Pons Flashcards
Medial Lemniscus function:
- Carries sensory information from the dorsal column to the thalamus
o Proprioception
o Fine discriminative touch o Vibrations
Trigeminal Lemniscus function
Carries sensory information from the face to the thalamus o Pain
o Temperature
o Crude touch
o Pressure
* These sensations are picked up by CN V (trigeminal) and this tract originates when fibers divide from the spinal nucleus of CN V at a lower level in the pons
Spinal Lemniscus function
Sensory information from the ventral and lateral spinothalamic tracts in the spinal cord to the thalamus
o Pain
o Temperature
o Crude Touch
o Pressure
Lateral Lemniscus function
- Carries hearing information from the contralateral cochlea to the inferior colliculus in the midbrain
- The fibers forming it cross in the trapezoid body
Ventral Spinocerebellar Tract function
- Ascending fibers carrying proprioceptive information from muscles, tendons and ligaments to the cerebellum
o Forms from lateral white column fibers at the levels of L2 to Coccis - This is used by the cerebellum as feedback on motor movement
o Aids movement co-ordination
Rubrospinal Tract function
Brings motor information from the red nucleus in the midbrain to flexor muscles
o Primarily distal flexors of upper extremities Regulates force, velocity and direction of movement
Tectospinal Tract function
Stimuli from the tectum to muscles of the eyes, head and neck
o Superior Colliculus→ Visual stimuli o Inferior Colliculus→ Auditory stimuli
Allows rapid response of the eyes, head and neck to visual and auditory stimuli
Medial Longitudinal Fasciculus funtion
- Ascending tract that connects the Nuclei of Cranial Nerves III, IV and VI
- Co-ordinates eye movements
- Can be damaged in multiple sclerosis
Motor nucleus of CN V (trigeminal) function
- Motor supply to structures of 1st pharyngeal arch (muscles of mastication)
o Temporalis
o Masseter
o Medial pterygoid
o Lateral Pterygoid
o Suprahyoid muscles - Special Visceral Efferent Fibers
Central/Principal Pontine Nucleus of CN V (trigeminal) function:
- Receives sensory information from the face o Fine touch of whole face
o Proprioception of the jaw - General Afferent Fibers
Superior Cerebellar Peduncles function :
- Connect the midbrain to the cerebellum
- A small piece can be seen at this level of the pons
Pontine Nuclei function :
- Synapse points of corticopontine motor fibers
o Impulse descends from the motor cortex
o Synapse at pontine nuclei
o Moves to the contralateral cerebellum through the
pontocerebellar fibers and the middle cerebellar
peduncles (see diagram) - This informs the cerebellum of the motor plan
o Aids movement co-ordination
Spinal Nucleus of CN V (trigeminal) function:
Extends from lower part of the pons to the top of the spinal cord
* Receives sensory information from the ipsilateral face o Pain
o Temperature o Crude touch o Pressure
* Some fibers leave the nucleus to form the trigeminal lemniscus higher up in the pons
* Also receives sensations from the middle ear through General Somatic Afferent Fibers of CN VII (facial)
Motor Nucleus of CN VII (facial) function
- Supplies muscles of 2nd pharyngeal arch (facial expression)
o Occipitofrontalis o Orbicularis oculi o Orbicularis ori
o Buccinator
o Platysma - Special Visceral Efferent Fibers
Superior Salivatory Nucleus of CN VII (facial) function
- Parasympathetic stimulus to lacrimal, palatine and salivary glands
- General Visceral Efferent Fibers