BRAIN STEM, CRANIAL NERVES, & SENSORY SYSTEMS Flashcards by Ella Heithoff

What are the subdivisions of the brain stem?

(Inferior to Superior):
Medulla oblongata
Pons
Midbrain

How well did you know this?

Not at all

Perfectly

What defines the border between the lowest part of the brain stem and the spinal cord?

Pyramidal decussation in the medulla oblongata (if you’re above it, you’re in the medulla. if you’re below it, you’re in the SC)

How well did you know this?

Not at all

Perfectly

Name 2 prominent surface landmarks of the medulla oblongata.

Ventral Surface:
Pyramids
Olivary eminence

Dorsal Surface:
Partially covered by cerebellum

How well did you know this?

Not at all

Perfectly

Which cranial nerves are associated with the medulla oblongata?

Glossopharyngeal (CN IX)
Vagus (CN X)
Hypoglossal (CN XII)

How well did you know this?

Not at all

Perfectly

What part of the ventricular system is associated with the medulla oblongata?

4th ventricle

How well did you know this?

Not at all

Perfectly

What part of the ventricular system is associated with the pons?

Floor of the 4th ventricle

How well did you know this?

Not at all

Perfectly

Which cranial nerves are associated with the pons?

Trigeminal (CN V)
Abducens (CN VI)
Facial (CN VII)
Vestibulocochlear (CN VIII)

How well did you know this?

Not at all

Perfectly

What surface landmarks are associated with the midbrain.

Dorsal:
Tectum (2 superior & 2 inferior colliculi)

Ventral:
Crus cerebri

How well did you know this?

Not at all

Perfectly

Which cranial nerves are associated with the midbrain?

Oculomotor (CN III)
Trochlear (CN IV)

How well did you know this?

Not at all

Perfectly

What part of the ventricular system is associated with the midbrain?

Cerebral aqueduct (the conduit between the 3rd and 4th ventricles)

How well did you know this?

Not at all

Perfectly

I Olfactory

Not connected to brainstem
Sensory
Extends from olfactory mucosa of nasal cavity to olfactory bulb
Neurons of bulb project directly to limbic cortex
Responsible for sense of smell

Modality (sensory, motor {somatic and/or visceral}, mixed)
Targets (sensory area and type of sensation, muscles or both)
Connection to brain stem:

How well did you know this?

Not at all

Perfectly

II Optic

Not connected to brainstem
Sensory
Carries signals from neural retina to thalamus
Half of info projects to ipsilateral thalamus and cortex
Half of info crosses to the contralateral thalamus and cortex (crossing occurs at the optic chiasm)

How well did you know this?

Not at all

Perfectly

III Oculomotor

Connects to midbrain
Motor

Somatic (aka voluntary), innervates skeletal muscle
5 extrinsic eye muscles:
Levator palpebrae superiors
Superior rectus
Inferior rectus
Medial rectus
Inferior oblique

Parasympathetic/Visceral Motor
2 intrinsic eye muscles:
Ciliary muscle (allows for accommodation for near vision, changing shape of lens during reading)
Sphincter pupillae (constriction of pupil)

How well did you know this?

Not at all

Perfectly

IV Trochlear

Connects to midbrain
Motor
Somatic (aka voluntary), innervates skeletal muscle
1 extrinsic eye muscle:
Superior oblique

How well did you know this?

Not at all

Perfectly

VI Abducens

Connects to pons
Motor
Somatic (aka voluntary), innervates skeletal muscle
1 extrinsic eye muscle:
Lateral rectus

How well did you know this?

Not at all

Perfectly

V Trigeminal

Connects to pons
Both (general sensory senses)
Has 3 branches:
Ophthalmic (sensory)
Maxillary (sensory)
Mandibular (sensory and motor)
Motor:
Muscles of mastication
Sensory:
Face and oral cavity
Presulcal (anterior 2/3) of the tongue, fine touch, proprioception, gross touch, pain, and temperature

VII Facial

Connects to pons
Both (special sensory senses)
Somatic (aka voluntary), innervates skeletal muscle
Motor:
Muscles of facial expression
Parasympathetic/Visceral Motor:
Submandibular and sublingual glands, nasal and oral mucosa, lacrimal glands
Sensory:
Presulcal (anterior 2/3) of the tongue, taste

VIII Vestibulocochlear

Connects to medulla
Sensory
Cochlear branch: carries auditory information from cochlea
Vestibular branch: carries information concerning balance from the vestibular apparatus and semicircular canals

IX Glossopharyngeal

Connects to medulla
Both
Sends nerve to the carotid body and carotid sinus, sensory for the carotid body
Somatic (aka voluntary), innervates skeletal muscle:
Motor:
Stylopharyngeus muscle (lifts throat during swallowing)
Sensory:
Postsulcal (posterior 1/3) of the tongue, general AND taste
Parasympathetic/Visceral Motor:
Parotid gland

X Vagus

Connects to medulla
Both
Somatic (aka voluntary), innervates skeletal muscle:
Motor:
Constrictor muscles of the pharynx
Intrinsic muscles of the larynx
Parasympathetic/Visceral Motor:
Thoracic and abdominal viscera, innervates the gut to the splenic flexure
Sensory:
Pharynx and Larynx

XI Accessory

Connects to medulla
Motor
Somatic (aka voluntary), innervates skeletal muscle
Motor:
Spinal portion arises in the cervical spinal cord and innervates the sternocleidomastoid and trapezius muscles

XII Hypoglossal

NOT associated with brainstem (associated with SC)
Motor
Somatic (aka voluntary), innervates skeletal muscle
Motor:
Intrinsic and extrinsic muscles of the tongue

Special senses CNs

I Olfactory
II Optic
VII Facial
VIII Vestibulocochlear
IX Glossopharyngeal

Extrinsic Eye Muscles CNs

III Oculomotor
IV Trochlear
VI Abducens

Face and Oral Cavity CNs

V Trigeminal VII Facial

Larynx, Pharynx, and Tongue CNs

IX Glossopharyngeal X Vagus XII Hypoglossal

Parasympathetic CNs

III Oculomotor VII Facial IX Glossopharyngeal X Vagus

Somatic Sensory Pathways (First-order neurons, Second-order neurons, and Third-order neurons)

First-order neurons (primary sensory neurons of the Dorsal Root Ganglia) carry signals from somatic receptors (in the skin) into the brain stem or spinal cord via cranial nerves or spinal nerves Second-order neurons carry signals from the spinal cord or brain stem to the thalamus; axons of second-order neurons decussate (i.e., cross the midline) to the opposite side before ascending to the thalamus Third-order neurons project from the thalamus to the primary somatosensory areas where conscious perception of sensations results

Visceral (Hollow Organs) Sensory Pathways

First-order neurons (primary sensory neurons of the Dorsal Root Ganglia) carry signals from visceral receptors (in hollow organs) into the brain stem or spinal cord via cranial nerves or spinal nerves Second-order neurons carry signals from the spinal cord or brain stem to the thalamus; axons of second-order neurons decussate (i.e., cross the midline) to the opposite side before ascending to the thalamus Third-order neurons project from the thalamus to the primary somatosensory areas where conscious perception of sensations results

Dorsal Column/Medial Lemniscus (DCML) System

Conveys information regarding fine touch and proprioception

Anterolateral System

(aka anterior and lateral spinothalamic tracts) Conveys information regarding gross touch, pain, temperature, and visceral sensation

Describe the chain of events from activation of a sensory receptor (fine touch and proprioception): DCML

Primary (first) sensory neuron: DRG Axons travel: Axons travel ipsilaterally in the dorsal columns of the SC a) Gracile fasciculus for lower body input b) Cuneate fasciculus for upper body input Second neuron: In the medulla Synapse/decussation: a) Gracile nucleus (lower body) b) Cuneate nucleus (upper body) * After decussation, ascends as medial lemniscus Third neuron: Ventral posterior nucleus of the thalamus Projection: Primary somatosensory cortex, located in the postcentral gyrus of the parietal lobe

Chain of Events from Activation of a Sensory Receptor (Gross Touch, Pain, Temperature, and Visceral Sensation) to Perception in the Brain (Anterolateral Pathway)

Primary (first) sensory neuron: DRG Second neuron: Dorsal horn of SC Synapse/decussation: Dorsal horn of SC Axons travel: Axons travel contralaterally to the anterior white matter of SC After decussation, ascends as anterolateral system (ALS) Third neuron: Ventral posterior nucleus of the thalamus Projection: Primary somatosensory cortex, located in the postcentral gyrus of the parietal lobe