SlideShare a Scribd company logo
1 of 76
Download to read offline
WELCOME
1
THE INSECT HEAD
2
Presented by:
Ch.Naga Satyasri
BAM-14-28
• The insect head is a hard, highly
sclerotized compact capsule bearing a
group of feeding appendages around the
mouth, sensory organs and internally a
major centre of neuroendocrine
coordination.
3
Head Segmentation
• According to phylogenetic considerations,
the insect head is in fact a product of
evolution and can be termed as
Syncephalon.
• It consists of two parts.
An anterior procephalon and
a posterior gnathocephalon.
4
PROCEPHALON
• The procephalon represents preoral region
of the head and bears two paired
structures, the eyes and antennae.
• The procephalon is thought to be derived
from the ancestral head, the
archencephalon or blastocephalon, after
an incorporation of at least one posterior
trunk segment of the ancestor.
• The brain is considered as a fused
ganglion of the procephalon.
5
GNATHOCEPHALON
• The gnathocephalon represents postoral
region of the head.
• It bears three paired structures;
the mandible, first maxillae and second
maxillae or labium. It is mostly developed
in order to equip the head with feeding
appendages.
6
7
• Embryological and morphological studies
suggest that the gnathocephalon is
composed of three segments, viz., the
mandibular, maxillary and labial segments.
• In an adult insect, these segments are
evident from their paired appendages.
• The suboesophageal ganglion is
undoubtedly, a composite ganglion of the
gnathocephalon.
8
• Based on the embryological studies, the
segments of insect head are six such as:
1. Pre antennal segment
2. Antennal segment
3. Intercalary segment
4. Mandibular segment
5. Maxillary segment
6. Labial segment
9
10
• 1.Preantennary segment:
It is recognized by its neuromere that forms
procerebrum of the brain and embryonic
appendages.
• 2.Antennary segment:
It is indicated by its neuromere that forms
deuterocerebrum of the brain and its
appendages are antennae.
• 3. Intercalary segment:
Intercalary segment is with feeding
appendages which are homologous with
antennae of crustacean and its neuromere,
tritocerebrum. Traces of this segment are
found in most embryos.
11
• 4.Mandibular segment:
It is indicated by its neuromere, the mandibular
ganglion and its appendages the first maxillae.
• 5.Maxillary segment:
It is recognized by its neuromere, the maxillary
ganglion and its appendages the first maxillae.
• 6.Labial segment:
Labial segment in with its appendages the labium
and neuromere, labial ganglion.
The neuromeres of the last three segments fuse
during development to form the sub-oesophagial
ganglion.
12
HEAD SKELETON
• The head of the insect loses its primary
segmentation during the post-embryonic
development.
• Due to enormous sclerotization, the head becomes
a hard skeletal capsule.
• It bears externally a set of sensory and gnathal
appendages.
• The sense organs include a pair of antennae, a pair
of compound eyes and two or three ocelli.
• The gnathal appendages comprise a pair of
mandibles, a pair of maxillae and a labium.
13
• The gnathal appendages constitute
collectively along the labrum and
hypopharynx, a well elaborated feeding
apparatus.
14
• The position of mouth parts in relation to
the body axis differs in different group of
insects. The mouth parts may project
downward, forward or backward and the
head, accordingly, is designated as the
following types.
15
Hypognathous head:
• The long axis of the head is vertical and
mouthparts are ventral i.e., pointing
downwards (primitive type). The occipital
foramen lies in or near transverse plane.
Ex: Grasshoppers, cockroach.
16
17
Prognathous head:
• The long axis of the head is horizontal,
mouthparts are anterior in position
occipital foramen is slightly inclined. Ex:
Soldiers of termites and larvae of
endopterygota
18
19
Opisthognathous head:
• Occurs in Homoptera and Hemiptera
where the head is deflexed backwards so
that mouthparts / proboscis slopes
backwards between the front legs.
20
21
HEAD SUTURES
• The head capsule of the matured insects is
differentiated into several regions by the
sutures.
• The sutures are nothing but the secondarily
developed fine groves.
• They are inflections or merely external
impressions of the internal stiff cuticular
ridges which provide mechanical support to
the cranial wall.
• These sutures are the product of
sclerotization and except the post-occipital
suture, others have no metameric
segmentation.
22
23
The Clypeo-labral suture:
• This suture represents the lower margin of
the clypeus.
• The labrum hanging down from the suture.
• It bears a prominent ridge internally.
• The ridge possesses an apodeme at the
centre. The apodeme provides an
insertion to the anterior retractor muscles
of the labrum.
24
25
26
The Clypeo-frontal or Epistomal suture:
• It occurs between the clypeus and the
frons.
• It bears laterally the anterior tentorial pits.
• It internally bears a strong inflection.
• Those inflection strengthens the lower part
of the head against the stretching of the
mandibles.
27
28
The Epircanial suture:
• It is a composite suture.
• It appears in the form of an inverted-Y above
the facial region in most of the insects.
• The stem is known as the coronal and lateral
arms, the frontal sutures.
• The epicranial suture is partially or even
completely reduced in some insects.
29
• It is totally lacking from the head of
apterygotes.
• Snodgrass (1935) and Du porte (1957)
stated that the epicranial suture represents
merely the line of weakness and can be
said in true sense as the ecdysial suture.
• It does not bear the skeletal ridge on the
inner surface and therefore does not
provide either a site for muscle attachment
or mechanical support to the head capsule
30
31
The Occipetal suture:
• It is horse-shoe or U-shaped suture, and well
evident on the posterior part of the head of the
orthopteroid insects.
• It starts from posterior articulations of the
mandibles of either side.
• Both the arms after running a long distance
and join one another above the occipital
foramen.
32
• It seperates the genal area from the post-genal
area of the lateral region of the head.
• It also differentiates the vertex from the
occiput in posterior region of the head.
• It forms an internal ridge strengthening the
posterior epicranial wall.
33
34
The post-occiput suture:
• It embraces the occipital foramen magnum
from the dorsal and lateral sides.
• Each end of the suture merges in the
hypostomal suture in ventral region.
• This site is well defined due to the
presence of the posterior tentorial pits.
• It possesses internally a strong epidermal
ridge, the post-occipetal ridge.
35
• It provides a site for the attachment of
prothoracic muscles which move a pair of
ventro-lateral condyles. The neck membrane
is firmly attached to this ridge.
• The condyles articulate with the neck
sclerites.
• It is the only suture having the metameric
significance. It alone marks the fusion of the
maxillary and labial segments of the head.
36
37
38
The Frontogenal or subocular suture:
• It develops on each lateral region of the
head. It starts from the junction of the
clypeofrontal and the subgenal sutures.
• It terminates in the close vicinity of the
lower margin of each compound eye.
• It is virtually well evident in the
orthopteroid insects.
39
The Subgenal Suture:
• These sutures occur on the lateral sides of
the head.
• Each suture joins the posterior tentorial pit
with the anterior tentorial pit of the same side.
• Each suture is divisible into two parts.
• One part of the subgenal suture is called the
hypostomal suture.
• The hypostomal suture runs from the
posterior tentorial pit up to the posterior
articulation of the mandible.
40
41
• The other part of the subgenal sututre is
called the pleurostomal suture.
• The pleurostomal suture arches over the
mandible and finally joins with the fronto-
clypeal and the fronto-genal sutures just
above the anterior articulation of the
mandibles.
• Internally, the subgenal sutures form the
submarginal, subgenal ridges.
• Each ridge extends from the posterior
tentorial pit to point just above the anterior
articulation of the mandible. 42
The subgenal sutures strengthen the cranial
wall along the lines of attachment of the
gnathal appendages
The Ocular suture:
• These sutures are the annular grooves
around the compound eyes. They form the
skeletal ridges internally.
43
44
The Antennal Sutures:
• The marginal depressed ring around the
antennal sockets are known as the antennal
sutures.
• Each suture gives internally the submarginal
ridge.
• The submarginal ridge in a large number of
insects bears a pivot like process known as
the antennifer.
• The antennifer provides articulation to the
antenna.
45
46
HEAD SCLERITES
The sclerites represent simply, the intersutural areas.
The head of the generalized insect is typically exhibiting
the following sclerites.
(a) The labrum
(b) The clypeus
(c) The frons
(d) The epicranium
(e) The occiput
(f) The post-occiput
(g) The Genae and subgenal areas
(h) The Ocular sclerites
47
48
(a) The labrum:
• It is freely attached to the lower margin of the
clypeus by the clypeolabral suture, generally
hanged over the mouth or preoral cavity and also
termed as an upperlip.
• In the fluid-feeding insects it undergoes various
modifications.
• Internally it forms anterior part of the
epipharyngeal wall of the preoral cavity.
• It is internally lined with the gustatory receptors
and can be moved upwards downwards and be
pulled and pushed, to some extent, due to the
elastic nature of the suture and muscle innervaton.
49
• The labrum is innervated by the following
three types of muscles.
(i) Compressor labral:
• They may occur in a pair on lateral sides
or a single median one. They are attached
by one end on the anterior and by the
other end on the posterior end wall of the
labrum. The compressors bring the
retraction, prolongation and contraction of
the labrum.
50
(ii) The anterior labral:
• They are paired but unbranched labral
muscles. They originate from the inner
surface of the frons. They move the labrum in
forward direction.
(iii) The Posterior Labral:
• They are the paired but branched labral
muscles. They originate from the anterolabral
regions of the frons. The muscles pull the
labrum backward.
51
52
(b) The clypeus
• This sclerite is demarcated by the
clypeolabral and clypeo –frontal sutures
from the anterior and posterior sides.
• It thus occupies the position in-between
the anterior labral and posterior frontal
sclerites.
• In some insects, it is completely or
partially divided into two parts by a
transverse suture.
53
• The posterior part is termed as the post-
clypeus and the anterior part is termed as
anteclypeus.
• Both parts of the clypeus can be seen in the
case of crickets.
• The post clypeus modifies into a convex
process, termed as the ginglimus of the
mandible.
• This is the sclerite on the head on which arise
the cibarial dilator muscles.
54
55
(c) The frons:
• It extends from the anterior clypeo-frontal
suture to the posterior frontal sutures.
• In the orthopteroid insects, it possesses the
median ocellus.
• In some cases, it may bear the lateral ocelli
also.
• The frons represent typically an upper facial
region of the head.
• The pharyngeal dilators, labral,
hypopharyngeal muscles and the adductors
of mandibles are usually inserted on the
middle of the frons.
56
57
(d) The Epicranium:
• The epicranium suture separates the epicranium
from the frons.
• It represents the entire upper region or top of the
head.
• It extends from the anterior frontal to the posterior
occipital suture.
• Above the frons, it is divided into two identical
lateral plates, known as parietals.
• The parietals are characterised by bearing the
antennae, lateral ocelli and compound eyes.
• The posterior undivided region of the epicranium is
known as vertex.
• It forms top of the head.
58
(f) The post-occiput:
• The occipital foramen is encircled from the
dorsal and lateral regions by a narrow
sclerite, the post-occiput.
• It lies between the occiput and the neck.
• The post-occiput is marked off from the
occiput by a transverse post-occipital
suture.
• When the post-occipital suture remains
absent, the posterior tentorial pits separate
the post occiput from the occiput.
59
• The dorasal muscles are attached to the
endoskeletal ridge of the post-occipetal
suture.
• These muscles are articulate the head freely.
The antero-lateral inner margin of the post-
occiput produces small processes.
• These sutures are termed as the occipital
condyles.
• Each condyle articulates with the anterior
lateral cervical sclerites.
60
61
(e) The occiput:
• It is U-shaped posterior or hinder cuticular
band. It represents the area from the
occipital to the postoccipetal sutures.
62
63
(g) The Genae and subgenal areas:
• The genae represent the lateral areas of the
head.
• On either side, the genae extend from the
compound eye to the mandibular trochantin.
• The hinder part develops in to the socket to
accommodate the mandibular condyle.
• Posterior to the occipital suture, each lateral
gena is commonly called as the postgena.
• Each postgena provides the condylar
articulation for the maxillae.
64
• The subgenal area above and below the
mandibles can be referred to as the
pleurostoma and hypostoma, respectively.
These areas are separated in some
insects by the suture, the hypostomal
suture.
• Similarly the pleurostomal suture
separates the pleurostoma from the base
of the mandibles.
65
(h) The Ocular sclerites:
• They form a cuticular ring around each
compound eye.
• (i) The Antennal sclerites: They form an
annulus at the base of the antenna. The
antennal sclerites are well developed in the
plecoptera.
• (ii) The Mandibular Trochantin: It occurs
quite distinctly between the mandibular base
and the pleurostoma or the pleurostomal
suture.
66
67
Tentorium:
• It is an endoskeleton structure.
• It is composed of three pairs of arms, the
anterior, posterior and dorsal tentorial
arms.
• The anterior tentorial arms develop from
the anterior tentorial pits in the subgenal or
epistomal suture.
68
• The posterior tentorial arms arise from the
posterior tentorial pits in the lower ends of
the post-occipital suture.
• The dorsal tentorial arms take origin in the
form of secondary out-growths of the
anterior arms.
• All these tentorial arms unite in the middle
forming an expanded central skeletal
platform.
• It may simply constitute a structure
resembling the X.
69
• The presence of a broad tentorial plate
occurs commonly in the pterygote insects
and is commonly known as the
corporotentorium.
The anterior tentorial pits:
• The anterior tentorial arms of the tentorium
arise from some part of subgena or epistomal
suture.
The posterior tentorial pits:
• The posterior tentorial arms of the tentorium
arise from ventral ends of post occipital
suture and lie in the lower extremities of post
occipital suture
70
71
Modifications in head capsule:
• The anterior frontoclypeal and posterior,
lateral as well as ventral regions of the
head capsule are greatly modified in some
insects.
72
1.Fronto-clypeal Region:
• The epistomal suture is wanting in cockroaches
and some other insects in which the clypeal region
can be separated from the frontal region by the
position of anterior tentorial pits.
• Sometimes the frontal sutures are also indistinct.
• In the Hemiptera, Hymenoptera and Lepidopteran
larvae, the frons is greatly suppressed.
• In these insects, on the basis of position of the
dilators of cibarium or that of buccal cavity, the
clypeal region can be recognised.
• Similarly the frontal region can be identified by the
position of a median ocellus and origin of labral
muscles.
73
2.Hypostomal bridge:
• In the lepidopteran larvae, the hypostomal
lobes do not unite together while in other
insects, they fuse at the middle forming a
complete hypostomal bridge in order to
close the foramen magnum ventrally
74
3.Gula:
• It is a ventral sclerotic plate of the head capsule
separating the foramen magnum from the base of
the labium.
• It is well developed in the insects having
prognathous head in order to place the mouth
parts in forward direction.
• The gula is separated from the laterally expanded
postgenae by the gular structures.
• The gular sutures are in fact modified post-
occipital sutures.
• The gula varies in length and width in different
species of Coleopteran and Neuroptera.
75
76

More Related Content

What's hot

Insect Excretory System
Insect Excretory SystemInsect Excretory System
Insect Excretory SystemAmani Riyadh
 
Sense organs of insects and their structure
Sense organs of insects and their structureSense organs of insects and their structure
Sense organs of insects and their structureManish pal
 
Insect thorax and abdomen
Insect thorax and abdomenInsect thorax and abdomen
Insect thorax and abdomenYuvraj Singh
 
Reproductive system in insect and its types
Reproductive system in insect and its typesReproductive system in insect and its types
Reproductive system in insect and its typesMr. Suresh R. Jambagi
 
Methods of insect collection, preservation, display and storage by Dr. T. Kri...
Methods of insect collection, preservation, display and storage by Dr. T. Kri...Methods of insect collection, preservation, display and storage by Dr. T. Kri...
Methods of insect collection, preservation, display and storage by Dr. T. Kri...krishnachaitanyatiru2
 
Insect wings & their modifications
Insect wings &  their modificationsInsect wings &  their modifications
Insect wings & their modificationsRupakSubhraSarkar
 
Body Segmentation of Insect and Head .pptx
Body Segmentation of Insect and Head .pptxBody Segmentation of Insect and Head .pptx
Body Segmentation of Insect and Head .pptxnaseeruddinshah2
 
Circulatory system of insects
Circulatory system of insectsCirculatory system of insects
Circulatory system of insectsManish pal
 
Insect wing, their modifications and wing coupling mechanism
Insect wing, their modifications and wing coupling mechanismInsect wing, their modifications and wing coupling mechanism
Insect wing, their modifications and wing coupling mechanismMr. Suresh R. Jambagi
 
orthoptera order of insect and its classification.
orthoptera order of insect and its classification. orthoptera order of insect and its classification.
orthoptera order of insect and its classification. Arvind Yadav
 
Physiology of excretion in insects
Physiology of excretion in insectsPhysiology of excretion in insects
Physiology of excretion in insectsbhavnesthakur
 
Reproductive System in Insects
Reproductive System in InsectsReproductive System in Insects
Reproductive System in InsectsChandini S Amaan
 

What's hot (20)

Insect Excretory System
Insect Excretory SystemInsect Excretory System
Insect Excretory System
 
Digestive system of Insects
Digestive system of InsectsDigestive system of Insects
Digestive system of Insects
 
Sense organs of insects and their structure
Sense organs of insects and their structureSense organs of insects and their structure
Sense organs of insects and their structure
 
Insect thorax and abdomen
Insect thorax and abdomenInsect thorax and abdomen
Insect thorax and abdomen
 
Insect Order : apterygota
Insect Order :  apterygotaInsect Order :  apterygota
Insect Order : apterygota
 
Reproductive system in insect and its types
Reproductive system in insect and its typesReproductive system in insect and its types
Reproductive system in insect and its types
 
Insect Order : coleoptera
Insect Order  :  coleopteraInsect Order  :  coleoptera
Insect Order : coleoptera
 
Inscet excretory system
Inscet excretory systemInscet excretory system
Inscet excretory system
 
Insect wings
Insect wingsInsect wings
Insect wings
 
Insects orders
Insects ordersInsects orders
Insects orders
 
Methods of insect collection, preservation, display and storage by Dr. T. Kri...
Methods of insect collection, preservation, display and storage by Dr. T. Kri...Methods of insect collection, preservation, display and storage by Dr. T. Kri...
Methods of insect collection, preservation, display and storage by Dr. T. Kri...
 
Insect wings & their modifications
Insect wings &  their modificationsInsect wings &  their modifications
Insect wings & their modifications
 
Body Segmentation of Insect and Head .pptx
Body Segmentation of Insect and Head .pptxBody Segmentation of Insect and Head .pptx
Body Segmentation of Insect and Head .pptx
 
Circulatory system of insects
Circulatory system of insectsCirculatory system of insects
Circulatory system of insects
 
Insect sense organs
Insect sense organsInsect sense organs
Insect sense organs
 
Insect wing, their modifications and wing coupling mechanism
Insect wing, their modifications and wing coupling mechanismInsect wing, their modifications and wing coupling mechanism
Insect wing, their modifications and wing coupling mechanism
 
orthoptera order of insect and its classification.
orthoptera order of insect and its classification. orthoptera order of insect and its classification.
orthoptera order of insect and its classification.
 
TYPES OF INSECT LEGS
TYPES OF INSECT LEGSTYPES OF INSECT LEGS
TYPES OF INSECT LEGS
 
Physiology of excretion in insects
Physiology of excretion in insectsPhysiology of excretion in insects
Physiology of excretion in insects
 
Reproductive System in Insects
Reproductive System in InsectsReproductive System in Insects
Reproductive System in Insects
 

Similar to Insect Head Anatomy

Insect head:- it’s origin, structure, function and modification in different ...
Insect head:- it’s origin, structure, function and modification in different ...Insect head:- it’s origin, structure, function and modification in different ...
Insect head:- it’s origin, structure, function and modification in different ...N.m.c.a
 
Anatomy head review
Anatomy head reviewAnatomy head review
Anatomy head reviewsarosem
 
Anatomy of Skullbase
Anatomy of SkullbaseAnatomy of Skullbase
Anatomy of SkullbaseJinu Iype
 
Adhesives in maxillofacial prosthesis /orthodontics courses in india
Adhesives in maxillofacial prosthesis /orthodontics courses in indiaAdhesives in maxillofacial prosthesis /orthodontics courses in india
Adhesives in maxillofacial prosthesis /orthodontics courses in indiaIndian dental academy
 
ZooCVABioIII.2013.Abante
ZooCVABioIII.2013.AbanteZooCVABioIII.2013.Abante
ZooCVABioIII.2013.AbanteMariel Marjes
 
Anatomy head review
Anatomy head reviewAnatomy head review
Anatomy head reviewsarosem
 
General Anatomy of the Skull and Central Nervous.pptx
General Anatomy of the Skull and Central Nervous.pptxGeneral Anatomy of the Skull and Central Nervous.pptx
General Anatomy of the Skull and Central Nervous.pptxRUTAYISIRE François Xavier
 
white fibres of cns modified
white fibres of cns modifiedwhite fibres of cns modified
white fibres of cns modifiedMed Study
 
Lec. 6 Body segmentation Structure of head & its types.ppt
Lec. 6 Body segmentation Structure of head & its types.pptLec. 6 Body segmentation Structure of head & its types.ppt
Lec. 6 Body segmentation Structure of head & its types.pptRKPANSE1
 
Adhesives......./certified fixed orthodontic courses by Indian dental academy
Adhesives......./certified fixed orthodontic courses by Indian dental academy  Adhesives......./certified fixed orthodontic courses by Indian dental academy
Adhesives......./certified fixed orthodontic courses by Indian dental academy Indian dental academy
 
2nd year MBBS anatomy mcqs with explanation
2nd year MBBS anatomy mcqs with explanation2nd year MBBS anatomy mcqs with explanation
2nd year MBBS anatomy mcqs with explanationFarhan Ali
 
Ns2. The Nervous System And Some Developmental Problems. Compressed File
Ns2. The Nervous System And Some Developmental Problems. Compressed FileNs2. The Nervous System And Some Developmental Problems. Compressed File
Ns2. The Nervous System And Some Developmental Problems. Compressed Filemedical
 
Review Of Skull And Cranial Cavity
Review Of Skull And Cranial CavityReview Of Skull And Cranial Cavity
Review Of Skull And Cranial CavityDr. Noura El Tahawy
 
Anatomy of the nose ppt-1.pptx
Anatomy of the nose ppt-1.pptxAnatomy of the nose ppt-1.pptx
Anatomy of the nose ppt-1.pptxBaksantino123
 

Similar to Insect Head Anatomy (20)

Insect head:- it’s origin, structure, function and modification in different ...
Insect head:- it’s origin, structure, function and modification in different ...Insect head:- it’s origin, structure, function and modification in different ...
Insect head:- it’s origin, structure, function and modification in different ...
 
Mental Status Examination.pptx
Mental Status Examination.pptxMental Status Examination.pptx
Mental Status Examination.pptx
 
Anatomy head review
Anatomy head reviewAnatomy head review
Anatomy head review
 
The Insect Head
The Insect HeadThe Insect Head
The Insect Head
 
ARTHROPODA MAHENDRA PAL12.pptx
ARTHROPODA MAHENDRA PAL12.pptxARTHROPODA MAHENDRA PAL12.pptx
ARTHROPODA MAHENDRA PAL12.pptx
 
Branchial arches
Branchial archesBranchial arches
Branchial arches
 
Anatomy of Skullbase
Anatomy of SkullbaseAnatomy of Skullbase
Anatomy of Skullbase
 
Adhesives in maxillofacial prosthesis /orthodontics courses in india
Adhesives in maxillofacial prosthesis /orthodontics courses in indiaAdhesives in maxillofacial prosthesis /orthodontics courses in india
Adhesives in maxillofacial prosthesis /orthodontics courses in india
 
ZooCVABioIII.2013.Abante
ZooCVABioIII.2013.AbanteZooCVABioIII.2013.Abante
ZooCVABioIII.2013.Abante
 
Anatomy head review
Anatomy head reviewAnatomy head review
Anatomy head review
 
General Anatomy of the Skull and Central Nervous.pptx
General Anatomy of the Skull and Central Nervous.pptxGeneral Anatomy of the Skull and Central Nervous.pptx
General Anatomy of the Skull and Central Nervous.pptx
 
insect head.pptx
insect head.pptxinsect head.pptx
insect head.pptx
 
white fibres of cns modified
white fibres of cns modifiedwhite fibres of cns modified
white fibres of cns modified
 
Lec. 6 Body segmentation Structure of head & its types.ppt
Lec. 6 Body segmentation Structure of head & its types.pptLec. 6 Body segmentation Structure of head & its types.ppt
Lec. 6 Body segmentation Structure of head & its types.ppt
 
Adhesives......./certified fixed orthodontic courses by Indian dental academy
Adhesives......./certified fixed orthodontic courses by Indian dental academy  Adhesives......./certified fixed orthodontic courses by Indian dental academy
Adhesives......./certified fixed orthodontic courses by Indian dental academy
 
2nd year MBBS anatomy mcqs with explanation
2nd year MBBS anatomy mcqs with explanation2nd year MBBS anatomy mcqs with explanation
2nd year MBBS anatomy mcqs with explanation
 
The limbic system
The limbic system The limbic system
The limbic system
 
Ns2. The Nervous System And Some Developmental Problems. Compressed File
Ns2. The Nervous System And Some Developmental Problems. Compressed FileNs2. The Nervous System And Some Developmental Problems. Compressed File
Ns2. The Nervous System And Some Developmental Problems. Compressed File
 
Review Of Skull And Cranial Cavity
Review Of Skull And Cranial CavityReview Of Skull And Cranial Cavity
Review Of Skull And Cranial Cavity
 
Anatomy of the nose ppt-1.pptx
Anatomy of the nose ppt-1.pptxAnatomy of the nose ppt-1.pptx
Anatomy of the nose ppt-1.pptx
 

More from Naga Satyasri Ch

More from Naga Satyasri Ch (9)

Toxicology
ToxicologyToxicology
Toxicology
 
Bees and wasps
Bees and wasps Bees and wasps
Bees and wasps
 
Pest surveillence and monitoring satyasri
Pest surveillence and monitoring  satyasriPest surveillence and monitoring  satyasri
Pest surveillence and monitoring satyasri
 
Systemic Acquired resistance
Systemic Acquired resistanceSystemic Acquired resistance
Systemic Acquired resistance
 
Pyrimidines
PyrimidinesPyrimidines
Pyrimidines
 
Role of carbohydrates in insect nutrition
Role of carbohydrates in insect nutritionRole of carbohydrates in insect nutrition
Role of carbohydrates in insect nutrition
 
Pests of maize
Pests of maizePests of maize
Pests of maize
 
Birds Management
Birds ManagementBirds Management
Birds Management
 
Insect Mouthparts
Insect MouthpartsInsect Mouthparts
Insect Mouthparts
 

Recently uploaded

Environmental acoustics- noise criteria.pptx
Environmental acoustics- noise criteria.pptxEnvironmental acoustics- noise criteria.pptx
Environmental acoustics- noise criteria.pptxpriyankatabhane
 
The Sensory Organs, Anatomy and Function
The Sensory Organs, Anatomy and FunctionThe Sensory Organs, Anatomy and Function
The Sensory Organs, Anatomy and FunctionJadeNovelo1
 
BACTERIAL DEFENSE SYSTEM by Dr. Chayanika Das
BACTERIAL DEFENSE SYSTEM by Dr. Chayanika DasBACTERIAL DEFENSE SYSTEM by Dr. Chayanika Das
BACTERIAL DEFENSE SYSTEM by Dr. Chayanika DasChayanika Das
 
dll general biology week 1 - Copy.docx
dll general biology   week 1 - Copy.docxdll general biology   week 1 - Copy.docx
dll general biology week 1 - Copy.docxkarenmillo
 
Measures of Central Tendency.pptx for UG
Measures of Central Tendency.pptx for UGMeasures of Central Tendency.pptx for UG
Measures of Central Tendency.pptx for UGSoniaBajaj10
 
Loudspeaker- direct radiating type and horn type.pptx
Loudspeaker- direct radiating type and horn type.pptxLoudspeaker- direct radiating type and horn type.pptx
Loudspeaker- direct radiating type and horn type.pptxpriyankatabhane
 
Introduction of Human Body & Structure of cell.pptx
Introduction of Human Body & Structure of cell.pptxIntroduction of Human Body & Structure of cell.pptx
Introduction of Human Body & Structure of cell.pptxMedical College
 
BACTERIAL SECRETION SYSTEM by Dr. Chayanika Das
BACTERIAL SECRETION SYSTEM by Dr. Chayanika DasBACTERIAL SECRETION SYSTEM by Dr. Chayanika Das
BACTERIAL SECRETION SYSTEM by Dr. Chayanika DasChayanika Das
 
CHROMATOGRAPHY PALLAVI RAWAT.pptx
CHROMATOGRAPHY  PALLAVI RAWAT.pptxCHROMATOGRAPHY  PALLAVI RAWAT.pptx
CHROMATOGRAPHY PALLAVI RAWAT.pptxpallavirawat456
 
6.1 Pests of Groundnut_Binomics_Identification_Dr.UPR
6.1 Pests of Groundnut_Binomics_Identification_Dr.UPR6.1 Pests of Groundnut_Binomics_Identification_Dr.UPR
6.1 Pests of Groundnut_Binomics_Identification_Dr.UPRPirithiRaju
 
ESSENTIAL FEATURES REQUIRED FOR ESTABLISHING FOUR TYPES OF BIOSAFETY LABORATO...
ESSENTIAL FEATURES REQUIRED FOR ESTABLISHING FOUR TYPES OF BIOSAFETY LABORATO...ESSENTIAL FEATURES REQUIRED FOR ESTABLISHING FOUR TYPES OF BIOSAFETY LABORATO...
ESSENTIAL FEATURES REQUIRED FOR ESTABLISHING FOUR TYPES OF BIOSAFETY LABORATO...Chayanika Das
 
FBI Profiling - Forensic Psychology.pptx
FBI Profiling - Forensic Psychology.pptxFBI Profiling - Forensic Psychology.pptx
FBI Profiling - Forensic Psychology.pptxPayal Shrivastava
 
Total Legal: A “Joint” Journey into the Chemistry of Cannabinoids
Total Legal: A “Joint” Journey into the Chemistry of CannabinoidsTotal Legal: A “Joint” Journey into the Chemistry of Cannabinoids
Total Legal: A “Joint” Journey into the Chemistry of CannabinoidsMarkus Roggen
 
Probability.pptx, Types of Probability, UG
Probability.pptx, Types of Probability, UGProbability.pptx, Types of Probability, UG
Probability.pptx, Types of Probability, UGSoniaBajaj10
 
Gas-ExchangeS-in-Plants-and-Animals.pptx
Gas-ExchangeS-in-Plants-and-Animals.pptxGas-ExchangeS-in-Plants-and-Animals.pptx
Gas-ExchangeS-in-Plants-and-Animals.pptxGiovaniTrinidad
 
Environmental Acoustics- Speech interference level, acoustics calibrator.pptx
Environmental Acoustics- Speech interference level, acoustics calibrator.pptxEnvironmental Acoustics- Speech interference level, acoustics calibrator.pptx
Environmental Acoustics- Speech interference level, acoustics calibrator.pptxpriyankatabhane
 
Advances in AI-driven Image Recognition for Early Detection of Cancer
Advances in AI-driven Image Recognition for Early Detection of CancerAdvances in AI-driven Image Recognition for Early Detection of Cancer
Advances in AI-driven Image Recognition for Early Detection of CancerLuis Miguel Chong Chong
 

Recently uploaded (20)

Interferons.pptx.
Interferons.pptx.Interferons.pptx.
Interferons.pptx.
 
Let’s Say Someone Did Drop the Bomb. Then What?
Let’s Say Someone Did Drop the Bomb. Then What?Let’s Say Someone Did Drop the Bomb. Then What?
Let’s Say Someone Did Drop the Bomb. Then What?
 
Environmental acoustics- noise criteria.pptx
Environmental acoustics- noise criteria.pptxEnvironmental acoustics- noise criteria.pptx
Environmental acoustics- noise criteria.pptx
 
The Sensory Organs, Anatomy and Function
The Sensory Organs, Anatomy and FunctionThe Sensory Organs, Anatomy and Function
The Sensory Organs, Anatomy and Function
 
BACTERIAL DEFENSE SYSTEM by Dr. Chayanika Das
BACTERIAL DEFENSE SYSTEM by Dr. Chayanika DasBACTERIAL DEFENSE SYSTEM by Dr. Chayanika Das
BACTERIAL DEFENSE SYSTEM by Dr. Chayanika Das
 
dll general biology week 1 - Copy.docx
dll general biology   week 1 - Copy.docxdll general biology   week 1 - Copy.docx
dll general biology week 1 - Copy.docx
 
Measures of Central Tendency.pptx for UG
Measures of Central Tendency.pptx for UGMeasures of Central Tendency.pptx for UG
Measures of Central Tendency.pptx for UG
 
PLASMODIUM. PPTX
PLASMODIUM. PPTXPLASMODIUM. PPTX
PLASMODIUM. PPTX
 
Loudspeaker- direct radiating type and horn type.pptx
Loudspeaker- direct radiating type and horn type.pptxLoudspeaker- direct radiating type and horn type.pptx
Loudspeaker- direct radiating type and horn type.pptx
 
Introduction of Human Body & Structure of cell.pptx
Introduction of Human Body & Structure of cell.pptxIntroduction of Human Body & Structure of cell.pptx
Introduction of Human Body & Structure of cell.pptx
 
BACTERIAL SECRETION SYSTEM by Dr. Chayanika Das
BACTERIAL SECRETION SYSTEM by Dr. Chayanika DasBACTERIAL SECRETION SYSTEM by Dr. Chayanika Das
BACTERIAL SECRETION SYSTEM by Dr. Chayanika Das
 
CHROMATOGRAPHY PALLAVI RAWAT.pptx
CHROMATOGRAPHY  PALLAVI RAWAT.pptxCHROMATOGRAPHY  PALLAVI RAWAT.pptx
CHROMATOGRAPHY PALLAVI RAWAT.pptx
 
6.1 Pests of Groundnut_Binomics_Identification_Dr.UPR
6.1 Pests of Groundnut_Binomics_Identification_Dr.UPR6.1 Pests of Groundnut_Binomics_Identification_Dr.UPR
6.1 Pests of Groundnut_Binomics_Identification_Dr.UPR
 
ESSENTIAL FEATURES REQUIRED FOR ESTABLISHING FOUR TYPES OF BIOSAFETY LABORATO...
ESSENTIAL FEATURES REQUIRED FOR ESTABLISHING FOUR TYPES OF BIOSAFETY LABORATO...ESSENTIAL FEATURES REQUIRED FOR ESTABLISHING FOUR TYPES OF BIOSAFETY LABORATO...
ESSENTIAL FEATURES REQUIRED FOR ESTABLISHING FOUR TYPES OF BIOSAFETY LABORATO...
 
FBI Profiling - Forensic Psychology.pptx
FBI Profiling - Forensic Psychology.pptxFBI Profiling - Forensic Psychology.pptx
FBI Profiling - Forensic Psychology.pptx
 
Total Legal: A “Joint” Journey into the Chemistry of Cannabinoids
Total Legal: A “Joint” Journey into the Chemistry of CannabinoidsTotal Legal: A “Joint” Journey into the Chemistry of Cannabinoids
Total Legal: A “Joint” Journey into the Chemistry of Cannabinoids
 
Probability.pptx, Types of Probability, UG
Probability.pptx, Types of Probability, UGProbability.pptx, Types of Probability, UG
Probability.pptx, Types of Probability, UG
 
Gas-ExchangeS-in-Plants-and-Animals.pptx
Gas-ExchangeS-in-Plants-and-Animals.pptxGas-ExchangeS-in-Plants-and-Animals.pptx
Gas-ExchangeS-in-Plants-and-Animals.pptx
 
Environmental Acoustics- Speech interference level, acoustics calibrator.pptx
Environmental Acoustics- Speech interference level, acoustics calibrator.pptxEnvironmental Acoustics- Speech interference level, acoustics calibrator.pptx
Environmental Acoustics- Speech interference level, acoustics calibrator.pptx
 
Advances in AI-driven Image Recognition for Early Detection of Cancer
Advances in AI-driven Image Recognition for Early Detection of CancerAdvances in AI-driven Image Recognition for Early Detection of Cancer
Advances in AI-driven Image Recognition for Early Detection of Cancer
 

Insect Head Anatomy

  • 2. THE INSECT HEAD 2 Presented by: Ch.Naga Satyasri BAM-14-28
  • 3. • The insect head is a hard, highly sclerotized compact capsule bearing a group of feeding appendages around the mouth, sensory organs and internally a major centre of neuroendocrine coordination. 3
  • 4. Head Segmentation • According to phylogenetic considerations, the insect head is in fact a product of evolution and can be termed as Syncephalon. • It consists of two parts. An anterior procephalon and a posterior gnathocephalon. 4
  • 5. PROCEPHALON • The procephalon represents preoral region of the head and bears two paired structures, the eyes and antennae. • The procephalon is thought to be derived from the ancestral head, the archencephalon or blastocephalon, after an incorporation of at least one posterior trunk segment of the ancestor. • The brain is considered as a fused ganglion of the procephalon. 5
  • 6. GNATHOCEPHALON • The gnathocephalon represents postoral region of the head. • It bears three paired structures; the mandible, first maxillae and second maxillae or labium. It is mostly developed in order to equip the head with feeding appendages. 6
  • 7. 7
  • 8. • Embryological and morphological studies suggest that the gnathocephalon is composed of three segments, viz., the mandibular, maxillary and labial segments. • In an adult insect, these segments are evident from their paired appendages. • The suboesophageal ganglion is undoubtedly, a composite ganglion of the gnathocephalon. 8
  • 9. • Based on the embryological studies, the segments of insect head are six such as: 1. Pre antennal segment 2. Antennal segment 3. Intercalary segment 4. Mandibular segment 5. Maxillary segment 6. Labial segment 9
  • 10. 10
  • 11. • 1.Preantennary segment: It is recognized by its neuromere that forms procerebrum of the brain and embryonic appendages. • 2.Antennary segment: It is indicated by its neuromere that forms deuterocerebrum of the brain and its appendages are antennae. • 3. Intercalary segment: Intercalary segment is with feeding appendages which are homologous with antennae of crustacean and its neuromere, tritocerebrum. Traces of this segment are found in most embryos. 11
  • 12. • 4.Mandibular segment: It is indicated by its neuromere, the mandibular ganglion and its appendages the first maxillae. • 5.Maxillary segment: It is recognized by its neuromere, the maxillary ganglion and its appendages the first maxillae. • 6.Labial segment: Labial segment in with its appendages the labium and neuromere, labial ganglion. The neuromeres of the last three segments fuse during development to form the sub-oesophagial ganglion. 12
  • 13. HEAD SKELETON • The head of the insect loses its primary segmentation during the post-embryonic development. • Due to enormous sclerotization, the head becomes a hard skeletal capsule. • It bears externally a set of sensory and gnathal appendages. • The sense organs include a pair of antennae, a pair of compound eyes and two or three ocelli. • The gnathal appendages comprise a pair of mandibles, a pair of maxillae and a labium. 13
  • 14. • The gnathal appendages constitute collectively along the labrum and hypopharynx, a well elaborated feeding apparatus. 14
  • 15. • The position of mouth parts in relation to the body axis differs in different group of insects. The mouth parts may project downward, forward or backward and the head, accordingly, is designated as the following types. 15
  • 16. Hypognathous head: • The long axis of the head is vertical and mouthparts are ventral i.e., pointing downwards (primitive type). The occipital foramen lies in or near transverse plane. Ex: Grasshoppers, cockroach. 16
  • 17. 17
  • 18. Prognathous head: • The long axis of the head is horizontal, mouthparts are anterior in position occipital foramen is slightly inclined. Ex: Soldiers of termites and larvae of endopterygota 18
  • 19. 19
  • 20. Opisthognathous head: • Occurs in Homoptera and Hemiptera where the head is deflexed backwards so that mouthparts / proboscis slopes backwards between the front legs. 20
  • 21. 21
  • 22. HEAD SUTURES • The head capsule of the matured insects is differentiated into several regions by the sutures. • The sutures are nothing but the secondarily developed fine groves. • They are inflections or merely external impressions of the internal stiff cuticular ridges which provide mechanical support to the cranial wall. • These sutures are the product of sclerotization and except the post-occipital suture, others have no metameric segmentation. 22
  • 23. 23
  • 24. The Clypeo-labral suture: • This suture represents the lower margin of the clypeus. • The labrum hanging down from the suture. • It bears a prominent ridge internally. • The ridge possesses an apodeme at the centre. The apodeme provides an insertion to the anterior retractor muscles of the labrum. 24
  • 25. 25
  • 26. 26
  • 27. The Clypeo-frontal or Epistomal suture: • It occurs between the clypeus and the frons. • It bears laterally the anterior tentorial pits. • It internally bears a strong inflection. • Those inflection strengthens the lower part of the head against the stretching of the mandibles. 27
  • 28. 28
  • 29. The Epircanial suture: • It is a composite suture. • It appears in the form of an inverted-Y above the facial region in most of the insects. • The stem is known as the coronal and lateral arms, the frontal sutures. • The epicranial suture is partially or even completely reduced in some insects. 29
  • 30. • It is totally lacking from the head of apterygotes. • Snodgrass (1935) and Du porte (1957) stated that the epicranial suture represents merely the line of weakness and can be said in true sense as the ecdysial suture. • It does not bear the skeletal ridge on the inner surface and therefore does not provide either a site for muscle attachment or mechanical support to the head capsule 30
  • 31. 31
  • 32. The Occipetal suture: • It is horse-shoe or U-shaped suture, and well evident on the posterior part of the head of the orthopteroid insects. • It starts from posterior articulations of the mandibles of either side. • Both the arms after running a long distance and join one another above the occipital foramen. 32
  • 33. • It seperates the genal area from the post-genal area of the lateral region of the head. • It also differentiates the vertex from the occiput in posterior region of the head. • It forms an internal ridge strengthening the posterior epicranial wall. 33
  • 34. 34
  • 35. The post-occiput suture: • It embraces the occipital foramen magnum from the dorsal and lateral sides. • Each end of the suture merges in the hypostomal suture in ventral region. • This site is well defined due to the presence of the posterior tentorial pits. • It possesses internally a strong epidermal ridge, the post-occipetal ridge. 35
  • 36. • It provides a site for the attachment of prothoracic muscles which move a pair of ventro-lateral condyles. The neck membrane is firmly attached to this ridge. • The condyles articulate with the neck sclerites. • It is the only suture having the metameric significance. It alone marks the fusion of the maxillary and labial segments of the head. 36
  • 37. 37
  • 38. 38
  • 39. The Frontogenal or subocular suture: • It develops on each lateral region of the head. It starts from the junction of the clypeofrontal and the subgenal sutures. • It terminates in the close vicinity of the lower margin of each compound eye. • It is virtually well evident in the orthopteroid insects. 39
  • 40. The Subgenal Suture: • These sutures occur on the lateral sides of the head. • Each suture joins the posterior tentorial pit with the anterior tentorial pit of the same side. • Each suture is divisible into two parts. • One part of the subgenal suture is called the hypostomal suture. • The hypostomal suture runs from the posterior tentorial pit up to the posterior articulation of the mandible. 40
  • 41. 41
  • 42. • The other part of the subgenal sututre is called the pleurostomal suture. • The pleurostomal suture arches over the mandible and finally joins with the fronto- clypeal and the fronto-genal sutures just above the anterior articulation of the mandibles. • Internally, the subgenal sutures form the submarginal, subgenal ridges. • Each ridge extends from the posterior tentorial pit to point just above the anterior articulation of the mandible. 42
  • 43. The subgenal sutures strengthen the cranial wall along the lines of attachment of the gnathal appendages The Ocular suture: • These sutures are the annular grooves around the compound eyes. They form the skeletal ridges internally. 43
  • 44. 44
  • 45. The Antennal Sutures: • The marginal depressed ring around the antennal sockets are known as the antennal sutures. • Each suture gives internally the submarginal ridge. • The submarginal ridge in a large number of insects bears a pivot like process known as the antennifer. • The antennifer provides articulation to the antenna. 45
  • 46. 46
  • 47. HEAD SCLERITES The sclerites represent simply, the intersutural areas. The head of the generalized insect is typically exhibiting the following sclerites. (a) The labrum (b) The clypeus (c) The frons (d) The epicranium (e) The occiput (f) The post-occiput (g) The Genae and subgenal areas (h) The Ocular sclerites 47
  • 48. 48
  • 49. (a) The labrum: • It is freely attached to the lower margin of the clypeus by the clypeolabral suture, generally hanged over the mouth or preoral cavity and also termed as an upperlip. • In the fluid-feeding insects it undergoes various modifications. • Internally it forms anterior part of the epipharyngeal wall of the preoral cavity. • It is internally lined with the gustatory receptors and can be moved upwards downwards and be pulled and pushed, to some extent, due to the elastic nature of the suture and muscle innervaton. 49
  • 50. • The labrum is innervated by the following three types of muscles. (i) Compressor labral: • They may occur in a pair on lateral sides or a single median one. They are attached by one end on the anterior and by the other end on the posterior end wall of the labrum. The compressors bring the retraction, prolongation and contraction of the labrum. 50
  • 51. (ii) The anterior labral: • They are paired but unbranched labral muscles. They originate from the inner surface of the frons. They move the labrum in forward direction. (iii) The Posterior Labral: • They are the paired but branched labral muscles. They originate from the anterolabral regions of the frons. The muscles pull the labrum backward. 51
  • 52. 52
  • 53. (b) The clypeus • This sclerite is demarcated by the clypeolabral and clypeo –frontal sutures from the anterior and posterior sides. • It thus occupies the position in-between the anterior labral and posterior frontal sclerites. • In some insects, it is completely or partially divided into two parts by a transverse suture. 53
  • 54. • The posterior part is termed as the post- clypeus and the anterior part is termed as anteclypeus. • Both parts of the clypeus can be seen in the case of crickets. • The post clypeus modifies into a convex process, termed as the ginglimus of the mandible. • This is the sclerite on the head on which arise the cibarial dilator muscles. 54
  • 55. 55
  • 56. (c) The frons: • It extends from the anterior clypeo-frontal suture to the posterior frontal sutures. • In the orthopteroid insects, it possesses the median ocellus. • In some cases, it may bear the lateral ocelli also. • The frons represent typically an upper facial region of the head. • The pharyngeal dilators, labral, hypopharyngeal muscles and the adductors of mandibles are usually inserted on the middle of the frons. 56
  • 57. 57
  • 58. (d) The Epicranium: • The epicranium suture separates the epicranium from the frons. • It represents the entire upper region or top of the head. • It extends from the anterior frontal to the posterior occipital suture. • Above the frons, it is divided into two identical lateral plates, known as parietals. • The parietals are characterised by bearing the antennae, lateral ocelli and compound eyes. • The posterior undivided region of the epicranium is known as vertex. • It forms top of the head. 58
  • 59. (f) The post-occiput: • The occipital foramen is encircled from the dorsal and lateral regions by a narrow sclerite, the post-occiput. • It lies between the occiput and the neck. • The post-occiput is marked off from the occiput by a transverse post-occipital suture. • When the post-occipital suture remains absent, the posterior tentorial pits separate the post occiput from the occiput. 59
  • 60. • The dorasal muscles are attached to the endoskeletal ridge of the post-occipetal suture. • These muscles are articulate the head freely. The antero-lateral inner margin of the post- occiput produces small processes. • These sutures are termed as the occipital condyles. • Each condyle articulates with the anterior lateral cervical sclerites. 60
  • 61. 61
  • 62. (e) The occiput: • It is U-shaped posterior or hinder cuticular band. It represents the area from the occipital to the postoccipetal sutures. 62
  • 63. 63
  • 64. (g) The Genae and subgenal areas: • The genae represent the lateral areas of the head. • On either side, the genae extend from the compound eye to the mandibular trochantin. • The hinder part develops in to the socket to accommodate the mandibular condyle. • Posterior to the occipital suture, each lateral gena is commonly called as the postgena. • Each postgena provides the condylar articulation for the maxillae. 64
  • 65. • The subgenal area above and below the mandibles can be referred to as the pleurostoma and hypostoma, respectively. These areas are separated in some insects by the suture, the hypostomal suture. • Similarly the pleurostomal suture separates the pleurostoma from the base of the mandibles. 65
  • 66. (h) The Ocular sclerites: • They form a cuticular ring around each compound eye. • (i) The Antennal sclerites: They form an annulus at the base of the antenna. The antennal sclerites are well developed in the plecoptera. • (ii) The Mandibular Trochantin: It occurs quite distinctly between the mandibular base and the pleurostoma or the pleurostomal suture. 66
  • 67. 67
  • 68. Tentorium: • It is an endoskeleton structure. • It is composed of three pairs of arms, the anterior, posterior and dorsal tentorial arms. • The anterior tentorial arms develop from the anterior tentorial pits in the subgenal or epistomal suture. 68
  • 69. • The posterior tentorial arms arise from the posterior tentorial pits in the lower ends of the post-occipital suture. • The dorsal tentorial arms take origin in the form of secondary out-growths of the anterior arms. • All these tentorial arms unite in the middle forming an expanded central skeletal platform. • It may simply constitute a structure resembling the X. 69
  • 70. • The presence of a broad tentorial plate occurs commonly in the pterygote insects and is commonly known as the corporotentorium. The anterior tentorial pits: • The anterior tentorial arms of the tentorium arise from some part of subgena or epistomal suture. The posterior tentorial pits: • The posterior tentorial arms of the tentorium arise from ventral ends of post occipital suture and lie in the lower extremities of post occipital suture 70
  • 71. 71
  • 72. Modifications in head capsule: • The anterior frontoclypeal and posterior, lateral as well as ventral regions of the head capsule are greatly modified in some insects. 72
  • 73. 1.Fronto-clypeal Region: • The epistomal suture is wanting in cockroaches and some other insects in which the clypeal region can be separated from the frontal region by the position of anterior tentorial pits. • Sometimes the frontal sutures are also indistinct. • In the Hemiptera, Hymenoptera and Lepidopteran larvae, the frons is greatly suppressed. • In these insects, on the basis of position of the dilators of cibarium or that of buccal cavity, the clypeal region can be recognised. • Similarly the frontal region can be identified by the position of a median ocellus and origin of labral muscles. 73
  • 74. 2.Hypostomal bridge: • In the lepidopteran larvae, the hypostomal lobes do not unite together while in other insects, they fuse at the middle forming a complete hypostomal bridge in order to close the foramen magnum ventrally 74
  • 75. 3.Gula: • It is a ventral sclerotic plate of the head capsule separating the foramen magnum from the base of the labium. • It is well developed in the insects having prognathous head in order to place the mouth parts in forward direction. • The gula is separated from the laterally expanded postgenae by the gular structures. • The gular sutures are in fact modified post- occipital sutures. • The gula varies in length and width in different species of Coleopteran and Neuroptera. 75
  • 76. 76