Week 2 Anatomy Unit 3

CN I

Olefactory

• Cribriform plate

• Sensory: Smell

CN II

Optic

• Optic canal

• Sensory: Vision

CN III

Oculomotor

• Superior orbital fissure

• Motor: eye movement

CN IV

Trochlear

• Superior orbital fissure

• Motor: superior oblique eye movement (up and down)

CN V

Trigeminal

• V1: Opothalamic (sensory): Superior orbital fissure

• V2: Maxillary (sensory): foramen rotundum

• V3: Mandibular (both): foramen ovale

  • Meningeal branch: foramen spinosum

• Sensory: chewing and facial sensation; Motor: muscles of mastication

CN VI

Abducens

• Superior orbital fissure

• Motor: Eye movement (lateral rectus muscle, sideways movement)

CN VII

Facial

• Internal acoustic meatus

• Motor and sensory: facial expressions, anterior taste, tear production

CN VIII

Vestibulocochlear

• Internal acoustic meatus

• Sensory: Hearing and balance (semicircular canals)

CN IX

Glossopharyngeal

• Jugular foramen

• Motor and sensory: swallowing, posterior taste

CN X

Vagus

• Jugular foramen

• Motor (palate, pharynx, larynx, trachea, bronchial tree, heart, GI tract) and sensory (pharynx, larynx, trachiobronchial tree, lungs, heart, GI)

CN XI

Accessory

• Jugular foramen

• Motor: Strenocleidomastoid and trapezius

CN XII

Hypoglossal

• Hypoglossal canal

• Motor: intrinsic and extrinsic muscles of the tongue

Mnemonic for sensory/motor control

Some say money matters, but my brother says big brains matter most

CSF Circulation Steps

1. Forms in the choroid plexus

2. Flows into the intraventricular foramen of Monro to get to 3rd ventricle

3. Goes to the cerebral aqueduct of Sylvius to get to 4th ventricle

4. Goes through 2lateral apertures (foramen of Luschka) and 1median aperture (foramen of magendie) into the subarachnoid space

5. At the arachnoid granulations/villi, CSF is reabsorbed into the venous blood of the dural venous sinuses

Diploic veins

Deoxygenated blood travels through the diploe of bone and drains into the dural venous sinuses

• Bridges the extracranial venous system to the intracranial venous system

Dural venous sinuses

Valveless channels in the dura mater that collect deoxygenated blood and cerebrospinal fluid (CSF) from the brain and direct it mainly into the internal jugular veins

• Veins we’ve studied in class

1

Cribiform plate

2

Optic canal

3

Superior orbital fissure

4

Foramen rotundum (CNV2, maxillary)

5

Foramen ovale (CNV3, Mandibular)

7

Internal acoustic meatus

8

Jugular foramen

9

Hypoglossal canal

Where does the spinal cord begin and end

Begins at the foramen magnum as a continuation of the medulla, ends around L1/2 in adults

How many spinal nerves are there

8 cervical

• C1-C7 exit superiorly from the vertebra; then C8 and future nerves exit inferiorly

12 thoracic

5 lumbar

5 sacral

1 coccygeal

Dermatomes

Somatic sensory innervation of spinal nerve roots

• If an injury was before the brachial plexus, we would see dermatome nerve distribution

Myotomes

What muscles are innervated by each spinal nerve root

What is the end of the spinal cord called

Conus medullaris

What structure is below the spinal cord

Cauda equina

• L1/L2- rest of the lumbar and sacral spinal canal

What is the end of the cauda equina called and what does it do

Filum terminale

• Anchors the spinal cord to the coccyx

• No nerves, just continuation of the dura mater (dural sac terminates at S2)

Anterior and posterior nerve roots

Anterior/ventral: motor (efferent)
Posterior/dorsal: sensory (afferent)

What arises from the spinal cord to become a spinal nerve

1. Rootlets come off the grey matter (cell bodies)

2. Become roots

   1. Anterior roots: motor (efferent)

   2. Posterior roots: sensory (afferent)

3. Become spinal nerve

4. Branch into rami

Dorsal (posterior) rami

Nerve supply to the skin, deep muscles of back, veretebral column joints

• Do not form plexuses

Ventral (anterior) rami

• Wrap around to form plexi

• Innervate skin and muscles of the trunk and limbs