Chapter 2 Gross Anatomy

cells specialized for nervous system function

collections of their processes

• peripheral nervous system (PNS)
•    -INcludes all parts of the system that are outside of the bony casings of the skull and spinal column
• central nervous system (CNS)
•    -INcludes all parts of the system that are within the skull and spinal column
•    -spinal column encases and protects the brain
•    *spinal cord and brain are continuous at the foramen magnum (hole at the base of the brain)

the reference position

nose end (also synonymous with rostral

buttocks end (tail end in lower animals)

back (also posterior)

front (also anterior)

superior (d) and inferior (v)

towards the midline

away from the midline

anterior-posterior cut which shows either the right or left side of the brain or spinal cord, usually sliced in the midline

sliced lateral to the midline

left-right cut which shows the dorsal or ventral side, made in the cerebral hemispheres or cerebellum-a top view of the hemispheres

• part of the CNS
• long column of:
•    -afferent nerve fibers ascending carrying info to brain
•    -efferent nerve fibers descending, carrying commands from brain
•    -interneurons and the cell bodies of these neurons

takes place locally in the spinal cord itself via local circuit neurons

Info from outside world enter the spinal cord and commands from the CNS exit the spinal cord via spinal nerves

since the spinal cord doesn't grow the same length as the spinal column, the bundle of spinal nerves that descends in the spinal column before exiting is called the cauda equina

• cervical vertebrae-first 7
• thoracic vertebrae-12
• lumbar-5
• sacral-5
• coccygeal-1-3

• carry motor and sensory info to and from the body
• correspond to vertebral level at which they exit (on the left and right)
• ed c1 is 1st cervical nerve

• function to all muscles below the level of the damage is lost
•    -if an individual has a spinal cord injury at the level of 
•       -c2, motor innervation to all muscles of respiration will be lost
•       -t6, motor innervation to the lower intercostals and all the accessory muscles of expiration will be lost

• sections of the spinal cord corresponding to the spinal nerves and overlying vertebrae are numbered in the same manner:
•    -the area of skin innervated by nerves related to a particular segment of the spinal cord is a dermatome
•    -the spinal cord has enlargements in lower cervical and lumbosacral areas known as the:
•       -brachial plexus and lumbosacral plexus
•             -formed by large numbers of nerve cell bodies and processes that collect in those areas
•             -ex-afferent and efferent nerves in the lumbosacral plexus innervate the lower extremeties

other cells of the nervous system that support neurons

areas of the cns composed primarily of cell bodies, as collections of neuron cell bodies appear grayish in color

areas composes primarily of neuron processes as a result of some specialized glia wrapping themselves around the processes of many neurons (forming insulating fatty layers, appearing whitish in color)

afferent nerves that pierce the spinal cord, bundled together

cell bodies outside of the spinal cord

efferent nerves that leave the spinal cord, bundled together (named for the side of the spinal cord they enter or exit)

• brainstem
•    -medulla oblongata
•    -pons
•    -midbrain
• diencephalon
• thalamus
• epithalamus
• hypothalamus
• cerebellum
• cerebrum (collectively the cerebral hemispheres)
• neuraxis-brainstem and spinal cord

• 1. cortex-most superficial part of each structure, primarily gray matter/neuron cell bodies
• 2. beep cerebellar nuclei-groups of cell bodies deep within the cerebellum
• 3. basal ganglia-groups of cell bodies deep within the cerebrum

• frontal, parietal, temporal and occipital
• wrinkled hillocks and grooves on the cortex: gyri and sulci
• deep sulci known as fissures

central sulcus or fissure of rolando

parietooccipital sulcus

sylvian fissure, insula

longitudinal fissure

massive white structure included in the fiber bundles connecting the two hemispheres

allow a lot of surface area to be contained and packed into the small area of the skull

how some areas of the brain are still identified, based on what some neuroanatomists referred to patches of the cortex with a uniformly similar cell pattern

portion of the cerebral cortex, hidden w/in the sylvian fissure, and is named for its seahorse shape in cross-section

in the midbrain, and is named for its black appearance (lesions have been implicated in parkinsons's disease)

large internal spaces

located at the rostral end of the brainstem

basal ganglia, caudate nucleus, globus pallidus, and putamen (as well as the substantia nigra and the subthalamic nucleus)

• phylogenetically the oldest part of the brain, and is the extension of the spinal cord inside the skull
• area of transition between the cerebrum and the spinal cord where many important functions are controlled

there is some descending pathways decussate (cross) in the pyramids (roughly triangular in shape)

• efferent and afferent fibers related to parts of the brainstem
• 12 pairs with 2 roles: bring info from the special senses and somatic senses of the face and head into the brain, and they send commands out to the muscles and glands of the head and neck to control behavior

tough membranes that protect the soft, gelatinous nervous system from contusion and infection

cushions the nervous system (important part of the circulatory system of the cns)