Neuronal Pathways, Spinal Cord, and Brainstem Lecture Review

Comprehensive practice questions covering neuronal pathways, spinal cord anatomy, reflexes, peripheral nerves, brainstem structures, and cerebellar functions.

What is the function of convergent pathways in the brain?

They synthesize data by receiving sensation from different limbs of the body and deciphering what to do next.

Provide examples of internal and external stimuli mentioned in the notes.

Internal stimuli include stomach growling and hunger; external stimuli include pain, pressure, and itch.

Compare the functions of the cervical and lumbar enlargements of the spinal cord.

The cervical enlargement supplies the upper limbs, while the lumbar enlargement supplies the lower limbs.

List the three layers of the spinal meninges and their characteristics.

1. Dura mater: thick, strong, tough connective tissue. 2. Arachnoid mater: contains the sub-arachnoid space with CSF. 3. Pia mater: includes the filum terminale and denticulate ligaments.

What structures anchor the spinal cord to the coccyx and dura mater?

The filum terminale anchors the spinal cord to the coccyx, while denticulate ligaments attach it to the dura mater.

Distinguish between ascending and descending nerve tracts in the spinal cord.

Ascending nerve tracts are all sensory, while descending nerve tracts are motor.

What types of cell bodies are found in the posterior, anterior, and lateral horns of the spinal cord?

The posterior (dorsal) horn contains cell bodies of secondary sensory neurons; the anterior (ventral) horn contains cell bodies of somatic motor neurons; the lateral horn contains cell bodies of autonomic motor neurons.

What is the definition of a reflex according to the notes?

An automatic response to a stimulus that occurs without conscious thought to maintain homeostasis.

Explain the roles of muscle spindles and the two types of motor neurons in a stretch reflex.

Muscle spindles are sensory receptors that respond to stretch. Gamma motor neurons control the sensitivity of the spindle, while alpha motor neurons innervate the muscle the spindle is embedded in.

What is the primary function of the Golgi Tendon Reflex?

It prevents contracting muscles from applying excessive tension to tendons, preventing damage.

What is the purpose of the crossed extensor reflex?

It causes extension of the opposite leg during a withdrawal reflex, allowing for a transfer of weight to that leg.

Define a Dermatomal Map.

A map showing how each spinal nerve receives sensory stimuli from the skin of a specific region of the body.

Identify the spinal nerve origins for the five main plexuses.

Cervical: $C1-C4$, Brachial: $C5-T1$, Lumbar: $L1-L4$, Sacral: $L4-S4$, Coccygeal: $S4-S5$.

Which nerve innervates the diaphragm and what are its spinal origins?

The Phrenic nerve, which originates from $C3, C4, \text{ and } C5$. A common mnemonic is "$C3, 4, \text{ and } 5$ keeps you alive."

What are the motor functions of the Axillary and Radial nerves?

The Axillary nerve abducts the arm; the Radial nerve extends the elbow, supinates, and extends the fingers.

What are the motor functions of the Musculocutaneous, Ulnar, and Median nerves?

Musculocutaneous: flexes elbow; Ulnar: flexes and adducts wrist and flexes fingers; Median: pronates forearm and hand, flexes and abducts wrist.

What are the motor functions of the Obturator and Femoral nerves?

The Obturator nerve adducts the thigh; the Femoral nerve flexes the hip and extends the knee.

Which nerve is responsible for plantar flexion of the foot and extension of the hip?

The Sciatic Tibial nerve.

Which nerves are responsible for dorsal flexion and eversion of the foot?

The Deep Peroneal nerve dorsal flexes the foot and extends the toes, while the Superficial Peroneal nerve plantar flexes and everts the foot.

What vital processes are regulated by the Medulla oblongata?

It regulates heart rate, blood vessel diameter (blood pressure), and respiration.

What is the significance of the pyramids and olives in the medulla?

Pyramids are descending motor tracts where fibers decussate (cross over); olives help regulate balance, coordination, and sound modulation.

Name the functions associated with the Pons.

It serves as a relay between the cerebrum and cerebellum (pontine), contains a sleep center, and a respiratory center that coordinates with the medulla.

Distinguish between the superior and inferior colliculi of the midbrain.

The superior colliculi allow for visual tracking and focusing on visual stimuli; the inferior colliculi are involved in hearing and reflexes to localize sound.

What is the clinical significance of the substantia nigra?

It contains dopamine neurons that are lost in Parkinson's disease; these are inhibitory neurons that decrease unwanted movement activity.

What is the primary role of the reticular formation?

It controls cyclic activities such as the sleep-wake cycle.

Describe the three functional regions of the cerebellum mentioned in the notes.

1. Flocculonodular lobe: balance and eye movement. 2. Vermis: posture, locomotion, and fine motor coordination. 3. Lateral hemispheres: planning, practicing, and learning complex movements.