Cranial Fossa: Brain and Spinal Cord PA 544 Tony Serino, Ph.D. Clinical Anatomy

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 mater Arachnoid Dura mater Meninges Centrum Epidural space Subdural space Subarachnoid space Dorsal Root Ganglion

Brain Meninges

Extensions of Dura Mater hold 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 Areas of Cerebrum

Primary Motor and Somatosensory Gyri

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

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.

RAS receives inputs from eye, ear and general 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.