The spinal cord and its associated spinal nerves contain ___________ that control the reactions to environmental changes.
The gray matter of the cord is a site for _______________ of action potentials.
sensory and motor
The white matter of the cord contains major _________and_________ tracts to and from the brain.
the end of the spinal cord between L1 - L2.
The bony vertebral column and The spinal meninges
Two types of connective tissue coverings protect the cord and provide physical stability
Dura mater, Arachnoid mater, and Pia mater
forms a sac that encloses the entire cord.
is a delicate avascular covering. It is attached to the inside
of the dura
The transparent _____ ____ is pressed-up against the cord and is filled with blood vessels that supply nutrients to it.
(SAS) in which cerebral spinal fluid (CSF) circulates.
runs between the dura mater and the more superficial ligamentum flavum (which lines the underside of the bony vertebral lamina).
lies between the dura and the arachnoid.
In the spinal column, the dura and arachnoid membranes are held firmly together so that the ___ space is often no more than a ____ space.
Arising from the conus medullaris is the ___, an extension of the pia mater that extends inferiorly and blends with the arachnoid and dura to anchor the spinal cord to the coccyx.
“horsestail” are the roots of thelower spinal nerves that angledown alongside the filum terminale.
The spinal cord has two enlargements, one in the ___ area from C4–T1, and another in the ___ area between T9–T12.
correlates with the sensory input and motor output to the upper extremities.
handles motor output and sensory input to and from the legs.
Two bundles of axons, called ____ connect each spinal nerve to a segment of the cord by even smaller bundles of axons called rootlets.
Posterior (dorsal) root
contain only sensory axons, which conduct nerve impulses from sensory receptors in the skin, muscles, and internal organs into the central nervous system.
Posterior (dorsal) root ganglion
Each posterior root has a swelling, the ______ , which contains the cell bodies of sensory neurons.
Anterior (ventral) root
contain axons of motor neurons, which conduct nerve impulses from the CNS to effectors (muscles and glands).
_________ is commonly administered to women about to go into labor. In this procedure, a needle is placed between the bones of the _________ until it just penetrates the ligamentum flavum yet remains ____ to the dura mater. It's only go to the ____.
A needle inserted into the ____ space for the purpose of _______ (for diagnosis or to reduce pressure) or to introduce a drug or contrast agent
Agents injected into the SAS include drugs such as ____, ____ agents, or analgesics, or contrast media for ______ procedures.
The pressure of CSF in the SAS can also be measured during a ___________.
L3 and 4, or L4 and 5,
The site used for most lumbar punctures is between the __________ lumbar vertebrae - below the termination of the actual cord in the region of the ________. With the needle in the SAS, CSF can be sampled.
In the spinal cord, the white matter is on the ___, and the gray matter is on the ____.
In the brain the white matter is on the _____, and the gray matter is on the _____.
The white matter of the cord
consists of millions of nerve fibers which transmit electrical information between the limbs, trunk and organs of the body, and the brain.
Anterior (ventral) gray horns
consist of somatic motor neurons.
Posterior (dorsal) gray horns
consist of somatic and autonomic sensory nuclei. It is the site of synapse between first-order sensory neurons coming in from the periphery, and second-order neurons which either ascend in the cord or exit back out as parts of reflex arcs.
lateral gray horns
contain cell bodies of autonomic motor neurons
goes from the spinal cord to the brain – it is an afferent tract that transmits sensations of pain, warmth, coolness, itching, tickling, deep pressure, and crude touch.
goes from the cortex of the brain to the spinal cord – it is an efferent tract.
are afferent tracts that convey nerve impulses for discriminative touch, light pressure, vibration, and conscious proprioception (awareness of tendon and joint position in space and their relative movements).
is an area of skin that is innervated by a single spinal nerve, indicated by the letters and number of a particular segmental nerve include:
- C6/C7 - thumb and index finger (“six shooter”)
- T4 - nipple line
- T10 - umbilicus
- L1-L5 - lower extremities “L for legs”)
are the paths of communication between the spinal cord and specific regions of the body. Arranged in fascicles surrounded by a perineurium, with the entire nerve sheathed by a CT epineurium.
The anterior rami of the segmental nerves may travel alone, or they can join together to form a plexus of nerves.
The cervical plexus,
celiac (solar) plexus,
sacral plexus, and
Major nerve plexuses, all formed from anterior rami of spinal nerves, and all located anterior to the spine: ____
formed by the anterior rami of C1-C5, serves the head, neck, and diaphragm.
arise from the cervical plexus to supply the major muscle of respiration (“C3,4,5 keep the diaphragm alive”).
supply the shoulders and upper limbs and formed by the anterior rami of C5-C8 and T1. It is divided into roots → trunks → divisions → cords → nerves.
long thoracic nerve
Some of the major nerves that arise from the brachial plexuses
a paralysis of the arm that most often occurs as an infant's head and neck are pulled toward the side at the same time as the shoulders pass through the birth canal. It happen also to any age where the nerves of the plexus are violently stretched.
Injuries to the brachial plexus or peripheral nerves, either at the plexus or occurring more distally, results in numbness, tingling and pain in the palm and fingers. Carpal tunnel syndrome is a common type
is formed by the anterior rami of L1-L4 to supply the anterolateral abdominal wall, external genitalia, and part of the lower limbs. The origin of the femoral and obturator nerves
is a fast, involuntary response to a stimulus.
In a ___ the integration takes place in the spinal cord, not the brain.
sensory neuron with motor neuron
is a pathway that a nerve impulse follows to produce a reflex.
Components of a reflex arc
include a sensory receptor and a sensory neuron, an integrating center inside the cord, an exiting motor neuron, and an effector (which is usually some sort of muscle or a gland which makes something move or secrete “involuntarily”).
Reflex arcs can be _____ (all neurons and effectors on the same side of the body)
Reflex arcs can be _____(the receptors and afferent neurons are on the opposite side of the body as the efferent neurons and effectors.) Example: The flexor (withdrawal) reflex
Flexor (withdrawal) reflex
where you touch the hot surface and you withdraw your hand right away
In addition to initiating the flexor reflex that causes you to withdraw the limb, the pain impulses from stepping on the tack also initiate a _____to help you maintain your balance.
The ______ in which the leg extends in response to stretch of the patellar tendon. This reflex can be blocked by damage in the corticospinal tracts from diabetes, neurosyphilis, or damage to the lumbar region of the spinal cord.
The ______ causes contraction of the calf when a force is applied to the Achilles tendon. It is absent after damage to the lower cord or lumbosacral plexus.
The________ or (plantar flexion) reflex is considered normal in adults if they flex (curl) the big toe when the sole of the foot is stimulated. If the sole of the foot is stimulated and the patient extends the big toe, it would indicate damage in the corticospinal tract.