1. Cranial Fossa: Brain and Spinal Cord
Clinical Anatomy
Tony Serino, Ph.D.

2. Cranial Fossa: Topic Objectives
Be able to describe the distribution of grey and white matter in the brain and spinal cord
Be able to describe the arrangement of the meninges and the differences between cranial and spinal meninges
Be able to describe blood flow to and from the cranial fossae
Be able to describe normal CSF flow
Be able to deduce consequence of CSF blockages
Be able to identify the major parts and regions of the brain and spinal cord and their development
Be able to describe the functions of selected areas of the brain
Understand brain blood flow and be able to predict vascular changes to the circle of Willis when an obstruction occurs in a single vessel
Be able to describe Cranial Nerve location and function
Be able to predict functional loss with CN paralysis

3. Central Nervous System (CNS)
Gray vs. White matter
Protection of CNS
Meninges
CSF flow
Brain
Development
Selected structures
Spinal cord

4. Cranial Fossa
Anterior
Middle
Posterior

5. CNS (Central Nervous System)
Brian and spinal cord
Displays gray and white matter
Gray matter are areas of CNS with many cell bodies of neurons present (little myelinated nerve fibers)
White matter are area of CNS with few cell bodies but many myelinated nerve fibers
Protected by bone and membranes

6. Gray and White Matter
Since the cerebrum and cerebellum outgrow their cores, gray matter ends up on outside of both structures.

7. Meninges Dura Mater –outermost; tough, fibrous CT
In brain, divided into two layers (periosteal and meningeal)
In spine, only one layer with fat filled space above the layer called the epidural space
Arachnoid –middle; web-like appearance
Potential space between Dura and arachnoid is the subdural space
Pia Mater –innermost, delicate membrane fused with CNS surface
Space between Pia and Arachnoid is the subarachnoid space

8. Meninges of the Spinal Cord
Epidural space
Pia mater
Arachnoid
Dura mater
Meninges
Subdural space
Subarachnoid space
Dorsal Root Ganglion
Centrum

9. Brain Meninges

10. Extensions of Dura Mater hold brain in cavity
Sellar diaphragm (not shown)

11. Venous Sinuses of Cranium
Superior Sagittal
Inf. Sagittal
Straight
Transverse
Cavernous
Sigmoid

12. Lateral Venous Lacunae
Arachnoid villi

13. Middle Meningeal Artery
Maxillary A.

14. Brain Ventricles

15. Choroid Plexus

16. CSF (cerebral-spinal fluid) Flow

17. Hydrocephalus
Blockage of CSF flow can lead to severe brain and/or head enlargement.
In an adult, such swelling would be fatal.

18. Brain
Development
Structures
Functional Areas

19. Neural Tube forming

20. Neural Tube

21. Brain Vesicles

22. Flexures and Cerebral Cortex Growth

23. Major Divisions of Brain
Brain Stem = midbrain + pons + medulla

24. Brain Anatomy (req’d)

25. Projections vs. Commissures

26. Functional Areas of Cerebrum

27. Primary Motor and Somatosensory Gyri

28. Basal Nuclei: cerebral nuclei
Putamen and Globus Pallidus
Subthalamic nuclei and the Substantia nigra are usually included

29. Reticular Formation
Extends along length of brain stem; used in maintaining alertness while awake; also includes motor nuclei such as centers for Cardiac,
Respiratory and Vasomotor control.

30. RAS receives inputs from eye, ear and general sensation to maintain alertness

31. Limbic System: functional system; responsible for emotion and memory
Cingulate Gyrus
Fornix
Mammillary body

32. Hypothalamus Control of Pituitary

33. Posterior Pituitary

34. Anterior Pituitary

35. Pineal Gland
Plays a major role in circadian rhythm control through its sympathetic connection to the hypothalamus
Melatonin increases at night and decreases during daylight
Implicated in the control of major life changes (such as the onset of puberty and adulthood

36. Internal Carotid Artery

37. Blood Supply (Circle of Willis)
Ant. Cerebral
Ant. Communicating
Middle Cerebral
Internal Carotid A.
Post. Communicating
Post. Cerebral
Basilar A.
Vertebral A.

38. Cranial Nerves

39. CN I: Olfactory Nerve covered by meninges and contain glial cells
Cribiform plate damage after trauma could lead to CSF leakage (runny nose after head trauma)
Pathway: Bulbtract  med and lat. stria prepiriform and amygdala

40. CN II: Optic Nerve Covered by meninges Leaves by optic canal
Pathway: nervechiasma  tracts  lat. geniculate and sup. colliculus  optic radiation to occipital lobe

41. CN III: Occulomotor Nerve
Superior Orbital Fissure
Midbrain
Pons
Oculomotor N. (III)
Ciliary ganglion
Inferior
Rectus muscle
Oblique muscle
Superior Rectus
muscle
Medial Rectus
Levator Palpabrae
Parasympathetic
Motor fibers
CN III: Occulomotor Nerve
Originates from brain stem: midbrain
Leaves via sup. orbital fissure
Path: occulomotor nucleus  muscles : levator palpebrae, sup., medial, inf. rectus, and inf. oblique. Separate branch from Edinger-Westphal nuclues  ciliary ganglion  parasym innervation to iris sphincter and ciliary muscle.
Palsy –leads to ptosis, diplopia, dilated pupil; gaze is “down and out”; pupil involvement usually due to increase cranial pressure due to surface location of fibers in nerve

42. CN IV: Trochlear Nerve Originates from brain stem: midbrain
Complete decussation in midbrain
Nucleus to Sup. oblique, runs the longest distance in cranial vault
Passes through sup. orbital fissure
In injury, affected eye is higher and deviated medially, head tilts away from lesion; hardest to diagnose

43. CN V: Trigeminal Nerve

44. CN VI: Abducens Nerve
Originates from brain stem: pons  goes to lateral rectus m.
Passes through sup. orbital fissure
Injury: affected eye deviates medially (crosseyed look) patient may turn head to compensate

45. CN VII: Facial Nerve

46. CN VIII: Vestibulocochlear Nerve

47. CN IX: Glossopharyngeal Nerve

48. CN X: Vagus Nerve

49. CN XI: Accessory Nerve

50. CN XII: Hypoglossal Nerve