Match each spinal nerve with the main structures it supplies. Radial nerve A. Anterior and lateral leg muscles and skin Inferior gluteal nerve B. Medial thigh muscles, skin of the superomedial thigh C. Abdominal muscles, skin of the abdomen Obturator nerve D. Muscles of the forearm that flex the hand, most intrinsic hand muscles, Phrenic nerve skin on medial hand Common fibular nerve E. Muscles on the posterior arm that extend the forearm, muscles of the Intercostal nerves forearm that extend the hand, skin on lateral hand F Diaphragm muscle Femoral nerve G. Gluteus maximus muscle Ulnar nerve H. Anterior thigh muscles, skin on anterior and medial thigh and leg 7 Number the events of a reflex arc from 1 (first event) through 5 (last event). CNS sends output via motor neurons to an effector. Sensory neurons bring the stimulus to the CNS. The muscle contracts. CNS processes and integrates the information. Sensory receptor detects the stimulus.
The Correct Answer and Explanation is :
Matching Spinal Nerves with Main Structures:
- Radial nerve: E. Muscles on the posterior arm that extend the forearm, muscles of the forearm that extend the hand, skin on lateral hand.
- Inferior gluteal nerve: G. Gluteus maximus muscle.
- Obturator nerve: B. Medial thigh muscles, skin of the superomedial thigh.
- Phrenic nerve: F. Diaphragm muscle.
- Common fibular nerve: A. Anterior and lateral leg muscles and skin.
- Intercostal nerves: C. Abdominal muscles, skin of the abdomen.
- Femoral nerve: H. Anterior thigh muscles, skin on anterior and medial thigh and leg.
- Ulnar nerve: D. Muscles of the forearm that flex the hand, most intrinsic hand muscles, skin on medial hand.
Reflex Arc Sequence:
- Sensory receptor detects the stimulus.
- Sensory neurons bring the stimulus to the CNS.
- CNS processes and integrates the information.
- CNS sends output via motor neurons to an effector.
- The muscle contracts.
Explanation (300 Words):
The spinal nerves play a vital role in motor and sensory functions, with each nerve supplying specific regions of the body. For example, the radial nerve innervates extensor muscles and supplies sensation to the lateral hand, essential for hand and wrist extension. The femoral nerve controls the quadriceps for knee extension and provides sensory input to the anterior thigh. The phrenic nerve, critical for respiration, innervates the diaphragm, while the obturator nerve focuses on the medial thigh muscles aiding leg adduction.
The reflex arc illustrates how the nervous system reacts to stimuli quickly. It begins when a sensory receptor detects a change, such as pain from a hot surface. This information travels via sensory neurons to the CNS, where it is processed and integrated. The CNS then sends signals through motor neurons to an effector, such as a muscle, which executes the response (e.g., pulling the hand away from the heat).
Reflex arcs ensure rapid, involuntary actions to protect the body. They bypass conscious brain processing, allowing the CNS to respond almost instantaneously. Understanding these pathways helps diagnose nerve damage or neurological conditions, as impaired reflexes or sensations can pinpoint specific nerves or spinal segments involved.