chapter 13, spinal cord Flashcards
What is the spinal cord?
The cylindrical nervous tissue that extends from the brainstem and transmits neural signals between the brain and body.
What is the cervical enlargement?
A widened section of the spinal cord supplying nerves to the upper limbs.
What is the lumbar enlargement?
A widened section supplying nerves to the lower limbs.
What is the medullary cone (conus medullaris)?
The tapered end of the spinal cord, located around L1-L2.
What is the cauda equina?
A bundle of nerve roots extending beyond the spinal cord.
What are meninges?
Protective layers surrounding the spinal cord and brain.
What is the dura mater?
The tough outermost layer of the meninges.
What is the arachnoid mater?
The middle layer containing cerebrospinal fluid (CSF).
What is the pia mater?
The delicate inner layer adhering to the spinal cord.
What is the epidural space?
The space between the dura mater and the vertebrae, containing fat and blood vessels.
What is the subarachnoid space?
The space between the arachnoid and pia mater, filled with CSF.
What is gray matter?
The region containing neuron cell bodies and synapses.
What does the dorsal (posterior) horn contain?
Contains sensory neuron synapses.
What does the ventral (anterior) horn contain?
Contains motor neuron cell bodies.
What is the lateral horn?
Found in thoracic and upper lumbar regions, contains autonomic motor neurons.
What is white matter?
Myelinated axons that form tracts to and from the brain.
What are ascending tracts?
Sensory pathways that carry signals to the brain.
What are descending tracts?
Motor pathways that carry signals from the brain to muscles.
What is decussation?
The crossing over of nerve fibers from one side of the body to the other.
What does the spinothalamic tract transmit?
Transmits pain, temperature, and crude touch.
What does the dorsal column-medial lemniscus (DCML) pathway transmit?
Transmits fine touch, vibration, and proprioception.
What does the spinocerebellar tract transmit?
Transmits unconscious proprioception to the cerebellum.
What is the corticospinal tract?
The primary motor pathway for voluntary movements.
What does the tectospinal tract control?
Controls reflexive movements of the head in response to stimuli.
What is the role of the reticulospinal tract?
Helps regulate muscle tone and posture.
How many pairs of spinal nerves are there?
31 pairs of nerves that carry motor, sensory, and autonomic signals between the spinal cord and the body.
What does the dorsal root carry?
Carries sensory information to the spinal cord.
What is the dorsal root ganglion?
A cluster of sensory neuron cell bodies.
What does the ventral root carry?
Carries motor signals from the spinal cord.
What are mixed nerves?
Contain both sensory and motor fibers.
What is the cervical plexus (C1-C5)?
Innervates the neck and diaphragm (includes the phrenic nerve).
What does the brachial plexus (C5-T1) innervate?
Innervates the upper limb.
What does the lumbar plexus (L1-L4) innervate?
Innervates the lower limb and abdominal wall.
What does the sacral plexus (L4-S4) innervate?
Innervates the buttocks, lower limb, and pelvic structures.
What is the coccygeal plexus (S4-Co1)?
Small network of nerves near the coccyx.
What is a reflex?
A rapid, automatic response to a stimulus.
What is a reflex arc?
The neural pathway involved in a reflex action.
What detects the stimulus in a reflex arc?
Receptor.
What carries the signal to the CNS in a reflex arc?
Afferent (sensory) neuron.
What processes information in the spinal cord or brainstem?
Integration center.
What carries the signal to an effector in a reflex arc?
Efferent (motor) neuron.
What is an effector?
The muscle or gland that responds.
What are somatic reflexes?
Involve skeletal muscles (e.g., patellar reflex).
What are autonomic reflexes?
Involve smooth muscle, glands, or cardiac muscle (e.g., pupillary reflex).
What is a monosynaptic reflex?
A reflex involving only one synapse (e.g., stretch reflex).
What is a polysynaptic reflex?
A reflex involving multiple synapses (e.g., withdrawal reflex).
What is an ipsilateral reflex?
The response occurs on the same side as the stimulus.
What is a contralateral reflex?
The response occurs on the opposite side of the stimulus.
What does the stretch reflex maintain?
Maintains muscle tone and posture (e.g., patellar knee-jerk reflex).
What does the withdrawal (flexor) reflex cause?
Causes a limb to withdraw from pain.
What does the crossed extensor reflex help maintain?
Helps maintain balance when withdrawing from a stimulus.
What does the tendon reflex prevent?
Prevents muscle damage from excessive tension.
What is spinal cord injury (SCI)?
Damage to the spinal cord causing loss of function.
What is paralysis?
Loss of motor function due to spinal cord damage.
What is paresthesia?
Abnormal sensation (e.g., tingling, numbness) due to nerve injury.
What is quadriplegia?
Paralysis of all four limbs (cervical spinal cord injury).
What is paraplegia?
Paralysis of the lower limbs (injury below the cervical region).
What is spina bifida?
A birth defect where the spinal column does not close properly.
What is amyotrophic lateral sclerosis (ALS)?
A neurodegenerative disease affecting motor neurons.
