Brainstem and CN (Medulla) Flashcards
Label this
Label this anterior view of the brainstem
What is the purpose of the aqueduct?
The aqueduct is for the flow of the CSF from the third ventricle to the fourth ventricle.
Label the fissures on the medulla
Label the external features of the ventral medulla
The medulla is divided into 2 parts, describe these
The part of the medulla that has the central canal running through it is called the closed part of the medulla.
As you go up the medulla central canal opens up into the fourth ventricle, this is the open part of the medulla
Label this dorsal medulla
Label the 5 main tracts on this spinal cord and briefly say what they do
Where do each of the cranial nerves emerge from?
CN1 and CN2: Olfactory and optic sensory nerve. From eye and nose. No connection to the brain stem directly, no nuclei from it
CN3 and CN4 present in the midbrain
5,6,7 in the pons. 5 also has extensions to the midbrain and the medulla.
6,7,8 in the pontomedullary junctions.
9,10,11 in the n. ambiguus
10 also has a dorsal nucleus of vagus
7,8,9 has another nucleus called the NTS in the medulla
CN12 emerges from hypoglossal nuclei in the medulla
Which cranial nerves are sensory and which are motor?
Some Say Money Matters, But My Brother Says Big Brains Matter Most
S- SENSORY
M- MOTOR
B- BOTH
Parasympathetic nerves- 3,7,9,10
Draw a diagram to compare each of the descending tracts
corticospinal= main motor tract, runs through all of the brainstem
Tectospinal, rubrospinal tract=structures within the midbrain which further relay further down in the spinal cord
Vestibulospinal tract= starts in the vestibular nuclei which then goes down towards the sc
Describe the corticospinal tract in detail.
Starts in the cerebral cortex. Ends in the sc
From the cerebral cortex, starts in areas: 4,6,3,2,1
Fibres descend to the internal capsule
Through internal capsule, go through the midbrain->pons->medulla
Fibres decussate at the pyramid and travel posteriorly backwards, forming the lateral CST
But 20% of fibres continue as the ventral CST
From the spinal cord, the neurones then relay into the interneurons-> ventral rami of the spinal nerves ->skeletal muscles.
Compare the dorsal column medial lemniscal pathway with the spinothalamic tract
Explain the level of motor decussation
In the corticospinal tract - 80% of the fibres cross over as the lateral corticospinal tract
This is called the decussation of pyramids.
What type of descending tracts is found at the level of motor decussation?
Descending Tracts: Spinal tract of trigeminal nerve - Carries pain and temp sensations from the face and neck
Explain the structures and what you would find at the level of sensory decussation
sensory decussation from the gracile and cuneate nucleus, which are responsible for fine touch, vibration, proprioception.
The fibres of this decussation= internal arcuate fibres, found at the superior part of the medulla. This forms the second neuron in the posterior column–medial lemniscus pathway.
CN11 would emerge from here.
Label this to show the level of sensory decussation
Describe and explain the mid olivary level
Which nuclei are found at the mid olivary level and what are their afferents/efferents?
What is the medial longitudinal fasiculus?
Describe the blood supply to the medulla
What can happen if the posterior inferior cerebellar artery is blocked? What are the symptoms
What happens if the anterior spinal artery is blocked?
Label this dorsal medulla
