Structure of the Nervous System

Midterm Results

Anatomical References  References are made assuming a mammalian animal (such as a rat) on four legs. For humans, assume they are on hands & knees.  Toward the nose – forward, front: Anterior Rostral  Toward the tail – backward, rear: Posterior Caudal

Anatomical References (Cont.)  Direction pointing up from the back (spine): Dorsal (like a shark’s fin)  Direction pointing down from the belly: Ventral  The line running down the center of the nervous system is the midline. Close to the midline is medial. Far from the midline is lateral (side)

Anatomical References (Cont.)  Some references describe relations between structures: The nose is medial to the eyes. The eyes are medial to the ears.  Structures on the same side are ipsilateral.  Structures on opposite sides are contralateral.

Kinds of Sections (Slices)  Midsagittal plane – a slice that splits the brain into two equal halves from front to back between the eyes (along longitudinal fissure). Sagittal planes – slices parallel to midsagittal.  Horizontal plane – a slice parallel to the ground passing through both eyes and ears.  Coronal plane – a slice perpendicular to the ground and the sagittal plane.

Parts of the CNS  Cerebrum – largest part of the brain. Split into two hemispheres along the longitudinal (sagittal) fissure.  Cerebellum – behind the cerebrum, controls movement.  Brain Stem – the stalk supporting the cerebrum and cerebellum, relaying information from the spinal cord. Controls vital functions (breathing, heart rate)

Peripheral Nervous System  Somatic PNS – includes all the spinal nerves that control movement and collect sensory information from skin, muscles, joints.  Autonomic NS (Visceral PNS) – innervates internal organs, blood vessels, glands. Heart rate, smooth muscles of intestine  Afferent – toward the CNS  Efferent – away from the CNS

Imaging Techniques (Scans)  Viewing the structure of the brain: CT or CAT – computed tomography (uses x-ray) MRI – magnetic resonance imagery (uses magnetic field)  Viewing brain activity (functioning): PET – positron emission tomography (measures radioactive substance in blood flow) fMRI – functional MRI (uses magnetic detection of blood flow)

Neocortex  The terms cortex and neocortex are used interchangeably when referring to humans. Only mammals have neocortex. Neocortex is used for different things in different species. Evolution has its greatest impact on the size and function of the neocortex.  Localization of functions to areas of the brain is referenced to Brodmann areas.