An Introduction to the Spinal Cord, Spinal Nerves, and Spinal Reflexes Flashcards
What is a spinal reflex?
It is a rapid, automatic nerve responses triggered by specific stimuli.
What are spinal reflexes controlled by?
They are controlled by the spinal cord alone (not the brain).
A sensory receptor is triggered and the sensory input travels over _____ nerves to the reflex centres in the brain.
cranial
The brain sends a _____ _____ over cranial nerves to the _______.
motor output
effectors
A sensory receptor is triggered and the sensory input travels over _____ nerves to the reflex centres in the spinal cord.
Spinal
The spinal cord sends a _____ _____ over spinal nerves to the _______.
motor output
effectors
Muscles, Glands and Adipose tissues are all examples of what?
Effectors
The spinal _____ is about 18 inches _____ and 1/2 inch ______.
cord, long, wide
The spinal cord itself is not as long as the ______ _______.
vertebral column
Where does the spinal cord end?
Between vertebrae L1 and L2
The spinal cord has bilateral ________.
symmetry
What do the grooves do to the spinal cord?
They divide the spinal cord into left and right.
Name the 2 grooves of the spinal cord.
- Posterior median sulcus – on posterior side
* Anterior median fissure – deeper groove on anterior side
What are enlargements of the spinal cord caused by?
The amount of gray matter in segment
The involvement with sensory and motor nerves of limbs.
Name the 2 spinal cord enlargements.
Cervical enlargement and Lumbar enlargement.
What is the role of the cervical enlargement?
Supplies nerves (innervation) to the shoulders and upper limbs
What is the role of the lumbar enlargement?
Provides innervation (supplies nerves) to structures of the pelvis and lower limbs.
What do the conus medullaris, filum terminale and cauda equina make up?
The distal end of the spinal cord.
What is the name of the thin, conical spinal cord below lumbar enlargement?
Conus medullaris
Name the thin thread of fibrous tissue at end of conus medullaris that attaches to the coccygeal ligament.
Filum Terminale
What is the Cauda Equina?
Nerve roots extending below conus medullaris
Spinal cord segments are based on ______ where spinal nerves originate.
vertebrae
Positions of spinal segment and vertebrae change with _______.
age.
Cervical nerves are named for ______ vertebra whereas all other nerves are named for _____ vertebra.
inferior, superior.
The two branches of spinal nerves are known as ____.
roots
Name the 2 roots of the spinal nerves.
Ventral root and Dorsal root.
What does the ventral root contain?
The ventral root contains axons of motor neurons.
What does the dorsal root contain?
The dorsal root contains axons of sensory neurons.
What contain the cell bodies of sensory neurons?
Dorsal Root Ganglia.
Distal to _____ root _____, the sensory and the motor ____ are bound together into a single _____ _______.
dorsal, ganglion, roots, spinal nerve.
What fibres to mixed nerves carry?
They carry both afferent (sensory) and efferent (motor) fibres.
What are the spinal meninges?
Specialized membranes that isolate the spinal cord from its surroundings.
Name 3 functions of the spinal meninges.
- Protecting spinal cord against bumps and shocks to the skin of the back
- Carrying blood supply
- Continuous with cranial meninges, which surround the brain
What is the viral or bacterial infection of meninges known as?
Meningitis
Name the 3 meningeal layers.
Dura mater
Arachnoid mater
Pia mater
The dura mater is the _____ layer of the spinal cord.
Outer
Name the middle meningeal layer.
Arachnoid mater
Name the inner meningeal layer.
Pia mater
What meningeal layer is tough and fibrous?
Dura mater
The dura layer contains dense ____ fibres that are orientated along the ______ axis of the cord.
collagen
longitudinal
The inner surface of the dura mater and the outer surface of the arachnoid mater are covered by simple ______ ________.
squamous epithelia
What is the epithelium on the outer surface of the arachnoid called?
The arachnoid membrane
What layer is a mesh of collagen and elastic fibres?
Pia Mater
Pia mater is bound to underlying _____ ______.
Neural tissue
The interlayer space between the dura mater and arachnoid mater is known as the _____ ______.
Subdural space
The interlayer space between the arachnoid mater and pia mater is known as the _____ ______.
Subarachnoid space
What does the subarachnoid space contain?
Arachnoid trabeculae (collagen and elastin fibre network)
What is the subarachnoid space filled with?
Cerebrospinal Fluid (CSF)
Cerebrospinal fluid (CSF) acts as a _____ _______.
Shock Absorber.
CSF carries dissolved ____, ______ and ______.
gases, nutrients and wastes.
Name the 2 types of matter.
Gray matter and white matter
White matter is _______.
superficial
What does white matter contain?
myelinated and unmyelinated axons
What does gray matter surround?
The central canal of the spinal cord
What does gray matter contain?
neuron cell bodies, neuroglia and unmyelinated axons
What are the projections of gray matter called?
Gray Horns
Name the 3 types of gray horns.
Posterior Gray Horns
Anterior Gray Horns
Lateral Gray Horns
PAL :)
_________ gray horns contain somatic and visceral sensory nuclei.
Posterior
What type of gray horns contain somatic motor nuclei?
Anterior Gray Horns
Where are lateral gray horns in?
They are in thoracic and lumbar segments
What do later gray horns contain?
visceral motor nuclei
Axons that cross from one side of cord to the other before reaching gray matter are called _________ ___________.
Gray Commissures
The cell bodies of neurons form functional groups called _______.
nuclei
What do both motor nuclei and sensory nuclei connect to?
Peripheral Effectors
Where are sensory nuclei found?
Dorsal/posterior
Where are motor nuclei found?
Ventral/anterior
What does sensory or motor nucleus location within gray matter determine?
It determines what body part it controls.
On each side of the spinal cord, in medial to lateral sequence, name what the somatic motor nuclei control.
- Muscles that control the pectorial girdle
- Muscles that move the arm
- Muscles that move the forearm and hand
- Muscles that move the hand and fingers
Because the spinal cord is so highly organised, what can we predict?
We can predict which muscles will be affected by damage to a specific area of gray matter.
The white matter on each side of the spinal cord can be divided into 3 regions called _______.
columns
Name the 3 white columns.
Posterior White Columns
Anterior White Columns
Lateral White Columns
PAL
Where do Posterior White Columns lie?
between posterior gray horns and posterior median sulcus.
_________ white columns lie between anterior gray horns and anterior median fissure.
Anterior
Anterior white commissure is an area where ______ _______ from one side of the _____ _____ to the ______.
axons, cross, spinal cord, other
Lateral white columns are located on each side of the spinal cord between _____ and ______ columns.
anterior, posterior.
Each column contains ______ whose axons share functional and structural characteristics.
tracts
Name this- a bundle of axons in the CNS that is somewhat uniform with respect to diameter, myelination and speed.
A tract
All axons within a tract relay the same type of _______ (____ or ______) in the same ______.
information, sensory, motor, direction
Where do ascending tracts carry information to?
The brain
What do descending tracts do?
Carry motor commands to the spinal cord.
The spinal cord has a narrow ___ ____.
central canal
What is the central canal surrounded by?
gray matter
gray matter is covered by a thick layer of ________ -__________.
white matter
_______ matter consists of ascending and descending axons.
white
The central nervous system is made up of the _____and ________
brain and spinal cord
What makes up the PNS?
Cranial nerves and spinal nerves.
Define spinal reflex.
A spinal reflex is a rapid, automatic response triggered by specific stimuli. Spinal reflexes are controlled in the spinal cord.
Identify the three spinal meninges.
Dura mater
Arachnoid mater
Pia mater
Damage to which root of a spinal nerve would interfere with motor function?
The ventral root of the spinal nerve
Differentiate between sensory nuclei and motor nuclei
Sensory nuclei- Relay and receive SENSORY information FROM peripheral RECEPTORS
but
Motor nuclei ISSUE MOTOR COMANDS TO peripheral EFFECTORS
A disease that damages myelin sheaths would affect which portion of the spinal cord?
The columns in the white matter of the spinal cord, because the columns are composed of bundles of myelinated axons.