what causes the patellar reflex? ; course hero

by Kaelyn Kuhlman Published 2 years ago Updated 1 year ago 6 min read

What is the patellar reflex Quizlet?

Jul 30, 2018 · Questions: A) What causes the patellar reflex? The patellar tendons being hit stretches the muscle spindle in the quadriceps femoris muscle. This produces a signal that synapses directly onto an alpha motor neuron in the spinal cord.

How does exercise affect the patellar reflex?

The reflex center for the patellar reflex is in the lumbar region of the spinal cord. A reflex such as the patellar reflex in which response is seen on the same side of the body to which the stimulus is applied is said to be ipsilateral. d. Mental activity can influence reflex activity, in part by increasing muscle tonus. i.

What is the mechanism of action of the patellar muscle?

Exercise 3 Testing a Stretch Reflex Data Table 3 Testing the Patellar Reflex. Exercise 3 testing a stretch reflex data table 3. ... Course Title BIOL 230; Type. Lab Report. Uploaded By mich262002. Pages 5 Ratings 100% (22) 22 out of 22 people found this document helpful;

Is there an interneuron in the patellar reflex arc?

When a tendon attached to the kneecap, or patellar tendon, is suddenly stretched, the brain directs the quadriceps muscle in the thigh to contract. This causes the kneejerk reflex that temporarily straightens the leg and ends with a slight tapering of the flexed knee.

What causes the patellar reflex?

The patellar reflex occurs when an abrupt change arises in muscle length; in this case, it is produced by the tendon stretching, which is caused when the hammer stroke is applied [3, 4]. The normal response must be a sudden leg extension.Jul 9, 2019

What activates the patellar reflex?

Tapping the patellar tendon pulls and stretches the quadriceps muscle and causes the sensory receptor of the muscle, called a muscle spindle fiber, to send a signal along the afferent neuron to the spinal cord (Figure 2).

What causes the patellar reflex quizlet?

The patellar reflux involves the rapid contraction of QUADRICEPS FEMORIS when a stretched patellar ligament is tapped. The result is rapid knee extension. The reflex tests the function of the L4 segment of the spinal cord and the corresponding nerve roots.

What affects the patellar reflex?

Hyperthyroidism and hypothyroidism are also known to affect reflexes such as the patellar tendon reflex. Hyperthyroidism is associated with hyperreflexia and accelerated relaxation of the contracting muscles of the deep tendon reflex.Feb 10, 2022

How do you trigger a knee reflex?

Part of a video titled Patellar Reflex Test | Knee Reflex Examination of Deep Tendons

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This is going to be looking at l2 to l4. And to find the tendon what you want to do is locate theMoreThis is going to be looking at l2 to l4. And to find the tendon what you want to do is locate the kneecap. And then go just a little bit right below it and the best way is to have the patient extend.

Why does the patellar reflex cause a negative feedback mechanism?

Why does the patellar reflex cause a negative feedback mechanism? The stretching of the muscle tendon causes the muscle to contract. Which two organ systems are both involved in reproduction?

What type of reflex is the patellar reflex quizlet?

The patellar (knee-jerk) reflex is an example of what type of reflex? It is an example of a stretch reflex.

What effect did the Jendrassik maneuver have on your patellar reflex Why?

Knee Jerk Reflex - with Jendrassik Maneuver

The Jendrassik maneuver will heighten (exaggerate) the patellar (knee-jerk) reflex by countering some of the normal descending inhibitory brainstem inputs to reflex arc interneurons.May 3, 2012

What is the response when the patellar tendon is tapped with a hammer quizlet?

When you tap a tendon with a reflex hammer, how does it elicit a response? Tapping the tendon stretches the muscle, and the muscle activates muscle spindles (receptors), which produce the reflex response.

What nerve causes the patellar reflex?

Part of a video titled 2-Minute Neuroscience: Knee-jerk Reflex - YouTube

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It can be an indication of a disorder or of damage to the nervous system. The knee-jerk reflex is aMoreIt can be an indication of a disorder or of damage to the nervous system. The knee-jerk reflex is a simple reflex arc that occurs at the level of the spinal cord. In other words the Associated

What causes poor knee reflex?

Usually, absent reflexes are caused by an issue with the nerves in the tendon and muscle. You may have other muscle symptoms along with areflexia, like weakness, twitching, or atrophy.Oct 25, 2021

What causes no knee-jerk reflex?

The normal response is a 'knee jerk'. This is an example of a reflex, which is an involuntary muscular response elicited by the rubber hammer tapping the associated tendon. When reflex responses are absent this could be a clue that the spinal cord, nerve root, peripheral nerve, or muscle has been damaged.

What is the patellar reflex?

The patellar reflex or knee-jerk (in American English knee reflex) is a stretch reflex which tests the L2, L3, and L4 segments of the spinal cord.

Which muscle is striked with a reflex hammer?

Striking of the patellar tendon with a reflex hammer just below the patella stretches the muscle spindle in the quadriceps muscle. This produces a signal which travels back to the spinal cord and synapses (without interneurons) at the level of L3 or L4 in the spinal cord, completely independent of higher centres.

Who first reported the knee jerk?

Wilhelm Heinrich Erb (1840–1921) and Carl Friedrich Westphal (1833–1890) simultaneously reported the patellar tendon or knee reflex in 1875. The term knee-jerk was recorded by Sir Michael Foster in his Textbook of physiology in 1877: "Striking the tendon below the patella gives rise to a sudden extension of the leg, known as the knee-jerk.".

What happens after a hammer tap?

After the tap of a hammer, the leg is normally extended once and comes to rest. The absence or decrease of this reflex is problematic, and known as Westphal's sign. This reflex may be diminished or absent in lower motor neuron lesions and during sleep. On the other hand, multiple oscillation of the leg (pendular reflex) following the tap may be a sign of cerebellar diseases. Exaggerated (brisk) deep tendon reflexes such as this can be found in upper motor neuron lesions, hyperthyroidism, anxiety or nervousness. The test itself assesses the nervous tissue between and including the L2 and L4 segments of the spinal cord.

What is patellar reflex?

Patellar reflex is the scientific name for the layman’s term called knee jerk. It is tested to check the reflexes of an individual to a sensation. Whenever you might have gone to a doctor for a problem, which may have a connection with sensory faculties, the doctor must have tapped a bit under your knee with a tendon hammer.

What is the somatic reflex?

Somatic or Autonomic. This reflex is a somatic reflex arc, which affects the muscles. It is a stretch reflex when a muscle or tendon is struck or hit. The jolt leads the muscle to contract, which in turn inhibits the muscle contraction as a result of being struck. They are fundamentally spinal reflexes, mediated by the spinal cord.

What is the function of the patella?

The patella also functions to allow for smooth movement of the knee in flexion and extension, and also protects the anterior surface of the knee joint.

What causes a patellar fracture?

The patella sits on the anterior surface of the femoral condyles, and is hence relatively vulnerable. Direct trauma to the knee is the commonest cause of patellar fracture. Symptoms include swelling of the knee and pain in the region. Surgery is the most usual treatment.

What is the patella of the knee?

The patella is also known as the kneecap. It sits in front of the knee joint and protects the joint from damage. It is the largest sesamoid bone in the body, and lies within the quadriceps tendon. The kneecap is an example of a bone we are all familiar with, and which has a significant functional role. In this article we will discuss the anatomy ...

Where is the patella located?

Anatomy. The patella is the largest sesamoid bone in the body and it lies within the quadriceps tendon in front of the knee joint. The bone originates from multiple ossification centres that develop from the ages of three to six, which rapidly coalesce. The patella is a thick, flat, triangular bone with its apex pointing downwards.

What stabilizes the patella?

The patella is stabilized by the horizontal fibers of vastus medialis, as well as the anterior projection of the lateral femoral condyle. The tension in the medial patellar retinaculum also helps in its stability. For more details about the anatomy of the patella, take a look below: Tibia and fibula Explore study unit.

What age does anterior knee pain occur?

It is one of the juvenile osteochondroses, and causes anterior knee pain. It is commonest in children aged twelve to fourteen years of age, and among those children that play a lot of sports. The same kind of symptoms have been reported where the quadriceps inserts onto the base of the patella.

What muscle is involved in knee jerk?

Patellar reflex also known as knee jerk is the contraction of quadriceps femoris muscle resulting in the extension of knee joint. The myotome that causes knee extension is L2-4 i.e. the femoral the lower two divisions of the femoral nerve. The patient is asked to relax their knee, and the patella ligament (below the tibial tuberosity, and above the tibial shaft) is struck.