Presentation on theme: "Spinal Cord and Peripheral Nerves Chapter 11"— Presentation transcript:
1 Spinal Cord and Peripheral Nerves Chapter 11 Joe Pistack MS/ED
2 Peripheral nervesThe brain, the spinal cord and the peripheral nervous system work together as a communication system.
3 Peripheral nervous system In the absence of spinal cord function, there is no sensory activity present.Person cannot feel any type of sensation.Lack of voluntary motor activity, cannot move.
4 Spinal cord Continuation of the brain stem. Tube like structure, located within the spinal cavity.17 inches long and extends from the foramen magnum to the level of the first lumbar vertebrae.
5 Lumbar puncture Lumbar puncture- a hollow needle is inserted into the subarachnoid space between L3 and L4.A sample of cerebrospinal fluid is withdrawn, sample is analyzed for elevated glucose, protein, bacteria and WBC’s.
6 Gray MatterGray matter-of the spinal cord is located in the center and shaped like a butterfly.Two projections of gray matter are the dorsal (posterior) horn and the ventral (anterior) horn.
7 Gray MatterCentral canal- opening or hole that extends the entire length of the spinal cord.Cerebrospinal fluid- flows from the ventricles in the brain through the central canal into the subarachnoid space.
8 White matter White matter- composed primarily of myelinated axons. Grouped together into nerve tracts.
9 White MatterAscending Tracts-carry information from the periphery, up the spinal cord, and toward the brain.Ex.- spinothalamic tract carries sensory information for touch, pressure and pain.Descending tracts-carries information from the brain, down the spinal cord, and toward the periphery.Ex.-motor tracts
10 Decussation Decussation- the crossing over from one side to the other. Most motor tracts decussate at the level of the brain stem.Most sensory tracts decussate in the spinal cord and travel up the spinal cord to the brain.
11 DecussationQuadriplegia-paralysis of all four extremities caused by the severing of the spinal cord at the neck region.Usually caused by an injury where the neck is compressed or bent excessively.Paraplegia-paralysis of the lower extremities, person has use of upper extremities.
12 Spinal nerves The spinal cord serves three main functions: Sensory pathwayMotor pathwayReflex centerSensory pathway-spinal cord serves as a pathway for information traveling from the periphery to the brain.EX.-pick your finger-information ascends the spinal cord to the brain where you experience the sensation.
13 Spinal NervesMotor Pathway-spinal cord provides a pathway for information coming from the brain and going to the periphery.Ex.-kicking a football-information needs to travel from the brain, down the spinal cord and to the muscles of the leg and foot.Reflex center-the spinal acts as a major reflex center.Ex. When you stick your finger, you automatically withdraw it from the object that you picked it with.
14 Reflexes Reflex- involuntary response to a stimulus. Ex. Touch a hot surface, pull hand away.Patellar or knee-jerk reflex-in response to a tap on your kneecap, your lower leg quickly and involuntarily pops up.
15 The Reflex arc Reflex arc-nerve pathway involved in a reflex. Four components of a reflex arc:(1) Receptor-area is stimulated.(2) Afferent or sensory neuron-nerve impulse is carried by the sensory neuron to the spinal cord.(3) Efferent or motor neuron-nerve impulse is carried by a motor nerve to the muscle.(4) Effector organ-the stimulated organ will move.
16 Organ Reflexes Reflexes help to regulate body function. Some reflexes are used for diagnostic purposes.Abnormal reflexes of the CNS may indicate lesions, tumors, or other neurological diseases such as MS
17 Organ reflexesPupillary reflex-regulates the amount of light that enters the eye.Bright light directed into the eye, muscles that control pupillary size constrict.Baroreceptor reflex-when blood pressure changes, these reflexes cause the heart and blood vessels to respond in a way that restores blood pressure to normal.
18 ReflexesBabinski reflex- stroking the lateral sole of the foot in the direction of heel to toe with a hard blunt object.In an adult, if the response is curling of the toes it is negative or normal.An abnormal response is dorsiflexion of the big toe, with fanning or the spreading of the other toes. Could be a sign or a lesion or damage to the spinal cord.
20 Peripheral nervous system Peripheral nervous system-consists of the nerves and ganglia located outside the CNS.Nerves are classified as follows:Sensory nerves-composed only of sensory neurons.Motor nerves-composed only of motor neurons.Mixed nerves-contains both sensory and motor neurons.
21 Peripheral nervous system Classified in two ways:Structurally-by parts.Functionally-according to what they do.Structurally-divides the nerves into the cranial and spinal nerves.Twelve pair of cranial nerves, each has a specific number, designated by a roman numeral, and a name.
22 Functions of the cranial nerves Carry sensory information for the special senses: smell, taste, vision and hearing.Carry sensory information for the general senses: touch, pressure, pain, temperature and vibration.Carry motor information that results in the contraction of the skeletal muscles.Carry motor information that results in the secretion of glands and contraction of cardiac and smooth muscle.
23 Cranial nerves I Olfactory A sensory nerve that carries information from the nose to the brain.Concerned with the sense of smell.Damage to this nerve may result in loss of sense of smell.
24 Cranial Nerves II Optic nerve sensory nerve that carries visual information from the eye to the brain, specifically the occipital lobe of the cerebrum.Damage to this nerve causes diminished eye site or blindness.
25 Cranial nerves III-Oculomotor primarily a motor nerve that causes contraction of the extrinsic eye muscles, thereby moving the eyeball in the socket.raises the eyelid and constricts the pupils of the eye.
26 Cranial nerves III Oculomotor Damage to this nerve interferes with raising the eyelid, results in ptosis (drooping of the eyelid).Compression of this nerve interferes with the ability of the pupil to respond to light.(sluggish pupillary response)With severe compression, the pupil may become fixed and dilated.
27 Cranial nerves IV- Trochlear Primarily a motor nerve that innervates one of the extrinsic muscles of the eyeball, helps to move the eyeball.Damage may cause double vision or inability to rotate the eye properly.
28 Cranial nerves V-Trigeminal mixed nerve with three branches supplying the facial region.Two sensory branches carry information regarding touch, pressure and pain from the face, scalp, eye, and teeth to the brain.Ophthalmic branch detects sensory information from the cornea.If cornea is touched, motor fibers will respond by eliciting blinking or secretion of tears.
29 Cranial nervesBoth the trigeminal and facial nerves participate in the corneal reflex.The motor branch innervates the muscles of mastication.Nerve damage causes a loss of sensation and impaired movement of the mandible.
30 Cranial nervesTrigeminal neuralgia or tic douloureux- inflammation of the trigeminal nerve.Pain may be triggered by eating, shaving, or exposure to cold temperatures.
31 Cranial nerves VI- Abducens Primarily a motor nerve, controls eye movement by innervating only one of the extrinsic eye muscles.Nerve damage prevents a lateral rotation of the eye At rest the eye drifts medially, toward the nose.
32 Cranial nerves VII-Facial A mixed nerve that performs mostly motor functions.Called the nerve of facial expressions. Allows us to smile, frown, and make other faces.Stimulates the secretion of saliva and tears.Sensory function is taste.
33 Cranial nervesIf the facial nerve is damaged, facial expression is absent on the affected side.This condition is Bell’s Palsy.One side of the face sags while the other side looks normal.
34 Cranial nerves Cosmetically, this condition is very distressing. Condition responds well to steroid therapy.
35 Cranial nerves VIII- Vestibulocochlear A sensory nerve that carries information for hearing and balance from the inner ear to the brain.The vestibular branch of this nerve is responsible for equilibrium, or balance and the cochlear branch is responsible for hearing.Damage to this nerve may cause loss of hearing or balance or both.
36 VIII Vestibulocochlear Accoustic neuroma is a tumor of the vestibulocochlear nerve. Patient presents with vertigo. (differentiate between dizziness and vertigo).
37 Cranial nerves IX Glossopharyngeal A mixed nerve that carries taste sensations from the posterior tongue to the brain.Motor fibers stimulate the secretion of salivary glands in the mouth.Other motor fibers innervate the throat and aid in swallowing.
38 Glossopharyngeal This nerve is associated with the gag reflex. Loss of the gag reflex places you at risk for choking.Sensory function is to regulate BP
39 Cranial NervesX VagusA mixed nerve that innervates the tongue, pharynx, larynx, and many organs in the thoracic and abdominal cavities.Nerve damage causes hoarseness or loss of voice, impaired swallowing, and diminished motility of the digestive tract.Sensory fibers also participate in the regulation of BP.
41 Cranial Nerves XI Accessory Primarily a motor nerve that supplies the sternocleidomastoid and the trapezius muscles.Controls the movement of the head and the shoulder regions.Nerve damage impairs the ability to shrug your shoulders.
43 Cranial nerves XII hypoglossal Primarily a motor nerve that controls movement of the tongue.Affects speaking and swallowing activities.Nerve damage causes the tongue to deviate toward the injured side.
46 Spinal nervesThirty-one pairs of spinal nerves emerge from the spinal cord.Each pair is numbered according to the level of the spinal cord from which it arises.
47 Spinal nerves The 31 pairs are grouped as follows: 8 pairs of cervical nerves.12 pairs of thoracic nerves.5 pairs of lumbar nerves.5 pairs of sacral nerves.1 pair of coccygeal nerves.
48 Spinal nerves Cauda equina- “horse’s tail”- area where the lumbar and sacral nerves exit from the vertebral column.
49 Spinal nerve plexusPlexuses-points where nerve fibers converge together.Three major nerve plexuses:Cervical plexusBrachial plexusLumbosacral plexusEach plexus will sort out the fibers and send them to specific parts of the body.
50 Spinal nerve plexusesCervical plexus-(C1 to C4): fibers from the cervical plexus supply the muscles and skin of the neck. Stimulate the contraction of the diaphragm.Brachial plexus-(C5 to C8, T1): supply muscles and skin of the shoulder, arm, forearm, wrist, and hand.The axillary nerve can be damaged with crutch walking. Patient should be taught not to put weight on the plexus or it will cause crutch palsy.
51 Spinal Nerve PlexusLumbosacral plexus- (T12, L1, to L5, S1 to S4): gives rise to the nerves that supply the muscles and skin of the lower abdominal wall, external genitalia, buttocks, and lower extremities.Sciatic nerve-longest nerve in the body, arises from the lumbosacral plexus.When the sciatic nerve is inflamed, it causes intense pain in the buttock and posterior thigh region.