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Cranial Fossa:Brain and Spinal Cord
PA 481 A&P
Tony Serino, Ph.D.
Biology Dept.
Misericordia Univ.
Central Nervous System (CNS)
• Gray vs. White matter• Protection of CNS
– Meninges– CSF flow
• Brain– Development– Selected structures
• Spinal cord– Selected structures
Cranial Fossa
Anterior
Middle
Posterior
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
Gray and White Matter
• Since the cerebrum and cerebellum outgrow their cores, gray matter ends up on outside of both structures.
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
Meninges of the Spinal Cord
Pia materArachnoid
Dura mater Meninges
Centrum
Epidural space
Subdural space
Subarachnoid space
Dorsal Root Ganglion
Brain Meninges
Extensions of Dura Materhold brain in cavity
Sellar diaphragm (not shown)
Venous Sinuses of Cranium
Superior Sagittal
Inf. Sagittal
Straight
Cavernous
Sigmoid
Transverse
Lateral Venous Lacunae
Arachnoid villi
Maxillary A.
Middle Meningeal A.
Middle Meningeal Artery
Brain Ventricles
Choroid Plexus
CSF (cerebral-spinal fluid) Flow
Hydrocephalus
• Blockage of CSF flow can lead to severe brain and/or head enlargement.
• In an adult, such swelling would be fatal.
Brain
• Development• Structures• Functional Areas
Neural Tube
forming
Neural Tube
Brain Vesicles
Flexures and Cerebral Cortex Growth
Major Divisions of Brain
Brain Stem = midbrain + pons + medulla
Brain Anatomy (req’d)
Projections vs. Commissures
Functional Anatomy of Brain
Functional Areas of Cerebrum
Primary Motor and Somatosensory Gyri
Basal Nuclei: cerebral nuclei
Putamen and Globus Pallidus
Subthalamic nuclei andthe Substantia nigra are usually included
Reticular FormationExtends along length of brain stem; used in maintaining alertnesswhile awake; also includes motor nuclei such as centers for Cardiac,Respiratory and Vasomotor control.
RAS receives inputs from eye, ear and genral sensation to maintain alertness
Limbic System: functional system; responsible for emotion and memory
Cingulate Gyrus
Fornix
Mammillary body
Hypothalamus Control of Pituitary
Posterior Pituitary
Anterior Pituitary
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
Internal Carotid Artery
Blood Supply(Circle of Willis)
Vertebral A.
Internal Carotid A.
Ant. Communicating
Post. Communicating
Ant. Cerebral
Post. Cerebral
Middle Cerebral
Basilar A.
Cranial Nerves
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: Bulbtract med and lat. stria prepiriform and amygdala
CN II: Optic Nerve•Covered by meninges•Leaves by optic canal•Pathway: nervechiasma tracts lat. geniculate and sup. colliculus optic radiation to occipital lobe
Superior Orbital Fissure Midbrain
PonsOculomotor N. (III)
Ciliaryganglion
InferiorRectus muscle
InferiorOblique muscle
Superior Rectusmuscle
Medial Rectusmuscle
Levator Palpabraemuscle
ParasympatheticMotor fibers
•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
CN III: Occulomotor Nerve
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
CN V: Trigeminal Nerve
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
CN VII: Facial Nerve
CN VIII: Vestibulocochlear Nerve
CN IX: Glossopharyngeal Nerve
CN X: Vagus Nerve
CN XI: Accessory Nerve
CN XII: Hypoglossal Nerve