Medulla Oblongata Flashcards
General external features of medulla
- anterior median fissure - continues with SC below, foramen caecum above
- posterior median sulcus - contd. below with SC, form triangular area of 4th ventricle above
- anterolateral sulcus - 12th N
- posterolateral sulcus - 9, 10, 11th N
- pontomedullary junction - 6, 7, 8th N
Structures in anterior part of medulla
Medial to lateral
- Pyramids
- Olives - posterolateral to pyramids - cover inferior olivary nucleus
- Hypoglossal N
- Inferior cerebellar peduncles - posterolateral to olives - connect medulla to cerebellum
- 9th, 10th, 11th cranial N
Structures in posterior part of medulla
Medial to lateral
Closed part:
1. Fasiculus gracilis - gracile tubercle - nucleus gracilis
2. Fasiculus cuneatus - cuneate tubercle - nucleus cuneatus
3. Tuberculum cinerium - spinal nucleus of trigeminal N
Open part:
1. Forms floor of 4th ventricle
Internal features of medulla at level of pyramidal decussation
- N. gracilis and cuneatus seen as projections
- N. of spinal tract of trigeminal N at apex of posterior horn
- Spinal N. of accessory N in anterior horn
- Diffuse zone with network of fibres and nerve cells in lateral white column - reticular formation
Internal features of white matter of medulla at level of sensory decussation
Posterior to anterior
- N. gracilis and cuneatus (NGC) are prominent
- Fasiculus gracilis and cuneatus occupy post. white column
- Internal arcuate fibres from NGC decussate and ascend as medial lemniscus
- Accessory cuneate nucleus - External arcuate fibres - enter inferior cerebellar peduncle
- Spinal N. and tract of trigeminal N
- Inferior olivary N.
- Pyramids
Internal features of grey matter of medulla at level of sensory decussation
- Nucleus tractus solitaris
- Dorsal nucleus of vagus
- Hypoglossal nucleus
Internal features of medulla at level of olives
- Hypoglossal nucleus
- Dorsal nucleus of vagus
- N. of tractus solitarius
- Vestibular N.
- Spinal N. and tract of trigeminal N
- Nucleus ambiguus
- Inferior olivary nucleus
- Pyramidal tract
- Arcuate N.
Nucleus ambiguus
- lies within reticular formation
- origin to motor fibres of 9th, 10th, 11th cranial N
Arcuate Nucleus
Receive fibres from cortex
Send efferents to cerebellum on opp. side
Through external arcuate fibres
Internal features of medulla at level of pontomedullary junction
- Lateral vestibular N.
2. Cochlear N.
Blood supply of medulla
- 2 Vertebral A
- Ant. and post. spinal A
- Ant. and post. inferior cerebellar A
- Basilar A
Lateral medullary syndrome of Wallenberg
Thrombosis of posterior inferior cerebellar A
- Contra. loss of pain and temp. in trunk and limbs
- Ipsi. loss of pain and temp. on face
- Ipsi. paralysis of palate, pharynx, larynx
- Ipsi. ataxia
- Giddiness
- Horner’s syndrome
Dejerine’s anterior bulbar syndrome
Thrombosis of vertebral A
- Contra. hemiplegia
- Ipsi. paralysis and atrophy of half tongue
- Contra. loss of position, vibration
