How does a rat lunge? - briefly
A rat lunges by quickly extending its forelimbs and thrusting its hind legs, generating a rapid burst of muscular contraction that propels the body forward. This action depends on coordinated spinal flexor activation and vestibular input to preserve balance during the movement.
How does a rat lunge? - in detail
Rats initiate a forward thrust by rapidly extending the hind limbs while the forelimbs remain in a flexed, weight‑bearing posture. The sequence begins with the activation of spinal interneurons that receive sensory input from whisker contacts or auditory cues. These interneurons release glutamate onto motor neurons innervating the gastrocnemius and soleus muscles, producing a powerful plantar flexion that pushes the pelvis forward.
Simultaneously, the lumbar and thoracic spinal segments coordinate a brief contraction of the abdominal wall, increasing intra‑abdominal pressure and stabilizing the trunk. The forelimbs then swing forward, driven by the biceps brachii and flexor carpi muscles, allowing the animal to close the gap between its nose and the target. The tail, controlled by the caudal musculature, arches to maintain balance and counteract the torque generated by the hind‑limb extension.
Key biomechanical components:
- Hind‑limb drive – explosive extension of the knee and ankle joints, generating the majority of forward momentum.
- Trunk stabilization – synchronized contraction of dorsal and ventral core muscles to prevent torsional wobble.
- Forelimb swing – rapid flexion and extension to complete the reach, coordinated by the brachial plexus.
- Tail adjustment – lateral flexion and elevation for balance correction during the airborne phase.
Neural control involves the mesencephalic reticular formation, which integrates multimodal sensory signals and modulates the timing of motor bursts. Dopaminergic pathways in the basal ganglia fine‑tune the vigor of the lunge, while the cerebellum refines the trajectory to avoid overshoot.
Environmental factors such as surface texture, incline, and obstacle proximity alter muscle recruitment patterns. On a slippery substrate, the rat increases plantar grip by engaging the intrinsic foot muscles more intensely, whereas an upward slope prompts greater hip extensor activation to overcome gravity.
The lunge concludes when the forepaws make contact with the target, at which point the animal transitions to a grasping posture, engaging the flexor digitorum profundus and opponens pollicis to secure the object. This rapid motor program, lasting approximately 120–150 ms, exemplifies the integration of sensory perception, central pattern generation, and precise musculoskeletal execution.