A completely immobile joint, that is a site of bony fusion (as indicated by the red circle on the image below) is called a:

Below is a magnified image of the medullary cavity of a developing Rat Bone. The medullary cavity contains bone marrow in both fetal and adult long bones.

What cell types would you expect to be present in bone marrow (fetal or adult)?

Below is an image of the developing Rat Knee Joint. Refer to the smaller image (top right) for the location of this magnified section.

What tissue is shown in this image?

Below is a magnification of the developing Rat Knee Joint. Refer to the smaller image (top right) for the location of this magnified section.

Observe the following:

• the articular surface of these bones are labelled, and
• the tissue type of the structure labelled A is similar to that of structure B.

What tissue type is found where structure A is labelled? What is the structure labelled B?

The structure/tissue on the left is:

The tissue below is:

The tissue below is:

The structure indicated with the red arrow is:

The structure indicated is:

TRACHEA

The trachea (label 26) is a tube that connects the pharynx and larynx to the left (label 29) and right (label 12) bronchi (and lungs), allowing the passage of air. You will learn more about this in Wk5 & 6.

The trachea has C-shaped rings. 

There are fifteen to twenty incomplete C-shaped tracheal rings of hyaline cartilage that reinforce the front and sides of the trachea to protect and maintain the airway (these are just visible in the specimen below).

The cartilaginous rings are incomplete posteriorly to allow the trachea to collapse slightly so that food can pass down the oesophagus (label 8). Thus there is a membranous wall at the back, without cartilage.

Circular bands of fibrous connective tissue join the tracheal rings together. 

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The trachea is lined with a layer of ciliated pseudostratified columnar epithelium. The epithelium contains goblet cells, that produce mucins, the main component of mucus. Mucus sits on top of the ciliated cells of the trachea to trap inhaled foreign particles that the cilia then move upward where it can be either swallowed into the stomach or expelled as phlegm.

The oesophagus is lined by stratified squamous epithelium without keratin. The epithelium of the oesophagus has a relatively rapid turnover, and serves a protective function against the abrasive effects of food. Protection is conferred by the secretion of mucus from underlying glands.

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Additional resources:

Visit an@tomedia section trachea & main bronchi

Go to An@tomedia (or access via Monash Library), then navigate to:

'Launch An@tomedia' > Thorax > Systems > #16 Trachea & main bronchi (see image below)

Checklist to consider:

1. Visualise the C-shaped rings on anterior and posterior view
2. What prevents the trachea and main bronchi from collapsing on inspiration? Click on the links

The trachea contains in its layers/wall, which of the following: