Week 1 Flashcards
A thick bundle of nerve fibers that connects the 2 hemispheres
Corpus callosum
Site of cerebellum
inferior to the cerebrum and occupies the posterior cranial fossa
Beginning of spinal cord
Continuation of MO at level of C1 below the foramen magnum
Lower end of spinal cord
Conus medullaris
Cervical enlargement
C5 - T1
Lumbar enlargement
L1 - S2
A bundle formed by The lumbar and sacral nerves which occupy the vertebral canal from L2 to S5.
cauda equina
A ligament that extends from the Conus medullaris to the back of the
coccyx.
Filum terminale
Ligaments that extend from the pia mater between the dorsal and ventral nerve roots to anchor the spinal cord to the dura.
denticulate ligaments
It is the lower part of the subarachnoid space. It extends from L2 to S2.
Lumbar Cistern
Contents of Lumbar cistern
- CSF
- Cauda equine
- filum terminale
Best site for lumbar puncture (spinal tap)
between the spines of L3 and L4 (sometimes L4 and L5)
Mention sensory cells of the dorsal horn
- Posteromarginal nucleus
- Substantia gelatinosa of Rolandi
- Nucleus proprius
- Nucleus dorsalis (Clarke’s nucleus)
Mention site and function of Nucleus dorsalis (Clarke’s nucleus)
at the base of the dorsal horn and extends from C8 to L2 segments. Associated with unconscious proprioception.
Mention site and function of Nucleus proprius
center of the dorsal horn. It mediates pain, temperature, touch and pressure sensations.
Mention site and function of Substantia gelatinosa of Rolandi
at the apex of the dorsal horn. It is associated with pain & temperature sensation.
Mention site and function of Posteromarginal nucleus
at the tip of the dorsal horn and mediates pain and temperature sensations.
Course of Single Anterior Spinal
Artery
descends in the anterior median fissure
of the spinal cord. supplies anterior 2/3 of
the spinal cord.
Course of Two Posterior Spinal
Arteries
descend along the posterolateral fissure. supply the posterior 1/3 of the spinal cord.
Course of artery of Adamkiewicz,
enters the spinal cord between segments T8 and L4. supplies most of the arterial blood supply for the lower half of the spinal cord
The embryonic origin of the NS
ectodermal
The embryonic source of the CNS
Neural tube
The embryonic source of the PNS
Neural crest
The embryonic source of the inner ear
Placodes
Development of neural tube begins during
3rd week
The embryonic origin of the cerebral hemisphere.
Telencephalon
The embryonic origin of the lateral ventricle
cavity inside each hemisphere (from Telencephalon)
The embryonic origin of the thalamus, hypothalamus, subthalamus and
epithalamus
Diencephalon
The embryonic origin of the third ventricle
The cavity inside Diencephalon
The embryonic origin of the midbrain
Mesencephalon
The embryonic origin of the cerebral aqueduct
The cavity inside Mesencephalon
The embryonic origin of the 4th ventricle.
The cavity inside Rhombencephalon
The embryonic origin of pons and cerebellum
Metencephalon (from Rhombencephalon)
The embryonic origin of medulla oblongata
Myelencephalon (from Rhombencephalon)
The neural tube fails to close in the spinal cord region.
Myelocele
The neural tube fails to close in the brain region
Anencephaly
The vertebral canal remain open posteriorly
Spina bifida
The defect covered by skin and hair. The spinal cord is usually normal
spina bifida occulta
The meninges project through the defect
forming a cyst. Normal spinal cord
Spina bifida with meningocele
The spinal cord and the meninges project
through the defect forming a cyst
Spina bifida with meningomyelocele
Herniation of the brain meninges only
Meningocele
Herniation of meninges and brain tissue
Meningoencephalocele
Herniation of meninges, brain and ventricular lumen
Meningohydroencephalocele
Connects the 2 lateral ventricles to the 3rd ventricle
foramen of Monro
Connects the 3rd ventricle to the 4th ventricle
aqueduct of sylvius
main source of CSF
choroid plexus of the ventricle mainly
the lateral ventricle
CSF leaves the 4th ventricle through
median foramen of Magendie and the two lateral foramina of Lushka.
The main site of drainage of CSF
the arachnoid villi and arachnoid granulation (which project into the dural venous sinuses)
Abnormal increase in the volume of the CSF with dilatation of ventricles and increase in the size of the head
Hydrocephalus
the commonest cause of hydrocephalus
Obstruction to the circulation
The law that explains Modality Discrimination at level of receptor
Muller law of specific nerve energy
The law that explains Modality Discrimination at central level
Labelled line principle
Explains Locality Discrimination
law of projection
Importance of rapidly adapting receptors?
inform CNS about onset, termination and change in intensity
Importance of slowly adapting receptors?
maintain sensory information so subserve vital functions
Receptors of crude touch
free nerve endings and hair follicle
pathway of crude touch
ventral spinothalamic
afferents of crude touch
A-delta nerve fibers and C non myelinated nerve fibers
Receptors of fine touch
Meissner’s corpuscles and Merkel’s discs
pathway of fine touch
Gracile and cuneate tracts
afferents of fine touch
A-beta nerve fibers
Receptors of pressure
Pacinian corpuscles and Ruffini endings
It is the ability to localize exactly the point of touch
with eyes closed
Tactile localization
Is the ability to feel 2 points of touch with eyes
closed as 2 separate points of touch provided that
the distance between the 2 points is greater than
minimal distance
Tactile discrimination
It is the ability to recognize a familiar object with
eyes closed
Stereognosis
Ability of the person with his eyes closed to recognize the nature of an object
Texture of materials
Receptors of pressure
Pacinian corpuscles and Ruffini endings
Pathway of pressure
Gracile and cuneate tracts
Receptors of vibration
Pacinian corpuscles and Meissner’s
corpuscles
pathway of vibration
Gracile and cuneate tracts
Function of muscle receptors (ms spindle and Golgi tendon)
inform CNS about changes in the ms length & the
rate of this change “velocity”
Function of joint receptors
Ruffini endings : continuously discharge impulses to
inform the C.N.S about the position of the joints
Pacinian corpuscles : inform the C.N.S about, the onset,
the termination and the velocity of the movement
Pathway of Proprioceptive Sense at subconscious level
spinocerebellar tracts
Cold receptors
encapsulated nerve endings transmitting their
signals by type A-delta nerve fibers.
Warm receptors
free nerve endings transmitting their signals
mainly by type C-nerve fibers.
Paradoxical cold sensation occurs at
45 -50 C
Maximum cold rate receptors discharge at
5 C
Heat pain receptors discharge at
45 C
Pathway of thermal sensation
anterolateral system (lateral spinothalamic tract)
Site of Somatic Sensory Area I (Area 3, 1, 2)
Post central gyrus of the parietal lobe
Function of somatic sensory area 1
receives nearly all somatic sensations (Fast pain, Fine touch, Fine grades of temperature, Deep sensations pressure, tension, vibration, position and movements)
Lesion in somatic sensory area 1
a) Inability to localize accurately the site of different
stimuli.
b) Inability to perceive minute differences in the
intensity of sensory stimuli.
c) Astereognosis i.e. inability to recognize the shapes or
forms or texture of materials.
d) Loss of fine touch and orientation of different parts
of body to each other.
Site of Somatic Sensory Area II (Area 40)
Parietal lobe posterior and inferior to lower end of area I
Function of Somatic sensory area II
Start the meaning of somatic sensations
Lesion in Somatic sensory area II
Defect in learning based on tactile discrimination
Site of Somatic Sensory Association Area (Area 5,7)
Parietal lobe behind area I and above area II
Functions of (Area 5,7)
- Give the meaning of all types of sensations received from primary sensory areas
- Transmit the pre-analyzed proprioceptive sensations to brain motor centers that helps in control and coordination of movements.
Lesion in (Area 5,7)
- Astereognosis (loss of ability to recognize the
complex objects). - Parietal lobe neglect: The sensory information from the opposite side of the body are ignored and neglected and even the brain forgets the other ½ of the body and often forgets to use the contralateral side of his body