Neuroanatomy - Week 4 - Brain Stem Flashcards
What direction is rostral?
Towards the front of the head
What direction is caudal?
Towards the occipital lobe
What’s the average size of the medulla oblongata?
3cm
What is the inferior cerebellar peduncle?
body of white matter that connects the
medulla with the cerebellum
Do the gracile and cuneate fasciculi continue from the spinal cord into the medulla?
Yes
How many nerves are attached to the medulla (CN9-12) and what are they?
4
Whats the ave. size of the pons?
2.5cm
What does The basal pons blends laterally into?
the middle cerebellar peduncles
What is the midbrain associated with?
- motor coordination (particularly eye movements)
- visual and auditory processing
- Arousal
- Conscousness
- Behavioural responses to fear & danger
Where is the midbrain located?
- Brain stem
- Extends from the base of thalamus to the pons
What is the pons associated with?
- Largest component of the brainstem
- Houses the nuclei of cranial nerves V- VIII
- Houses pontine nuclei which facilitates corticopontocerebellar communication
- Helps regulate sleep and breathing
Where is the pons located?
Between the medulla oblongata and the midbrain
What is the medulla oblongata associated with?
- Most caudal part of the brainstem
- Connects to spinal cord
- Houses nuclei of cranial nerves XI - XII
- Regulates respiration, cardiovascular system, GIT
What is the brainstem function?
Carries ascending and descending tracts between forebrain and spinal cord
- Regulates breathing, digestion, cardiovascular activity
What cranial nerves does the brain stem house?
Cranial Nerves III - VII
What is bilateral to the anterior median fissure?
Medullary pyramids aka pyramidal tracts
What do the medullary pyramids contain?
Fibres from the corticospinal tracts
What are the medullary pyramids key function?
Controlling voluntary movements
What is pyramidal decussation?
Site for corticospinal fibre decussation
What is decussation?
- The cross over of corticospinal fibres
- Where one side of the brain controls the other side of the body
What part of the brainstem does pyramidal decussation occur?
Medulla Oblongata
What is the pontomedullary junction?
The border between the pons and medulla oblongata
- Marked by the inferior pontine sulcus
How many cranial nerves emerge from the pontomedullary junction?
3
What are the 3 nerves that emerge from the pontomedullary junction?
- Abducents nerve (CN VI)
- Facial nerves (CN VII)
- Vestibulocochlear nerve (CN VIII)
What are the 3 nerves that emerge from the pontomedullary junction?
- Abducents nerve (CN VI)
- Facial nerves (CN VII)
- Vestibulocochlear nerve (CN VIII)
What is the central groove through the pons?
- Basilar groove
(houses basilar artery)
What cranial nerve emerges from the anterolateral aspect of the pons?
Trigeminal nerve (CN V)
What are the 2 parts of the trigeminal cranial nerve?
- Motor root (smaller)
- Sensory root (large)
What is the largest cranial nerve?
Trigeminal nerve
What is the name of the groove connecting the pons to the midbrain?
Superior pontine sulcus
What is the midbrain associated with?
- Motor control
- Sound and visual processing
- Thermal regulation
What are the cerebtal peduncles?
- 2 sides of the midbrain
What cranial nerves does the midbrain behold?
- Oculomotor nerve (CNIII)
- Trochlear nerve (CN IV)
What is the only cranial nerve NOT to originate on the anterior aspect of the brainstem?
Trochlear nerve (CN IV)
What is another name for the midbrain?
Mesencephalon
What is the shortest part of the brainstem?
Midbrain
Name 5 key Medulla oblongata anatomical landmarks
- Pyramid
- Olive
- Inferior cerebellar peduncle
- Cuneate
- Gacile tubercles (below obex)
- Floor of 4th ventricle (above obex)
Name 4 key anatomical landmarks associated with the Pons
- Basal parts of pons
- Middle cerebellar peduncle
- Superior cerebellar peduncle
- Floor of 4th ventricle
Name 3 key anatomical landmarks associated with the Midbrain:
- Interpenduncular fossa
- Basis pedunculi
- Inferior or superior colliculus
What’s the average size of the midbrain?
1.5cm
The spinothalamic tract is formed from…
axons that arise in the contralateral dorsal horn of the spinal cord
The superior cerebellar peduncles consist largely of what?
fibers leaving the cerebellum
The substantia nigra and the periaqueductal gray matter are present at what levels of the midbrain?
All levels of the midbrain
Preganglionic parasympathetic nuclei include what 3 nucleuses?
- Edinger-Westphal nucleus
- dorsal nucleus of the vagus
- nucleus ambiguus
The only general somatic sensory nuclei
are the three components of what nuclear complex?
Trigeminal
The only visceral sensory nucleus is the…?
Solitary nucleus
What type of data do Spinoreticular Fibers transmit?
- Sensory
- Especially from the skin and internal organs
What type of sensory data are the Spinothalamic and Spinotectal Tracts associated with?
- Pain
- Tempoerature
- Touch
What do the Spinothalamic and Spinotectal Tracts merge to become?
spinal lemniscus
What are proprioceptive signals associated with?
Movement
What type of signals do the dorsal and ventral spinocerebellar tracts mainly carry?
Proprioceptive signals
cuneocerebellar fibers provide a pathway to the cerebellum from what areas?
Neck & upper limb
What are 4 tracts that originate in the midbrain?
- Central tegmental tract
- Rubrospinal tract
- Tectospinal tract
- Tectbulbar fibers
What are 4 tracts that originate in the midbrain?
- Central tegmental tract
- Rubrospinal tract
- Tectospinal tract
- Tectbulbar fibers
What is the dorsal nucleus of the vagus nerve?
the larg- est parasympathetic nucleus in the brain stem
Vestibulocochlear Nerve receive afferent communications from where?
Cochlear and vestibular divisions of the 8th cranial nerve
What is the fasciculus gracilis associated with?
- Ascending sensory pathway
- Lower limb
- Below T6
- Fine touch
- Vibration
- Proprioception
What is the fasciculus cuneatus associated with?
- Ascending sensory pathway
- Upper limb
- T6 & above
- Fine touch
- Vibration
- Propriotception
What sensory elements is the anterior spinothalamic tract associated with?
- Crude touch
- Pressure
What is the lateral spinothalamic tract sensory inputs?
- Pain
- Temperature
What do the posterior spinocerebellar, anterior spinocerebellar and spino-olivary tracts all have in common?
- They all transmit ascending proproception of the lower limbs to cerebellum
What do the cuneocerebellar and rostral spinocerebellar both have in common?
Both transmit ascending proprioception of the UPPER limbs to the cerebellum
What is descending spinal cord transmission associated with?
Motor signals and muscle movement
What are the 2 largest pyramidal tracts called?
Anterior and lateral corticospinal tracts
Is the lateral corticospinal tract contralateral or ipsilateral?
Contralateral
Is the anterior corticospinal tract contralateral or ipsilateral?
Ipsilateral
What is the rubrospinal descending motor tract associated with controlling?
Fine motor control
What does the medial reticulospinal tract fascilitate?
Contraction and muscle tone
What does the lateral reticulospinal tract do?
- Inhibits muscle contraction
- Reduces muscle tone
- Associated with automatic breathing
What does the lateral reticulospinal tract do?
- Inhibits muscle contraction
- Reduces muscle tone
- Associated with automatic breathing
What is the vestibulospinal tract associated with?
Balance and posture
What is the tectospinal tract associated with?
Head movement and vision coordination
The dorsal part of the spinal cord is associated with ascending or descending sensory input?
Ascending
The anterior part of the spinal cord is associated with descending or ascending motor transmission?
Descending/efferent
