Brain
Cranial meninges (Out to
in)
- Duramater
- Arachnoid
- Piamater
CSF secreating folding
or stretches called choroid plexuses and arachnoid villi helps in CSF
absorption.
Communication between
ventricles
- Each lateral
ventricle------------(Intraventricular foramen/foramen of
monro)---------->3rd ventricle
- 3rd ventricle-------------(cerebral
aqueduct of sylvinus/aqueduct of sylvinus)------------->4th ventricle
CSF leave ventricle and
enter subarachnoid apace through two lateral foramina of Luschka and median
foramen of Magendie in fourth ventricle.
Piamater and Arachnoid
mater are together called leptomeninges.
- Sub Dural Space-(Arachnoid and
Duramater)--------> filled with serous fluid
- Sub Arachnoid Space-(Duramater
and Piamater)--------> Filled with CSF
Grey matter- Outer
White matter- Inner
Mid brain--------> 4
lobes----------------> Corpora quadrigemina
Lession in broca’s area
results in inability to produce words and speech(in Frontal lobe).
Olfactory lobe distinct
in rabbit and attached to anterior end of cerebrum but indistinct in human.
Limbic system- the emotional
brain
Amaygdala is considered
as “Window of Limbic System”.
Thalamus
Receive and send sensory
impulses.
Hypothalamus
Functions @SEAT2
Sex, Sleep
Emotion, Endocrine
Appetite, ANS
Thirst, Temperature
Hypothalamus joins
pituitary gland by infundibulum.
Hemiplega-------->
Half paralyzed--------->Opposite frontal lobe damaged.
Cerebral
hemisphere(cerebral cortex) consistsof gyri(raised), sulsi(depression).
Hemisphere are connected
by myelinated nerve called corpus callosum. Presence of corpus callosum
is the exclusive character of mammal.
Corpora quadrigemina
-----> 4 swelling
mammals
Mid-brain of Frog has
two oval optic sacs.
Pons
Apneustic and
pneumotaxic center in this area helps to control respiration.
4th ventricle
lies between surface of pons and cerebellum.
Medulla Oblongata
Respiratory center,
Cardiac center and vasomotor center.
Cerebellum
Maintain body balance,
muscle coordination.
Alcohol suppress
cerebellum temporarily.
Peripheral nervous system
Cranial nerves
12 pairs of cranial nerves in mammals, 10 pairs of cranial nerves in fishes and amphibians.
Vagus control
heartbeat(parasympathetic)
Largest and
thickest------------> Trigeminal(Dentist nerve)
Smallest---------------->Abducens
Thinnest---------------->Trochlear
Longest------------------->Vagus
Spinal Cord and nerves
Grey
matter---------------> In
White
matter--------------> Out
Butterfly or H-shaped(Spinal Cord).
Posterior horn or dorsal
horn consists of sensory neurons whereas anterior horn or ventral horn consists
of motor neurons.
Spinal
nerves--------------------> 31 pairs(All mixed nerves)
Cervical-------------->
8 pair
Thorax--------------->12
pair
Lumbar--------------->
5 pair
Saccral---------------->5
pair
Coccygeal------------->
1 pair
Frog has 10 pairs of
spinal nerves and in Rana tigrina it is 9 pairs.(37 pairs in rabbit).
Accessory and
Hypoglossal(Cranial nerves). Absent in frog.
Spinal cord of frog
tapers posteriorly in Urostyle as Filum terminale or cauda equina.
Spinal nerve passes
through gland of Swammerdam(Ca+ rich) after emersing from spinal cord.
Autonomic nervous system
|
Parasympathetic |
Sympathetic |
|
(cranio-saccral) |
(thoraco-lumbar) |
|
Acetocholine |
Noradrenaline |
|
Penis erection |
Semen ejaculation |
Nerve impulse
Resting potential
(Polarized)----------------> -70mV
Active potential
(Depolarized)---------------> 45mV
Repolarization---------------------------------->
-70mV
Alzheimer’s
disease(Dementia)------------->hyposecreation of acetycholine (old age
disease)