Module Exam 6: Somatosensory System Flashcards
Awareness and precise location of very delicate mechanical stimuli
Tactile sense
Enumerate General senses
Light touch, Temperature, Pain, Pressure & Proprioception(vibration sense) “LTPPP”
Tactile sense includes
Two-point sense, Graphesthesia & Fine touch/Stereognosis “TGF”
Ability to recognize objects by touch alone
Stereognosis/Fine touch
Ability to recognize numbers or letters drawn on the skin
Graphesthesia
Ability to distinguish stimulation by one or two points applied on the skin
Two-point sense
Involves stimuli applied to subcutaneous structure firmly pressing on the skin with blunt object and by squeezing subcutaneous structures
Pressure/Deep touch
Temperature variations
Hot & Cold
Type of pain that is sharp, pricking and well localized
Fast pain
Type of pain that is dull, burning type and diffuse
Slow pain
Awareness of the position of parts of the body; tested by passively moving a limb or one of its parts to a certain position and having the subject move the opposite limb to the same position.
Position/Posture sense
Awareness of active or passive movements of parts of the body; tested by passively flexing and extending individual fingers and toes , hand and foot, forearm and leg etc. with eyes closed, the subject should be able to recognize the direction, speed and range of the movement.
Motion sense
Receptor for touch, pressure and proprioception
Mechanoreceptors
Receptors for pain
Nocireceptors
Receptors for warm/cold
Thermoceptors
General sensation receptors for Touch
Meissner’s corpuscle, Merkel’s disc, Hair follicle ending & Golgi mazzoni “mmHg”
General sensation receptors for Pressure
Pacinian corpuscle
General sensation receptors for Pain
Free nerve endings
General sensation receptors for Cold temp
Krause end bulb
General sensation receptors for Hot
Ruffini’s corpuscle
General sensation receptors for Proprioception
Tendon & Muscle spindles
Area of the skin supplied by the somatosensory fibers from a single spinal nerve; useful in localizing the levels of lesion.
Dermatomes
Dermatome: C2
Back of the head
Dermatome: C5
Tip of Shoulder
Dermatome: C6
Thumb
Dermatome: C7
Middle finger
Dermatome: C8
Small finger
Dermatome: T4-T5
Nipple
Dermatome: T10
Umbilicus
Dermatome: L1
Inguinal
Dermatome: Big toe
L4-L5
Dermatome: S1
Small toe
Dermatome: S5
Perineum
Ascending tracts
Spinothalamic tract & Dorsal/Posterior Column
Ascending Tract for touch & pressure
ASTT
Ascending tracts for position sense, 2 pt discrimination fine, discriminative vibration sense & Stereognosis
Dorsal/Posterior Column
Ascending tract for pain & temp
LSTT
Anterior Column Ascending Tracts
Ventral Spinothalamic gyrus & Spino-olivary nuclei
Lateral Column Ascending Tracts
Dorsal Spinocerebellar cortex, Ventral spinocerebellar cortex, Lateral spinothalamic gyrus & Spinotectal tectum “DVLS”
Posterior Column Ascending Tracts
Fasciculus gracilis & Fasciculus cuneatus
Located median to anterior roots. Origin is Free nerve endings for light touch and pressure. Destination is at _________.
Ventral Spinothalamic gyrus. Post-central.
Located at the junction of anterior & lateral white columns. Origin is at cutaneous & proprioceptive organs. Destination is at ___________
Spino-olivary nuclei. Inferior Olivary.
Located at the periphery of the lateral white column. Originates from muscle spindle, tendon organs & joint receptors. Destination is at ___________.
Dorsal spinocerebellar cortex. Cerebellar.
Located at periphery of lateral white column. Originates from the muscle spindle, tendon organs and joint receptors. Destination is at __________.
Ventral Spinocerebellar cortex. Cerebellar.
Located at the medial to ventral spinocerebellar tract. Originates from free nerve ending for pain & temp. Destination is at __________.
Lateral Spinothalamic gyrus. Post central.
Located at the Anterior to Lateral Spinothalamic. Destination is at ________.
Spinotectal tectum. Midbrain.
Located beside dorsomedian sulcus. Originates from meissner’s, pacinian, tendon organs & muscle spindle. Destination is at _________.
Fasciculus gracilis gyrus. Post central.
Located between Fasciculus gracilis & posterior gray column. Originates from meissner’s, pacinia, muscle spindle and tendon organs. Destination is at _________.
Fasciculus cuneatus gyrus. Post central.
Somatosensory pathway consist of three neurons namely
Sensory Ganglia, SC or Brainstem and Thalamus
Pain & Temperature Pathway
Refer to handout
Discriminative touch and pressure pathway
Refer to handout
Conscious Proprioception Pathway
Refer to handout
Somatic Sensory arising from Face: trigeminal ganglion
Gasserian/Semilunar ganglion
Three division of the Trigeminal somatic sensory
Opthalmic, Maxillary & Mandibular
Pain & Temp Pathway of Face: Receptor - N1 (___________), N2 (________), N3 (____________) and __________.
Gasserian/Semilunar Ganglion. Nucleus of trigemino Spinal Tract. ventral postero medial nucleus of thalamus. Post central gyrus.
Touch and Pressure Pathway of Face: Receptor - N1 (___________), N2 (________), N3 (____________) and __________.
Gasserian/Semilunar Ganglion. Main sensory nucleus. ventral postero medial nucleus of thalamus. Post central gyrus.
Touch and Pressure Pathway of Face: Receptor - N1 (___________), N2 (________), N3 (____________) and __________.
Mesencephalic nucleus. Main sensory nucleus. ventral postero medial nucleus of thalamus. Post central gyrus.
Episodes of sharp, stabbing pain that radiates over the areas innervated by sensory branches of the maxillary or mandibular divisions of CN V. Triggered by moving the mandible, smiling or yawning, or by cutaneous stimulation. May be caused by pressure on or interruption of the blood supply of the trigeminal ganglion.
Trigeminal Neuralgia (Tic Douloureux)
Loss of sensitivity to pain in all or part of the body
Anesthesia
An abnormally reduced sensitivity to touch
Hypoesthesia
An abnormal or unexplained tingling, pricking or burning sensation on the skin
Paresthesia
An abnormally heightened sensitivity of part of the body
Hyperesthesia
Spinal cord Hemisection. Contralateral loss of pain and temp. Ipsilateral loss of proprioception. And ipsilateral manifestation of upper and lower motor neurom lesions.
Brown-Sequard’s syndrome
Loss of pain and thermal sensations on the Contralateral side about 1-2 segments Below the level of the lesion.
Anterolateral system
Progressive cavitation around the central canal; loss of pain & temp sensations in hands & forearm (common in cervical) Dissociated sensory loss.
Syringomyelia
Lateral corticospinal tract damage: ipsilateral upper motor neuron weakness. Posterior column: ipsilateral vibration & proprioception loss. Anterolateral system: contralateral pain and temperature loss.
Hemicord lesion
Small lesions. Damage to the spinothalamic fibers crossing in the ventral commissure causes bilateral regions of sensory loss of pain and temp. Cervical: _________ distribution.
Central cord lesion. Classic cape.
Caused by neurosyphylis; dorsal root involvement with secondary degeneration of dorsal columns (loss of vibration and position sense)
Tabes dorsalis
Clinical signs of injury to the Lemniscal Pathway
Inability to recognize limb position, Astereognosis, Loss of two point discrimination, Loss of vibration sense and (+) Romberg sign
Vibration and proprioception loss below the level of the lesion
Posterior cord damage
Degenerative changes in the vertebral column caused by _______.
Spondylosis. Osteoarthritis.
Causes degenerative changes at the articulating surfaces of the 4th, 5th and 6th cervical vertebrae.
Repeated trauma and Aging
Burning pain, hyperesthesia and partial analgesi were due to pressure on
Posterior roots
Wasting, weakness and fasciculations were due to pressure on
Anterior roots