csf HW

What are the three functions of CSF?

• Buoyancy:

• Protection

• Environmental stability

Where is CSF made?

CSF is produced by the choroid plexus in each brain ventricle.

What structures make up the choroid plexus?

Ependymal cells and capillaries within the pia mater.

How is CSF produced?

Blood plasma is filtered from capillaries and modified by ependymal cells.

How much CSF is produced per day?

Approximately 500 mL per day.

what are the 1st 3 places cerebrospinal fluid (CSF) travels to during circulation?

1. Lateral ventricles

2. Interventricular foramina

3. Third ventricle

what are the 2nd 3 places cerebrospinal fluid (CSF) travels to during circulation?

1. Cerebral aqueduct

2. Fourth ventricle

3. Subarachnoid space (around the brain and spinal cord)

what are the last 2 places cerebrospinal fluid (CSF) travels to during circulation?

1. Arachnoid villi absorb excess CSF

2. Dural venous sinuses return CSF to the blood

What is the full pattern of cerebrospinal fluid (CSF) circulation?

1. Lateral ventricles

2. Interventricular foramina

3. Third ventricle

4. Cerebral aqueduct

5. Fourth ventricle

6. Subarachnoid space (around the brain and spinal cord)

7. Arachnoid villi absorb excess CSF

8. Dural venous sinuses return CSF to the blood

what does CSF buoyancy do?

• Buoyancy: Supports more than 95% of the brain’s weight.

what does CSF protection do?

• Protection: Cushions the brain and spinal cord against sudden movements.

what does CSF environmental stability do?

1. Delivers nutrients and chemicals,

2. removes waste products,

3. protects nervous tissue from chemical fluctuations.

Olfactory nerve (CN I) motor innervation

None. It is purely somatic sensory, responsible for smell.

Optic nerve (CN II) motor innervation

None. It is purely somatic sensory, responsible for vision.

Oculomotor nerve (CN III) somatic motor innervation

Innervates four skeletal eye muscles:

• Superior rectus

• Inferior rectus

• Medial rectus

• Inferior oblique

Oculomotor nerve (CN III) parasympathetic/visceral motor innervation

Iris muscles and ciliary muscle.

Trochlear nerve (CN IV) somatic motor innervation

Superior oblique muscle.

Trigeminal nerve (CN V) somatic motor innervation

Muscles of mastication

• masseter,

• temporalis,

• medial pterygoid,

• and lateral pterygoid through the mandibular branch.

Abducens nerve (CN VI) somatic motor innervation

Lateral rectus muscle.

Facial nerve (CN VII) somatic motor innervation

Muscles of facial expression.

Facial nerve (CN VII) visceral motor innervation

Lacrimal gland, submandibular gland, and sublingual gland.

Vestibulocochlear nerve (CN VIII) motor innervation

None. It is purely somatic sensory for hearing and equilibrium.

Glossopharyngeal nerve (CN IX) somatic motor innervation

Stylopharyngeus muscle.

Glossopharyngeal nerve (CN IX) visceral motor innervation

Parotid salivary gland.

Vagus nerve (CN X) somatic motor innervation

Throat muscles and muscles involved in swallowing.

Vagus nerve (CN X) visceral motor innervation

Thoracic and abdominal organs.

Spinal accessory nerve (CN XI) somatic motor innervation

Trapezius and sternocleidomastoid muscles.

Hypoglossal nerve (CN XII) somatic motor innervation

Intrinsic and extrinsic tongue muscles.

Somatic motor vs. Visceral motor distinction

• Somatic motor innervates skeletal muscles.
• Visceral motor innervates smooth muscle, cardiac muscle, and glands.

Purely sensory cranial nerves

Cranial nerves I (olfactory), II (optic), and VIII (vestibulocochlear).