A lecture for undergraduate medical students

1. GENERAL ARRANGEMENT
&
DEVELOPMENT OF BRAIN
BY
DR. ABDUL QADEER
MBBS; FCPS; FICS

2. PARTS OF BRAIN
PART SUBDIVISIONS
1. Forebrain
(Prosencephalon)
A. Telencephalon (Cerebrum)
B. Diencephalon (Thalamencephalon)
a) Thalamus
b) Hypothalamus
c) Metathalamus
d) Epithalamus
e) Subthalamus
2. Midbrain
(Mesencephalon)
1. Crus cerebri
2. Substantia nigra
3. Tegmentum
4. Tectum
3. Hindbrain
(Rhombencephalon)
A. Metencephalon
1. Pons
2. Cerebellum
B. Myelencephalon (Medulla oblongata)

3. DEVELOPING BRAIN

4. DEVELOPING BRAIN

5. LOBES OF BRAIN
 Frontal lobe
1. Sup. middle & inf.
fronatl gyri
2. Pre-central gyrus
 Parietal lobe
1. Post-central gyrus
2. Sup. & inf. Parietal
lobules
 Temporal lobe
1. Superior, middle &
inferior temporal gyri
 Occipital lobe

9. DEVELOPMENT OF NERVOUS SYSTEM
 During the 3rd week of development,
ectoderm on the dorsal surface of the
embryo forms NEURAL PLATE
 Neural plate changes to NEURAL GROOVE
 NEURAL FOLDS appear & deepen the
neural groove to form NEURAL TUBE
 Neural tube starts fusing at the center, hence
leaving the openings i.e. ANTERIOR AND
POSTERIOR NEUROPORES

12. DEVELOPMENT OF NERVOUS SYSTEM
 Neural tube closure completes within 28
days
 The anterior neuropore closes first
 The posterior neuropore closes after 2 days

14. FORMATION OF NEURAL CREST
 During the formation of neural tube, some of
the cells of neural plate remain as a strip of
ectodermal cells
 That strip lies between the neural tube and
the covering ectoderm, known as neural
crest.

15. NEURAL CREST
 The neural crest cells will differentiate and
hence give rise to the cells of:
1. Posterior root ganglia
2. Sensory ganglia of the cranial nerves
3. Autonomic ganglia
4. Cells of supra-renal medulla
5. Melanocytes

17. CLINICAL NOTES
 SPINAL CORD INJURIES:
1. Dislocation /fracture dislocation of cervical
vertebrae Respiration stops if spinal
cord is completely severed above the
segmental origin of phrenic nerves (C3-5)
Paralysis of diaphragm Death.
2. Fracture and dislocation in lumbar vertebral
region may involve nerves/roots and lesion
accordingly.

18. HERNIATED INTERVERTEBRAL DISCS
 Protrusion nucleus pulposus through anulus
fibrosus of the disc may cause:
1. Central compression or
2. Lateral compression
 Depending on involvement of sensory or
motor roots
 May lead to SCIATICA OR CAUDA EQUINA
SYNDROME / PARAPLEGIA etc

19.  Involvement of L-5 motor root weakens
dorsiflexion of the ankle
 Involvement of S-1 motor root causes
weakness of planter flexion, hence
weak/absent ankle jerk reflex
 A large, central, bilateral protrusion may
cause urinary retention

20. SPINAL TAP / LUMBAR PUNCTURE (LP)
 Indications may be:
1. To take CSF sample for microscopic or
bacteriologic examination OR
2. To inject drugs for spinal anesthesia
 An imaginary line joining the highest points
on the iliac crest passes over the 4th lumbar
spine
 Spinal anesthesia given above or below the
4th lumbar vertebra

21. STRUCTURE PIERCE BY LP NEEDLE (2.5 TO 10
CM)
1. Skin
2. Superficial fascia
3. Supraspinous ligament
4. Interspinous ligament
5. Ligamentum flavum
6. Areolar tissue containing internal vertebral
venous plexus
7. Dura mater
8. Arachnoid mater

22. CSF PRESSURE
 When the patient is in recombent position,
normal CSF pressure is about 60 to 150 mm
of water
 The pressure shows oscillations
corresponding to the movents of respiration
and the arterial pulse

23. QUECKENSTEDT SIGN
 Compression of the internal jugular vein in
the neck will raise the cerebral venous
pressure and inhibits the absorption of CSF
in the arachnoid granulations, thus showing
the raised CSF pressure by manometery.
 If this rise does not occure, the test is
positive
 The positive test may be due to a block of
the sub-arachnoid space in the vertebral
column which may be caused by:
1. Tumor of the spinal cord or its meninges

24. CAUDAL ANESTHESIA
 Anesthetic solution may be injected into the
sacral canal through the sacral hiatus
 This is used by obstetricians for painless
labor and operations of anorectal regions

25. HEAD INJURIES
 Bruises
 Fractures of skull (common in adults than
infants) because of resilient bones fibrous
sutural ligaments
 In adults, inner table of the skull (Diploe) is
brittle
 Sutural ligaments begin to ossify during
middle age
 Adult skull, when injures eggshell shaped
 Young child’s skull table tennis ball
“POND” fracture (Ping-pong fracture)

27. BRAIN INJURIES
 Contrecoup injury
 Epidural (Extradural) hemorrhage
 Subdural hemorrhage
 Sub-arachnoid hemorrhage
 Cerebral hemorrhage (Contusion)
 Shaken-Baby syndrome
 Diffuse axonal injury
 Space-occupying lesions (SOLs)

28. EXTRADURAL (SUBDURAL) HEMATOMA

29. SUBDURAL HEMATOMA

30. SUBDURAL HEMATOMA

31. SDH WITH MIDLINE SHIFT

32. CEREBRAL CONTUSION

33. X-RAY SKULL (FRACTURE)

34. X-RAY SKULL (FRACTURE)

35. CT SCAN

36. MRI

37. PET

38. DIAGNOSIS
 Plain x-ray skull (AP & Lateral views)
 Computed tomography (CT)
 Magnetic resonance imaging
 Positron emission tomography (PET) uses
radio-active isotopes

39. BRAIN
THE END