Skeleton and Joints

What name is given to the cells that secrete ground substance and collagen to form the rigid gel of cartilage?

Cartilage has its own blood and nerve supply.

Why must cartilage be relatively thin?

When deformed, [blank_start]proteoglycans[blank_end] in the cartilage 'give up' fluid. When the force is removed, fluid is 'drawn back in'. This provides a mass movement of [blank_start]nutrient[blank_end] supply and [blank_start]metabolite[blank_end] removal.

Bones provide a store of calcium and which other element?

Label this image of a long bone to show the different parts.

What name is given to the line that forms after the epiphysial plate stops producing bone (i.e. when growth stops)?

There are three types of cells in bone. [blank_start]Osteoblasts[blank_end] form new bone via the production of osteoid. They also control the deposition of calcium and other minerals. [blank_start]Osteocytes[blank_end] are formed when an osteoblast become embedded in the matrix they secrete. These can send out 'branches' to connect to other cells of their kind. [blank_start]Osteoclasts[blank_end] dissolve bone to prep for repair and replacement. They are usually formed from the fusion of multiple cells, meaning they are multinucleate.

What name is given to the bones of the head and trunk?

What name is given to the bones that support the appendages (i.e. the limbs and the pelvis)?

Label this image with the classifications of each type of bone.

Which type of ossification occurs whereby the bone develops by replacing hyaline cartilage in the embryo?

Endochronal ossification is the origin of all bones below the skull except the...

Fill in the blanks below to describe the process of endochronal ossification. 1. A bone [blank_start]collar[blank_end] forms around the [blank_start]hyaline[blank_end] cartilage model. This occurs when the perichondreum is vascularised, supplying nutrients which allow the [blank_start]mesenchymal[blank_end] cells to differentiate into [blank_start]osteoblasts[blank_end] which gather at the diaphysis wall. 2. [blank_start]Chondrocytes[blank_end] within the central cavity enlarge, causing the matrix to [blank_start]calcify[blank_end]. This matrix is then impermeable to nutrients causing the cells within to [blank_start]die[blank_end]. This forms a cavity supported by the bone collar. 3. The [blank_start]periosteal bud[blank_end] invades the cavity. forming spongy bone. 4. [blank_start]Osteoblasts[blank_end] break down new spongy bone to form the [blank_start]medullary[blank_end] cavity. The [blank_start]secondary[blank_end] ossification centres appear at the [blank_start]epiphyses[blank_end]. 5. Once ossification of the epiphyses is complete, hyaline cartilage remains only at the epihyseal [blank_start]plates[blank_end] and the [blank_start]articular[blank_end] surfaces.

What name is given to the connective tissue containing arteries, veins, lymphatics and nerves that invades the central cavity of a developing bone to deliver osteogenic cells?

Intramembranous ossification forms mainly flat bones such as the cranial bones and the clavicle.

Fill in the blanks to describe the process of intramembranous ossification. 1. [blank_start]Mesenchymal[blank_end] cells aggregate and differntiate into [blank_start]osteoblasts[blank_end], forming the [blank_start]ossification[blank_end] centre. The osteoblasts begin to secrete [blank_start]osteoid[blank_end] inwards towards this centre. 2. [blank_start]Peripheral[blank_end] msecnhymal cells continue to differentiate. Osteoblasts become trapped in the central space and differentiate into [blank_start]osteocytes[blank_end]. 3. The ostoid [blank_start]calcifies[blank_end] and hardens to form the hardened bone matrix. 4. Osteoid continues to be deposited randomly around embryonic [blank_start]blood vessels[blank_end] to form the trabeculae. 5. The remaining mesenchymal cells around the central bone differentiate into the [blank_start]periosteum[blank_end]. [blank_start]Lamellar[blank_end] bone replaces spongy bone at the outer edges of the trabecular bone in compact layers.

What is an osteon?

Osteons are aligned in the same direction in compact bone.

Label this diagram to show the different histological structures within bone.

An osteon forms a cylindrical structure with a central cavity. In the centre is the [blank_start]Haversian[blank_end] canal. This contains [blank_start]blood vessels[blank_end] and nerve fibres to supply the bone. Surrounding the Haversian canal are concentric layers of compact matrix known as [blank_start]lamellae[blank_end]. These lamella are connected by [blank_start]canaliculi[blank_end] and contain spaces known as [blank_start]lacunae[blank_end] which are occupied by [blank_start]osteocytes[blank_end].

What name is given to the canals which connect adjacent osteons via their Haversian canals and connect these Haversian canals to the periosteum?

What is the periosteum?

How does trabecular bone help withstand pressure?

Fill in the blanks to describe the inner structure of trabecular bone.

What classification name is given to joints where two bones are united by collagen?

Which type of fibrous joint is seen only in the skull whereby the cranial bones are joined by interdigitations and Sharpey's fibres?

Sharpey's fibres join two cranial bones together at a suture joint and consist of bundles of what type of collagen?

What type of fibrous joint is formed when an interosseus ligament joins two bones, often seen in the lower arm and leg between adjacent long bones?

What type of fibrous joint binds the teeth to bony sockets in the maxilla mandible consisting of tough ligaments?

Cartilaginous joints occur where two bones are united by cartilage.

A symphysis is a [blank_start]cartilginous[blank_end] joint where two adjacent bones join. The apposing surfaces of the two bones are covered in [blank_start]cartilage[blank_end] but are separated by an intervening disc of [blank_start]fibrocartilage[blank_end]. This contains numerous bundles of thick [blank_start]collagen[blank_end] fibres to provide resistance against shock. Symphysis are found between the spinal vertebrae and between the [blank_start]pubic[blank_end] bones of the pelvis.

A synchrondrosis is a [blank_start]cartilaginous[blank_end] joint that develops between bones of [blank_start]endochronal[blank_end] origin. A solid plate of [blank_start]hyaline[blank_end] cartilage occurs between the two apposing surfaces forming the epiphyseal [blank_start]plate[blank_end] and is seen between ribs and the [blank_start]sternum[blank_end].

What name is given to a joint where two ends of bone are united by a fibrous capsule even though they don't technically make contact with one another?

Fill in the blanks on this diagram to label the 6 different types of synovial joint.

What name is given to the sacs filled with synovial fluid that occur where structures move in tight apposition to prevent bone-bone contact?

The synovial membrane lines the capsule but not the articular surface.

Fill in the blanks to label the synovial joint shown here.

The viscosity of the synovial fluid is constant.

What happens to the hyaline cartilage on the articular surface of a bone at a synovial joint when force is exerted on the bone?

Which part of the synovial joint has a rich capillary network and allows both secretion and absorption of the synovial fluid?

[blank_start]Concentric[blank_end] contraction is muscle contraction that increases tension on a muscle as it shortens to generate force. [blank_start]Eccentric[blank_end] contraction is muscle contraction occurring as it lengthens under load. [blank_start]Isometric[blank_end] contraction is contraction that does not change the length of the muscle as it holds a steady load.

A [blank_start]uniaxial[blank_end] joint can move about one axis of movement. A [blank_start]biaxial[blank_end] joint can move about two axes of movement perpendicular to one another. A [blank_start]multiaxial[blank_end] joint can move about three or more axes of movement. A [blank_start]non-axial[blank_end] joint can move in all directions.