Dr. Michael P. Gillespie. Kyphosis – exaggeration of the thoracic curve Lordosis – an...

Dr. Michael P. Gillespie

Kyphosis – exaggeration of the thoracic curve

Lordosis – an exaggeration of the lumbar curve or cervical curve

Lumbar spine stenosis – narrowing of the spinal canal

Scoliosis – lateral bending of the vertebral column

Bony vertebraeMeningesCerebrospinal fluid (produced in the brain)

The spinal cord is located within the vertebral canal of the vertebral column.

The vertebral foramina form the canal.The vertebrae form a shelter for the cord.The vertebral ligaments, meninges and CSF

also provide protection.

White matter – contains the sensory and motor tracts (“highways”).

Gray matter – site for integration (summing) of action potentials.

Spinal nerves – connect the CNS to sensory receptors, muscles, and glands.

Connective tissue coverings that encircle the spinal cord and brain.Spinal meninges.Cranial meninges.

3 spinal meninges.Dura mater (most superficial).

Epidural space – between dura mater and wall of vertebral canal.

Arachnoid mater (middle layer) – spider web arrangement.Subdural space – between dura and arachnoid.

Pia mater (innermost layer).Subarachnoid space – between arachnoid and pia –

contains CSF.Denticulate ligaments – extend from pia and fuse with

arachnoid.

Cervical enlargement – nerves to and from the upper limbs

Lumbar enlargement – nerves to and from the lower limbs

Conus medullaris – the spinal cord tapers to a conical portion

Filum terminale – an extension of the pia mater that anchors the spinal cord to the coccyx

Cauda equina “horse’s tail”Spinal nerves – paths of communication

between the cord and the nerves innervating specific regions of the bodyPosterior (dorsal) root

Sensory nerve axonsPosterior (dorsal) root ganglion – swelling – cell

bodiesAnterior (ventral) root

Motor nerve axons

Spinal tap (lumbar puncture).Local anesthetic is given and a long

needle is inserted into the subarachnoid space.

Uses.Withdraw CSF for diagnosis.Introduce antiobiotics, contrast media,

anesthetics.Introduce chemotherapy.Measure CSF pressure.

Anterior median fissure.Posterior median sulcus.

Gray commissure – form the crossbar of the “H.”Anterior (ventral) gray horns – cell bodies of

somatic motor neurons and motor nuclei.Posterior (dorsal) gray horns - cell bodies of

somatic and autonomic sensory nuclei.Lateral gray horns – cell bodies of autonomic

motor neurons that regulate smooth muscle, cardiac muscle and glands.

Central canal – in the center of the gray commissure.

White columns.Sensory (ascending) tracts.Motor (descending) tracts.

2 principle functions.Nerve impulse propagation – white matter

tracts.Sensory impulses flow toward the brain.Motor impulses flow from the brain.

Information integration – gray matter.

The name of the tract often indicates its position in the white matter and where it begins and ends.

Lateral and anterior spinothalamic tracts.Convey impulses for pain, warmth, tickling,

itching, deep pressure, and a crude sense of touch (poorly localized).

Posterior columns.Convey impulses for proprioception,

discriminative touch, 2 point discrimination, light pressure sensations, and vibrations.

Direct pathways – convey precise voluntary movements.Lateral corticospinal.Anterior corticospinal.Corticobulbar.

Indirect pathways – govern automatic movements (I.E. Reflexes).Rubrospinal.Tectospinal.Vestibulospinal.

Reflex – a fast, unplanned sequence of actions that occurs in response to a particular stimulus.

Location of integration.Spinal reflex.Cranial reflex – integration in brain stem.

Types of reflexes.Somatic reflexes – contraction of skeletal

muscles.Autonomic (visceral) reflexes – responses of

smooth muscle, cardiac muscle, and glands.

Reflex arc (reflex circuit) - the pathway followed by nerve impulses.

Sensory receptor.Distal end of a sensory neuron.Responds to a stimulus.

Sensory neuron.Nerves terminate in the brain stem or spinal

cord.

Integrating center.Monosynaptic reflex arc - A synapse between a

sensory neuron and a motor neuron.Polysynaptic reflex arc – one or more

interneurons and a motor neuron.

Motor neuron.Effector.

The part of the body that responds to the motor nerve impulse.Somatic reflex – the effector is a skeletal muscle.Autonomic reflex – the effector is smooth muscle,

cardiac muscle or a gland.

Reflexes are normally predictable.They can provide information about the

health of the nervous system.

Damage or disease anywhere along the reflex arc can cause the reflex to be absent or abnormal.

Somatic reflexes can be tested by tapping or stroking the body surface.

Autonomic reflexes cannot be tested easily because the visceral receptors are deep inside the body.

Stretch reflexTendon reflexFlexor (withdrawal) reflexCrossed (extensor) reflex

A stretch reflex causes contraction of a skeletal muscle in response to stretching of the muscle.

Monosynaptic reflex arc.Ipsilateral reflex.This reflex helps avert injury by

preventing overstretching of a muscle.Reciprocal inhibition – when the stretched

muscle contracts, the antagonistic muscle(s) relax.

The tendon reflex controls muscle tension by causing muscle relaxation before muscle forces become so great that they tear tendons.

Ipsilateral reflex.Sensory receptors – tendon (Golgi tendon)

organs.

Causes withdrawal from a painful stimulus.

This reflex causes contraction of the flexor muscles with causes withdrawal from a painful stimulus.

Ipsilateral reflex.Several motor units at different levels of

the spinal cord are recruited – intersegmental reflex arc.

Reciprocal innervation occurs.

Helps you maintain balance.Contralateral reflex arc.Reciprocal innervation occurs.

The plantar flexion reflex is elicited by stroking the lateral outer margin of the sole.

The normal response is curling under of the toes.

Babinski sign – the great toe extends – this indicates damage to the descending motor pathways.

The babinski sign is normal in children under 18 months due to incomplete myelination of the axons.

The spinal nerve has two connections to the cord: a posterior root and an anterior root.

The posterior and anterior roots unite to form a spinal nerve at the intervertebral foramen.

The posterior root contains sensory axons and the anterior root contains motor axons; Therefore, the spinal nerve is a mixed nerve.

Endoneurium – surrounds individual axons.Perineurium - surrounds bundles of axons

called fascicles.Epineurium – surrounds the entire nerve.

After passing through the IVF, the spinal nerve forms rami (branches).Posterior (dorsal) ramus.Anterior (ventral) ramus.Meningeal branch.Rami communicantes – serves the autonomic

nervous system.

A network of axons.Principle plexuses:

Cervical plexus.Brachial plexus.Lumbar plexus.Sacral plexus.Coccygeal plexus.

The nerves have branches named for the structures they innervate.

The cervical plexus supplies the skin and muscles of the head, neck, and superior part of the shoulders and chest.

The phrenic nerves arise from the cervical plexus and innervates the diaphragm.

“C3, 4 & 5 keep the diaphragm alive.”

The brachial plexus provides the entire nerve supply of the shoulders and upper limbs.

Major nerves:Axillary nerve – supplies deltoid and teres

minor mm.Musculocutaneous nerve – supplies arm

flexors.Radial nerve – supplies posterior arm and

forearm mm.Median nerve – supplies anterior forearm mm

and some hand mm.Ulnar nerve – supplies anteromedial mm of the

forearm and most of the hand muscles.

Known as “waiter’s tip position”.Results from forceful pulling away of the

head from the shoulder.

Caused by improper intramuscular injections into the deltoid or when the cast is applied too tightly around the mid-humerus.

Indicated by wrist drop.

Numbness, tingling, and pain in the palm and fingers.

Inability to pronate the forearm.Weak wrist flexion.

Inability to abduct or adduct the fingers.Atrophy of the interosseous mm of the hand.“Clawhand”.Loss of sensation over the little finger.

Paralysis of the serratus anterior mm.The scapula protrudes.“Winged scapula”.

The lumbar plexus supplies the anterolateral abdominal wall, external genitals, and part of the lower limbs.

Femoral nerve injury.Can be caused by a stab or gunshot wounds.Inability to extend the leg and lost sensation.

Obturator nerve injury.Complication of childbirth.Paralysis of the adductor muscles of the leg

and loss of sensation.

The sacral plexus supplies the buttocks, perineum and lower limbs.The sciatic nerve originates here.

The coccygeal plexus supplies a small patch of skin in the coccygeal region.

Injury to the sciatic nerve causes sciatica – pain the extends from the buttock, down the posterolateral aspect of the leg and to the foot.Damage to the fibular nerve can cause:

Footdrop.Equinovarus – inverted foot.

Calcaneovalgus – injury of the tibial portion of the sciatic nerve resulting in dorsiflexion.

Specific segments of skin that are innervated by specific spinal segments or specific cranial nerves.

The nerve supply in adjacent segments overlaps somewhat.

Knowing which spinal segments supply each dermatome allows us to determine the location of nerve damage.

Meningitis – inflammation of the meninges.Nerve block – loss of sensation in a region

due to injection of a local anesthetic.Neuralgia – pain along the course of a

sensory nerve.Neuritis – inflammation of the nerves.Paresthesia – abnormal sensation.