General Histology II- Nervous Tissue

Perineurium

wraps fascicle

Epineurium

wraps entire nerve

Vasa nervorum

blood vessels that nourish nerve fibers and thier coverings

CNS

Brain and spinal cord

PNS

nerves, ganglia, plexus

Afferent sensory nerves

convey neural impulses from sensory organs to the CNS

General sensory fibers

sensations of skin, pain and proprioceptive sensations from muscles, tendons, and joints

Visceral sensory fibers

sensations of organs

Efferent motor

conveys neural impulses from CNS to effector organs (muscles and glands)

Somatic motor fibers

transmits impulses to skeletal muscle

Visceral motor fibers

transmit impulses to smooth muscle, cardiac muscle and glandular tissues

Brain matter

gray outer, white inner

Spinal cord matter

gray inner, white outer

Peripheral Nervous System

conduct impulses to or away from the CNS

Ganglia

collection of nerve cell bodies

Nerves

bundle of axons

Cranial nerves

12 pairs, arise from the CNS, but act in the PNS, can convey sensory or motor fibers

Spinal nerves

31 pairs

2 nerve roots arise from rootlets…

anterior nerve roots are motor fibers, and posterior nerve roots and sensory fibers that form a dorsal root ganglion (prevents overload)

Nerve roots combine to become a mixed spinal nerve then…

both anterior and posterior rami are motor and sensory fibers

Posterior rami of spinal nerves supplies

Synovial joints of vertebral column, Deep muscles of the back, Overlying skin in a segmental pattern

Anterior rami of spinal nerves supply

Muscles of the anterior & lateral regions of the trunk, Muscles of the upper & lower limbs, Skin to all these regions in a segmental pattern, Forms nerve plexuses (i.e., brachial plexus)

Nerves Plexuses

formed by combining and intermingling of anterior rami to form a new set of nerves

Dermatomes

unilateral area of skin supplies by a single (right or left) spinal nerve

Myotome

unilateral mass of muscle supplied by a single spinal nerve

Parasympathetic Nervous System

homeostatic/ anabolic, rest and digest

Sympathetic Nervous System

catabolic, energy producing, fight or flight

Location of parasympathetic nervous system

cranial and sacral region

Sympathetic nervous system location

thoracolumbar and vertebral column

Paravertebral ganglia

right and left sympathetic trunks on each side of vertebral column

white rami comunicantes

presynaptic sympathetic fibers leave anterior rami and pass to sympathetic trunks

gray rami comunicantes

postsynaptic sympathetic fibers re-enter the spinal nerves to distribute to anterior and posterior rami of that spinal nerve

Prevertebral (pre-aortic) ganglia

nerve plexuses surrounding main branches of abdominal aorta