The Brainstem, Cranial nerves and their nuclei

ANHB2217

what are the 3 major divisions of the brain and what are some of their roles

Midbrain- ex. vision, hearing, motor control, sleep and wakefulness, alertness, temperature regulation

Pons- ex. respiration, control of involuntary actions, sensory roles (hearing, equilibrium, taste), motor roles (eye movement, facial expressions, chewing, swallowing, secretion of saliva and tears)

Medulla oblongata- ex. control of ventilation, cardiovascular and vasomotor control, Reflex centers of vomiting, coughing, sneezing and swallowing

dorsal

ventral

lateral

Identify the 18 features of the mid sagittal brain

Cingulate gyrus

Corpus callosum

Fornix

Anterior commissure

Hypothalamus

Pituitary gland

Mamillary bodies

Midbrain

Pons

Medulla oblongata

Spinal cord

Interthalamic adhesion

Thalamus

Pineal gland

Superior colliculus

Inferior colliculus

Cerebellum

Name the 10 +2cranial nerves

Olfactory (1) and optic (2) nerve attach directly to the forebrain while rest attach to brainstem

Oculomotor (3)

Trochlear (4)

Trigeminal (5)

Abducens (6)

Facial (7)

Vestibulocochlear (8)

Glossopharyngeal (9)

Vagus (10)

Accessory (11)

Hypoglossal (12)

CN1: olfactory

Sensory, motor, parasympathetic

Function

Innervates where

Sensory

Smell

Innervates olfactory epithelium via olfactory bulb—>olfactory tract which sit within olfactory sulcus

CN2: optic

Sensory, motor, parasympathetic

Function

Innervates where

Sensory

Function: Vision

How: Innervates retina to transmit visual info from the retina to the brain

Optic nerve→ optic chiasma→ optic tract

CN3: Oculomotor

Sensory, motor, parasympathetic

Function

Innervates where

Examples of issues that could arise from damage to this CN

Motor

• Function: Movement of the eyeball

• How: Innervates extraocular muscles (superior, inferior and medial rectus, inferior oblique, levator palpebrae muscles)

Parasympathetic

• Function: Pupillary constriction

• How: pupillary constrictor and ciliary muscle of the eyeball via ciliary ganglion

Issue with this CN can cause dilated pupil and drooping eyelid, constricted pupil and upper lid elevation, dilation and drooping eyelid

CN4: Trochlear

Sensory, motor, parasympathetic

Function

Innervates where

Examples of issue that could arise from damage to this CN

Motor

Function: Movement of the eyeball down and medially

How: Only innervates the superior oblique muscle

Trochlear (4) Nerve Palsy: One iris that is higher than the other, double vision, head tilt

CN5: trigeminal

Sensory, motor, parasympathetic

Function

Innervates where

Sensory

• Function: General sensation

• How: Innervates face, scalp, cornea, nasal and oral cavities, cranial dural mater

Motor

• Function: 1. Opening and closing of the mouth, 2. Tension on tympanic membrane

• How: 1. Innervation of the muscles of mastication, 2. Innervation of tensor tympani muscle

Abducens

Sensory, motor, parasympathetic

Function

Innervates where

Examples of issue that could arise from damage to this CN

Motor

Function: Movement of the eyeball away from the midline

How: Innervates the lateral rectus muscle

Abducens (6) Nerve Palsy: One eye is pulled to look towards the midline, double vision, head rotate to look

CN7: Facial

Sensory, motor, parasympathetic

Function

Innervates where

Sensory

• Function: Taste

• How: Innervates anterior 2/3rd of tongue

Motor

• Function: 1. Facial movement, 2. Tension on middle ear bones

• How: 1. Innervates muscles of facial expression, 2. Innervates stapedius muscle

Parasympathetic

• Function: Salivation and lacrimation

• How: Innervates salivary and lacrimal glands

CN8: Vestibulocochlear

Sensory, motor, parasympathetic

Function

Innervates where

Sensory

Function: 1. Vestibular sensation, 2. Hearing

How: 1. Innervates vestibular apparatus, 2. Innervates cochlea

CN9: Glossopharyngeal

Sensory, motor, parasympathetic

Function

Innervates where

Sensory

• Function: 1. Generation sensation and taste, 2. General sensation of eustachian tube, 3. Chemo- and baroreception

• How: 1. Innervates pharynx, posterior 1/3rd of tongue, 2. Innervates eustachian tube, middle ear, 3. Innervates carotid body and carotid sinus

Motor

• Function: Swallowing

• How: Innervates stylopharyngeus muscle

Parasympathetic

• Function: Salivation

• How: Innervates parotid salivary gland

CN10: Vagus

Sensory, motor, parasympathetic

Function

Innervates where

Sensory

• Function: 1. Generation sensation and taste, 2. Chemo- and baroreception, 3. Visceral sensation

• How: 1. Innervates pharynx, larynx, oesophagus, external ear, 2. Innervates aortic bodies aortic arch, 3. Innervates thoracic and abdominal viscera

Motor

• Function: Speech and swallowing

• How: Innervates soft palate, pharynx, larynx, upper oesophagus

Parasympathetic

• Function: Control of cardiovascular, respiratory and gastrointestinal systems

• How: Innervates thoracic and abdominal viscera

CN11: Accessory

Sensory, motor, parasympathetic

Function

Innervates where

Motor

• Function: Movement of the head and shoulder

• How: Innervates the sternomastoid and trapezius muscles

CN12: Hypoglossal

Sensory, motor, parasympathetic

Function

Innervates where

Motor

• Function: Movement of the tongue

• How: Innervates the intrinsic and extrinsic muscles of the tongue

identify the cranial nerves

Identify the cranial nerves