Lecture Notes - Axial Skeleton

 Lab Manual Ch 9 - Overview of Skeletal System

 Axial vs Appendicular Skeleton

• Use the hanging skeletons in class to identify axial and appendicular bones:

The Appendicular Skeleton includes the bones of the upper and lower extremities (appendages): the pectoral girdle (scapula, clavicle), humerus, radius, ulna, hand bones; the pelvic girdle (os coxae), femur, tibia, fibula, patella and foot bones

Lab Manual Ch 10 - Bone Classes, Markings and Anatomy

 Exercise 10-1: Bone Classes

Go over this exercise on your own - not much emphasis will be placed on this material

 Exercise 10-2: Long Bone Structure

• Be sure to look at the sagittal/transverse sections of cow femurs at the front lab bench
• long bones like the femur and humerus are made up of long shafts, called diaphyses, and 2 enlarged ends, called epiphyses; in between the diaphysis and epiphyses are growth zones called metaphyses
• when the bones are growing in childhood, the growth zones are made up of cartilage and developing bone; at maturity, bone growth ceases and these zones become completely ossified
• the central part of the diaphysis, the medullary cavity, is hollow and lined with a thin membrane, called the endosteum, which contains bone cells (osteoblasts and osteoclasts)
• the medullary cavity and the cancellous (spongy) bones contain yellow marrow, a fatlike substance
• the spongy bone in the epiphyses of the femur and humerus, in addition to the ribs, sternum and vertebrae, contain red marrow in the adult
• the entire surface of the bone, except for the articular surfaces, is covered by the periosteum - fibrous connective tissue that is well vascularized; the inner layer of the periosteum contains osteoblasts, which produce bone tissue, and osteoclasts, which break it down
• the surfaces of each epiphysis are covered with smooth articular cartilage, specifically hyaline cartilage

Exercise 10-3: Microscopic Anatomy of Compact and Spongy Bone

• compact bone - organized into osteons (Haversian systems), consisting of rings of lamellae, containing osteocytes, around a central canal, where blood vessels run - use femur microscope slide
• osteoblasts - create bone from minerals and collagen
• osteoclasts - destroy bone to liberate minerals into the bloodstream
• together, osteoblasts and osteoclasts regulate the levels of calcium and phosphorus in the blood, and control the composition and structure of bone tissue
• spongy or cancellous bone - made up of an irregular network of thin plates, the trabeculae; red marrow fills the spaces between the trabeculae; the osteocytes sit in lacunae within the trabeculae - use fetal bone microscope slide

Exercise 10-4: Chemical Composition of Bone

• the matrix of bone consists of protein (collagen), which lends flexibility to bone, and minerals (hydroxyapatite, a molecule containing calcium and phosphorus), which lends structural strength - be sure to look at the chicken bones at the side bench - one set has had the minerals leached out of it by acid (vinegar); the other set has had the collagen cooked out of it - can you tell which is which?

Exercise 10-5: Terminology - Bone Processes, Depressions and Openings

• Be sure to view the demonstration materials in the lab to see examples of these terms:

Fossa - a shallow depression or dent in a bone; eg., cranial fossae

Sulcus - a groove or furrow

Meatus - a canal or long tubelike passageway; eg., external acoustic meatus

Sinus - a cavity in bone; eg., sinuses of the skull

Condyle - a rounded, knucklelike knob on a bone, which articulates with another bone; eg., occipital condyles

Tuberosity - a large, roughened process on a bone that serves as a point of attachment for muscle; eg., ischial and tibial tuberosity

Tubercle - a small rounded process

Trochanter - a very large process; eg., greater trochanter of the femur

Head - a portion of bone supported by a narrower part, called the neck; eg., the head of the femur

Crest - a narrow ridge of bone; eg., iliac crest

Spine - a sharp slender process; eg., vertebral spines (spinous processes)

Suture - where 2 plates of bone interconnect; eg., skull sutures

Conchae - curved scrolls of bone; eg., nasal conchae

Lab Manual Ch 11: The Skull

Skull - know all structures, foramina (and any blood vessels that go through the foramina - we will learn what cranial nerves go through each of the foramina in the nervous system lab) as listed in the syllabus; use your lab manual and ArtPak figures as guides to finding the structures

 Fetal Skulls - be able to identify the fontanels

 Lab Manual Ch 12: Vertebral Column and Thoracic Cage

 Vertebral Column - know all structures on the vertebrae, be able to distinguish the different types of vertebrae, as listed in the syllabus; use your lab manual and ArtPak figures as guides to finding the structures

 Thoracic Cage - know the parts of the sternum; know the difference between true, false and floating ribs