Podcast
Questions and Answers
Which component is NOT a part of an intervertebral disc?
What is the primary function of intervertebral discs?
Which type of abnormal curvature of the spine is known as 'sway back'?
What is the smallest transverse process located in the vertebral column?
Signup and view all the answers
Which muscle is primarily responsible for the lateral flexion of the vertebral column?
Signup and view all the answers
What type of reflex arc involves only sensory and motor neurons?
Signup and view all the answers
Which sacral structure articulates with the last lumbar vertebra above?
Signup and view all the answers
What role does the Sternocleidomastoid muscle play in spinal movement?
Signup and view all the answers
Which reflex is exemplified by the knee jerk response?
Signup and view all the answers
Which back muscle is responsible for extension and lateral flexion of the vertebral column?
Signup and view all the answers
What is the primary role of Golgi tendon organs in muscle function?
Signup and view all the answers
Which of the following accurately describes antagonistic muscle pairs?
Signup and view all the answers
What anatomical feature is characteristic of the L5 vertebra?
Signup and view all the answers
Which spinal reflex involves both the agonist and antagonist muscles to create movement?
Signup and view all the answers
What is the primary function of spinal ligaments?
Signup and view all the answers
What does areflexia indicate regarding the myotatic reflex circuit?
Signup and view all the answers
Which myotome is responsible for thumb extension and finger flexion?
Signup and view all the answers
What is the primary function of Merkel's disks?
Signup and view all the answers
What sensory pathway is primarily affected by unilateral damage to the medulla?
Signup and view all the answers
Which nerve root is responsible for knee extension?
Signup and view all the answers
Which of the following conditions is characterized by ataxic wide gait and loss of touch and proprioception?
Signup and view all the answers
Which receptor is most associated with sensing vibration?
Signup and view all the answers
What does a positive Romberg sign indicate in a patient?
Signup and view all the answers
In the context of the Dorsal Column Medial Lemniscus Pathway, where does decussation occur?
Signup and view all the answers
Which procedure allows for the measurement of cerebrospinal fluid (CSF) pressure?
Signup and view all the answers
What is the primary characteristic of the somatic motor system?
Signup and view all the answers
Which type of neuron directly causes muscle contraction?
Signup and view all the answers
Which structure serves as a carrier fluid for local anesthesia in a subarachnoid block (SAB)?
Signup and view all the answers
What is the function of alpha motor neurons in the somatic nervous system?
Signup and view all the answers
What role do spinal interneurons play in motor control?
Signup and view all the answers
In the context of motor neuron recruitment, what does an increase in tension generated imply?
Signup and view all the answers
Which pathway is primarily responsible for controlling distal limb movement?
Signup and view all the answers
Which type of nerve fibers are involved in the neospinothalamic tract responsible for fast pain transmission?
Signup and view all the answers
What is the effect of damage to the anterolateral system?
Signup and view all the answers
Which neurotransmitter is primarily involved in the fast pain response of the spinothalamic tract?
Signup and view all the answers
Which type of pain is characterized as dull and poorly localized, often arising from internal organs?
Signup and view all the answers
What condition is specifically associated with cavity formation in the cervical spine leading to bilateral loss of pain and temperature sensation?
Signup and view all the answers
What is the primary role of nociceptors in the pain pathway?
Signup and view all the answers
Which phenomenon describes the perception of pain in a limb that has been amputated?
Signup and view all the answers
Which type of thermoreceptor is most numerous and responds to a broad range of cold temperatures?
Signup and view all the answers
Study Notes
Foramina
- Vertebral foramen: The hole in the center of each vertebra that allows the spinal cord to pass through.
- Intervertebral foramen: The space between two vertebrae where spinal nerves exit the spinal cord.
- Transverse foramen: The hole in the transverse process of cervical vertebrae (C1-C7) that allow blood vessels to pass through.
Intervertebral Disks
- Comprise ¼ length of the spinal column
- Found between each vertebra for movement and shock absorption
- Components:
- Nucleus pulposus: Gelatinous center of the disc
- Annulus fibrosus: Tough, fibrous outer layer of the disc
- Vertebral end plates: Cartilaginous plates that cover the top and bottom of the disc
Intervertebral Disc & Herniation
- Herniation: Protrusion of the nucleus pulposus through the annulus fibrosus, referred to as a "herniated disc."
- Herniated disc can result in nerve root compression.
Abnormal Curvatures of the Spine
- Kyphosis: Exaggerated outward curvature of the thoracic spine (hunchback).
- Lordosis: Exaggerated inward curvature of the lumbar spine (swayback).
- Scoliosis: Lateral curvature of the spine.
Regional Characteristics of Vertebrae
- Atlas (C1):
- Supports the skull and head.
- No body or spine.
- Articulates with occipital condyles, forming the atlanto-occipital joint for head flexion/extension.
- Articulates with the axis (C2), forming the atlantoaxial joint for head rotation.
- Axis (C2):
- Smallest transverse process.
- Has a prominent odontoid process.
- Vertebra Prominens (C7):
- Longest spinous process, allowing for palpation.
- Attachments for supraspinous ligaments and ligamentum nuchae.
- Thoracic Vertebrae:
- Costal facets for articulation with ribs.
- Transverse processes.
- L5:
- Largest body.
- Mammillary and accessory processes.
- Sacrum:
- 5 fused sacral vertebrae.
- Foramina for the passage of nerves.
- Articulates with the last lumbar vertebra, the coccyx, and the iliac portion of the hip bones.
- Coccyx:
- 4 coccygeal vertebrae.
- Attachment for ligaments.
Muscles that Affect the Spine
- Back muscles stabilize the spine.
- Flexion, rotation, or extension movements.
- Extensors: Back of the spine, enable standing and lifting objects.
- Flexors: Front of the spine, abdominal muscles, enable bending forward, lifting, and controlling lower back arch.
- Muscles are supported by fascia.
Examples of Specific Muscles Associated with Movement of the Spinal Cord
- Thoracic Region:
- Longissimus thoracis: Extension and lateral flexion of the vertebral column and rib rotation.
- Iliocostalis thoracis: Extension and lateral flexion of the vertebral column and rib rotation.
- Lumbar Region:
- Psoas major: Hip flexion and vertebral column flexion.
- Quadratus lumborum: Lateral flexion of the vertebral column.
- Cervical Region (Anterior):
- Sternocleidomastoid: Head movement, extension, rotation, and flexion.
- Posterior Cervical:
- Longissimus cervicis: Extension of cervical vertebrae.
- Longissimus capitis: Head rotation/pulls backward.
Reflex Arcs
- Neural pathways that control reflex actions.
- Sensory neurons receive stimulation, and effectors (muscle cells) respond.
- Reflex actions are involuntary responses to a specific stimulus.
- Types of reflex arcs:
- Autonomic: Internal organs.
- Somatic: Muscles.
- Neuron reactions:
- Monosynaptic: Sensory + motor neurons.
- Polysynaptic: Multiple interneurons.
- Components:
- Sensor organ
- Sensory neuron
- One or more synapses
- Motor neuron
- Effector (muscle).
Myotatic Reflex
- Deep tendon reflexes (stretch reflexes), example: Knee jerk reflex.
- When a muscle is stretched with a load, it reflexively contracts.
- Automatic regulation of muscle length, monitored by muscle spindles.
- Monosynaptic reflex.
- Physiologic function = resist gravity.
- A lesion in any part of the reflex circuit results in areflexia.
- Common reflex arcs:
- Brachioradialis (C5-C6)
- Biceps (C6-C7)
- Triceps (C6-C7)
- Knee (L2-L4)
- Ankle (S1)
Inverse Myotatic Reflex
- Reflex inhibition of muscle contraction, stimulated by active muscle contraction.
- Protects a muscle from overload during extreme contraction.
- Provides a tension feedback system for regulating muscle tension in sustained contraction.
- Mediated by Golgi tendon organs, also known as the Golgi reflex.
Reciprocal Inhibition
- Antagonistic muscle pairs:
- Agonist: Muscle that causes the movement.
- Antagonist: Muscle that opposes the action.
- Reciprocal inhibition: During simple movement, the antagonist muscle is inhibited, allowing the agonist to contract.
- Mediated by spinal interneurons.
- Example: Biceps/Triceps and Hamstring/Quadriceps.
Spinal Ligaments & Tendons
- Ligaments connect bone to bone, helping to stabilize joints.
- Tendons attach muscle to bone.
- Limited blood supply in ligaments and tendons slows healing.
Spinal Cord Ligaments
- Stabilize the vertebral column, provide flexibility while limiting excessive movement and limiting damage.
- Two primary spinal ligament systems:
- Intra-segmental: Hold individual vertebrae together.
- Inter-segmental: Hold many vertebrae together.
- Strongest ligament: Ligamentum flavum.
Clinical Considerations: Tissues Involved in Epidural Placement
- Lumbar Puncture:
- Tapping the lumbar subarachnoid space, usually between L3-L4 or L4-L5.
- Allows for:
- Measurement of cerebrospinal fluid (CSF) pressure.
- Bacteriologic and chemical examination of CSF.
- Introduction of anesthetics.
- Caudal Anesthesia:
- Blocks spinal nerves in the epidural space.
- Anesthetic agents injected into the epidural space.
- SAB (Subarachnoid Block):
- Local anesthetic injected into the subarachnoid space with CSF acting as a carrier.
- Requires a smaller volume.
- Epidural:
- Local anesthetic injected into the epidural space, in lumbar, sacral, or thoracic locations.
- Requires a larger volume, no carrier fluid needed.
Review of Somatic Motor Systems, Tracts, Reflex Arcs, Special Senses
Somatic Motor Systems
- Two neural outputs from the CNS:
- Somatic motor system
- Autonomic nervous system
- Somatic motor system:
- Voluntary.
- Part of the Peripheral Nervous System.
- Controls locomotion, fine movements, posture, and equilibrium.
- Acts on motor neurons.
- Carries motor and sensory information to/from the CNS.
- Consists of nerves to skin, sensory organs, and all skeletal muscles.
- Responsible for processing sensory information like hearing, touch, and sight.
Neural Pathway for Skeletal Muscle Contraction
- Upper motor neurons in the CNS.
- Lower motor neurons of the somatic nervous system.
- Lower motor neurons can be part of cranial or spinal nerves and innervate muscle fibers, directly causing contraction.
Somatic Nervous System Motor Unit - Alpha Motor Neurons
- Single motor neuron.
- Alpha motor neurons (also called lower motor neurons) innervate skeletal muscle.
- Cause muscle contractions and movement.
- Motor neuron pool: Group of motor neurons that innervate fibers within the same muscle.
- Originate in the spinal cord or brainstem.
- End on skeletal muscle.
- Release acetylcholine (Ach).
- Stimulate muscle contraction.
- Motor neuron recruitment generates more tension.
Spinal Control of Alpha Motor Neurons
- 3 inputs:
- Upper motor neurons:
- From the cortex and brainstem.
- Synapse with lower motor neurons.
- Control movement through control of the lower motor neurons.
- Spinal interneurons:
- Extensive spinal circuitry.
- Central pattern generators.
- Sensory neurons:
- Provide feedback about muscle length and tension.
- Upper motor neurons:
- Motor neurons release Ach at the neuromuscular junction.
Motor Tracts - Movement
Descending Motor Tracts
-
Lateral Pathways
- Upper and lower motor neurons.
- Involved in distal limb control.
Spinal Nerves and Dermatomes
- 31 pairs of spinal nerves, named for the vertebrae from which they emerge.
- Cervical, 12 thoracic, 5 lumbar, 1 coccygeal.
- Dermatomes exist for each spinal nerve starting at C2.
- Help localize sensory levels.
Myotome Nerve Roots & Muscle Actions
- C4: Shoulder shrugs.
- C5: Shoulder abduction and external rotation; elbow flexion.
- C6: Wrist extension.
- C7: Elbow extension and wrist flexion.
- C8: Thumb extension and finger flexion.
- T1: Finger abduction.
- L2: Hip flexion.
- L3: Knee extension.
- L4: Ankle dorsiflexion.
- L5: Big toe extension.
- S1: Ankle plantarflexion.
- S4: Bladder and rectum motor supply.
Dermatomic Symptoms of Spinal Nerve Infections
- Viruses may infect spinal nerves causing pain in the dermatomic area.
- Herpes zoster (shingles) migrates along a spinal nerve, affecting the area served by that nerve.
Dorsal Column Medial Lemniscus Pathway
- Conveys discriminative touch, vibration, and proprioceptive sensory input.
- Decussates at the medulla.
- Unilateral damage below the medulla results in ipsilateral loss of sensation.
- Damage above the medulla results in contralateral loss of sensation.
- Main pathway involves a three-neuron chain:
- First-order neuron: Found in somatosensory receptors.
- Second-order neuron: Found in the dorsal column nuclei of the caudal medulla.
- Third-order neuron: Found in the thalamus.
Specialized Touch Receptors
- Merkel's disks: Slowly adapting, sensing steady pressure.
- Meissner's corpuscles: Rapidly adapting, sensing rapid changes in skin contact.
- Ruffini's endings: Slowly adapting, sensing local stretching of the skin.
- Pacinian corpuscles: Very rapidly adapting, sensing vibration.
- Hair follicles: Transduce hair displacement.
Secondary Somatosensory Areas
- Posterior parietal cortex integrates touch with other sensations.
- Agnosia: Inability to recognize objects despite normal sensations.
- Astereognosis: Inability to recognize objects through touch.
Diseases Affecting the DCMLS
- Vitamin B12 neuropathy and Tabes dorsalis:
- Ipsilateral sensory deficits below the lesion (pathway decussates at the medulla).
- Tabes dorsalis: Late manifestation of syphilis.
- Impaired sensations from demyelination of the dorsal column:
- Ataxic wide gait with loss of touch and proprioception.
- Paresthesias with altered sensations.
- Bladder dysfunction such as urinary retention.
- Positive Romberg sign.
- Impaired sensations from demyelination of the dorsal column:
- DORSALIS (mnemonic)
- D: Dorsal column degeneration
- O: Orthopedic pain (Charcot joints)
- R: Reflexes decreased
- S: Shooting pain
- A: Argyll-Robertson pupils
- L: Locomotor ataxia
- I: Impaired proprioception
- S: Syphilis
Anterolateral System (Spinothalamic)
- Sensory pathway from skin to thalamus.
- Conveys pain and temperature sensory input.
- Decussates 1-2 spinal cord segments above and below the entry of the peripheral afferent neuron.
- Damage results in contralateral loss of sensation 1-2 spinal cord segments below the lesion.
- Two types of spinothalamic tracts:
- Neospinothalamic tract: Fast type A delta nerve fibers, terminating in the dorsal horn of the spinal cord. Glutamate is the neurotransmitter.
- Paleospinothalamic tract: Slow type C nerve fibers, terminating in the substantia gelatinosa. Morphine and its derivatives inhibit mu receptors here.
Disease - Syringomyelia
- Cavity formation in the cervical spine (fluid-filled cavities).
- Bilateral loss of pain and temperature sensation.
- Compression of motor neurons results in flaccid paralysis of the upper extremities.
Transmission of Pain and Temperature Sensation
- Pain and temperature pathway: Three neuron chain.
- Pain sensation is protective.
- Superficial pain: Body surface.
- Initial pain: Sharp, highly localized, fast ("prickly"), carried by small type A delta fibers (myelinated), caused by thermal or mechanical stimuli.
- Delayed pain: Diffuse, burning, dull, and aching, poorly localized, slow, carried by type C nerve fibers (unmyelinated), caused by thermal, mechanical, or chemical stimuli.
- Deep pain: From muscles and joints.
- Nociceptors: Pain receptors.
- Pain sensation flow chart:
- Tissue damage
- Activation of nociceptors
- Action potentials travel along sensory neurons to the spinal cord.
- Synapses with interneurons in the spinal cord.
- Signals travel up the spinothalamic tract to the thalamus.
- Thalamus sends signals to the cortex, where pain is perceived.
Other Types of Pain
- Visceral pain: Pain arising from internal organs.
- Dull, burning, poorly localized sensation.
- Referred pain: Pain arising from the viscera, but perceived on the body surface.
- Phantom sensations: Perceptions occurring after limb or organ removal.
- Sensations of pain, touch, temperature, pressure, itchiness, and movement.
- Phantom limb pain: Feeling pain in an absent limb or portion of a limb after amputation, congenital limb deficiency, or spinal cord injury.
- Phantom limb sensation: Sensory phenomena other than pain felt in an absent limb or portion of a limb.
- ~80% of amputees experience phantom sensations.
Temperature Sensation
- Cold fibers:
- Most numerous type of thermoreceptor.
- Respond to a wide range of temperatures.
- Warm fibers:
- Respond to a narrower range of temperatures.
- Both types are rapidly adapting.
- Both help protect against hot and cold, and aiding in recognizing wet and slipperiness.
- Play a minor role in control of core temperature.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on spinal anatomy, intervertebral disks, and common pathologies like herniation. This quiz covers important topics such as the types of foramina, components of disks, and spinal curvatures. Gain a deeper understanding of spinal health and function.
