In this section on the ear we'll look mainly at the external and middle ear. The inner ear is so delicate, and so encased in hard bone, that it can't be well shown by dissection. We'll start with the external ear.
The external ear consists of the auricle, which projects from the side of the head, and the external auditory meatus or ear canal, which passes inwards to the tympanic membrane. We'll look at the auricle first.
The folded outer rim of the auricle is the helix. The helix spirals down into the floor of the central concavity, the concha. The rim of the concha is defined by this curved ridge, the antihelix.
Two projections, the tragus, and the antitragus, partly hide the entrance to the external auditory meatus. The shape of the upper three quarters of the auricle is determined by the cartilage that forms its framework. We'll divide the auricle along this line to see the cartilage.
Here's the cut edge of the auricular cartilage. It's highly elastic. The skin of the the auricle is attached to the cartilage closely on the front, less closely on the back. The lowest part of the auricle, the lobule, contains no cartilage. To look at the external auditory meatus we'll remove the auricle, and the surrounding skin.
The external auditory meatus is lined with skin. It isn't straight: it curves slightly upwards, then slightly backwards. The external meatus ends medially at the ear drum, or tympanic membrane. This is part of the tympanic membrane: we'll see all of it in a minute.
The outer part of the external meatus is supported by a partial tube of cartilage. Here's the cut edge of the cartilage: it's continuous with the cartilage of the auricle. To see it better we'll remove the surrounding soft tissue.
Here's the cartilage of the external auditory meatus: it extends much further below, than it does above. To see where we are we'll take a look at the same area in a dry skull. Here's the bony opening of the external auditory meatus. The cartilage of the external auditory meatus is attached to bone here.
Here's the beginning of the zygomatic arch, here just below it is the temporomandibular joint. The condyle and neck of the mandible lie just in front of the external auditory meatus.
Going back to the dissection, here's the capsule of the temporomandibular joint. With a finger in the external meatus, it's easy to feel the condyle moving.
Now we'll remove the mandible, so that we can look at the external meatus from in front. Here's where the cartilage of the external meatus attaches to bone. We'll remove the cartilage, to see the bony part of the external auditory meatus. This brings us closer to the tympanic membrane: here it is. To get a complete view of it we'll remove this part of the bone.