Medulla Flashcards
Total brain weight
0.5%
Cranial nerve associated with Medulla or the pons medullary junction
Cranial nerve 6 to 12
Abducens
Facial
Vestibulocochlear
Glossopharyngeal
Vagus
Spinal/ accessory
Hypoglossal
*located in the caudal medulla, point at which the fourth ventricle narrows to become the central canal of the spinal cord
*sensitive to pressure stimuli which cause vomiting.
OBEX
Maturing neurons of the basal plate of the medulla give rise to:
*Hypoglossal nucleus- somatic efferent cells
*Dorsal Motor Vagal Nucleus *Inferior Salivatory Nucleus- Both contain visceral efferent cells
*Nucleus Ambiguus- somatic efferent cells
Caudal to the Obex
Hypoglossal and Dorsal Motor Vagal Nuclei are small and can be found in the central gray surrounding the central canal.
Rostral to the Obex
Located medially to the sulcus limitans
cranial nerve nuclei derived from the alar plate in the medulla and their corresponding functional components include:
Vestibular and Cochlear Nuclei (Somatic Afferent)
§ Solitary Nucleus (Visceral Afferent)
§ Spinal Trigeminal Nuclei (Somatic Afferent)
cranial nerve nuclei derived from the alar plate in the medulla and their corresponding functional components include:
Vestibular and Cochlear Nuclei (Somatic Afferent)§ Solitary Nucleus (Visceral Afferent)§ Spinal Trigeminal Nuclei (Somatic Afferent)
ANTERIOR MEDULLA
anterior (ventral) aspect of the medulla is characterized by
Anterior median fissure (longitudinal ridge)
two laterally adjacent longitudinal ridges, the pyramids
olive (inferior olivary eminence)
ANTERIOR MEDULLA
Rootlets of the hypoglossal nerve (CN XII) exit?
Pre-olivary sulcus- a shallow groove located between the pyramid and the olive
ANTERIOR MEDULLA
emerges at the ponsmedullary junction, generally in line with the rootlets of CN XII.
Abducens nerve (vi)
LATERAL MEDULLA
a shallow trough, located between the restiform body and the large eminence formed by the underlying inferior olivary nucleus.
Post-olivary sulcus or retro-olivary sulcus
LATERAL MEDULLA
Nerve that emerges from the post-olivary sulcus.
CN IX (glossopharyngeal nerve) and CN X (vagus nerve)
LATERAL MEDULLA
accessory nerve is made up of:
Axons that arise from cells in the upper levels of the cervical spinal cord (C1 to C5 or C6)§ Ascend through the Foramen Magnum§ Coalesce to form the accessory nerve (CN XI)§ Exit the skull via the jugular foramen along with the glossopharyngeal and vagus nerves.
LATERAL MEDULLA
Emerge from the posterolateral medulla at the pons-medulla interface
facial nerve (CN VII), along with its intermediate root, and the vestibulocochlear nerve (CN VIII)
LATERAL MEDULLA
*Often incorrectly referred to as an acoustic neuroma
*Is a tumor of the vestibular portion of the CNVIII and is a lesion located at the cerebellopontine angle
Vestibular schwannoma
POSTERIOR MEDULLA
Caudal to the level of the obex, the posterior surface of the medulla is characterized by:
The gracile and cuneate fasciculi and their respective tubercules § Gracile and cuneate tubercules are formed by the underlying gracile and cuneate nuclei
POSTERIOR MEDULLA
*Contains a variety of afferent cerebellar fibers and becomes progressively large as it extends toward the pons-medulla junction
*Rostolateral to the gracile and cuneate tubercles and forming a prominent elevation on the posterolateral aspect of the medulla
RESTIFORM BODY
Blood supply to the entire medulla and to the choroid plexus of the fourth ventricle arises from
branches of thevertebral arteries
Blood supply to the entire medulla and to the choroid plexus of the fourth ventricle arises from branches of the vertebral arteries The exceptions are:
Portion of the choroid plexus that extends out of the foramen of Luschka § Adjacent cochlear nuclei (supplied by branches of the anterior inferior cerebellar artery, a branch of the basilar artery)
