Brainstem Objectives

The midbrain has what CNs connect

2 CNs connect here (III and IV)

The Pons has what CNs connect

4 CN connect here (V, VI, VII,VIII)

The Medulla has what CNs connect

4 CN connect here (VIII, IX, X, XII)

What are the two longitudinal sections of the brain stem

basilar, tegmentum

Basilar

primarily motor, Located anteriorly, Has descending axons from the cerebral cortex to Spine, brainstem, pontine, and reticular formation

Basilar motor nuclei

substantial nigra, pontine nuclei, inferior olive

Tegmentum

adjusts neural activity, integrates sensory, and regulates CN function, located posteriorly

The tegmentum regulates the

Reticular formation, sensory nuclei, ascending sensory tracts, CN nuclei, and medial longitudinal fasciculus

The midbrain has an additional longitudinal section that is posterior to the tegmentum called the

tectum

Tectum

reflexive control of intrinsic and extrinsic eye muscles and head movement

Three functions of the reticular formation

Integrates sensory and cortical info, Regulates somatic motor activity, autonomic function, and consciousness, Modulates nociceptive info

Four major reticular nuclei

ventral tegmental area (VTA), Pedunculopontine nucleus (PPN), Raphe nuclei, Locus Coeruleus

Ventral tegmental area (VTA)

Produce dopamine for reward

Pedunculopontine nucleus (PPN)

Influences movement to improve gait and posture

Raphe nuclei

Has profound effects on mood, Descending nociceptive info to respond to pain sources

Locus Coeruleus

directs attention

Medial reticular area

regulates autonomic functions

Primary Functions of the medulla

Controls eye and head movement (CN VIII), Conveys nociceptive and temperature from the face (CN VII), Coordinates swallowing (CN IX + X), Regulates cardiovascular, respiratory, and visceral activity (CN X)

Functions of the pons

Processes motor info from the cerebral cortex and send that info to the cerebellum, Also has nuclei for CN V to VIII functions

Location of the midbrain

the uppermost part of the brainstem, connects to the diencephalon, divided into 3 areas

The three areas of the midbrain

basis pedunculi, tegmentum, tectum

Basis pedunculi Formed by

cerebral peduncles and substantia nigra of basal ganglia circuit

Tegmentum

Helps motor cortex coordinate complex movements, balance, and posture, Maintains activity to generate movement

Rectum pretectal area

mediates reflexes involving eye

Tectum Inferior colliculi

relays auditory info from cochlea to superior colliculi and medial geniculate body of thalamus

Tectum Superior colliculi

brainstem centers for orientation, receives sensory and motor, involved in reflexive eye and head movement

What artery branches supply the brainstem and cerebellum

vertebral and basilar artery

The vertebral artery combines to form

basilar a. at the pontomedullary junction, This includes the posterior cerebral arteries which supply the midbrain

Vertical tract signs typically cause

CL signs based on desiccation area

Corticobrainstem tract lesions

can cause upper and lower motor neuron dysfunction

Wallenberg’s syndrome

brainstem lesion (lateral medulla) with both signs, IL limb ataxia and loss of nociceptive info from face, CL loss on nociceptive info from body

Brainstem region ischemia

Abrupt onset of neurologic symptoms including dizziness, incoordination, etc.

Locked In Syndrome

consciousness intact, but UMN damage prevents voluntary movements (often basilar artery stroke)

Tumors in brainstem

can cause increased intracranial pressure. This may cause headache, nausea, vomiting, CN disorders, hydrocephalus, and ataxia

Dysphagia

difficulty swallowing (CN V, VII, IX, X, XII)

Dysarthria

difficulty speaking (CN V, VII, X, XII)

Diplopia

double vision (CN III, IV, VI)

Dysmetria

inability to control distance of movements and coordination