Pns: Exam 4 Prep

The facial nerve controls the muscles of facial expression, including those responsible for closing the eye and raising the corner of the mouth. Therefore, if a patient is unable to close their eye and their mouth droops on one side of the face, it suggests that the facial nerve has been damaged.

Trauma to the vestibulocochlear nerve can lead to problems in balance. The vestibulocochlear nerve is responsible for transmitting sensory information from the inner ear to the brain, including information about balance and hearing. Damage to this nerve can disrupt the brain's ability to interpret these signals, resulting in balance problems.

The phrenic nerve does not arise from the brachial plexus. The brachial plexus is a network of nerves that innervate the upper limb, while the phrenic nerve is responsible for innervating the diaphragm, which is involved in breathing. Therefore, the phrenic nerve is not part of the brachial plexus and is the correct answer.

A baroreceptor is not an example of an exteroceptor because it is a type of interoceptor. Exteroceptors are sensory receptors that detect stimuli from the external environment, such as touch, temperature, and pressure. Baroreceptors, on the other hand, are located in blood vessels and organs and detect changes in blood pressure, which is an internal stimulus. Therefore, baroreceptors do not fit the definition of an exteroceptor.

The abducens nerve supplies innervation to the lateral rectus muscle of the eye. This means that it is responsible for controlling the movement of the eye towards the side (abduction). If the abducens nerve is damaged or paralyzed, it can result in the inability to move the eye laterally, leading to a condition called abducens nerve palsy.

Bell's palsy is a condition that is characterized by paralysis of the facial muscles. This means that the muscles on one side of the face are unable to move, resulting in drooping or weakness of the affected side of the face. Bell's palsy is often caused by inflammation of the facial nerve, which controls the muscles of the face. This condition can cause difficulties with facial expressions, speaking, and eating. Treatment for Bell's palsy may include medications, physical therapy, and sometimes surgery, depending on the severity of the paralysis.

The correct simple spinal reflex arc follows the sequence of events: receptor, afferent neuron, integration center, efferent neuron, and effector. This sequence allows for the detection of a stimulus by the receptor, the transmission of the signal through the afferent neuron to the integration center (such as the spinal cord), the processing of the signal at the integration center, the transmission of the response signal through the efferent neuron, and the execution of the response by the effector.

The spinal nerves exiting the cord from the level of L4 to S4 form the sacral plexus. The sacral plexus is a network of nerves that supplies the pelvic region and lower limbs. It is formed by the anterior rami of the spinal nerves L4 to S4, which come together and give rise to various branches that innervate the muscles and skin of the buttocks, posterior thigh, and lower leg. The sacral plexus is responsible for controlling movement and sensation in these areas.

A fracture of the ethmoid bone could result in damage to the olfactory nerve. The olfactory nerve is responsible for the sense of smell and passes through small openings in the ethmoid bone called the cribriform plates. If these plates are fractured, it can lead to damage or compression of the olfactory nerve, causing a loss or impairment of the sense of smell.

Nociceptors are specialized sensory receptors that detect potentially damaging stimuli that result in pain. These receptors are responsible for transmitting signals to the brain, alerting it to potential harm or injury. Unlike other types of sensory receptors like interoceptors, proprioceptors, and photoreceptors, nociceptors specifically respond to painful stimuli, allowing the body to respond and protect itself from potential harm.

After axonal injury, regeneration in peripheral nerves is guided by Schwann cells. Schwann cells are a type of glial cell that are found in the peripheral nervous system. They play a crucial role in the regeneration process by forming a pathway for the regrowing axons, secreting growth factors, and providing structural support. Schwann cells also produce myelin, which insulates the axons and helps facilitate faster nerve conduction. Therefore, they are essential in guiding and supporting the regeneration of axons after injury.

Afferent nerves are the nerves that carry impulses towards the central nervous system (CNS). These nerves transmit sensory information from the body's periphery to the brain and spinal cord, allowing us to perceive and interpret sensations such as touch, pain, and temperature. Unlike efferent nerves, which carry impulses away from the CNS to initiate motor responses, afferent nerves are responsible for sensory input. Therefore, afferent nerves are the correct answer for this question.

A fall or an improperly delivered gluteal injection could result in sciatica. Sciatica is a condition characterized by pain, numbness, or tingling that radiates along the sciatic nerve, which runs from the lower back down the back of each leg. Injuries or trauma to the buttocks, such as a fall or an injection that damages the sciatic nerve, can lead to inflammation and compression of the nerve, causing the symptoms of sciatica.

The olfactory nerve is the first cranial nerve and is responsible for the sense of smell. Unlike the other options listed, it is purely a sensory nerve and does not contain any motor fibers. The facial nerve, oculomotor nerve, and trigeminal nerve all contain both motor and sensory fibers, allowing them to control both movement and sensation in various areas of the face and head.

The question asks about the cranial nerves that have neural connections with the tongue. The cranial nerves that innervate the tongue are the glossopharyngeal (IX), facial (VII), and trigeminal (V) nerves. The trochlear nerve (IV) does not have neural connections with the tongue.

The cervical nerve is not a branch of the trigeminal nerve because the trigeminal nerve is responsible for sensory information from the face, while the cervical nerves originate from the spinal cord and innervate the neck and upper back. Therefore, the cervical nerve is not directly related to the trigeminal nerve and is not a branch of it.

Striking the "funny bone" refers to hitting the ulnar nerve, which is located near the elbow. This nerve is responsible for providing sensation to the pinky finger and half of the ring finger. When the ulnar nerve is struck or compressed, it can cause a tingling or electric shock-like sensation in the forearm and hand. Therefore, the correct answer is ulnar nerve.

In a crossed-extensor reflex, when the right arm is grabbed, it triggers a reflex action where the right arm flexes to protect itself. Simultaneously, the left arm extends to provide support and balance. This reflex is important for maintaining stability and preventing falls when one side of the body is suddenly disturbed. Therefore, the correct answer is that the left arm would extend.

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Inborn or intrinsic reflexes are involuntary, yet may be modified by learned behavior. This means that these reflexes occur automatically and without conscious control, but they can also be influenced and altered by previous experiences and learned responses. This suggests that while these reflexes are innate and instinctive, they can be shaped and modified through conditioning and practice.

Pattern recognition refers to the ability to identify and interpret patterns or familiar objects in our environment. It allows us to recognize and differentiate between different objects, such as faces. This process involves the brain's ability to match incoming sensory information with stored information and memories, enabling us to identify familiar faces or objects. Spatial discrimination, magnitude estimation, and perceptual detection are different processes that are not directly related to recognizing familiar faces.

If the ventral root of a spinal nerve were cut, it would result in a complete loss of voluntary movement. The ventral root is responsible for carrying motor signals from the spinal cord to the muscles, allowing us to consciously control our movements. When this root is cut, the motor signals are unable to reach the muscles, leading to a complete loss of voluntary movement in the tissue or region that the nerve supplies.

All processing at the circuit level going up to the perceptual level must synapse in the thalamus. The thalamus is a crucial structure in the brain that acts as a relay station, receiving sensory information from various parts of the body and sending it to the appropriate areas of the cerebral cortex for further processing and interpretation. It plays a vital role in sensory perception, attention, and consciousness. Without the thalamus, the integration and transmission of sensory information would be disrupted, leading to impaired perception and cognitive functioning.

Ganglia associated with afferent nerve fibers contain cell bodies of sensory neurons. This statement is the most correct because ganglia are clusters of neuron cell bodies that are typically associated with peripheral nerves. Afferent ganglia specifically contain cell bodies of sensory neurons, which transmit sensory information from the periphery to the central nervous system. This is in contrast to efferent fibers, which carry motor signals from the central nervous system to the periphery. Therefore, the statement accurately describes the function and location of ganglia associated with afferent nerve fibers.

Nociceptors are the receptors that detect pain and are responsible for transmitting signals related to tissue damage. These receptors adapt most slowly because they need to continuously signal the presence of pain in order to protect the body from harm. Unlike other receptors like touch, smell, and pressure receptors, which adapt quickly to constant stimuli, nociceptors need to maintain their sensitivity to ensure that potential threats to the body are detected promptly. Therefore, nociceptors adapt more slowly compared to other receptors.

The flexor muscles in the anterior arm, including the biceps brachii and brachialis, are innervated by the musculocutaneous nerve. This nerve originates from the brachial plexus and supplies motor fibers to these muscles, allowing for flexion of the forearm at the elbow joint. The musculocutaneous nerve also provides sensory innervation to the skin on the lateral forearm.

The cranial nerve with a dual origin (brain and spinal cord) is the accessory nerve. This nerve originates from both the brainstem and the upper spinal cord, specifically from the medulla oblongata and the spinal cord segments C1-C5. It is responsible for controlling the movement of certain neck muscles, allowing for head and shoulder movements.

Pressure, pain, and temperature receptors in the skin are exteroceptors. Exteroceptors are sensory receptors that are sensitive to stimuli originating outside the body, such as pressure, pain, and temperature on the skin. These receptors provide information about the external environment and help us perceive and respond to various sensory stimuli.

The trochlear nerve conveys proprioceptor impulses from the superior rectus muscle to the brain. Proprioceptors are sensory receptors that provide information about the position and movement of our body parts. The superior rectus muscle is responsible for elevating the eye and rotating it inward. Therefore, the trochlear nerve carries the sensory information related to the position and movement of the superior rectus muscle to the brain.

The correct order of subdivisions of the brachial plexus is roots, trunks, divisions, and cords. This order represents the sequential branching and organization of the nerves that make up the brachial plexus. The roots are the initial branches that arise from the spinal cord, followed by the trunks which form from the convergence of the roots. The divisions are then formed by the splitting of the trunks, and finally, the cords are created by the merging of the divisions. This order is important in understanding the pathway and innervation of the nerves in the brachial plexus.

The cervical plexus is a network of nerves located in the neck region. Irritation of a major nerve in this plexus can lead to hiccups. Hiccups are involuntary contractions of the diaphragm muscle, and the diaphragm is innervated by the phrenic nerve, which arises from the cervical plexus. Therefore, if there is irritation or disruption of the phrenic nerve, it can cause hiccups.

The correct answer is femoral. The femoral nerve is a major nerve of the lumbar plexus. It originates from the second, third, and fourth lumbar nerves and provides motor and sensory innervation to the muscles of the thigh and leg. It is responsible for controlling movements such as hip flexion and knee extension, as well as providing sensation to the front of the thigh and lower leg.

The sciatic nerve is a combination of the common fibular and tibial nerves. These two nerves merge together in the pelvis to form the sciatic nerve, which is the largest nerve in the body. The common fibular nerve supplies sensation to the front and side of the leg and controls certain muscles in the leg and foot. The tibial nerve supplies sensation to the back of the leg and sole of the foot, as well as controls certain muscles in the leg and foot. Together, these two nerves make up the sciatic nerve, which provides both sensory and motor functions to the lower extremity.

The somatosensory system is responsible for processing sensory information from the body. It involves multiple levels of neural integration, including perceptual, receptor, and circuit levels. However, the segmental level is not a main level of neural integration in the somatosensory system. This level refers to the specific segments of the spinal cord where sensory information is received and processed. While important for relaying sensory information, it is not considered a main level of integration like the perceptual, receptor, and circuit levels.

Quality estimation is not an aspect of sensory perception. Sensory perception refers to the process of receiving and interpreting information from the senses, such as sight, hearing, taste, smell, and touch. Spatial discrimination involves the ability to perceive and differentiate between different locations or spatial relationships. Feature attraction refers to the ability to focus on specific features or characteristics of a stimulus. Magnitude estimation involves perceiving and judging the intensity or magnitude of a stimulus. Pattern recognition involves the ability to recognize and identify patterns or familiar stimuli. Quality estimation, on the other hand, does not directly relate to the perception of sensory information.

The patellar "knee jerk" reflex is an example of a stretch reflex. This reflex occurs when the patellar tendon is tapped, causing a stretch in the quadriceps muscle group. Sensory neurons detect this stretch and send signals to the spinal cord, where motor neurons are activated to contract the quadriceps muscle and extend the leg. This reflex helps to maintain balance and stability by quickly adjusting muscle tension in response to sudden stretches.

Transduction is the process of converting stimulus information into nerve impulses. This means that when a stimulus is detected by sensory receptors, it is transformed into electrical signals that can be transmitted by nerve cells. These nerve impulses can then be relayed to the brain for further processing and interpretation.

The correct answer is that the stimulus energy must be converted into the energy of a graded potential called a transduction potential. This is an incorrect statement because a transduction potential refers to the conversion of stimulus energy into a receptor potential, not a graded potential. A graded potential is a change in membrane potential that can vary in amplitude, whereas a receptor potential is a type of graded potential specifically generated by sensory receptors in response to a stimulus.

The posterior side of the thigh, leg, and foot is served by the tibial nerve.

Feeling a gentle caress on your arm involves the activation of tactile receptors in the skin. Pacinian corpuscles are specialized receptors that detect deep pressure and vibrations, rather than gentle caresses. Therefore, they would not be involved in this particular sensation. Meissner's corpuscles, tactile discs, and hair follicle receptors are all types of tactile receptors that can detect light touch and would likely be involved in feeling a gentle caress on the arm.

The Golgi tendon reflex is a reflex that causes muscle relaxation and lengthening in response to muscle tension. When the Golgi tendon organ, located in the tendons of muscles, detects excessive tension, it sends inhibitory signals to the muscle, causing it to relax and lengthen. This reflex helps protect the muscle from injury by preventing excessive tension and allowing for controlled movement.