1. Biology 161 Lab – Brain and Ventricles Scott.lehbauer@lethbridgecollege.ab.ca

2. Brain Structures

3. Brain Structures Hypothalamus – found below the thalamus it caps the brain stem and forms the walls of the 3rd ventricle. It is the main visceral control center and vital in overall body homeostasis functions including: Autonomic Control Center Center for Emotional Response Body Temperature Regulation Regulation of food Intake Regulation of water balance Regulation of sleep-wake cycles Control of Endocrine Function Hypothalamus

4. Brain Structures Pituitary Gland – sits securely in the sella turcica of the sphenoid bone. It is shaped like a pea at the end of a stalk. It is a major endocrine organ secreting at least 9 hormones including growth hormone, thyroid stimulating hormone and follicle stimulating hormone to name a few. Pituitary Gland

5. Brain Structures Corpus Callosum – is the largest commissure which by definition connect the two hemispheres of the brain. It lies superior to the lateral ventricles. it allows the two hemispheres to coordinated function Corpus Callosum

6. Brain Structures Pons – “bridge” is the bulge in the brainstem between the midbrain and the medulla oblongata. Is chiefly composed of conduction fibers which complete the pathway between the higher brain centers and the spinal cord. Pons

7. Brain Structures Medulla Oblongata – the most inferior part of the brain stem. It blends into the spinal cord at the base. Plays a crucial role in the autonomic reflex center. Important visceral motor nuclei include Cardiovascular center Respiratory centers Additional centers that control Vomiting, hiccupping, swallowing, coughing and sneezing. Medulla Oblongata

8. Brain Structures Cerebellum – “Small Brain” accounts for about 11% of total brain mass. Located dorsal to the medulla and pons. Processes information from the cerebral motor cortex and visual and equilibrium pathways, and “instructs” motor centers which result in proper balance, posture, smooth coordinated skeletal muscle movements. Cerebellum

9. Brain Structures Thalamus – “inner room” is a deep well hidden brain region. It contains a large number of nuclei. Each nuclei receives and deciphers information from the cerebral cortex and other areas “relay station”. The thalamus plays an integral in mediating sensation, motor activities, cortical arousal, learning and memory. Thalamus

10. Brain Structures Midbrain – a conduction pathway between the higher and lower brain centers. Contains the corpora quadrigemina Midbrain

11. Brain Structures Corpora Quadrigemina Corpora quadrigemina – “quadruplets” which is 4 raised dome-like protrusions on the dorsal midbrain surface. Visual reflex center – coordinates head and eye movements to follow moving objects. Auditory Reflex center – reflexive response to sharp sounds that cause you to turn your head towards and startling sound “startle reflex”

12. Brain Structures Cerebrum – gray matter localizes and interprets sensory inputs. Controlsvoluntary and skilled skeletal muscle activity. Functions in intellectual and emotional processing Important in initiation of skeletal muscle movements Cerebrum

13. Cerebral Lobes Parietal Lobe Frontal Lobe Occipital Lobe Temporal Lobe Cerebellum

14. Brain Structures - Ventricles Are continuous spaces which reside inside the tissue of the brain They are continuous with the central canal of the spinal cord. They are full of Cerebral Spinal Fluid

15. Brain Ventricles

16. Brain Structures - CSF CSF (Cerebral Spinal Fluid) – is found in and around the brain and spinal cord. It forms and liquid cushion and gives buoyancy around the CNS. The CSF reduces the weight of the brain by 97% and prevents the brain from crushing itself. It also protects the CNS from trauma and helps nourish the brain.

17. Brain Structures - CSF Choroid Plexus – these structures hang from the roof of the ventricles and produce CSF. Arachnoid Villi – knob like projections which protrude through the dura mater into the superior sagittal sinus. CSF is absorbed into the venous blood of the dural sinus here. Choroid Plexus Arachnoid Granulations

18. Brain Structures - Ventricles 1st and 2nd Ventricles “lateral ventricles” are deep within either cerebral hemisphere. Are large C-shaped ventricles Foramen of Munroe – “interventricular foramen” which attaches the lateral ventricles to the narrow 3rd ventricle 1st and 2nd Ventricles

19. Brain Structures - Ventricles 3rd Ventricle Thin medial ventricle Aqueduct of Sylvius “cerebral aqueduct” connects the 3rd and forth ventricle Aqueduct of Sylvius 3rd Ventricle

20. Brain Structures - Ventricles 4th Ventricle – lies in dorsal to the pons and superior medulla. It is continuous with the central canal of the spinal cord. Central Canal of Spinal Cord - Continues down the spinal cord from the ventricles of the brain. 4th Ventricle Central Canal

22. Hydrocephalus “Water on the brain” is a condition where the CSF cannot be drained or reabsorbed. CSF accumulates and exerts pressure on the brain

23. Hydrocephalus Hydrocephalus is treated by inserting a shunt into the ventricles to drain the excess fluid into a vein in the neck or abdomen.

24. Brain Structures - Meninges Meninges – “membrane” are three connective tissue membranes that lie just outside the CNS (Brain and Spinal Cord). Their functions include; Cover and protect the CNS Protect blood vessels and enclose the venous sinuses Contain CSF Form partitions in the skull

25. Brain Structures - Meninges

26. Brain Structures - Meninges Dura Mater – “tough mother” is the strongest layer. Two layered sheet of fibrous connective tissue. Arachnoid - Forms a loose brain covering. Separated from the dura matter by a serous cavity “Subdural space” The “subdural space” is filled with fluid Superior Sagittal Sinus Dura Mater Arachnoid

27. Brain Structures - Meninges Subarachnoid Space Web-like extensions span this space and attach the arachnoid to the pia matter. This space is filled with CSF and large blood vessels Pia Mater “gentle mother” is composed of delicate connective tissue and is full of tiny blood vessels. This is the only layer that clings tightly to the brain following every contour.

29. Meningitis may develop in response to a number of causes, most prominently bacteria, viruses and other infectious agents, but also physical injury, cancer, or certain drugs Dura Mater Brain with Meningitis

30. Spina Bifida “forked spine” results from the incomplete formation of the vertebral arches is a developmental birth defect involving the neural tube: incomplete closure of the embryonic neural tube results in an incompletely formed spinal cord. the vertebrae overlying the open portion of the spinal cord do not fully form and remain un fused and open This allows the abnormal portion of the spinal cord to stick out through the opening in the bones

31. 3 Types Spina bifida occulta – not severe results in a small tuft of hair on the back and has no neurological ramifications. Spina bifida meningocele – more severe, a sac-like cyst protrudes from the child’s spine. The cyst contains CSF and Meninges. Spina bifida myelomeningocele – similar to above only the cyst contains neural structures. The more neurological structures the cyst contains the more neurological impairment.

32. Spina Bifida There is no treatment for the neurological defects caused by spina bifida. Doctors will perform surgery to close the vertebral column to prevent further damage and infection. An infant with Spina Bifida