Midbrain

div style=”display:none;”>

Midbrain

Main Text

TERMINOLOGY

Abbreviations

• Cerebrospinal fluid (CSF)
• Cranial nerves (CN): Oculomotor nerve (CNIII), trochlear nerve (CNIV)

Synonyms

• Midbrain, mesencephalon

Definitions

• Midbrain: Portion of brainstem that connects pons and cerebellum with forebrain

GROSS ANATOMY

Overview

• Butterfly-shaped upper brainstem that passes through hiatus in tentorium cerebelli
• Composed of gray matter formations, CN nuclei (CNIII-CNIV), and white matter tracts
• 3 main parts

Cerebral peduncles : White matter tracts

– Continuous with pontine bulb and medullary pyramids

Tegmentum : CN nuclei, gray matter nuclei, white matter tracts

– Continuous with pontine tegmentum

– Ventral to cerebral aqueduct

Tectum (quadrigeminal plate) : Superior and inferior colliculi

– Dorsal to cerebral aqueduct
• Midbrain connections

Rostral (superior): Cerebral hemispheres, basal ganglia, and thalami

Dorsal (posterior): Cerebellum

Caudal (inferior): Pons
• Cerebral aqueduct passes through dorsal midbrain between tectum posteriorly and tegmentum anteriorly, connecting 3rd and 4th ventricles
• Adjacent CSF cisterns

Interpeduncular: Anterior, contains CNIII

Ambient (perimesencephalic): Lateral, contains CNIV

Quadrigeminal plate: Posterior, contains CNIV
• Blood supply by vertebrobasilar circulation

Small perforating branches from basilar, superior cerebellar, and posterior cerebral arteries

Cerebral Peduncles (Crus Cerebri)

• Corticospinal, corticobulbar, and corticopontine fibers
• Cerebral peduncles separated in midline by interpeduncular fossa

Mesencephalic Tegmentum

• Directly continuous with pontine tegmentum, contains same tracts
• Multiple white matter tracts (not resolved on conventional imaging)

Medial longitudinal fasciculus : Oculomotor-vestibular

Medial lemniscus : Somatosensory

Lateral lemniscus : Auditory

Spinothalamic tract : Somatosensory

Central tegmental tract : Motor
• Gray matter formations

Substantia nigra : Pigmented nucleus, extends through midbrain from pons to subthalamic region, important in movement

– Pars compacta: Contains dopaminergic cells (atrophied in Parkinson disease)

– Pars reticularis: Contains GABAergic cells

Only gold members can continue reading. Log In or Register to continue

Share this:
Click to share on Twitter (Opens in new window)
Click to share on Facebook (Opens in new window)

Related posts:

Frontal Pole (Area 10) Intracranial Venous System Overview Inferior Parietal Lobule (Areas 39, 40) Attention Control Network Medulla Ventricles and Choroid Plexus

Stay updated, free articles. Join our Telegram channel

Tags: Imaging Anatomy Brain and Spine

Mar 13, 2021 | Posted by admin in NUCLEAR MEDICINE | Comments Off

Full access? Get Clinical Tree

Get Clinical Tree app for offline access

Get Clinical Tree app for offline access