Brainstem and cranial nerves Flashcards
What are the three parts of the brainstem?
Midbrain
Pons
Medulla Oblongata
What is the pineal gland and why is it unique?
Almost everything in the brainstem is bilateral but the pineal gland isn’t - roof of midbrain on midline
It is responsible for regulating circadian rhythms (melatonin secretion)
What are colliculi and their functions?
4 bumps on roof of midbrain near pineal gland called colliculi (superior and inferior)
Superior – coordination of eye and neck movement
Inferior – auditory responses (survival)
What is the trochlear nerve and why is it unique?
Only cranial nerve from the back of the brainstem
It supplies the superior oblique muscles of the eye
How many dorsal columns are there are what do they do?
2 dorsal columns
Main sensory tracts sending information about fine touch and proprioception (body in space)
What is the roof of the midbrain called?
tectum
What are some of the structural features (including any nerves that emerge) of the midbrain?
Optic chiasm
The mammillary (memory and limbic system) bodies are part of the hypothalamus
Oculomotor nerve – conjugate eye movement
Cerebral peduncle – corticospinal fibre tract that holds cerebrum to the brainstem
Which nerve emerges from the pons and what does it do?
Trigeminal nerve emerges here - muscles of chewing
What are some of the nerves that emerge from the pontomedullary junctions and what do they do?
Abducens nerve (VI) – lateral rectus muscle
Facial nerve (VII) – musculature of face
Vestibulocochlear nerve (VIII) – balance and hearing
What are some of the nerves that emerge from the medulla and what do they do?
Glossopharyngeal nerve – tongue/pharynx function
Vagus nerve – PNS innervation to viscera
Accessory nerve – sternocleidomastoid & trapezius
Hypoglossal nerve – intrinsic muscles of tongue
What is the pyramidal decussation?
Where fibre lines cross and give rise to contralateral control - found in the medulla
What is the functional classification of cranial nerves?
General somatic afferent (GSA): Skin and mucous membrane sensation
General visceral afferent (GVA): GI tract, heart, vessels and lungs
General somatic efferent (GSE): Muscles for eye and tongue
General visceral efferent (GVE): Preganglionic PNS
What is the functional classification of cranial nerves? (special to head and neck)
Special somatic afferent (SSA) – vision, hearing, equilibrium
Special visceral afferent (SVA) – smell and taste
Special visceral efferent (SVE) – chewing, facial expression, swallowing, vocal sounds and turning head
Describe embryonic spinal cord and brainstem development
- The dorsal Alar plate and the ventral Basal plate
- The nerves are also clumped according to their purpose so the GSA fibres for example are all clumped
- During development the Alar plate splits and you get a lateral movement so in the brainstem the sensory nuclei are lateral while the motor nuclei remain medial
- Cranial nerve nuclei are arranged in the brainstem with sensory nuclei lateral and the motor nuclei in the midline
Which nerves are found at each level of the brainstem and are they motor or sensory?
Midbrain:
Sensory – Trigeminal.
Motor – Edinger Westphal, oculomotor, trochlear.
Pons:
Sensory – Trigeminal, vestibulocochlear.
Motor – Trigeminal, abducens, facial, salivary.
Medulla:
Sensory – Trigeminal, solitarius.
Motor – Salivary, vagus, ambiguus, hypoglossal.
Cervical Spinal Cord:
Sensory – Trigeminal?
Motor – Accessory.
(motor is medial and lateral is sensory - TO SEE THE ACTUAL TYPES LOOK AT NOTES)
