Hands on and insides out
There will always be a place for the traditional biological model in the school laboratory. These three-dimensional, portable, strong multi-part structures enable students and teachers to pull organisms and organs apart, reassemble, handle and orientate them without training or access to electricity.
Because students use their hands as well as eyes to examine a model, those who have learning difficulties which can be helped by a variety of stimuli have a chance to gain real understanding of anatomical structure. And the level of detail here makes these models suitable for the most elementary to the most advanced classes.
The torso is about half natural size. Most of the skin, muscle and rib cage have been stripped from the vertical surface so the internal organs of the thorax and abdomen are shown in relation to each other. The heart, lungs, liver, stomach and intestinal tract can all be removed to reveal organs and structures such as the kidneys, adrenal glands, ureters and the main blood vessels.
Some of the component organs also "come apart", like the anterior wall of the heart which can be removed, revealing the heart valves and the inner cavities. The stomach can be halved to show the mucous membrane relief and the front half of the right kidney taken out to expose the renal calices, renal pelvis and renal blood vessels. Also shown are the small and large intestines, the pancreas and relevant major blood vessels. The superficial muscle groups are there, revealing the projection of the inner organs on to the body surface.
The model ear is about two-and-a-half times the natural size, and shows the organ of hearing and balance labyrinth and cochlea in its natural position inside the petrosal bone and its association with the middle ear, outer ear and Eustachian tube. The position of the inner ear in relation to the neighbouring blood vessels and adjacent nerves is also shown. The inner ear of the model can be taken out to demonstrate the mechanism by which sound waves are transmitted and the function of the semicircular canals with their ampullae. The tympanic membrane with malleus and incus can also be removed.
By holding the two parts together, the bridge formed by the auditory ossicles and their connection to the inner ear on one side and the tympanic membrane on the other can be shown. The external auditory meatus, middle ear and inner ear are cut to enable teachers to demonstrate the sequence of sound-transmitting cavities.
The model eye is three times larger than life and is shown with the six external muscles attached. Taken apart it reveals such detail as the extension of the retina and the retinal blood vessels, the yellow spot, the numerous ciliary processes and the iris. The cornea, lens and vitreous body are transparent, which makes their role in the transmission of light easy to perceive. The size of the model, like many of the others, makes it best suited to use with small groups.
The human heart is modelled life size. This can be a revelation in itself, especially when it is held against the teacher's chest or inside the rib cage of a skeleton. The front wall can be removed, demonstrating the valves and the inner cavities.