Neuro Tracts and Spinal Cord Lesions Foundations

Tracts: Ascending

• Posterior Column-Medial Lemniscal: ______ ______, __________ and ______​

  • FC

  • FG

• Spinothalamic (also called the ______ _______)

  • _____ and _____ ​

• _______ Tracts (Data only ascends to the ____)​

• Sensory receptors are specific to their ______

• Sensory neuron cells bodies → _____​

• Dermatome: Peripheral region innervated by sensory fibers from a…

• Posterior Column-Medial Lemniscal: Light touch (called ”fine, discriminative touch” in the book), proprioception and vibration​

  • Fasciculus Cuneatus​

  • Fasciculus Gracilis​

• Spinothalamic (also called the anterolateral system)​

  • Pain and temp ​

• Spinocerebellar Tracts (Data only ascends to the CB)​

• Sensory receptors are specific to their modality​

• Sensory neuron cells bodies → DRG​

• Dermatome: Peripheral region innervated by sensory fibers from a single nerve root level

Posterior Column-Medial Lemniscal

• Dorsal Column: Fasciculi _____ (T6 and below) and ______ (Above T6) ​

• Carries:

3 Neuron pathway​

1. Begins at the _____ ______ (____ _____, ______ _____, ______ ____)

2. Ascends the ____ in the Fasciculus _____ or _____ and synapses in the _____ or _____ N of the Lower _____. _____ here to ascend via the _____ ______

Ends in the _____ _____ ______

• Dorsal Column: Fasciculi Gracile (T6 and below) and Cuneate (Above T6) ​

• Carries light touch, proprioception and vibration​

3 Neuron pathway​

1. Begins at the nerve endings (muscle spindle, Pacinian Corpuscle, Ruffini Ending)

2. Ascends the SC in the Fasciculus Cuneate or Gracile and synapses in the Gracile or Cuneate N of the Lower Medulla. CROSSES here to ascend via the MEDIAL LEMNISCUS​

Ends in the Post central Gyrus (Sensory association area, 3,1,2)

Spinothalamic (AKA: anterolateral)

• Carries

3 Neuron pathway​

1. Begins at the nerve endings (____ _____, ______ _____ _____)

2. ALL axons enter the central ____ matter and CROSS over via the ____ _____ _____. ​

3. These axons ascend via the ____ pathway

Continues to the

• Carries pain, temp and gross or crude touch​

3 Neuron pathway​

1. Begins at the nerve endings (Merkel’s Receptor, Bare nerve ending)

2. ALL axons enter the central gray mater and CROSS over via the Anterior Gray Commissure. ​So they cross at the level they enter.

3. These axons ascend via the Spinothalamic pathway

Continues to the Post central Gyrus (Sensory association area, 3,1,2)

• Incoming sensory data from the external world enters the CNS via receptors​

• There are (5) functional types of receptors:​

  • Mechanoreceptors: Respond to ….

  • Thermoreceptors: Respond to changes in ….

  • Nociceptors: Respond to any stimulus that might cause ____ _____ → usually referred to as ____ ______

  • Electromagnetic Receptors: ____ and ____ of the eyes​

  • Chemoreceptors: Responsible for chemical changes associated with …

• Incoming sensory data from the external world enters the CNS via receptors​

• There are (5) functional types of receptors:​

  • Mechanoreceptors: Respond to mechanical deformation **​

  • Thermoreceptors: Respond to changes in temperature​

  • Nociceptors: Respond to any stimulus that might cause tissue damage → usually referred to as pain receptors **​

  • Electromagnetic Receptors: Rods and cones of the eyes​

  • Chemoreceptors: Responsible for chemical changes associated with taste and smell AND O2/Co2 changes in the blood

Lateral Corticospinal Tract (LCST)

• Most clinically important ____ pathway​

• Controls movements of the _____

• Approx 70% originates in the _____ _____ _____ (Area _)​

• Remainder originates in ___-___ area (Area _)​

• 85% of descending motor fibers come from the ______​

• The LCST is ______, crossing at the level of the ____ (Known as the ______ _______)

• Most clinically important motor pathway​

• Controls movements of the extremities​

• Approx 70% originates in the primary motor cortex (Area 4)​

• Remainder originates in pre-motor area (Area 6)​

• 85% of descending motor fibers come from the LCST​

• The LCST is CONTRALATERAL, crossing at the level of the medulla (Known as the medullary pyramids)

Lateral Corticospinal Tract (LCST): Path

• Arises from _______ (______ _____)

• Exit via ____ root to form the ____ portion of the Spinal Nerve ​

• Somatotopic organization: ____ more Lateral than ____​

• Arises from cortex (internal capsule)

• Exit via ventral root to form the motor portion of the Spinal Nerve ​

• Somatotopic organization: LE more Lateral than UE​

Anterior Corticospinal (ACST)

• Controls ______ movement​

• 15% of descending motor fibers come from the _____​

• The ACST is ______ – fibers never _____

• arises from _______

• Exit via _____ root to form the ____ portion of the Spinal Nerve

• Controls proximal movement​

• 15% of descending motor fibers come from the ACST​

• The ACST is IPSILATERAL – fibers never cross​

• arises from cortex (internal capsule)

• Exit via ventral root to form the motor portion of the Spinal Nerve

New cards

Lesion Game: Is weakness ipsilateral or contralateral?

• Cortex​

• Internal Capsule​

• Midbrain​

• Pons​

• Medulla​

• S Cord

• Cortex​- contralateral

• Internal Capsule​- contralateral

• Midbrain​- contralateral

• Pons​- contralateral

• Medulla​-

  • superior- contralateral

  • inferior- ipsilateral after crossing

• S Cord- ipsilateral

Hemicord lesion

• _______ ______ loss of proprioception, light touch, and vibration + motor

• ________ _______ loss of pain, temp, crude touch

• SAME SIDE loss of proprioception, light touch, and vibration + motor

• OPPOSITE SIDE loss of pain, temp, crude touch

Posterior cord syndrome

______ _____ of proprioception, light touch, and vibration _______

Total loss of proprioception, light touch, and vibration bilaterally

Anterior cord syndrome

total loss of

total loss of motor and pain, temp, crude touch bilaterally