Principles Of Anatomy & Physiology, Chapter 13, Spinal Cord Flashcards
Meninx (sing.)/ Meninges (pl.)
Three protective, connective tissue covering that encircle the spinal cord and brain. From superficial to deep they are the (1) dura mater, (2) arachnoid mater, and (3) pia mater.
Dura Mater
The most superficial of the three spinal meninges is a thick strong layer composed of dense irregular connective tissue. The ______ forms a sac from the level of the foramen magnum in the occipital bone, where it is continuous with the meningeal ______ of the brain, to the second sacral vertebra. The ______ is also continuous with the epineurium, the outer covering of the spinal and cranial nerves.
Epidural Space
A space between the dura mater and the wall of the vertebral canal.
Arachnoid Mater (Arachnoid)
This layer, the middle of the meningeal membranes, is a thing, avascular covering comprised of cells and thing, loosely arranges collagen and elastic fibers. It is called the _______ because of it's spider's web arrangement of delicate collagen fibers and some elastic fibers. It is deep to the dura mater and it continuous through the foramen magnum with the _______ of the brain.
Subdural Space
A thin space between the dura mater and the arachnoid mater. Contains interstitial fluid.
Pia Mater
The innermost meninx is a thin transparent connective tissue layer that adheres to the surface of the spinal cord and brain. It consists of thin squamous to cuboidal cells within interlacing bundles of collagen fibers and some fine elastic fibers. Within the _____ are many blood vessels that supply oxygen and nutrients to the spinal cord. Triangular shaped membranous extensions of the _____ suspend the spinal cord in the muddle of its dural sheath.
Subarachnoid Space
Space between the arachnoid mater and the pia mater. Contains shock-absorbing cerebrospinal fluid.
Spinal Tap (Lumbar Puncture)
A long hollow needle is inserted into the subarachnoid space to withdraw cerebrospinal fluid (CSF) for diagnostic purposes.
Denticulate Ligaments
Extensions. Thickenings of the pia mater. They project laterally and fuse with the arachnoid mater and the inner surface of the dura mater between the anterior an posterior nerve roots of the spinal nerves on either side. Extending along the entire length of the spinal cord, the _______ project the spinal cord against sudden displacement that could result in shock.
Cervical Enlargement
Superior enlargement. Extends from the fourth cervical vertebra (C4) to the first thoracic vertebra (T1). Nerves to and from the upper limbs arise from this enlargement.
Lumbar Enlargement
Inferior enlargement. Extends from ninth to the twelfth thoracic vertebra. Nerves to and from the lower limbs arise from this enlargement.
Conus Medullaris
Inferior to the lumbar enlargement, the spinal terminates as a tapering, conical structure called the _______, which ends at the level of the intervertebral disc between the first and second lumbar vertebrae in adults.
Filum Terminale
Arising from the conus medullaris is the _______, an extension of the pia mater that extends inferiorly, fuses with the arachnoid mater and dura mater, anchors the spinal cord to the coccyx.
Cauda Equina
Bundle of nerve roots that branch off the bottom of the spinal cord. Nerves arise from the lumbar, sacral, and coccygeal regions of the spinal cord. Meaning "horse's tail".
Spinal Nerve
Paths of communication between the spinal cord and specific regions of the body.
Posterior (Dorsal, Sensory) Root
Contain only sensory axons, which conduct nerve impulses from sensory receptors in the skin, muscles, and internal organs into the CNS.
Posterior (Dorsal, Sensory) Root Ganglion
A swelling of the posterior root. Contains the cell bodies of sensory neurons.
Anterior (Ventral, Motor) Root
Contain axons of motor neurons, which conduct nerve impulses from the CNS to effectors (muscles and glands).
Anterior Median Fissure
A wide groove on the anterior (ventral) side of the brain.
Posterior Median Sulcus
A narrow furrow on the posterior (dorsal) side of the brain.
Gray Commissure
Forms the crossbar of the H.
Central Canal
A small space in the center of the gray commissure. It extends the entire length of the spinal cord and is filled with cerebrospinal fluid.
Anterior White Commissure
Anterior to the gray commissure. Connects the white matter of the right and left side of the spinal cord.
Horns
The grey matter on each side of the spinal cord is subdivided into regions called ______.
Columns
Group of white matter tracts in the spinal cord.
Ascending (Sensory) Tract
Consist of axons that conduct nerve impulses toward the brain.
Descending (Motor) Tract
Consist of axons that carry nerve impulses from the brain.
Endoneurium
Individual axons within a nerve, whether myelinated or unmyelinated, are wrapped in _______, the innermost layer. Consists of a mesh of collagen fibers, fibroblasts, and macrophages.
Fascicle
Groups of axons with their endoneurium are held together in bundles called ______.
Perineurium
Each fascicle is wrapped in ______, the middle layer. The ______ is the thickest layer of connective tissue. It consists of ip to 15 layers of fibroblasts within a network of collagen fibers.
Epineurium
Outermost covering of the entire nerve is the _______. It consists of fibroblasts and thick collagen fibers.
Plexus
Axons from the anterior rami of spinal nerves, except for thoracic nerves T2-T12, do not go directly to the body structures they supply. Instead, they form networks on both the left and right sides of the body by joining with various members of axons from anterior rami of adjacent nerves. Such a network of axons is called a ________.
Cervical Plexus
Formed by the roots (anterior rami) of the first four cervical nerves (C1-C4), with contributions from C5. There is one on each side of the neck alongside the first four cervical vertebrae. Supplies the skin and muscles of the head, neck, and superior part of the shoulders and chest.
Brachial Plexus
Formed by the roots (anterior rami) of spinal nerves C5-C8 and T1. Extends inferiorly and laterally on wither side of the last four cervical and first thoracic vertebrae. It basses above the first rub posterior to the clavicle and then enters the axilla. Provides almost the entire nerve supply of the shoulders and upper limbs.
Lumbar Plexus
Formed by the roots (anterior rami) of spinal nerves L1-L4. Unlike the brachial plexus, there is minimal intermingling of fibers in this plexus. Supplies the anterolateral abdominal wall, external genitals, and parts of the lower limbs.
Sacral Plexus
Formed by the roots (anterior rami) of spinal nerves L4-L5 and S1-S4. This plexus is largely anterior to the sacrum. Supplies the buttocks, perineum, and lower limbs. The largest nerve in the body, the sciatic nerve, arises from this plexus.
Dermatome
The area of the skin that provides sensory input to the CNS via one pair of spinal nerves or the trigeminal (V) nerve is called a ______.
Spinal Reflex
When integration takes place in the spinal cord gray matter, the reflex is a ______. An example is the familiar patellar reflex (knee jerk)
Cranial Reflex
If integration occurs in the brain stem rather than the spinal cord, the reflex is called a ______. An example is the tracking movements of your eyes as you read this sentence.
Somatic Reflex
This reflex involves the contraction of skeletal muscles.
Autonomic (Visceral) Reflex
This reflex is generally not consciously perceived. It involves the response of smooth muscle, cardiac muscle, and glands. Heart rate, digestion, and urination are controlled my this reflex.
Reflex Arc
The pathway followed by nerve impulses that produce a reflex is a ________.
Receptor
Responds to a stimulus by producing a generator or receptor potential.
Monosynaptic Reflex Arc
A reflex pathway having only one synapse in the CNS.
Polysynaptic Reflex Arc
Involves more than two types of neurons and more than one CNS synapse.
Effector
Muscle of gland that responds to motor impulses.
Stretch Reflex
Causes contraction of skeletal muscle in response to stretching of muscle.
Muscle Spindle
Slight stretching of a muscle stimulates sensory receptors in the muscle called _______.
Ipsilateral Reflex Arc
Sensory nerve impulses enter the spinal cord in the same side from which motor nerve impulses leave it.
Reciprocal Innervation
Components of a neutral circuit simultaneously cause contraction of one muscle and relaxation of its antagonist.
Tendon Reflex
Operates as a feedback mechanism to control muscle tension by causing muscle relaxation before muscle force becomes so great that tendons might be torn.
Tendon Organ
Sensory receptor for tendon reflex.
Flexor Reflex
Involves post synaptic reflex arc. Results from painful stimulus. Ex: step on a tack and immediately withdraw your leg.
Intersegmental Reflex Arc
sensory signal enters the spinal cord at one level, and the motor output leaves the cord from a higher or lower level
Crossed Extensor Reflex
Reflex involved in pulling away from painful stimulus and balancing with opposite limb
Contralateral Reflex Arc
sensory impulses enter on one side of the spinal cord and motor impulses exit on the opposite side
Patellar Reflex
a reflex extension of the leg resulting from a sharp tap on the patellar tendon
Achilles Reflex
The response of this reflex is plantar flexion when the achilles (calcaneal) tendon is tapped with the reflex hammer.
Babinski Sign
Extensions of the great toe in response to gentle stroking of the outer margin of the soul of the foot is called a positive ____.
Abdominal Reflex
Normal response is the ipsilateral contraction of the abdominal muscles with an observed deviation of the umbilicus towards the stroke.
Pupillary Light Reflex
Normal response is constriction of same-sided pupils (direct) and simultaneous constriction of the other pupil (consensual) when light is advanced across pupil.
Monoplegia
paralysis of one limb
Diplegia
paralysis of both upper limbs or both lower limbs
Paraplegia
Paralysis (loss of sensation of voluntary movement) of the lower part of the body and both legs.
Hemiplegia
paralysis of one side of the body
Quadriplegia
paralysis of all four limbs
Complete Transection
spinal cord is severed from one side to the other, cutting all sensory and motor tracts
Hemisection
partial transection of the cord on either the right or left side
Spinal Shock
An immediate response to spinal cord injury characterized by loss of reflex function
Areflexia
absence of a reflex
Shingles
Infection of PNS caused by herpes zoster, the virus that also causes chicken pox.
Poliomyelitis
A viral infection of the gray matter of the spinal cord.
Epidural Block
Injection of anesthetic drug into the epidural space (between dura mater and cerebral column) in order to cause a temporary loss of sensation.
Meningitis
Acute infection of the meninges.
Myelitis
Inflammation of the spinal cord
Neuritis
Inflammation of a nerve or nerves
Sciatica
Inflammation of the sciatic nerve