[BNS] BRAINSTEM GEN. & MEDULLA

Pituitary Stalk

Median eminence of tuber cinereum

Infundibulum

Stalk located underneath the chiasm and serves as attachment of the pituitary gland

CN V Portio Major

Which division of the trigeminal nerve is responsible for face and neck sensation

CN V Portio Minor

Which division of the trigeminal nerve is responsible for the muscles of mastication

mid-laterally of the pons

CN V is found at which part of the pons

Facial Intermediate Nerve (Wrisberg nerve)

Found between between CN VII and VII and responsible for visceral and sensory functions of facial nerve

Pyramids

Continuation of the descending corticospinal (motor) tracts in the medulla

Olives

Prominences that are lateral to the pyramids that functions as motor coordinator between cerebellum and motor systems

F; Covers only upper half of the rostral medulla

T/F: Olives cover only lower half of the caudal medulla

CN XII

What cranial nerve emerges in the pre-olivary sulcus

Pyramidal Decussations

This structure is found at the spinomedullary junction where crossing of tracts happens

Cerebellopontine angle

Angle between the pons and cerebellum, where the VIII, VII, and some of the V

Superior colliculi

What structure in the Quadrigeminal Plates is responsible for visual reflexes

Inferior colliculi

What structure in the Quadrigeminal Plates is responsible for auditory reflexes that allows the eyes/head to move in response to a stimulus

Rhomboid Fossa

Floor of the 4th ventricle

Superior CP

Cerebral peduncle that is efferent to the cerebellum that carry fibers going back to the brainstem and to higher areas

Middle CP

CP that is afferent to the cerebellum which carries transverse and descending fibers from pons to cerebellum

Inferior CP

CP that serves as connections to the vestibula

genu of the facial nerve, nucleus of the abducens nerve

What are the structures found internally in the Facial Colliculi

Hypoglossal Trigones, Vagal Trigone, Vestibular Area

What are the structures found in the Upper Medulla

Hypoglossal Trigones

Protrusions of the hypoglossal nucleus found inside

Vagal Trigone

Structure where the dorsal motor nucleus of the vagus nerve is found inside

Gracile fasciculus

Sensory fibers from the dorsal column that carry sensory information from the lower extremities below T6

Cuneate fasciculus

Sensory fibers from the dorsal column that carry sensory information from proprioception, fine touch, and vibration upper extremities T6 and up

Central canal

What is the ventricular system found at the level of the caudal medulla

F; No descending sensory fibers

T/F: Tegmentum contains descending sensory fibers

Basis

Most ventral segment of the brainstem where descending corticospinal tract or motor tract are located

Magendie aperture

This aperture drains into the cisterna magna where 4th ventricle transitions into central canal

Foramen of Luschka

Drains into pontine aperture/cisterns

Vertebral Artery

Supply the anterior part of the medulla

PICA

Supplies the dorsolateral medulla

Anterior spinal artery

Supplies the anterior and anteromedian part of the medulla

Posterior spinal artery

Supplies the caudal part of the medulla

pontomedullary junction

Where is the basilar artery formed? (location/landmark)

Posterior cerebral artery (PCA)

Addtl Info: Terminal branch of basilar artery

Main blood supply of thalamus

SCA

Supplies lateral rostral pons, caudal midbrain

CN III

cranial nerve that is sandwiched between SCA and PCA at the pontomesencephalic junction

MCA

Which is not part of the Circle of Willis

Tegmentum

descending corticospinal tract and sensory fibers pass through this layer of the brainstem (serves as a conduit for the tracts)

1) Corticospinal tract

2) Dorsal columns/Medial lemniscus

What are the two tracts that decussates at the pyramidal decussation at the caudal medulla

Dorsal column/medial lemniscus

Responsible for discriminative sensation (somatosensory) and conscious proprioception

ipsilaterally

Before decussation of Dorsal Column/Medial Lemniscus, the fibers or tract proceed ipsilaterally or contralaterally?

F; Decussates at spinal cord via Lissauer’s tract at the same spinal cord level or 1-2 levels up

T/F: The Ascending Spinothalamic Tract decussate at the caudal medulla

Contralateral

In the medulla, the Dorsal Column/Medial Lemniscus ascends contralateral or ipsilateral to the thalamus?

Spinocerebellar Tract

Tract that carries unconscious proprioception

Ventral/Anterior CT

Descending motor tract that do not decussate at the caudal medulla (pyramids)

Pneumotaxic Center

Reflex center in the pons that inhibits the length of ramping by the inspiratory center → shallow, faster breaths

Dorsolateral pontine reticular formation

At the midbrain-pontine junction, this structure contains nuclei that regulate REM sleep

Dorsal group (DI = VE)

In the medulla, the inspiratory center/area is found

Area Postrema

Also known as the chemoreceptor trigger zone, which is externally represented by the Obex

T

T/F: Area Postrema detects circulating hormones involved in vomiting, thirst, hunger, and blood pressure control, as well as the chemoreceptor trigger zone for vomiting

T

T/F: Sulcus limitans is stretched in the fourth ventricle and displaced laterally at the level of the Pons and the rostral Medulla

Visceral

Structures next to (nearest) sulcus limitans have what type of function

Caudal end Rhomboid fossa (Obex)

The rostral and caudal medulla are delineated by which structure

Stria medullaris of fourth ventricle

Posterior boundary of the medulla

Rhomboid fossa

Forms floor of 4th ventricle

Sulcus Limitans

This divides each half of the rhomboid fossa into medial eminence and lateral vestibular area

Obex

Caudal junction of walls of 4th ventricle in which vomiting center can be found

Inferior Olivary Complex

Internal structure that is only found at the level of the rostral medulla and presents with a worm-like structure

Descending (spinal trigeminal) nucleus

Conveys pain, thermal, and tactile sense from face, forehead, and mucous membranes of nose and mouth

Taste fibers from anterior tongue (CN VII) and posterior tongue (CN IX)

The rostral part of the NTS receives what kind of fibers (sensory information)

Inferior (CN IX) salivatory nucleus

Nucleus in the medulla that innervates the Otic ganglion to stimulate parotid gland

Dorsal vagal nucleus (CN X)

Occupies medial portion of vagal trigone in floor of 4th ventricle and gives rise to preganglionic parasympathetic fibers

Bilateral

T/F: Anything that affect decussation of pyramids causes ipsilateral weakness

Medial longitudinal fasciculus (MLF)

Sensory fibers that runs in the causal medulla responsible for conjugate sacchadic eye movement

Internal arcuate fibersInternal arcuate fibers

Fibers that would be coming from the nuclei gracile and cuneate that would cross towards the opposite medial lemniscus (crossing sensory fibers)

Olives

This is internally represented as inferior olivary nuclei (ION)

F; no longer seen

T/F: Gracile and cuneate fasciculus are still seen in rostral or open medulla

Nucleus ambiguus

The SVE function of CN IX originates from which nucleus

Stylopharyngeus

The SVE function of CN IX innervates which structure/muscle

T

T/F: Slight dysphagia (swallowing difficulty) is an effect of damage/denervation if the branchial motor or branchiogenic branch of CN IX

Inferior salivatory nucleus; Salivary secretion of the parotid gland

Origin of GVE function of CN IX and Function

Superior ganglion of Glossopharyngeal nerve

Origin of GSA function of CN IX

Posterior ⅓ of the tongue, soft palate, skin of the external ear and auditory canal (for somatosensation)

Distribution of GSA function of CN IX

Loss of gag reflex from ipsilateral stimulus

Effect of Damage/Denervation of GSA function of CN IX

O: Inferior (petrosal) ganglion; Superior part of the NTS

F: Taste for the posterior ⅓ of the tongue

Origin and Function of SVA function of CN IX

O: Inferior part of the NTS

F: Reflexes from the carotid body and sinus, mucosa of pharynx

Origin and Function of GVA function of CN IX

Stylopharyngeus

The SVE (Motor) of CN X innervates all laryngeal muscles except for

DORSAL MOTOR NUCLEUS OF THE VAGUS to thorax and abdomen

Origin of GVE (Motor) of CN X

SPINAL TRIGEMINAL NUCLEUS

Origin of GSA (Sensory) of CN X

Taste, POSTERIOR PHARYNGEAL WALL

Function of GSA (Sensory) of CN X

O: NTS

D: lower pharynx, pressure receptors, chemoreceptors

Origin and Distribution of GVA (Sensory) of CN X

CN X

Uvular Paralysis is caused by the injury of what nerve

Non-paralyzed side

Rationale: If there is weakness on one side, the stronger side will pull it toward its own side, resulting in uvular deviation away from the weak side and toward the strong side

Uvular Paralysis goes towards what side of lesion

Foramen Magnum; Jugular Foramen

Posterior roots ascend and enter which structure and exit which structure

SVE to all laryngeal muscle (except Cricothyroid)

Cranial Division of CN XI gives off what function

GSA to Trapezius and SCM

Spinal Division of CN XI gives off what function

Left side

If there is a left spinal accessory nerve injury, winging of the scapula would occur on which side?

Contralateral weakness

The effect of injury in sternocleidomastoid muscle affects which side

PALATOGLOSSUS

The GSE of CN XII supplies all intrinsic and extrinsic muscles of the tongue except for

Towards (Ipsilateral)

Tongue deviates toward which side of weakness or pathology

mainly Vertebral Artery

What is the blood supply of the rostral medulla

PICA

What is the blood supply of the posterolateral part of medulla

L: Medial Medulla

A: ASA and Vertebral A.

Location and Artery Involved in Dejerine Syndrome

L: Lateral Medulla

A: PICA

Location and Artery Involved in Wallenberg Syndrome

Hypoglossal nucleus - Ipsilateral tongue paralysis

Rationale:

CST and Dorsal Column = Contralateral effect

Clinical manifestations of Dejerine Syndrome involves contralateral manifestations except for which structure that involves ipsilateral effect

Deficits in pain and temperature of body from LST (Contralateral)

All findings of the Wallenberg syndrome are ipsilateral EXCEPT

T: Presents with vomiting, vertigo, and nystagmus

T/F: Wallenberg Syndrome also involves the Vestibular nuclei

• Ipsilateral cerebellar signs (ataxia)

• Ipsilateral deficits in pain and temperature sensation from face (Spinal Trigeminal Nucleus & Tract)

• Ipsilateral laryngeal, pharyngeal, and palatal hemiparalysis (Nucleus Ambiguus)

• Ipsilateral Horner’s syndrome (all eye problems)

What are the ipsilateral manifestations of Wallenberg (PICA) Syndrome