Unit 2 Flashcards
Bone
- is mineralized, firm connective tissue
- is found only in vertebrates
Use of Bone (6)
- support
- leverage
- protection
- mineral reservoir
- sensory framework/insulator
- blood/immune cell production
Types of Bone Cells (4)
- Osteoblasts
- Osteocyte
- Osteoclasts
- Osteogenic cells
Osteoblasts
- responsible for forming new bone
- found in the growing portions of the bone
- incapable of mitotic division
- become osteocytes
Osteocyte
- primary cells of mature bone
- maintain the mineral concentration of matrix
- originate from calcified osteoblasts
Osteogenic Cells
stem cells that differentiate into osteoblasts
Osteoclasts
- responsible for bone resorption
- originate from monocytes and macrophages from osteogenic cells
- continually breaking down bone - can be used for releasing calcium stored in the bone
Classifications of Bone (5)
bone can be classified by:
1. shape
2. composition
3. formation
4. role
5. developmental/embryonic origin
Bone Shapes (5)
- long
- short
- Flat
- Irregular
- Sesamoid
Long Bones
- rectangular
- longer than they are wide
ex: femur, fingers, ribs
Short Bones
- relatively square
- about the same length as width
ex: carpals, tarsals
Flat Bones
“squamous” or thin
- can be curved
ex: sternum
Irregular Bones
odd, rough geometry
ex: vertebral, cranial
Sesamoid Bones
- small, roundish (oval), thick
- anchor joints
- look like sesame seeds
ex: patella
Bone Composition (2)
- Spongy Bone
- Compact Bone
Compact Bone
dense to withstand compressive forces
- in diaphysis
Spongy
(cancellous) bone has open spaces and supports shifts in weight distribution (more flexible)
- open network w/ trabeculae
- in epiphysis
Trabeculae
openings, spaces in bone
Osteons
Circular formations found in compact bone
Lamella
sheet/layer
Bone Marrow
makes immune cells
Flat Bone Layers (3 types)
Like a sandwich
- Periosteum
- Compact
- Spongy
- Compact
- Periosteum
Formation of Bone
- Endochondral Ossification
- Intramembranous Ossification
Endochondral Ossification (Long Bone)
- Cartilage develops and becomes calcified during fetal development
- Osteoblasts cover diaphysis
- Blood vessels bring osteoblasts into cartilage. Spongy bone forms at primary ossification center
- Medullary cavity forms, secondary ossification center forms in epiphysis
- Growth continues through childhood while cartilage is present at growth plates
Intramembranous Ossification (Flat Bones)
- Condensation of Mesenchyme
- Deposition of osteoid tissue by osteoblasts - form periosteum
- Honeycomb of bony trabeculae, mineral deposition, form spongy bone
- Surface bone filled by bone deposition, compact bone forms around spongy bone middle
Dermal Bone
- very dense
- good at protection
- okay to keep in water (aquatic animals)
- very heavy (bad for land animals)
Foramina
- openings, holes, or passages especially in the bone
- allow passages of nervous vascular elements through bone
Roles of the Skull (4)
- support and protect sensory organs
- support and protect brain, CNS
- support, reflect feeding and feeding mechanism
- support, reflect respiration and respiratory mechanism
Evolutionary Skull
- previously, only role was protecting sensory organs
- developed the eye socket, ability to chew
Difficulties of a “helmet” skull
- no accommodation for swelling
- no where to let information exit
Functions of Cranial Bones (2)
- surround and protect the brain
provide extensive area for muscle attachment (move eyes, jaw, and head)
Functions of Facial Bones (3)
- protect and support entrances to the digestive and respiratory tracts
- actively involved in respiration and mastication (chewing)
- provide areas for muscle attachment that control facial expressions
Occipital Bone
the single bone that forms the posterior (back) of the skull and the posterior base of the cranial cavity
holds foramen magnum and occipital condyles
- site of attachment for neck muscles
Condyle
“knuckle” a round prominence at the end of a bone, often a joint
Frontal Bone
unpaired bone that forms the forehead, roof of orbit, and floor of anterior (internal) cranial fossa, frontal sinuses
Temporal Bone
- pair of bones on the sides of the skull
- contributes to zygomatic arches
- forms articulation with the mandible
- protect the sense organs of inner ear
Temporal Fenestra (window)
- opening in temporal region of the skull
- develop at junctions of multiple bones
- allow jaw muscles to bulge and contraction
- gives rise to essential chewing functions
Parietal Bone
paired bones that form most of the upper lateral side of the skull; they join together at the top of the skull
Sphenoid Bone
Forms much of the base of the central skull and extends laterally to contribute to the sides of the skull
Maxillary Bone
Forms the upper jaw, much of the hard palate, the medial floor of the orbit, and the lateral base of the nose
- hold upper teeth
- maxillary sinuses
Palatine
posterior part of hard palate
forms secondary hard palate (maxilla + palatine)
Secondary Hard Palate
maxilla + palatine
gives separation of nasal and oral cavities to chew and breathe at the same time (efficiency)
Nasal Bones
Paired bones that articulate with each other to form bridge of the nose
- support the cartilages hat from the lateral walls of the nose
Zygoma
Paired irregular bone that defines the anterior and lateral portions of the face (the cheekbones)
Mandible
Lower jaw/jawbone “chew bone”
Hyoid Bone
- does not articulate with any other bone
- the inferior portion is connected to the thyrohyoid ligament
- the superior portion is suspended from the mandible via muscles
- supports the tongue
Auditory Ossicles
External auditory meatus
- 3 ear bones
- malleus
- incus
- stapes
Axial Skeleton
Skeletal elements of the long axis of the body
- vertebrae/vertebral column
- ribs and sternum
Vertebral Column
- composed of interlocking vertebrae
- chain that is linked
- motion matters and flexibility
- can be cartilaginous (cartilage) or osseus (bones)
What happens without a rib cage?
- increases the amount of motion
- primarily protects the nerve cord and blood vessels
Functions of Vertebral Column
- movement
- flexibility
- protect the nerve cord (dorsal tubular nerve cord)
- structure for body
Regional Specificity
The different regions of the vertebrae have varying specific functions
Cervical
Of or like the neck
- hold up the neck
Thoracic
Chest/thorax
Sacrum
Butt bone - 5 fused vertebrae for support
Coccyx
Tailbone
Posterior
Toward back
Anterior
Toward front
Lumbar
- support whole body weight and holds you up
What causes lower back pain?
- weak lumbar
- shift, rupture, or bulge in vertebrae
- intervertebral disc issues
- can be strengthened with exercise and stretching to improve muscle pain
Cervical Vertebrae
- thin and small
- hold up neck
- transverse foramina are unique to these
- bifid (y-shaped) spine
- limits movement and gives more support
Atlas and Axis
1st and 2nd Cervical Vertebrae
- work together to cradle and move the skull independently of the body
Thoracic Verebrae
Thorax: mid-body
- support more mass of the body
- centrum is larger
- added flexibility, movement
- more places for muscles to attach
- overlapping
~ allows for movement
~ longitudinal ridges
~ flexion (modest)
~ stabilize
Lumbar Vertebrae
- short and square
- surface area for muscle attchment
- stability
- supports much of the body weight
Sacral Vertebrae
Form sacrum
- 5 fused vertebrae for more stability and shock absorption
- resistance to high forces
- support body weight
- resist gravity
- allows you to move
Earliest form of Vertebral Column
- float in water
- flexibility
- just protect nerve and blood vessels
Amphibians - Evolution to land
- increase range of motion
- more flexibility
- all vertebrae are the same
- origin of atlas to hold head up
- “fish with legs”
- breathe through skin, don’t need rib cage
Reptiles - Evolution
- increase travel
- specialization in vertebrae
- breathe by negative pressure (gastralia)
Birds - Evolution
- more cervical vertebrae = more head rotation
- specialized
- cervical, thoracic
- controlled crash landing
- sacrum and lumbar vertebrae fused to absorb force
- ribs modified with uncinate process because different ventilation
Sternum
- a mid-ventral endochondral structure
- secures ribs, provides origin sites for chest muscles, protects heart, and lungs
- muscle attachment and support
Appendicular Skeleton
The limbs - lateral (arms/legs)
Limbs of Ancestral Vertebrates
- 1 bone in brachium and thigh (humerus and femur)
- 2 bones in distal limb portions (tibia/fibula, radius/ulna)
- manis/pes with 5 digits
Evolution of Limbs
- used to be short, thick bones to bear weight
- different angle to solely hold up the body and allow for movement
- Primary function to support the body
- bones were elongated for new functions
Roles of Limbs
- arms and legs are similar but fundamental roles are different
- different by how they are shaped, attached
Pectoral Girdle
- attached the forelimb to axial skeleton
- includes scapula, clavicle, and associated soft tissues
- attached more loosely
- does not bear body weight
- more muscle to bone to increase motion
- used to be heavy and primarily functioned for support of the body
Pelvic Girdle
- attached very tightly
- bears lots of weight
- increase bone to bone interactions to absorb force
Humerus
Upper arm bone
- has contour and is uneven to allow for more muscle attachement
Radius and Ulna
Two bones that make up the forearm
- radius rotates while ulna is essentially held in the same place
- interosseous membrane connects them to increase support
Scapula
- wide and flat = allows muscle attachment
- scapular spine = fine muscle movement
Clavicle
- held by soft tissue
- gives movement of the arm above perpendicular range
- can dislocate
- muscle, loose joints for range of motion
Femur
- on an angle - increase angle puts more stress on the knees
- strength and twist
- trochanter gives angles and area for muscle attachment
Tibia and Fibula
- combined increase balance
- malleolus are anchors and stabilize against certain movements
- functionally one bone
- are not one bone because it would limit the flexibility too much
Patella
Embedded in the tendon
- increases flexibility and range of motion in the knee
The Foot
- reduce sideways rotation
- increase up-down rotation (dorsal-ventral)
- arch = spring in your step
- heavier bones in the feet, more solid
- Talus holds all body weight and gives flexibility
- extending the Achilles’ tendon increases power
Hind limb
- early = single joint
- later = more joints to increase motion
- some fusion of bones to absorb force
Innominate Bones
- fuse with sacrum
- fuse at pubic symphysis
- more estrogen receptors on fibrous tissue
- more estrogen = more prone to damage bc looser
- more testosterone usually stabilizes estrogen amounts
- over time, the acetabulum developed
Fused bone …
ABSORBS FORCE ON IMPACT
Ribs
Bony struts that fuse with vertebrae
- only humans ribs attach to sternum
Function of ribs
- hold muscles
“Hangars” - protection
- muscle attachment
- volume for breathing
- structure
