What is the name of the ridge that is visible on either side of the ventral midline of the medulla?
Pyramid (corticospinal tract). Consists of descending fibres originating from ipsilateral cerebral cortex. Fibres cross over at the decussation.
Where on the dorsal aspect of the brainstem would you find the gracile and cuneate tubercles?
Where on the dorsal aspect of the brainstem would you find the gracile and cuneate fascicles?
Caudal - mid medulla.
Where on the dorsal aspect of the brainstem would you find the inferior cerebellar peduncle?
Where on the dorsal aspect of the brainstem would you find the middle cerebellar peduncle?
Most lateral structure of the pons.
Where on the dorsal aspect of the brainstem would you find the superior cerebellar peduncle?
Most medial peduncle, rostral to others. Rostromedial pons.
Where on the dorsal aspect of the brainstem would you find the inferior colliculli?
Where on the dorsal aspect of the brainstem would you find the superior colliculli?
What are peduncles?
White matter bundles that connect the brainstem to the cerebellum/cerebrum.
What type of fibres are carried in the gracile and cuneate fascicles?
First order sensory neurones, continuing rostrally from the spinal cord to termination in nuclei gracilis and cuneatus.
What is the function of the inferior colliculli?
Constitutes part of the ascending acoustic (auditory) projection. Ascending auditory fibres terminate here.
What is the function of the superior colliculli?
Part of the visual system. Afferents originate from the visual cortex of occipital lobe and frontal eye field of frotal lobe. These fibres are concerned with controlling eye movements (saccidic, smooth pursuit), also involved in the accomodation reflex.
What are 'smooth pursuit' eye movements?
Slow tracking movements of the eyes designed to keep a moving stimulus on the fovea. Such movements are under voluntary control.
What are saccadic eye movements?
Rapid, ballistic movements of the eyes that abruptly change the point of fixation. They range in amplitude from the small movements made while reading, for example, to the much larger movements made while gazing around a room. May be voluntary or involuntary.
In which regions of the brainstem is the central canal expanded to form the fourth ventricle?
Caudal pons and rostral medulla on the dorsal aspect.
What structure sits on the roof of the fourth ventricle?
The ventral cerebellum.
What are the distinguishing features of the ventral surface of the medulla oblongata?
Pyramids (medial - with decussation) and olives (rostrolateral).
What are the distinguishing features of the ventral surface of the pons?
Ventrolateral surface of middle cerebellar peduncle (i.e. the big bulge).
To which side of the brainstem do all but one of the cranial nerves attach?
The ventral side.
Which cranial nerves attach to the midbrain?
III (3) Oculomotor
IV (4) Trochlear
Which cranial nerves attach to the pons?
V (5) Trigeminal
VI (6) Abducens
VII (7) Facial
Which cranial nerves attach to the medulla oblongata?
VIII (8) Vestibulocochlear
IX (9) Glossopharyngeal
X (10) Vagus
XI (11) Axillary
XII (12) Hypoglossal
What name is given to the angle between the medulla, pons and cerebellum?
Which cranial nerves are likely to be compressed by an acoustic neuroma (tumour of Vestibulocochlear nerve)? What might the symptoms be?
V-VII (5-7) (trigeminal, facial, vestibulocochlear).
Dizziness, deafness, cerebellar ataxia.
How would you test olfactory (CNI) nerve function?
Ask them if they have noticed a change in olfactory perception. Test smell in each nostril separately (closing the other).
How would you test optic (CNII) nerve function?
Test visual acuity, visual fields, colour perception and pupillary light reflex. Perform fundoscopy.
How do you test function of the oculomotor (CNIII) nerve?
Inspect for ptosis, nystagmus and eye position (PERRLA). Test eye movement in H pattern. Accommodation reflex - finger to nose.
How would you test the function of the trochlear (CNIV) nerve?
As you would the oculomotor.
How would you test the function of the trigeminal (CNV) nerve?
Sensory part - light touch tested in each of 3 divisions of the nerve with point stimulus. Test corneal reflex.
Motor part - palpate temporalis and masseter when jaw is clenched. Test pteregoids.
How would you test the function of the abducens (CNVI) nerve?
?As you would the oculomotor.