PERIPHERAL NERVOUS SYSTEM DR M.MAGDY PROFESSOR OF ANESTHESIA

The part of the nervous system outside the CNS Consists mainly of the nerves that extend from the brain (12 pairs of cranial nerves) and spinal cord (31 pairs of spinal nerves). Functions: Sends signals to the CNS Receives and transmits motor signals from the CNS Stimulates effectors

Cranial Nerves Function 1 Olfactory Sense of smell 2 Optic Sense of vision 3 Oculomotor Eye movements 4 Trochlear Aids muscles that move the eyes 5 Trigeminal Eyes, tear glands ,scalp, forehead, teeth , gums, lips, and mouth muscles 6 Abducens Lateral rectus Muscle 7 Facial Taste, facial expressions, tear and salivary glands 8 Vestibulocochlear Hearing and equilibrium 9 Glossopharyngeal Pharynx, tonsils tongue and carotid arteries; stimulates salivary glands 10 Vagus Speech, swallowing, heart muscle, smooth muscle and certain glands 11 Accessory Muscles of the soft palate, pharynx, larynx and neck 12 Hypoglossal Tongue movement

31 pair of spinal nerves which emerge from spinal cord 8 cervical. 12 thoracic. 5 lumbar. 5 sacral. 1 coccygeal.

Somatic Nervous System→ Responsible for receiving and processing sensory input from the skin, muscles, tendons, joints, eyes, tongue, nose and ears as well as excite the voluntary contraction of skeletal muscles. Autonomic Nervous system Motor neurons that control involuntary responses involving the organs, glands, and smooth muscles. Some voluntary control over the responses can come from relaxation, meditation, etc., which reduce perceptions of stress and in turn reduce the stress response.

The Sympathetic nervous system Portion of the autonomic nervous system that produces the “fight or flight” response: Dilation of pupils Increased heart and breathing rates Constriction of blood vessels Inhibits digestion

The parasympathetic nervous system Portion of the autonomic nervous system that produces the “rest and ruminate” response: Constricts pupils Dilates blood vessels Reduces heart and breathing rates. Stimulates digestion

Protection of the spinal cord The spinal cord is covered by The vertebral column The Dural sheaths The CSF

THE DURAL SHEETH Dura mater A tough fibrous coveting Arachnoid mater A web like covering ,under it the CSF Pia mater These Dural sheath are continuous with the Dural sheath covering the brain

Protection of the spinal cord Functions of CSF: It protects the brain tissue from injury in case of trauma( Shock absorber) It plays an important role in flushing metabolic toxins or waste from the brain's tissues. It supplies nutrients to nervous system tissue

nerve plexus  nerve plexus is a plexus (branching network) of intersecting nerves. A nerve plexus is composed of afferent and efferent fibers that arise from the merging of the anterior rami of spinal nerves and blood vessels

 Function of nerve plexus:- Control of skeletal muscle is shared by different axons that originate in adjacent levels of the spinal cord. This means that damage to a single level of the spinal cord is less likely to result in total paralysis of a muscle innervated by nerves from that plexus

Main nerve plexus Cervical Plexus—Serves the Head, Neck and Shoulders. ... Brachial Plexus—Serves the Chest, Shoulders, Arms and Hands. ... Lumbar Plexus—Serves the Back, Abdomen, Groin, Thighs, Knees, and Calves. ... Sacral Plexus—Serves the Pelvis, Buttocks, Genitals, Thighs, Calves, and Feet.

Cervical plexus:-is a network of nerve fibres that supplies innervation to some of the structures in the neck and trunk. It is located in the posterior triangle of the neck, halfway up the sternocleidomastoid muscle,

he brachial plexus is a network (plexus) of nerves (formed by the ventral ramus of the lower four cervical nerves and first thoracic nerve (C5, C6, C7, C8, and T1) .This plexus extends from the spinal cord, through the cervico-axillary canal in the neck, over the first rib, and into the armpit

The Lumbar is formed by the divisions of the first four lumbar nerves (L1-L4) and from contributions of the subcostal nerve (T12), which is the last thoracic nerve It is the main nerve supply of  skin and muscles of the abdominal wall, thigh, and external genitalia. The largest nerve that forms part of the lumbar plexus is the femoral nerve, which innervates the anterior thigh muscles and some of the skin distal to the inguinal ligament

Sacral plexus:- which provides motor and sensory nerves for the posterior thigh, most of the lower leg and foot, and part of the pelvis. It is part of the lumbosacral plexus and emerges from the lumbar vertebrae and sacral vertebrae (L4- S4)

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