The Brainstem Flashcards
What is the basilar circus?
Shallow sulcus where the basilar artery runs
What is the bulbopontine sulcus?
The line between the pons and the medulla
What is the anterior median fissure?
The line down the front of the medulla
What happens at the decussation of pyramids?
80% of descending corticospinal fibres cross over the midline
What is the ventral lateral sulcus?
The groove dividing the pyramid and the olive- it is where the rootlets of the hypoglossal nerve exit
What are the two main divisions of the midbrain?
Dorsal tectum and ventral tegmentum
What is the medulla?
Conical continuation of the spinal cord within the skull, beginning at the foramen magnum.
Where does the dorsal tectum lie?
Dorsal to the aqueduct of the midbrain and the fourth ventricle
Where does the ventral tegmentum lie?
Ventral to the aqueduct of the midbrain and the fourth ventricle
What is the interpeducular fossa?
The space between the crus cerebri
What are the cerebral peduncles/crus cerebri?
A large collection of fiber bundles in the ventral midbrain, which originate in the cerebral cortex
What are mammillary bodies?
Small round bodies, located on the undersurface of the brain that, as part of the diencephalon, form part of the limbic system
What is a pyramid?
An elongated swelling (eminence) marking the position of the underlying fibres passsing from the cerebral hemisphere to the cord, the corticospinal tracts
What is the decussation of the pyramids?
Diagonally oriented bundles of fibres crossing the fissure, where 80% of corticospinal fibres corss the midline to enter the opposite lateral white column of the spinal cord
What is the olive?
A swelling (eminence) caused by the presence of the underlying inferior olivary nucleus and is concerned with the control of movement
What is the inferior cerebellar peduncle?
A thick bundle of white matter passing into the cerebellum whihc forms the posterolateral margin of the medulla
What is the tectum?
The midbrain dorsal to the aqueduct, it is made up of the colliculi (aka the corpora quadrigemina)
What is the tegmentum?
The midbrain ventral to the aqueduct, it is made up of nerve fibres entering and leaving the cerebral hemispheres, nerve nuclei etc
What is the superior colliculi?
Part of the visual system concerned with eye reflexes
What is the inferior colliculi?
Part of the autitory system concerned with the reflex of looking towards a loud noise
What is the superior cerebellar peduncle?
A fibre bundle passing from the cerebellum to the midbrain
What is the pineal gland?
An endocrine gland that synthesises melatonin whihc modulates sleep patterns in both circadiam and seasonal cycles
What does the inferior brachium do?
Conveys auditory information from the medial geniculate body to the inferior colliculi
What does the superior brachium do?
Conveys visual information form the lateral geniculate body to the superior colliculi
What is the gracile tubercle?
A round swelling on either side of the medulla midline overlying the gracile fasciculus
What is the gracile fasciculus involved in?
Involved in carryin fine touch, vibration, two-point discrimination and proprioception from the lower limb
What is the cuneate tubercle?
A swelling lateral to the gracile tubercles, overlying the cuneate fasciculus
What is the cuneate fasciculus invovled in?
Involved in carrying fine touch, vibration, two-point discrimination and proprioception from the upper limb
What cranial nerve nuclei does the tegmentum carry ?
Carries the nuclei of:
Abducens (6)
Facial (7)
Trigeminal (5- motor division- muscles of mastication)
Glossopharyngeal (9)
Vagus (10)
Accessory (11)
Hypoglossal (12)
What is the floor of the 4th ventricle called?
Rhomboid fossa
What connects the third anf fourth ventricles
The cerebral aqueduct runs through the midbrain and interconnects the third and fourth ventricles
What is the substantia nigra?
A black band of nerve cells overlying the crus cerebri (cerebral peduncles), ventro-lateral to the red nucleus on each side
What is the red nucelus?
A circular mass of grey matter ventro-lateral to the cerebral aqueduct, often appears pink
The nuclei underlying the gracile and cuneate tubercles are called the dorsal column and are a major relay site for which pathway?
Dorsal column sensory pathway
aka dorsal column medial lemniscal system
What is Bell’s Palsy?
Acute unilateral inflammation of the facial nerve (lower motor neurone)
Symptoms:
Pain behind ear
Paralysis of facial muscles
Failure to close the eyes
Signs:
Absent corneal reflex
Hyperacusis (certain sounds heard unpleasantly loudly)
Lodd of taste on anterior 2/3s pf tongue
What is Bulbar Palsy?
Impairment of the functions of the cranial nerves that arise from the medulla (Nerves 9-12). Caused by motor nuerone disease and Guillain-Barre syndrome
Symptoms:
Dysphagia (difficulty swallowing)
Slurring of speech
Dysphonia (difficulty forming sounds)
Excess saliva- dribbling
Signs:
Wasting and fasciculating tongue
Absent gag reflex
What is central pontine myelinoysis?
Destruction of myelin in the pons- occurs when low sodium levels are corrected too quickly
Symptoms:
Confusion
Balance problems
Dysphagia (difficulty swallowing)
Hallucinations
Reduced consciousness
Slurred speech
Tremor and weakness in the face or limbs
