Chapter 13 Spinal Cord And Spinal Nerves Flashcards
Composed of 100 million neuron’s and even more neuroglia
Spinal cord
Contain neural circuits that Control some of most rapid reactions to environmental changes
Spinal cord and its associated spinal nerves
A quick automatic response to certain stimuli that involves neuron’s only in the spinal nerves and spinal cord
Spinal cord reflex
Site for integration (summing) of excitatory post synaptic potentials and inhibitory postsynaptic potentials
Gray matter of the spinal cord
Arise as Neurotransmitter molecules interact with their receptors at synapses in the spinal cord
Graded potentials
Highways
White matter
Contains a dozen major sensory and motor tracks which function as highways along which sensory input travels to the brain and motor output travels from the brain to skeletal muscles and other effectors
Spinal cord
Delicate and does not respond well to injury or damage
Nervous tissue of the central nervous system
Protective layers off the central nervous system
Skull and vertebral column a space between two of the meningeal membranes containing cerebrospinal fluid that suspends the CNS tissue no in a weightless environment while surrounding it with the shock absorbing hydraulic cushion
Located with in the vertebral canal of the vertebral column
Spinal cord
Formed by the vertebral foramina of all of the vertebrae stacked one on top of the other.
Vertebral ligaments, meninges and cerebrospinal fluid provide additional protection
Vertebral column
Are three protective connective tissue coverings that encircle the spinal cord and brain
Meninges
Surrounds the spinal cord
Spinal meninges
Encircles the brain
Cranial meninges
Three spinal Meninges
Dura mater
Arachnoid mater
Pia Mater
Space between the dura Mater in the wall of the vertebral canal
Epidural space
Most superficial spinal meninges,thick strong layer composed of dense irregular tissue
Dura mater
Then avascular covering comprised of cells and thin loosely arranged collagen and elastic fibers. Layer middle of the meningeal membranes
Arachnoid Mater
Thin transparent connective tissue layer that adheres to the surface of the spinal cord and brain consist of thin squamous to cuboidal cells. With in interlacing bundles of collagen fibers and some fine elastic fibers. innermost meninx
Pia Mater
Triangular shaped membranous extensions. Thickenings of the pia mater
Denticulate Ligaments
Project laterally and fuse with the arachnoid Mater and inner surface of the dura Mater between the The anterior and posterior nerve roots of the spinal nerves
Denticulate ligaments
Protects the spinal cord against sudden displacement that could result in shock
Denticulate ligament
Contains shock absorbing cerebrospinal fluid located between the arachnoid Mater and pia mater
Sub arachnoid space
Removal of cerebrospinal fluid from the sub arachnoid space
Spinal tap
Inflammation of the meninges
Meningitis
Is roughly oval in shape for that then slightly anteriorly and posteriorly in adults if it extends from the medulla oblongata to the superior border of the second lumbar vertebra
Spinal cord
Pathway for sensory input to the brain and motor output from the brain
Spinal cord
Procedure used to diagnose pathologies and to introduce antibiotics contrast media anesthetics and chemotherapeutic drugs
Spinal tap or lumbar puncture
Contain cervical and lumbar enlargements that serves as points of origin for nerves to the extremities
Spinal cord
Tapered portion of the spinal cord from which arise the filum terminale and cauda equina
Conus medullaris
Flat the cylinder 16 to 18 inches long and 3/4 inch diameter an adult ends at L2 a newborn and L for growth of cord stops at age 5
cervical enlargement -upper limbs
Lumbar enlargement -lower limbs
External anatomy of spinal cord
Conus medullaris
Filum terminale
Caudae equinae (horses tail)
Spinal segment
Inferior end of spinal cord
Going shaped end of spinal cord
Conus medullaris
Thread like extension of pia mater
stabilizes spinal cord in Canal
Filum Terminale
Dorsal and ventral roots of lowest spinal nerves
Caudae Equinae (Horses Tail)
Area of cord from which each pair of spinal nerves arises
Spinal segment
Paths of communication between the spinal cord and most of the body
Spinal nerves
Two points of attachment that connect each spinal nerve to a segment of the spinal cord
Roots
Eight pairs of cervical nerves
12 pairs of thoracic nerves
five pairs of lumbar nerves five pairs of sacral nerves
one pair of coccygeal nerve
The 31 pairs of spinal nerves
Begin as roots
Spinal nerve
Outgoing motor fibers
Ventral or anterior root
Cell bodies of sensory nerves
Dorsal root ganglion
Penetrate the white Mater of the spinal cord and divided into right and left sides
Anterior median fissure and posterior median sulcus
Shaped like the letter H are a butterfly and is surrounded by white Matter
Gray matter
Consists primarily of cell bodies of neurons and neuroglia and in myelinated axons and dendrites of association and motor neuron’s
Gray matter
Forms the crossbar of the H shaped gray matter
Gray commissure
Consists of bundles of myelinated axons of motor and sensory neurons
White matter
Continues with fourth ventricle of brain
Central canal
Shaped like the letter H or butterfly contains neuron cell bodies, unmyelinated axons and dendrites
Paired dorsal and ventral a gray horns
lateral horns only present in thoracic spinal cord
Gray commissure crosses the midline
Gray Matter
Anterior to the gray commissure
Connects the white matter of the right and left sides of the spinal cord
Anterior white commissure
Divided into horns contain cell bodies of neurons
Gray matter
Divided into columns each column contains distinct bundles of nerve axons that have a common origin or destination and carry similar information
White matter
Distinct bundles of nerve axons
Tracts
Covers gray matter
White matter
Deeper than a posterior median sulcus
Anterior median fissure
Contain axons that form ascending and descending tracts
Anterior lateral and posterior white columns
To principal functions of the spinal cord
White matter tracts are highways for nerve impulse conduction to and from the brain
Gray matter receives and integrates incoming and outgoing information
Conduct nerve impulses toward the brain the Lateral and anterior spinothalamic tracts and the posterior column tract
Sensory (ascending)
Conduct impulses down the cord
Motor (descending)tracts
Include lateral and anterior corticospinal and corticobulbar tracts
Direct pathways
Include rubrospinal, tectospinal and vestibulospinal tracts
Indirect pathways
Function of tracts
Highways for sensory and motor information
Naming of tracts
Indicate position and direction of signal
Ascend
Sensory tracts
Descend
Motor tracts
Function of tracts
Highways for sensory and motor information
Impulses travel from spinal cord towards
Brain (thalamus) found in anterior part of spinal cord
Motor tracts
Pyramidal tract
Extra pyramidal tract
Sensory tracts
Spinothalamic tract
Posterior column
Spinocerebellar
Pain temperature the pressure and crude touch
Spinothalamic tract function
Proprioception,discriminative touch two point discrimination pressure and vibration
Posterior columns
Precise voluntary movements
Direct pathways (corticospinal and corticobulbar
Programming automatic movements posture and muscle tone equilibrium and coordination of visual reflexes
Indirect pathways (rubrospinal vestibulospinal)
Fast predictable automatic response to changes in their environment that helps to maintain homeostasis
Reflex
May be spinal cranial somatic or autonomic
Reflexes
Serves us and integrating center for spinal reflexes occurs in the gray matter
Spinal cord
Specific nerve impulse pathway
Reflects arc
Five components of reflex arc
Receptor sensory neuron integrating center motor neuron effector
Simplest type of pathway
Reflex arc
Specific neural circuits include at least one synapse
Pathways
Helps maintain homeostasis by permitting the body to make exceedingly rapid adjustments to homeostatic imbalances
Reflexes
Include the stretch reflex tendon reflex Flexor reflex crossed extensor reflex all exhibit reciprocal innervention
Somatic spinal reflexes
Operates as a feedback mechanism to control muscle length by causing muscle contraction
Prevents injury from overstretching biggest muscle contracts when it is stretched
Mono synaptic ipsilateral reflex arc
Stretch reflex or patellar reflex
Muscle spindle signals stretch of muscle motor neuron activated and muscle contracts
Events of stretch reflex
Sets muscle spindle sensitivity as it sets muscle tone
Brain
Antagonistic muscles relax as part of reflex
Reciprocal innervation(polysynaptic-interneuron)
Operates as a feedback mechanism to control muscle tension by crossing muscle relaxation when muscle force becomes too extreme ipsilateral polysynaptic reflex
Tendon reflex
Kosice contraction of ipsilateral muscle group
Reciprocal innervation or polysynaptic
Golgi tendon organs are in tendon activated by stretching of tendon in inhibitory neuron is stimulated
Tendon reflex
Is ipsilateral and is a protective or drywall reflects that moves and them to avoid pain
Flexor or withdrawal reflex
Resulting in contraction off flexor muscles to move a limb to avoid injury or pain
Flexor and crossed extensor reflexes
Is contralateral helps to maintain balance during the flexor reflects
Crossed extensor reflex
Balance maintaining reflects that crosses the synchronized extension of the joints of one limb and flex ion of the joints in the opposite limb
Crossed extensor reflexes
Step on tack (pain fibers send signal to spinal cord)
interneurons branch to different spinal cord segments
motor fibers in several segments are activated more than one muscle group group activated to lift foot off of tack
Flexor reflex
Lifting for left foot requires extension of right leg to maintain one’s balance
pain signals cross to opposite spinal cord
Crossed extensor reflex
Stimulated by interneurons to hold up the bodyweight
Contra lateral extensor muscles
When extensors contract flexors relax
Reciprocal innervation
Stroke the lateral margin of the sole
normal response is curling under the toes
Plantar flexion reflex
Upward Fanning of toes due to incomplete my myelination in child
Babinski sign
Connects the CNS to sensory receptors muscles and glands and are part of the peripheral nervous system
Spinal nerves
Formed by roots of the lower lumbar sacral and coccygeal nerves are not in line with their corresponding vertebrae
Cauda equina
Connects to the cord via an interior and the posterior root
Spinal nerves
Is a mixed nerve
Spinal nerve
Contains sensory axons
Posterior root
Contains motor axons
Anterior root
8 pairs of cervical nerves
C1-c8
12 pairs of thoracic nerves
T1-t12
Five pairs of lumbar nerves
L1-L5
Five pairs of sacral nerves
S1-S5
Made of 31 pairs of spinal nerves and mix sensory and motor nerves
Spinal nerves
A single axon within an emdoneurium
Fiber
A bundle of fibers within a perineurium
Fascicles
A bundle of fascicles within an epineurium
Nerve
Grouped within connective tissue sheaths
Spinal nerve axons
Wrapping of each nerve fibers
Endoneurium
Surrounds group of nerve fibers forming a fascicle
Perineurium
Covering of entire nerve
Epineurium
Blends into it at inter-vertebral foramen
Dura mater
Around each axon
Emdoneurium
Around entire nerve
Epineurium
Around each fascicle
Perineurium
Form from dorsal and ventral roots
Branch into dorsal and ventral rami
Spinal nerves
Supply skin and muscles of back
Dorsal rami
Form flexes supply anterior trunk and limbs
Ventral rami
Supply meninges, vertebrae and blood vessel
Meningeal branches
Joining of ventral rami of spinal nerves form
Found in neck, arms, low back and sacral regions
Nerve networks or plexuses
No plexuses in
Thoracic region
Supplies the skin and muscles of the head neck and upper part of the shoulders connects with some cranial nerves and supplies the diaphragm
Cervical plexus
Causes respiratory arrest
Damage to the spinal cord above the origin of the phrenic nerves c3-c5
Breathing stops because
The phrenic nerves no longer send impulses to the diaphragm
C-1 C-5 ventral rami
Supplies parts of head neck and shoulders
Cervical plexus
Keeps diaphragm alive
Phrenic nerve
Damage to cord above C3
Respiratory arrest
Constitutes the nerve supply for the upper extremities and a number of neck and shoulder muscles
Brachial plexus
Wrist drop carpal tunnel syndrome clawhand wing scapula, Erb-Duchene policy or waiters tip palsy, kumphe’s
Nerve disorders resulting from injury to the brachial plexus
C-5 through T1
Ventral rami
Basses superior to first rib and under clavicle
Brachial plexus
Musculocutaneous nerve
Elbow flexors
Radial nerve
Shoulder and elbow extensors
Flexors of wrist and hand
Median and ulnar nerve
Supplies the anterolateral abdominal wall external genitals and part of the lower extremities
Lumbar plexus
Largest nerve arising from the lumbar plexus
Femoral nerve
Inability to extend the leg and loss of sensation in the skin over the Antero medial aspect of the thigh
Injury to the femoral nerve
Common complication of childbirth and results in paralysis of the abductor muscles of the leg and loss of sensation over the medial aspect of the thigh
Obturator nerve injury
Supplies the buttocks perineurium
and part of the lower extremity
Sacral plexus
Largest nerve in the body
Sciatic nerve
Branches results in sciatica pain that extends from the butt back down to the back of the leg
Injury today sciatic nerve, and common peroneal portion
Injury can occur due to a herniated disc dislocated hip osteoarthritis of the lumbar spine pressure from the uterus during pregnancy or improperly administered gluteal injection
Sciatic nerve injury
Anterior to the sacrum the ventral rami of L4 to L5 and S1 to S4
Supplies buttocks, perineurium and part of lower limb
Sacral plexus
L4 to S3 supplies post high and all below knee
Sciatic nerve
Produces foot drop or numbness
Peroneal nerve injury
Produces calcaneovalgus or loss of function under dear your leg and dorsum of
Tibial nerve injury
Located behind the knee
Common peroneal nerve and tibial nerve
Pain extending from the buttocks down the leg to the foot
Sciatica
The skin over the entire body supplied by spinal nerves that carry somatic sensory nerves impulses into the spinal cord
Dermatomes
All spinal nerves except C1 innervate specific constant segments of the skin skin segments are called
Dermatomes
Supplied by cranial nerve V
Skin on face
Damage regions of the spinal cords can be distinguished by patterns of numbness over what region
Dermatome region
Must be done over three adjacent spinal nerves
Infusing local anesthetics or cutting roots
Injury that severs the cord loss of sensation and motor control below the injury
Spinal cord
Inflammation of nerves cost by injury vitamin deficiency or poison
Neuritis
Infection of peripheral nerve by chickenpox virus causes pain skin discoloration line of skin blisters
Shingles
Viral infection costing motor neuron death and possible death from cardiac failure or respiratory arrest
Polo myelitis
Waiters tip position fall on his shoulder
Erb-Duchene palsy
Improper deltoid injection or tight cast wrist drop
Radial nerve injury
Numb palm and fingers inability to pronate and flex fingers
Median nerve injury
Inability to adduct/abduct fingers atrophy of interosseous
Ulnar nerve injury or clawhand
Paralysis of serratus anterior can’t of abduct above horizontal
Long thoracic nerve injury or winged scapula