lab 9 questions

In the spinal cord, what type of transmission (sensory/motor) travels through the:

a. Ventral horn?

1. b. Dorsal horn?

2. c. Ascending spinal tracts?

3. d. Descending spinal tracts?

• a. Ventral horn? Motor transmission.

• b. Dorsal horn? Sensory transmission.

• c. Ascending spinal tracts? Sensory transmission to the brain.

• d. Descending spinal tracts? Motor transmission from the brain.

What causes the cervical enlargement of the spinal cord?

An increased amount of gray matter required to supply the nerves of the upper limbs.

Where is the filum terminale located?

It extends from the inferior end of the conus medullaris (at the level of the second lumbar vertebra) to the coccyx.

What is the conus medullaris?

the tapered, conical terminal portion of the spinal cord.

What is the cauda equina?

The collection of spinal nerves extending from the inferior end of the spinal cord (resembling a horse's tail).

In the spinal cord, which is deep to the other: the white matter or the gray matter?

The gray matter is deep to the white matter.

What is the area of gray matter found between the lateral halves of the spinal cord?

The gray commissure.

The subarachnoid space is filled with what fluid?

Cerebrospinal fluid (CSF).

1. Which major nerves arise from the following plexuses?

   • a. Cervical:

   • b. Brachial:

   • c. Lumbar:

d. Sacral:

• a. Cervical: Phrenic nerve.

• b. Brachial: Nerves supplying the upper limb, such as the musculocutaneous, median, ulnar, and radial nerves.

• c. Lumbar: Femoral nerve.

d. Sacral: Sciatic nerve.

In terms of function, how does the dorsal spinal root vary from the ventral spinal root?

The dorsal root contains sensory (afferent) fibers, whereas the ventral root contains motor (efferent) fibers.

What is the endoneurium?

A delicate layer of connective tissue that surrounds individual nerve fibers (axons) within a nerve.

How do tracts differ from nerves?

Tracts are bundles of parallel nerve fibers in the CNS, while nerves are bundles of parallel nerve fibers in the PNS.

What is a mixed nerve?

A nerve that contains both sensory (afferent) and motor (efferent) fibers.

The diaphragm's contractions are regulated by which nerve?

The phrenic nerve.

The muscles of the arm, such as the biceps brachii, have which innervation?

The musculocutaneous nerve.

The extensor muscles of the hand are controlled by which nerve?

The radial nerve.

The sciatic nerve is composed of two nerves. Name them.

The tibial nerve and the common fibular (peroneal) nerve.

A person has feeling from the deltoid and biceps brachii region but no feeling from the wrist extensors. Where on the spinal cord has injury occurred?

The injury is likely around the C5-C6 cervical spinal cord segments.

Which one of the meninges is just superficial to the surface of the brain?

The pia mater.

What fluid is found in the ventricles of the brain?

Cerebrospinal fluid (CSF).

Into what space does fluid flow from the cerebral aqueduct?

The fourth ventricle.

What is the difference between a gyrus and a sulcus?

A gyrus is an elevated ridge on the surface of the cerebral hemispheres, while a sulcus is a shallow groove separating adjacent gyri.

Name all the lobes of the cerebrum

Frontal lobe, parietal lobe, temporal lobe, occipital lobe, and insula.

What is the function of the precentral gyrus?

It serves as the primary motor cortex, controlling voluntary skeletal muscle movements.

What sense does the temporal lobe alone interpret?

Hearing (auditory sense) and smell (olfactory sense).

What physical depression separates the temporal lobe from the parietal lobe?

The lateral sulcus (or lateral fissure).

What structure connects the cerebral hemispheres?

The corpus callosum.

Name the major regions of the midbrain.

Cerebral peduncles, corpora quadrigemina (superior and inferior colliculi), and the cerebral aqueduct.

What is the function of the cerebellum?

It processes input from other brain areas to coordinate skeletal muscle activity, balance, and posture.

John "pulled a-hemisear" by hitting his temporal against a wall. What damage might he have done to the function of his brain, particularly the functions associated with the frontal lobe?

Impacts near the frontal area can affect executive functioning, decision-making, reasoning, and voluntary motor output.

What functional damage to the frontal lobe may result from John hitting his forehead against a wall while "pulling a no-brainer"?

impairment to John's intelligence and creativity

If a stroke had affected all the sensations interpreted by the brain concerning only the face and the hands, how much of the postcentral gyrus would be affected?

approximately one-half of the postcentral gyrus (representing the sensory homunculus for the face and hands) would be affected.

Describe what effect the loss of an entire cerebral hemisphere would have on specific functions, such as spatial awareness or the ability to speak.

It would cause contralateral sensory and motor deficits, loss of language capabilities (if the dominant hemisphere is lost), and significant deficits in spatial awareness/processing.

Aphasia is loss of speech... If the Broca area were affected by a stroke, would the ability to assemble coherent sentences be affected, or would the ability to pronounce the words be affected?

Broca's area handles speech production and motor speech coordination, so the ability to produce coherent spoken words and fluent sentences would be impaired.

Describe the following nerves in terms of function (sensory, motor, or both)

1. 
   

• Optic nerve:

• Trochlear nerve:

• Glossopharyngeal nerve:

• Hypoglossal nerve:

• Vagus nerve:

1. 
   

• Optic nerve: Sensory (vision)

• Trochlear nerve: Motor (superior oblique eye muscle)

• Glossopharyngeal nerve: Both (sensory for taste/pharynx, motor for pharyngeal muscles/salivation)

• Hypoglossal nerve: Motor (tongue muscles)

• Vagus nerve: Both (parasympathetic innervation to visceral organs, sensory from viscera/pharynx)

Name the cranial nerve that innervates the anterior tongue

Facial nerve (CN VII - taste) or Mandibular branch of Trigeminal (CN V3 - general sensation)

Name the cranial nerve that innervates the ear

1. 
   

• Vestibulocochlear nerve (CN VIII - hearing/balance) and facial/vagus/glossopharyngeal for outer ear sensory components

Name the cranial nerve that innervates the mandible

Mandibular division of the Trigeminal nerve (CN V3)

Name the cranial nerve that innervates the eye

Oculomotor (CN III), Trochlear (CN IV), and Abducens (CN VI) for muscles; Optic (CN II) for vision

Name the cranial nerve that innervates the stomach

Vagus nerve (CN X)

Name the cranial nerve that innervates the Lateral rectus muscle of the eye:

Abducens nerve (CN VI)