Anatomy of Brain - Traumatic Brain Injury

Anatomy of Brain and Traumatic Brain Injury

1. TRAUMATIC BRAIN INJURY Anatomy of Brain

2. DEVELOPMENT OF BRAIN Neurulation : Process of formation of neural tube. Occurs in 3 rd week of development Notochord gives signal to ectoderm Ectoderm thickens to form neural plate Neural plate invaginates to form neural groove Neural tube forms by the invagination of neural groove because of continuous signal from notochord

3. Neural Crest cells formed at the junction of surface ectoderm and neural groove Called as 4 th germ layer/ migratory cells/ Mesenchyme cells

4. DERIVATIVES OF VESICLES:

5. DEVELOPMENT OF VENTRICLES Venticles : cavity inside brain Cavity inside : TELENCEPHALON– Lateral ventricles DIENCEPHALON- Third ventricle MIDBRAIN- Cerebral aqueduct of sylvius RHOMBENCEPHALON- 4 th ventricle

6. BASICS OF NEUROANATOMY Nucleus is the aggregation of cell bodies in CNS Nucleus is derived from Neuroectoderm Nucleus forms the Grey Matter Ganglions are the aggregation of cell bodies in PNS Ganglions are derived from neural crest cells Axons- White matter (Fasciculus/Lemniscus) Collection of Axons in CNS- Tract Collection of Axons in PNS- Nerve

7. GLIAL CELLS Cells Function Derived from Astrocytes Blood Brain Barrier Neuroectoderm Microglial Cells Phagocytic cells Mesodermal derivative Oligodendrocytes Myelin sheath formation in CNS Neuroectoderm Schwann Cells Myelin sheath formation in PNS Neural Crest Cells Ependymal cells Lining of ventricles Neuroectoderm

8. CEREBRUM It is the largest section of brain Made up of two cerebral hemispheres Two cerebral hemispheres are connected to each other by corpus callosum Cerebral cortex is folded into gyri which are separated from each other by sulci It has 4 lobes namely: Frontal, Parietal, Occipital and Temporal

9. Functional areas of cerebral cortex

10. Motor Homunculus Electrical stimulation of primary motor area elicits contraction of muscles of opposite side of the body Contralateral half of the body is represented upside down, except face. The pharyngeal region and tongue are represented in the most ventral and lower part of the gyrus Followed by face, hand, arm, trunk and thigh. Leg, foot and perineum are on the medial surface

11. Sensory Homunculus The area of the cortex that receives sensations from a particular part of body is proportional to the intricacy of sensations received from it. Thus, the thumb, fingers, lips and tongue have a disproportionately large representation

12. CEREBELLUM It is situated in the posterior cranial fossa behind the pons and medulla. It has grey matter which is highly folded The arrangement is called ‘arbor vitae’

13. Parts of cerebellum Two surfaces (Superior, Inferior) Three lobes (Anterior, Middle, Flocculonodular ) Three fissures (Horizontal, Primary, Posterolateral) Three morphological divisions ( Archicerebellum , Neocerebellum , Paleocerebellum )

14. Functions of cerebellum It controls voluntary movement of same side of the body Coordinates contraction of skeletal muscles Regulate posture and balance Plays important role in cognition, learning from experiences and language processing

15. BRAIN STEM Brain stem is made up of 3 structures: Mid brain Pons Medulla

16. Mid Brain It is 2 cm long connects the forebrain with the hindbrain Corpora quadrigemina : 4 swellings in posterior midbrain 2 superior colliculus  LGB  optic pathway 2 inferior colliculus  MGB  auditory pathway At the level of superior colliculus  3 rd Nerve At the level of inferior colliculus 4 th nerve

17. Each half of the midbrain anterior to the aqueduct is called the cerebral peduncle. Cerebral peduncle is subdivided into: a)Crus cerebri , anteriorly b)Substantia nigra , in the middle c)Tegmentum, posteriorly Functions are: a) Relay information for vision and hearing. b) Dopamine produced in the substantia niagra

18. Pons 2.5 cm long extends from cranial end of medulla oblongata to the cerebral peduncles of midbrain. Cranial nerves V, VI, VII, and VIII Contains nuclei that deals with the respiration, swallowing, bladder control, hearing, equilibrium

19. MEDULLA The medulla is the lowermost part of brainstem extending from the lower border of pons to a plane and is continuous with the spinal cord. It acts as: i )Cardiovascular centre: Regulate rate and force of heart beat ii) Medullary rhythmic centre: maintain basic rhythm of breathing. iii) Vasomotor centre : Regulate blood pressure. iv) Others : Vomiting, swallowing, cough, hiccup, and sneezing, etc.

20. MEDULLA

21. BASAL GANGLIA Basal nuclei (Nuclei inside the cerebrum) Lateral to thalamus Divides into: Caudate nucleus Lentiform nucleus Lentiform nucleus contains: Putamen Globus pallidus

22. Internal capsule Projection fibres that connect cortex to subcortical structures Parts: Anterior limb Genu- Cortico nuclear tract Posterior limb- Cortico spinal tract Sublentiform - Auditory fibres Retrolentiform - Optic fibres

23. Thalamus P aired gray matter structure of the diencephalon L ocated near the center of the brain . M ade up of a series of nuclei responsible for the relay of the different sensory signals I nternal medullary laminae divide it into anterior, medial, and lateral groups of nuclei

24. Thalamus F unctional components: Reticular and intralaminar nuclei - A rousal and pain regulation Sensory nuclei - S ensory domains except olfaction Effector nuclei - M otor  language function Associative nuclei - C ognitive functions Limbic nuclei - M ood and motivation

25. CSF & VENTRICLES CSF is a clear, colorless, liquid actively secreted by choroid plexus. Choroid plexus is derived from Tela choroid (tuft of capillaries) Minor contributions done by: Ependymal cells lining the ventricles Brain substance through perivascular space.

26. CIRCULATION OF CSF Central canal of Spinal cord

27. BLOOD BRAIN BARRIER BBB is a selective semi-permeable membrane between blood and interstitium of brain composed of: Capillary basement membrane Tight junction between endothelial cells Pericytes Astrocyte end feet

28. BLOOD BRAIN BARRIER Functions of BBB: Creating & maintaining homeostasis for neuronal functions Defending against toxins Communication between periphery and CNS Providing nutrition to brain

29. Blood Supply of Brain ( Carotido - Basilar system) Internal Carotid artery Branch of common carotid at the level of C3 – C4 No branches in neck Enters cranial cavity through carotid canal pass inside petrous temporal bone Pass inside cavernous sinus Gives 5 branches in intracerebral part; 2 terminal branches (Middle & anterior cerebral artery)

30. Basilar artery First part of subclavian artery gives rise to Vertebral artery 4 th part of vertebral artery passes through foramen magnum and joins with opposite vertebral artery to form Basilar artery

31. Circle of Willis It is situated at the base of brain in the interpeduncular fossa. Internal carotid & Posterior cerebral arteries connected by Posterior communicating artery. Both anterior cerebral arteries are connected by means of Anterior communicating artery.