Lecture 6: Overview and Organisation of the Brainstem Flashcards
The four Components of the Brainstem include:
Four components of the brainstem:
1 ● Tectum (posterior/dorsal)
2 ● Ventricular System
3 ● Tegmentum
4 ● Basal portion (anterior/ventral)
Parts of the Midbrain and what can be found there?
Tectum (posterior),
Ventricular System,
Tegmentum,
Basal portion (anterior)
Tectum (posterior):
1. Superior colliculi (visual relay nuclei) Inferior 2. colliculi (auditory relay nuclei)
Ventricular System
1. cerebral aqueduct
Tegmentum
1. Red nuclei
2. CN III and CN IV nuclei Spinothalamic tract &
3. Medial Lemniscus
Basal portion (anterior)
1. Substantia nigra
2. Corticospinal and c
3. orticobulbar tracts
Understanding the Oculomotor Nerve CNII:
General Somatic Efferent GSE vs General Visceral GVE
General Somatic Efferent GSE:
1. Superioir rectus,
2. Medial Rectus,
3. Inferior Oblique
4. Levator Palpebrae
5. Superioris
General Visceral GVE:
1. Constrictor pupiliae
2. Ciliary muscles
Parts of the PONS and what can be found there?
Tectum (posterior),
Ventricular System,
Tegmentum,
Basal portion (anterior)
Tectum (posterior)
1. Superior medullary velum
2. Inferior medullary velum
Ventricular System
1. Fourth ventricle
Tegmentum
1. CN V (5), CN VI (6), CN VII (7) , CN VIII (8) nuclei Ascending & descending tracts
2. Reticular formation
Basal portion (anterior)
1. Transverse pontine fibres
2. Corticospinal fibres
3. corticobulbar fibres
Parts of the MEDULLA OBLONGATA and what can be found there?
Tectum (posterior),
Ventricular System,
Tegmentum,
Basal portion (anterior)
Tectum (posterior)
1. Fasciculi cuneatus
2. Fasciculi gracilis
3. Tuberculum cinereum
Ventricular System
1. Central Canal
Tegmentum
1. CN IX, CN X, CN XII nuclei Ascending & descending tracts (9,10,11)
Basal portion (anterior)
1.Pyramids: corticospinal & corticobulbar tracts 2. Olives: inferior olivary nuclei
Sensory vs Motor Nuclei?
Sensory nuclei are posterolateral.
Motor nuclei are anteromedial.
Sensory nuclei are posterolateral.
- located towards the back (posterior) and to the side (lateral) of the structure being referred to.
This arrangement is often observed in structures like the thalamus, where sensory information from various sensory modalities is received, processed, and relayed to other regions of the brain.
Motor nuclei are anteromedial.
- situated towards the front (anterior) and towards the middle (medial) of the structure being described.
This arrangement is often seen in structures like the brainstem, where motor nuclei such as the cranial nerve motor nuclei or nuclei involved in voluntary motor control are located.
Seven classifications of fibre types:
Afferent fibres types (derived
from the alar plate):
Efferent fibres types (derived
from the basal plate):
Afferent fibres types (derived
from the alar plate):
1 ● Special somatic (SSA)
2 ● General somatic (GSA)
3 ● Special visceral (SVA)
4 ● General visceral (GVA)
Efferent fibres types (derived
from the basal plate):
1 ● General visceral (GVE)
2 ● Special visceral (SVE)
3 ● General somatic (GSE)
Four nuclei associated with V
The tuberculum cinereum overlies the spinal trigeminal nucleus and tract.
- Chief sensory nucleus of V processes touch, vibration & conscious proprioception.
- Spinal trigeminal nucleus processes pain & temperature.
- Mesencephalic nucleus process non-conscious proprioception from muscles of mastication.
- Motor nucleus of V = LMN to muscles of mastication & tensor tympani.
Understanding Facial Nerve CNVII? (4)
- Facial nerve proper: motor fibres to muscles of facial expression, cell bodies in facial nucleus.
- Nervus intermedius: parasympathetic fibres, special sensory fibres & general somatic afferent fibres.
- Pre-ganglionic parasympathetic fibre cell bodies located in superior salivatory nucleus.
- Special sensory (taste) fibres synapse in the nucleus solitarius.
Understanding Vestibulocochlear nerve (CN VIII)
- 3
- Vestibular nerve: special sensory afferents from vestibular apparatus (balance).
- Cochlear nerve: special sensory afferent from the cochlea (hearing).
- Nuclei in the posterior proximal medulla oblongata.
Understanding the Glossopharyngeal nerve (CN IX) =7
- Motor (somatic & visceral) fibre cell bodies located anteromedially in medulla oblongata.
- Sensory (general, visceral & special) fibres synapse in nuclei located posterolateral.
- LMN with cell bodies in nucleus ambiguus supply stylopharyngeus m.
- Pre-ganglionic parasympathetic fibres with cell bodies in the inferior salivatory nucleus supply the parotid gland.
- Taste fibres from the posterior 1⁄3 tongue synapse is rostral nucleus solitarius.
- Visceral afferent fibres from carotid body & sinus project to caudal nucleus solitarius.
- General sensory fibres from pharynx & skin behind auricle project to spinal trigeminal nucleus.
Understanding the Vagus nerve (CN X) =5
- Pre-ganglionic parasympathetic fibres will cell bodies in the dorsal motor nucleus of vagus project to viscera of neck, thorax and abdomen.
- General visceral afferent fibres from viscera of neck, thorax & abdomen project to the nucleus solitarius.
- Special sensory (taste) fibres from epiglottis project to the nucleus solitarius.
- General sensory fibres from external acoustic meatus, meninges surrounding jugular foramen, pharynx & larynx project to the spinal trigeminal nucleus.
- LMN to muscles of palate, pharynx, larynx & (1 in tongue) have cell bodies in nucleus ambiguus.
Understanding the Cerebral Arterial Circle:
Anterior System = internal carotid
Posterior System = vertebral-basilar
Understanding the Brain Stem Blood Supply: 6
- 2 x vertebral arteries branch from subclavian arteries.
- Vertebral arteries join to form basilar artery.
- 2 x posterior spinal arteries 1 x anterior spinal artery
- Majority of cerebral peduncles supplied by posterior cerebral arteris and superior cerebellar artery.
- Majority of pons supplied by basilar artery.
- Majority of medulla supplied by vertebral artery branches
