CN I + CN XI + Cervical plexus

Gyri = ?

Folds

Postcentral gyrus

Sensory area

Precentral gyrus

Motor area

Sulci = ?

Grooves

What does the central sulcus divide?

Frontal and parietal lobes

What does the lateral sulcus divide?

Parietal and temporal lobes

What does the parieto-occipital sulcus divide?

Pariatal and occipital lobes

Fissues = ?

Clefts

What are the structures within the diencephalon?

Epithalamus, thalamus, hypothalamus

What is controlled by the epithalamus?

Emotion, sleep wake cycles, mood

What is the role of the thalamus?

Relay point for sensory and motor info (somatic signals)

What is the function of the hypothalamus?

Coordination center for homeostasis (autonomic signals)

Function of CSF

Buffer to protect the brain while the head moves

What cells secrete CSF and where are they located?

Epithelial cells; Choroid plexus in ventricles of the brain

Describe the circulation of CSF

Through ventricles and into subarachnoid space around spinal cord

What is the total volume of CSF?

90-150 mL

How much CSF is produced per day?

400-500 mL

Where does excess and used CSF go to?

Absorbed into venous system

Describe hydrocephalus?

Increased CSF volume leading to increased intercranial pressure

Why will infant’s heads become larger when they have hydrocephalus?

Because their sutures haven’t fused

What are arachnoid granulations?

Protrusions of arachnoid mater and subarachnoid space into superior sagittal sinus or plexus around it, including lateral lakes.

What is the function of arachnoid granulations?

Transport CSF into venous sinus system (regulate CSF volume)

Compare the distribution of arachnoid granulations in newborns and adults.

Newborns have microscopic AG (because their brains are smaller and they have other means to remove CSF). Adults have AG concentrated around the sagittal sinus

Skull fractures in what area can cause CSF to leak?

Frontal nasal area

Clinical presentation of CSF leak

CSF rhinorrhea (clear and watery)

Where do skeletal muscle signals begin?

Primary motor cortex (precentral gyrus)

Where are somatosensory signals processed?

Primary somatosensory cortex (postcentral gyrus)

What do somatomotor and somatosensory signals relay through?

Thalamus

Define a homonculus

A map of corresponding regions in each gyrus distorted by concentration

Function of upper motor neurons (UMN)

Integrates all excitatory and inhibitory signals from cortex → translates to a movement signal

What are the 3 tracts of somatomotor signal?

Anterior corticospinal, Lateral corticospinal, Corticonuclear fibers

Anterior contricospinal tract

Voluntary movement of trunk muscles

Lateral corticospinal tract

Voluntary movement of limb muscles

Corticonuclear fibers

Motor signals to cranial nerves

Function of lower motor neurons (LMN)

Transmit signals to muscle

What are the 3 types of LMN

Somatic motor neurons, Special visceral efferent brachial motor neurons, General visceral motor neurons

Path of somatomotor signal from axon of UMN to muscle

Axons of UMN relay through thalamus → Spinal cord → Synapse directly onto LMN → Signal transmitted to muscle

Path of somatosensory signal from primary sensory neurons to postcentral gyrus

Primary sensory neurons in peripheral ganglia → Thalamus → Postcentral gyrus

Describe the somatosensory pathway when you touch something with your hands.

Sensory endings in skin, Splanchnic n., Sympathetic trunk, White communicating ramus, Ventral ramus, Spinal n., DRG, Dorsal horn, Peripheral ganglia, Thalamus, Postcentral gyrus

How are autonomic signals transmitted through the spinal cord?

Hypothalamospinal tract

CN I

Olfactory nerve

Fiber components of CN I

Special sensory (smell)

Where are olfactory receptors located?

Olfactory epithelium (lateral wall and midline of nose)

Pathway of CN I

Unmyelinated processes of olfactory cells pass through cribiform plate, Olfactory bulb, Brain

Lateral olfactory stria

Primary olfactory cortex

Medial olfactory stria

Autonomic response to olfaction (ex/ salivation)

Anosmia

Inability to detect smell

Hyposmnia

Reduced ability to smell

Smell distortion

Change in smell

How to test for CN I

Strong stimulus presented to one nostril at a time and patient asked to sniff

CN XI

Accessory nerve

Fiber components of CN XI

Somatomotor

Pathway of CN XI

Ventral horn of C1-5, Spinal root, Through foramen magnum, Jugular foramen (with CN X), Muscle

What structures does CN XI innervate?

Trapezius and SCM

How to test for CN XI

SCM: place hand on side of face and ask patient to rotate against hand; Trapezius: Place hand on shoulders and ask patient to shrug

What layer is the SCM in?

Investing layer

What layer is trapezius in?

Investing layer

Origin (SCM)

Mastoid process and lateral superior nuchal line

Attachment (SCM)

Manubrium of sternum and medial 1/3 of clavicle

Function - unilateral (SCM)

Medial latearl head rotation

Function - bilateral posterior fibers (SCM)

Head extension

Function - bilateral anterior fibers SCM

Head flexion

Origin (Trapezius)

Median nuchal line and spinous process

Attachment (Trapezius)

Scapula and clavicle (ends)

Function - upper fibers bilateral (Trapezius)

Head extension

Function - upper fibers unilateral (Trapezius)

Lateral head flexion

Function - upper fibers (Trapezius)

Elevate and rotate scapula

Function - middle fibers (Trapezius)

Retract and rotate scapula

Function - lower fibers (Trapezius)

Depress and rotate scapula

Cervical plexus origin

Arises with contributions from C1-5 ventral rami (C5-T1 also contribute to brachial plexus)

Fiber components of cervical plexus

Somatosensory and somatomor

List the 6 autonomic plexuses

Celiac, Myenteric, Submucosal, Pharyngeal plexus of CN X, Pharynx, Cardiac

What are the somatosensory branches of the cervical plexus?

Lesser occipital, greater auricular, transverse cervical, supraclavicular, phrenic

What are the somatomotor branches of the cervical plexus?

Ansa cervicalis, nerve to thyroid, phrenic

Which branch of the cervical plexus goes to the meninges?

C1 (sensory)

Which branch of the cervical plexus goes to the lesser occipital n.?

C2 (sensory)

Which branch of the cervical plexus goes to the greater auricular n.?

C2-3 (sensory)

Which branch of the cervical plexus goes to the transverse cervical n.?

C2-3 (sensory)

Which branch of the cervical plexus goes to the supraclavicular n.?

C3-4 (sensory)

Which branch of the cervical plexus goes to the phrenic n.?

C3-5 (mixed)

Which branch of the cervical plexus goes to the inferior root of ansa cervicalis?

C2-3 motor

Which branch of the cervical plexus goes to the superior root of ansa cervicalis?

C1 (motor)

What does ansa cervicalis innervate?

Somatomotor to infrahyoid muscles (except thyrohyoid)

What nerve does C1 hitchhike on to reach thyrohyoid?

Hypoglossal (CN XII)

What does the lesser occipital n. innervate?

SS to back of head

What does transverse cervical n. innervate?

SS to anterior neck

What does supraclavicular n. innervate?

SS to superior clavicle

What does greater auricular n. innervate?

SS around ear and angle of mandible

Describe puncta nervosa

Location for anesthetic located at the midpoint of the posterior side of SCM

What does the phrenic nerve innervate?

SS and SM to diaphragm

What anatomic structure does the phrenic nerve run superficial to?

Anterior scalene

What is referred/viscerosensory pain?

Pain perceived in a location distant from the actual site of injury of pathology