Plastic region Stress (force/c.s. area) Strain (deformation) Elastic region 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 CT B – Molecular structure of the material

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

Bone Growth and 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 = cartilage Purple = calcified cartilage Pink = bone

B – enlarged detail of bone formation Blue = cartilage Purple = calcified cartilage Pink = 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 ligament Periosteum Dermal bone 1. Coronal suture

Functional synarthroses Reinforced frontal nasal Not synarthroses

Synchondroses

Sympases –Fibrocartilage –Some elastin 1.Symphysis mentalis 2.Synchondrosis sphenooccipitalis 3.Synchondrosis intraoccipitalis anterior 4.Fonticulus posterior 5.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 parts A. Braincase (elements touching brain). B. Face or Rostrum

Neurocranium Protects brain Arises as cartilage (ontogenetically and phylogenetically) Replaced by bone Chondrocranium