Head (Cephalon)

Head in insects is in a solid capsule, as a result of coalescence of the six segments of embryonic: akron, antenaly, interkalary, mandibulary, maxillary, labialis. On his head are his lip components consisting of the upper lip (labrum), the lower lip (labium), the upper jaw (mandible) and lower jaw (maxilla). By analyzing embryonic development, it was concluded that all the lip parts except labrum incurred from the of jointed limbs.

On the head there are the following limbs:

• one pair of tentacles,
• simple and complex eyes (ocele and facete).

The head being composed of the following components:

• frons
• vertex
• occiput – back of the head
• foramen occipitale – back of the head opening
• clypeus – head shield
• gene – faces
• tempore

The shape of the head may be: globular, oval, elongated and flattened.

Head position can be:

• Ortognatly – when the mouth turned down, and forehead forward.
• Prognatly – mouth turned forward, and forehead is on the up.
• Hypognatly – forehead is facing up, and the mouth are placed between the front legs.

Neck region (cervix) – colum

-The link between the head and chest. Consists of a cylindrically shaped membrane, in which are embedded sklerits. Extends from foramen occipitale to the front chest. Cervix sklerits are the most developed at orders Orthoptera and Odonata.

Tentacles – Antennas

All insects except the insects belong to the order Protura have one pair of tentacles. Length of tentacles can be very different, Length of tentacles can be very different from those that are very developed, to those who are very reduced, especially in larval instars. Tentacles are located between or in front of the eyes. Consist of three parts:

• basic ancle (scapus),
• holder (pedicelus),
• whip (flagellum)

Scapus is fixed in the membranous portion of the head, which is called antenifer, and can boot in any direction and it is the longest of all the ancles.

Pedicelus is the second, it’s short and it is Dzonston’s acustic organ.

Flagellum is the longest part and is usually divided into a number of similar rings that are connected with membrane.

At orders Pterygota and Sanura tentacles are powered by muscle (levator and depressor). For starting tentacles serve the muscles that are attached to the pedicelus and the scapus, and called flexor and extensor. Number of rings that builds whip is different, and with different orders and can range up to 25.

Types of tentacles:

• Bristly – each ring is tapered from the base to the top
• Thready – rings have a cylindrical shape of the same thickness
• Stringy – rings look like beads
• Serrated – each ring has a triangular elongation
• Pectinate – rings have teeth like a comb
• Plumose – rings having 1 or more additives with both sides
• Head lettuce – segments are at the top increased
• Fan – are extended to the top of the whip on the side as a fan
• Head lettuce with bristles – head lettuce type, which have a thickening of the head lettuce addition in the form of bristles and feathers.