plastic region stress (force/c.s. area) strain (deformation) elastic region yield point fracture

Plastic region

Str

ess

(for

ce/c

.s.

area

)

Strain(deformation)

Ela

stic

regi

on

Yield point fracture

Connective tissues (revisited)

• Extracellular matrix / producing cells = High

• ECM– HOH, Proteins, Carbs.– Ex. “loose fibrous CT”, dense CT, Tendon, Ligament,

Bone, etc.

• Morphology of CT:– Collagen/Elastin ratio– Arrangement of fibers

• dependent upon forces acting on the material.

A – major components of Loose, fibrous CTB – Molecular structure of the material

Arrangement of collagen fibers in dense CTA – dense irregular CT (dermis of skin)B – layers of a ligamentC – cable-like arrangement of a tendon

Bone Growthand Joints

Bone growth and remodeling

• Two (three) types of bone:

1. Membrane bone – bone forming within connective tissue (=dermal bone)

– Neurocranium (skull), scapula

Osteoblasts osteoid trabeculae (small beam)

Types of bone (continued)

2. Cartilage replacement bone

1. Endochondral bone – bone that forms within cartilage

2. Perichondral bone – forms in CT on surface of bone

– Long bones

Development of the femur in a late embryo or fetus of a mammal.A – original cartilage being replaced by bone on periphery (perichondral bone)

original cartilage being replaced by bone within cartilage (endochondral bone)

Blue = cartilagePurple = calcified cartilagePink = bone

B – enlarged detail of bone formation

Blue = cartilagePurple = calcified cartilagePink = bone

Notes on Joints (articulations)

• Structure and function dependent upon:– Degree and direction of movement needed– Forces acting upon the joint– Nature of the material at articulation

• C – C• B – B• C – B

Classification based on overall movement and material

• Synarthroses – restricted movement– Sutures

Sutural ligamentPeriosteum

Dermal bone Dermal bone 1. Coronal suture

Functional synarthroses

• Reinforced

frontal nasal

Not synarthroses

• Synchondroses

• Sympases– Fibrocartilage– Some elastin

1.Symphysis mentalis

2.Synchondrosis sphenooccipitalis3.Synchondrosis intraoccipitalis anterior4.Fonticulus posterior5.Synchondrosis intraoccipitalis posterior

Diarthroses (synovial joints)

• Lots of movement– Knee– Jaw

Functional Types of Joints

Gliding joints

Cranial and Visceral Skeletons

Chapter 9

The cranial skeleton

• Three phylogenetic elements: A. Chondrocranium (= neurocranium). B. Splanchnocranium (= visceral skeleton). – Supports gills (gill arches), – In gnathostomes:

• jaws • ear • hyoid apparatus

C. Dermatocranium. Dermal bones.

Tetrapod Skull

• Two basic partsA. Braincase (elements touching brain). B. Face or Rostrum

Neurocranium

• Protects brain

• Arises as cartilage (ontogenetically and phylogenetically)

• Replaced by bone

• Chondrocranium