral extensions of the sacrum

Auricular articular surface Site of articulation with os coxae of pelvic girdle: Forms strong sacroiliac joint

Sacral foramina permit passage of nerves to pelvic organs and gluteals

coccyx

• Fusion of 4 coccygeal vertebrae
         - Begins about age 25

• Attachment site for several ligaments and muscles

• In elderly, may ultimately fuse with the sacrum

thoracic cage

Bony framework for the chest
Consists of
• Thoracic vertebrae posteriorly
• Ribs laterally
• Sternum anteriorly
Protective enclosure around thoracic organs
Attachment sites for many muscles

ribs

• Elongated, curved, flattened bones

• Originate on thoracic vertebrae

• End in anterior wall of thorax

• 12 pairs of ribs
  True ribs (ribs 1–7)
  • Connect individually to the sternum by costal cartilages
  • Smallest true rib is the first
  False ribs (ribs 8–12)
  • Costal cartilages not attached directly to the sternum
  • Ribs of 11–12 without a connection to sternum called floating ribs

what consists of the ribs

Head at the vertebral end of the rib
• contains articular facets: articulate with superior costal facet of vertebrae
Neck lies between head and tubercle
Tubercle articulates with transverse costal facet of transverse process of vertebrae
Angle site where tubular shaft begins to curve
• Shaft attaches muscles of the pectoral girdle, trunk and intercostal muscles that move the ribs
Costal groove marks the path of nerves and blood

sternum

Breastbone: Flat bone forming anterior midline of thoracic wall
Manubrium widest most superior portion
• clavicular notches articulate sternum with clavicles
• suprasternal notch between the clavicular notches
• costal notches articulations for first ribs’ costal cartilages
Body longest part
• attaches to costal cartilages from ribs 2-7
• articulates with manubrium at sternal angle
Xiphoid process smallest part, at tip of sternum
• attaches to sternal body, doesn’t ossify until age 40

vertebral body

thick anterior weight-bearing structure

vertebral arch

posterior to body

vertebral foramen

opening enclosed by body with vertebral arch

vertebral canal

formed by stacked vertebral foramina, contains the spinal cord

pedicles

originate from posterolateral margins of body

laminae

extend posteromedially from posterior edge of pedicle

spinous process

projects posteriorly from laminae junctions

transverse process

lateral projections on both sides of vertebral arch

superior and inferior articular processes

originate at junction between pedicles and laminae, have smooth surface articular facet-articulate with vertebra either above or below

intervertebral discs

pads of fibrocartilage separating vertebral bodies, shock absorbers, allows vertebral column to blend

true ribs

ribs 1-7, connect individually to the sternum by costal cartilages

false ribs

ribs 8-12, costal cartilages not attached directly to the sternum