Module 7 Flashcards
- continuous with meninges of brain, protect spine, carry blood supply
- surrounds the spinal cord
Meninges
- tough fibrous tissue; epidural space: contain loose connective tissue and adipose, anesthetic injection site
Dura mater
- simple squamous epithelium; subarachnoid space is filled with CSF and contains trabeculae (collagen/elastin fiber network)
Arachnoid
- bound to spinal cord; made of collagen and elastic fibers
Pia mater
- extend from pia to dura matter and stabilize side to side movements
- gives stability of the cord
Denticulate ligaments
- protected by the vertebral body. The format in the axial cut is an H-shaped gray matter surrounded by the white matter. The gray matter has a dorsal and ventral horn.
- is symmetric. Cervical and Lumbar enlargement caused by amt of motor neurons in gray matter
- extends from the cervicomedullary junction down to the level of L1 and L2
Spinal cord
Thoracic, Lumbar, Sacral may have a __.
lateral horn
Sympathetic vs Parasympathetic
At the level of your thoracic T1 to L2 that will be your sympathetic outflow.
S1-S4 parasympathetic outflow.
Potential Spaces in the Spinal Cord
- Epidural Space - filled with fat
- Subdural Space
- Subarachnoid Space - contains CSF
Blood Supply of the Spinal Cord
- two posterior spinal arteries to support the posterior part
- one anterior spinal artery
Posterior and Anterior root
Posterior root - going into the dorsal Horn
Anterior root - going out of the ventral horn
*this two will unite to form the spinal root (carries sensory and motor fiber)
Cervical and Lumbar Part
- Cervical and Lumbar part are fatter because they serve the limbs; means more nerve bodies
- part of the pia mater; goes down and attaches itself to the coccyx
Filum Terminale
- space that is created where there is no more cord is occupied by __
Cauda Equina
- this cord will go out above the vertebral body
C1-C7
- cords that will exit below the vertebral body
C8 going down
- usually have a discrepancy of about 2 segments
- eg T4 vertebra will correspond to T6 spinal cord segment
Upper half of the thoracic
- spinal segments usually have a discrepancy of about 3 segments
- eg T11 vertebral body will correspond to L1 spinal cord segment
Lower half of the thoracic and Lumbar
- limited only for the sensory which is the dorsal column
Posterior
9 cell layers or laminae:
1-6 dorsal,
7 intermediate,
8-9 ventral
- separate dorsal gray column from surface of spinal cord
Zone of Lissauer
- axons contribute to lateral spinothalamic; pain temp
Nucleus posterior marginalis
- pain, temp, light touch; contribute axons to lateral and ventral spinothalamic; have Mu and Kappa opioid receptors;
Substantia gelatinosa (II)
- fine touch and proprioception; pain and temp; contribute to lateral spinothalamic, ventral spinocerebellar
Nucleus proprius (III,IV,V)
- supplies posterior or dorsal spinocerebellar tract; fine touch and proprioception
Nucleus dorsalis
- Transmit impulses concerned with specific sensory modalities
- Transmit impulses from stretch receptors and tactile receptors that project directly or via relay nuclei to the cerebellum
- Impulses projected to the cerebellum play an important role in the regulation of muscle tone and coordination of motor function
ASENDING TRACTS
Posterior column: Fasciculus Gracilis and Cuneatus → Spinal Cord synapse in Nucleus Gracilis/Cuneatus (at the level of the medulla) → cross in lower medulla → (Ventral Posterolateral) Thalamus → Postcentral gyrus
- Discriminating tactile and kinesthetic sense
Dorsal Column Medial Lemniscal Pathway
Nucleus Gracilis vs Nucleus Cuneatus
Gracilis - Gitna; supplies the lower half of the body
Cuneatus - lateral; supplies the upper half of the body
Finely/unmyelinated lateral bundle of dorsal root → bifurcate after entering zone of Lissauer: ascending and descending branches (it descends/ascends by 1 or 2 spinal segments)→ terminate on interneurons of dorsal horn in laminae 6,7→ decussate via ventral commissure→ ventral posterolateral nucleus of thalamus→ parietal lobe (pain and temp)
*Laminar: sacral – ventrolateral, cervical – dorsomedial; temp – dorsolateral to pain
Lateral Spinothalamic Tract
Lateral Spinothalamic Tract
- Laminae I, IV and V
- Spinal Cord→Cross in the anterior white commissure→ thalamus→ Postcentral gyrus
- Pain and thermal sense
- Laminae I, IV, and V
- Spinal Cord → Cross in the anterior white commissure→ thalamus→ Postcentral gyrus
- Conveys impulses associated with light touch
Anterior Spinothalamic Tract
- Laminae I and V of posterior horn
- Spinovisual reflex: posterior root (Spinal Cord)→Cross in the anterior white commissure→ superior colliculus and lateral regions of the periaqueductal gray
Spinotectal Tract
- Dorsal nucleus of clarke, uncrossed
- Spinal Cord → inferior cerebellar peduncle → rostral and caudal vermis
- Carries proprioceptive information from the LOWER LIMBS TO THE IPSILATERAL CEREBELLUM.
Posterior Spinocerebellar Tract
- Follow the posterior spinocerebellar tract
- Terminate on the cells of the accessory cuneate nucleus →inferior cerebellar peduncle→ lobule V of cerebellar cortex
- Carries proprioceptive information from the UPPER LIMBS TO THE IPSILATERAL CEREBELLUM.
- Continuation of posterior spinocerebellar tract
Cuneocerebellar Tract
- Laminae V, VI and VIII, crossed
- Spinal Cord→superior cerebellar peduncle→ anterior cerebellar vermis
- Carries proprioceptive information from the lower limbs.
- The fibres decussate twice – and so terminate in the ipsilateral cerebellum
Anterior Spinocerebellar Tract
- Another component of the spinocerebellar circuitry where impulses from spinal cord are relayed to the cerebellum via parts of the inferior olive
- Posterior columns→ nucleus cuneatus/gracilis→ accessory olivary nuclei
Spino-olivary Tract
- Cells of the posterior horn
- Spinal cord → reticular formation in the brainstem
- Behavioral awareness, modification of motor and sensory activities and in the modulation of electrocortical activity
Spinoreticular Fibers
- Ill-defined pathway coursing through ventrolateral pathway of cord, synapsing on the reticular formation of the brainstem without crosssing → eventually it will terminate on the intralaminar nucleus of the thalamus (poorly localized pain sensation)
Spinoreticular Fibers
COMMON SENSES
- Touch
- Pain
- Temperature
- Position
- Vibration
- Stereognosis-form (stereoanesthesia- checking for the integrity of nerves)
- higher cortical function; knowing what the object is from its size, shape and texture
Stereognosis
- intact nerve fiber but when you ask the pt to close their eyes they don’t know the object is by its form
Stereoagnosia
- increased sensitivity to touch, pain, and temperature
Hyperesthesia, hyperalgesia and hyperthermesthesia
- extreme over-response to pain; increase threshold for pain but once they detect the pain they will have exaggerated reaction; Late nadedetect ung pain pero exaggerated na ang pagreact
Hyperpathia
- abnormal perception of pain from a nonpainful stimulus, with delayed perception and aftersensation. Common in trigeminal neuralgia
- they are the patient that even when they talk or chew, they will experience pain
- nonpainful stimulus being detected as pain
Allodynia
- multiple, very severe, electric shock-like pains. Common in Sciatica
Neuralgia
- uncomfortable sensations (spontaneous sensations) of numbness, tingling, pins and needles or burning pain
Paresthesias and dysesthesias
- unbearable, burning, relentless pain. Pt who have taken drugs, cancer (they have adverse drug reaction eg chemotherapy drug)
Causalgia
- any abnormal sensation described as unpleasant (more intense than paresthesia);
Dysesthesia
Muscle spindle contain intrafusal fibers: the nuclear chain fiber that give information on muscle length and nuclear bag fibers that give information on the rate of change in muscle length. You therefore have two types of receptor:
- flower spray endings for muscle length
- annulospiral endings for muscle ength and velocity.
These receptors (muscle spindle) belong to neurons that eventually synapse on your alpha motor neurons, completing the arch for your __.
myotatic reflex
The __ is located on muscle tendons, the Ib afferent fiber eventually synapse on inhibitory interneurons, mediating your inverse stretch reflex which helps prevents injury to the tendon from too much tension. It supposed to relax rhe muscle.
Golgi tendon organ
Joint: Pacinian
Joint movement
Joint: Rufini
Joint angle
Joint: Golgi Tendon Organ
Joint torque
- Touch, flitter or movement
Meissner corpuscle
- Vibration, ticke
Pacinian corpuscle
-Skin stretch, warmth
Ruffini corpuscle
- detecting touch movement
Hair follicle
- Pressure
Merkel complex
- Sharp pain or cool/cold (Axon Group III)
- Dull or aching pain, or touch or warm (Axon Group IV)
Free Nerve endings
GENERAL PRINCIPLES IN TESTING SOMATIC SENSATIONS:
- Demonstrate and describe the tests
- Have patient close the eyes to avoid visual cues
- Compare: Right vs. Left; Normal vs. Abnormal
- Skin areas differ greatly in sensitivity
- Plan follow-up examination to recheck any doubtful results
- Determine whether sensory deficits match a central pathway, dermatomal, plexus or peripheral nerve pattern or a nonorganic distribution
- Recognize that the Pt’s mental state, legal wrangling or secondary gain from the illness may drastically alter sensory test results
TRIGEMINOTHALAMIC PATHWAY (Nucleus)
- Spinal tract and Nucleus of V: pain and temperature sensation at the level of the medulla
- Chief sensory nucleus of V: vibration, proprioception and light touch/tactile discrimination
- Mesencephalic nucleus of V: (at the midbrain) unconscious proprioception of muscle
CRANIAL V SENSORY EXAMINATION
- INSTRUCTION: Ask the Pt to say touch in response to each touch by a wisp of cotton
- Touch alternate areas and sides of the face randomly
- If the history indicates a specific area of sensory loss, start sensory testing in normal area, then start in the middle of the abnormal area and work outward
ANATOMY
- Afferent: CN V
- Efferent: CNVII
TECHNIQUE
- Use free piece of cotton rolled to a fine point
Instruct the Pt to look to one side and a little up
- Bring the cotton directly in from the side to avoid entering the field of vision
THE CORNEAL REFLEX
Problem on the CN V on the Right, When you do a corneal reflex, where is the slow blink?
BOTH because the problem is the afferent arm
Problem on the CN VII on the Right (partial bell’s palsy), corneal reflex on the right, where is the slow blink?
Right because the problem is the efferent arm
Problem on the CN VII on the Right (partial bell’s palsy), corneal reflex on the left, where is the slow blink?
Right because you have a normal CN V on the left but you have a problem in CN VII on the right (so whenever you blink and check the corneal reflex, the blink on the right will be slow)
- Largest number of spinothalamic fibers arise from cells in laminae I, IV, and V contralaterally
- Conveys impulses associated with “light touch”
- Receptors: Meissner’s corpuscle (tactile
ANTERIOR SPINOTHALAMIC TRACT
TESTING LIGHT TOUCH SENSATION
- For screening purposes, test only the dorsum of the hands and feet in addition to the face
- Transmits impulses for pain and thermal sense
- Cells of origin largely in laminae I, IV and V
- Cross to the opposite side
- Fibers related to thermal sense tend to be posterior to those related to pain
- Receptors: free nerve endings (pain), cold and heat receptors of dermatome
LATERAL SPINOTHALAMIC TRACT
TEMPERATURE AND PAIN DISCRIMINATION
- INSTRUCTION: Ask the Pt to close their eyes
- TUNING FORK or LITTLE FINGER TEST
- PAIN: Avoid the horny skin of the palms and soles; Delayed and Deep Pain
Testing for Delayed and Deep Pain Sensation
- Testing delayed pain: pinching the dorsum of the patient’s foot briskly between the fingernails of your thumb and index finger. Normally, the person will feel the immediately.
- Deep pain can be tested by squeezing hard on the Achilles tendon or a muscle. You can also press very hard on a bony surface. The patient may feel pain some seconds after ending the compression.
- usually result in contralateral pain and temperature sensation
- usually caused by Multiple Sclerosis, Trauma, Tumors of the cord
SPINOTHALAMIC TRACT LESIONS
- Discriminating tactile sense (touch and pressure) and kinesthetic sense (position and movement)
- Receptors: pacinian corpuscle, unencapsulated joint receptor, Golgi and Meissner’s corpuscle
DORSAL COLUMN PATHWAY