What levels of spinal nerves would need to be intact in order for Matt to still
ID: 225837 • Letter: W
Question
What levels of spinal nerves would need to be intact in order for Matt to still have a patellar (knee-jerk) reflex? Explain the mechanism of the patellar reflex. Include the muscles and nerves involved. What would an absence of a patellar reflex or diminished patellar reflex entail? What is the clinical term for the absence/decrease of this reflex? What would cause a hyperactive reflex? What levels of spinal nerves would need to be intact in order for Matt to still have an Achilles reflex (ankle-jerk) reflex? Explain the mechanism of the Achilles reflex. Include the muscles and nerves involved. What might an absence of this reflex be significant of? Do these tests assess the integrity and function of sensory pathways? Motor pathways? Or both?Explanation / Answer
what level of spinal nerve to be intact in order tomatt to still have patellar reflex?
Ans:-pattelar reflex is the strech reflex which test the lumber segment of spinal cord.spinal neve intact at the level of L3 in the spinal cord to matt to still have patellar reflex.
Mechanism of patellar reflex:-
a reflected action or movement; the sum total of any particular automatic response mediated by the nervous system. Areflex is built into the nervous system and does not need the intervention of conscious thought to take effect.
The kneejerk is an example of the simplest type of reflex. knee jerk is also known as patellar reflex.
When the knee is tapped, the nerve that receives this stimulussends an impulse to the spinal cord, where it is relayed to a motor nerve.
This causes the quadriceps muscle at the front ofthe thigh to contract and jerk the leg up. This reflex arc, involves only two nerves and one synapse.
Striking the patellar ligament with a reflex hammer just below the patella stretches the muscle spindle in the quadriceps muscle.
Which produces a signal which travels back to the spinal cord and synapses at the level of L3 in the spinal cord, completely independent of higher centres.
From there, an alpha motor neuron conducts an efferent impulse back to the quadriceps femoris muscle, triggering contraction.
This contraction, coordinated with the relaxation of the antagonistic flexor hamstring muscle causes the leg to kick. This is a reflex of proprioception which helps maintain posture and balance, allowing to keep one's balance with little effort or conscious thought.
The patellar reflex is a clinical and classic example of the monosynaptic reflex arc. There is no interneuron in the pathway leading to contraction of the quadriceps muscle.
Clinical term of absence and decrease of these reflex-
By clinically the absence or decrease of this reflex is and known as Westphal's sign. This reflex may be diminished or absent
causes of hyperactive reflex:-
these are the cause of hyperactive reflex.
Achillies Reflex:-
The ankle jerk reflex, also known as the Achilles reflex.
It occurs when the Achilles tendon is tapped while the foot is dorsi-flexed. A positive result would be the jerking of the foot towards its plantar surface. Being a deep tendon reflex, it is monosynaptic. It is also a stretch reflex.
These are monosynaptic spinal segmental reflexes.
The reflex is a movement in a muscle when a tendon is tapped, usually with a small hammer.
If a reflex is decreased or absent, a nerve supplying the muscle might be impaired or compressed.
The Achilles tendon connects the muscle at the back of the calf to the heel bone.
When the Achilles reflex is tested, the Achilles tendon is tapped while the foot is relaxed at a right angle to the rest of the leg.
The reflex is occure on a scale of zero to four, with zero meaning that the reflex is absent.
A score of zero or one for the Achilles reflex often indicates a compression in the S1 or S2 region of the spine, which are at the base of the spine around the tailbone.
This type of compression is associated with sciatica, back pain that travels through the buttock and down the sciatic nerve of one leg.
Other common causes of a reduced or absent Achilles reflex include a herniated disk, hypothyroidism and hypothermia. A qualified health professional must test the Achilles reflex to make a diagnosis.
sensory pathway:-
Sensory information from the periphery of the animal ascends through the spinal cord and enters the higher levels of the brain.
There are numerous pathways which allow different types of information to be passed to the brain.
In sensory pathway somatic sensation include pain, touch, temperature and kinaesthesia This sensory information is sent to one of two destinationsi.e the cerebral cortex or the cerebellum.
When sensory information is relayed to the cerebral cortex, information first passes via the thalamus.
The signal may be relayed one or more times by the thalamus en route to the cortex.
This sensory information reaches higher levels within the brain and therefore consciousness.
Motar pathway:-
Motor pathways carry signals from the brain to skeletal muscle and smooth muscle.
such as those contained in glands.
The system consists of upper and lower motor neurones.
The information provided below is primarily focussed on the motor pathways that coordinate skeletal muscle movement.
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