Unraveling the Dynamics of Hip Flexion

Explore the Muscular Landscape of the Hip Flexor: A Comprehensive Guide

The hip flexor muscle group plays a crucial role in propelling our body forward and providing stability to our hips. Understanding the anatomy and function of these muscles is essential for maintaining optimal hip health and mobility. In this comprehensive guide, we delve into the intricate world of hip flexors, examining their anatomy, clinical significance, and effective strengthening exercises.

Sub-Title: Unraveling the Dynamics of Hip Flexion

Join us on a journey to discover the muscular components responsible for hip flexion. We will explore their anatomical locations, key functions, and nerve innervation. From the powerhouse iliacus to the supportive tensor fasciae latae, each muscle contributes uniquely to the overall movement and stability of the hip. This guide empowers you with the knowledge to understand, assess, and improve hip flexor function, optimizing your performance and well-being.

1. Primary Hip Flexors: An Introduction

Primary Hip Flexors: An Introduction

The primary hip flexors are a group of three muscles located deep within the hip region. These muscles work in unison to propel the hip forward, a crucial movement for walking, running, and other activities that require hip flexion.

1. Iliacus

The iliacus is the largest and strongest of the primary hip flexors. It originates from the inner surface of the pelvis (iliac fossa) and inserts onto the lesser trochanter of the femur. The iliacus is innervated by the femoral nerve and primarily responsible for hip flexion. Additionally, it contributes to stabilizing the sacroiliac joint, which connects the pelvis to the spine.

2. Psoas Major

The psoas major is located anterior to the iliacus and originates from the lumbar vertebrae and inserts onto the lesser trochanter of the femur. It is innervated by the lumbar plexus and plays a dual role in hip flexion and trunk rotation. When the psoas major contracts, it flexes the hip and, if the hip is fixed, it bends the trunk forward and laterally rotates the spine.

3. Psoas Minor

The psoas minor is a smaller, less prominent muscle located anterior to the psoas major. It originates from the lumbar vertebrae and inserts onto the iliopubic eminence of the pelvis. The psoas minor is innervated by the lumbar plexus and assists the psoas major in hip flexion.

Iliacus: The Powerhouse of Hip Flexion

Iliacus: The Powerhouse of Hip Flexion

The iliacus muscle is the largest and strongest of the primary hip flexors. It plays a vital role in propelling the hip forward and stabilizing the sacroiliac joint.

Attachments and Blood Supply

The iliacus originates from the inner surface of the pelvis (iliac fossa) and inserts onto the lesser trochanter of the femur. It receives its blood supply from the iliolumbar artery.

Function

The primary function of the iliacus is to flex the hip. It works in conjunction with the other hip flexors, the psoas major and psoas minor, to bring the thigh forward. Additionally, the iliacus plays a role in stabilizing the sacroiliac joint. When the iliacus contracts, it helps to compress the sacroiliac joint and prevent excessive movement.

Understanding the anatomy and function of the iliacus muscle is essential for maintaining optimal hip health and mobility. Strengthening the iliacus can improve hip flexion strength and stability, which can benefit a variety of activities, including walking, running, and cycling.

Psoas Major: A Multifaceted Flexor and Rotator

Psoas Major: A Multifaceted Flexor and Rotator

The psoas major is a long, spindle-shaped muscle located deep within the abdomen and pelvis. It plays a dual role in hip flexion and trunk rotation, making it a versatile and important muscle for a variety of movements.

Attachments and Innervation

The psoas major originates from the lumbar vertebrae (T12-L5) and inserts onto the lesser trochanter of the femur. It is innervated by the lumbar plexus.

Function

The primary function of the psoas major is to flex the hip. It works in conjunction with the other hip flexors, the iliacus and psoas minor, to bring the thigh forward. Additionally, the psoas major plays a role in trunk rotation and spinal stabilization. When the psoas major contracts on one side of the body, it rotates the trunk towards that side. It also helps to stabilize the lumbar spine and prevent excessive forward bending.

Understanding the anatomy and function of the psoas major muscle is essential for maintaining optimal hip and spinal health. Strengthening the psoas major can improve hip flexion strength and mobility, as well as enhance trunk stability and rotation. This can benefit a variety of activities, including walking, running, and sports that require rotational movements.

Psoas Minor: The Lesser-Known Contributor

Psoas Minor: The Lesser-Known Contributor

The psoas minor is a small, spindle-shaped muscle located deep within the abdomen and pelvis. It is often overshadowed by its larger companion, the psoas major, but it plays a subtle yet significant role in hip flexion.

Location, Attachments, and Innervation

The psoas minor originates from the bodies and transverse processes of the T12 and L1 vertebrae. It inserts onto the iliopubic eminence of the pelvis. The psoas minor is innervated by the lumbar plexus.

Function

The primary function of the psoas minor is to flex the hip. It works in conjunction with the other hip flexors, the iliacus and psoas major, to bring the thigh forward. However, the psoas minor is a weaker hip flexor compared to the iliacus and psoas major, and its contribution to hip flexion is relatively small.

Despite its small size and limited contribution to hip flexion, the psoas minor is an important muscle for maintaining optimal hip function. It helps to stabilize the hip joint and prevent excessive movement. Additionally, the psoas minor plays a role in trunk rotation and spinal stabilization.

Understanding the anatomy and function of the psoas minor muscle is essential for a comprehensive understanding of the hip flexor muscle group. While it may not be as well-known as the iliacus or psoas major, the psoas minor is a valuable contributor to hip flexion and overall hip stability.

2. Secondary Hip Flexors: Providing Support

Secondary Hip Flexors: Providing Support

The secondary hip flexors are a group of muscles that assist the primary hip flexors in bringing the thigh forward. While they are not as powerful as the iliacus, psoas major, and psoas minor, they play an important role in overall hip movement and stability.

1. Tensor Fasciae Latae

The tensor fasciae latae (TFL) is a long, flat muscle located on the lateral side of the thigh. It originates from the iliac crest and inserts onto the iliotibial band. The TFL is innervated by the superior gluteal nerve.

The primary function of the TFL is to tense the iliotibial band, which helps to stabilize the knee joint. However, the TFL also assists in hip flexion and external rotation.

2. Sartorius

The sartorius is the longest muscle in the human body. It originates from the anterior superior iliac spine and inserts onto the medial surface of the tibia. The sartorius is innervated by the femoral nerve.

The primary function of the sartorius is to flex the hip and knee joints, as well as to rotate the lower leg medially. It also assists in stabilizing the knee joint.

3. Rectus Femoris

The rectus femoris is one of the four muscles that make up the quadriceps group. It originates from the anterior inferior iliac spine and inserts onto the patella. The rectus femoris is innervated by the femoral nerve.

The primary function of the rectus femoris is to extend the knee joint. However, it also assists in hip flexion, particularly when the knee is flexed.

Understanding the anatomy and function of the secondary hip flexors is essential for a comprehensive understanding of hip movement and stability. These muscles work together with the primary hip flexors to provide a wide range of motion and stability to the hip joint.

Tensor Fasciae Latae: Stabilizing Force and Hip Flexor

Tensor Fasciae Latae: Stabilizing Force and Hip Flexor

The tensor fasciae latae (TFL) is a long, flat muscle located on the lateral side of the thigh. It plays an important role in stabilizing the iliotibial band (ITB) and assisting in hip flexion.

Attachments and Innervation

The TFL originates from the iliac crest and inserts onto the iliotibial band. It is innervated by the superior gluteal nerve.

Function

The primary function of the TFL is to tense the ITB. The ITB is a thick band of fascia that runs along the lateral side of the thigh, from the hip to the knee. When the TFL contracts, it tightens the ITB, which helps to stabilize the knee joint and prevent excessive inward movement of the knee (valgus). Additionally, the TFL assists in hip flexion, particularly when the hip is extended. It also plays a role in external rotation of the hip.

Understanding the anatomy and function of the tensor fasciae latae muscle is essential for a comprehensive understanding of hip movement and stability. Strengthening the TFL can help to improve hip stability and reduce the risk of knee injuries.

Sartorius: The Longest Muscle and a Gentle Flexor

Sartorius: The Longest Muscle and a Gentle Flexor

The sartorius is a long, slender muscle located on the medial side of the thigh. It is the longest muscle in the human body, running from the anterior superior iliac spine to the medial surface of the tibia.

Attachments and Innervation

The sartorius originates from the anterior superior iliac spine and inserts onto the medial surface of the tibia, just below the knee joint. It is innervated by the femoral nerve.

Function

The primary function of the sartorius is to flex the hip and knee joints, as well as to rotate the lower leg medially. It is a weak hip flexor compared to the iliacus, psoas major, and psoas minor, but it plays an important role in knee flexion and rotation. Additionally, the sartorius helps to stabilize the knee joint and prevent excessive lateral movement of the patella.

Understanding the anatomy and function of the sartorius muscle is essential for a comprehensive understanding of hip and knee movement. Strengthening the sartorius can help to improve hip and knee flexion, as well as medial rotation of the lower leg.

Rectus Femoris: Quadriceps Powerhouse with Flexor Capabilities

Rectus Femoris: Quadriceps Powerhouse with Flexor Capabilities

The rectus femoris is a large, powerful muscle located on the anterior side of the thigh. It is one of the four muscles that make up the quadriceps group, and it plays a primary role in knee extension.

Attachments and Innervation

The rectus femoris originates from the anterior inferior iliac spine and inserts onto the patella. It is innervated by the femoral nerve.

Function

The primary function of the rectus femoris is to extend the knee joint. It is the most powerful knee extensor muscle, and it is essential for activities such as walking, running, and jumping. Additionally, the rectus femoris assists in hip flexion, particularly when the knee is flexed. However, it is a weaker hip flexor compared to the iliacus, psoas major, and psoas minor.

Understanding the anatomy and function of the rectus femoris muscle is essential for a comprehensive understanding of knee movement and stability. Strengthening the rectus femoris can help to improve knee extension strength and power, as well as hip flexion when the knee is flexed.

3. Clinical Significance: Understanding Hip Flexor Issues

Clinical Significance: Understanding Hip Flexor Issues

Hip flexor injuries and dysfunctions are common among athletes and individuals who engage in activities that require repetitive hip flexion, such as running, cycling, and weightlifting. These conditions can range from mild muscle strains to more serious tears and ruptures.

Common Conditions

• Hip Flexor Strain: A strain is a tear in the muscle or tendon. Hip flexor strains can occur due to overexertion, sudden movements, or inadequate warm-up. Symptoms include pain, tenderness, and stiffness in the hip area.
• Hip Flexor Tendinitis: Tendinitis is the inflammation of a tendon. Hip flexor tendinitis can be caused by overuse, friction, or trauma. Symptoms include pain, swelling, and tenderness around the affected tendon.
• Hip Flexor Bursitis: Bursitis is the inflammation of a bursa, which is a fluid-filled sac that reduces friction between bones and tendons. Hip flexor bursitis can occur due to overuse or direct trauma to the hip. Symptoms include pain, swelling, and tenderness in the hip area.

Assessment and Treatment

Assessment of hip flexor injuries and dysfunctions typically involves a physical examination and medical history. Imaging tests, such as X-rays or MRI scans, may be necessary to confirm the diagnosis and rule out other conditions.

Treatment for hip flexor injuries and dysfunctions depends on the severity of the condition. Mild strains and tendinitis can often be treated with rest, ice, compression, and elevation (RICE) protocol, along with physical therapy to restore range of motion and strength. More severe tears or ruptures may require surgery to repair the damaged tissue.

Understanding the clinical implications of hip flexor issues is essential for proper diagnosis, treatment, and prevention. If you experience persistent pain or discomfort in your hip area, it is important to consult a healthcare professional for evaluation.

Hip Flexor Strain: Causes and Management

Hip Flexor Strain: Causes and Management

A hip flexor strain is a tear in the muscle or tendon of the hip flexor muscle group. It is a common injury among athletes, particularly those involved in sports that require repetitive hip flexion, such as running, cycling, and soccer.

Causes

Hip flexor strains can be caused by a variety of factors, including:

• Overexertion
• Sudden movements
• Inadequate warm-up
• Muscle imbalances
• Trauma

Symptoms

The most common symptom of a hip flexor strain is pain in the hip area. The pain may be sharp or dull, and it may worsen with activity. Other symptoms may include:

• Tenderness to the touch
• Stiffness
• Reduced range of motion
• Bruising
• Swelling

Management

Treatment for a hip flexor strain depends on the severity of the injury. Mild strains can often be treated with rest, ice, compression, and elevation (RICE) protocol. More severe strains may require physical therapy or, in rare cases, surgery.

RICE Protocol

The RICE protocol is a common treatment for acute soft tissue injuries, such as hip flexor strains. It involves:

• Rest: Avoid activities that aggravate the pain.
• Ice: Apply ice packs to the injured area for 15-20 minutes at a time, several times a day.
• Compression: Wrap the injured area with an elastic bandage to reduce swelling.
• Elevation: Keep the injured area elevated above the level of your heart to reduce swelling.

Physical Therapy

Physical therapy can help to improve range of motion, strength, and flexibility in the hip flexor muscles. A physical therapist can also teach you exercises to help prevent future injuries.

Surgery

Surgery is rarely necessary for hip flexor strains. However, it may be an option for severe tears or ruptures that do not respond to conservative treatment.

Hip Flexor Tendinitis: Inflammation and Its Impact

Hip Flexor Tendinitis: Inflammation and Its Impact

Hip flexor tendinitis is the inflammation of the tendons that attach the hip flexor muscles to the bones of the pelvis and femur. It is a common condition among athletes and individuals who engage in activities that involve repetitive hip flexion, such as running, cycling, and dancing.

Causes

Hip flexor tendinitis is caused by overuse of the hip flexor muscles. This can occur due to:

• Excessive training
• Sudden increases in activity level
• Poor technique
• Muscle imbalances
• Trauma

Symptoms

The most common symptom of hip flexor tendinitis is pain in the hip area. The pain may be worse with activity, particularly activities that involve hip flexion. Other symptoms may include:

• Tenderness to the touch
• Stiffness
• Reduced range of motion
• Creaking or popping sounds in the hip
• Weakness in the hip flexor muscles

Treatment

Treatment for hip flexor tendinitis typically involves rest, ice, compression, and elevation (RICE) protocol. Other treatments may include:

• Physical therapy: A physical therapist can help to improve range of motion, strength, and flexibility in the hip flexor muscles. They can also teach you exercises to help prevent future injuries.
• Corticosteroid injections: Corticosteroid injections can help to reduce inflammation and pain. However, they should be used sparingly, as they can weaken the tendons over time.
• Surgery: Surgery is rarely necessary for hip flexor tendinitis. However, it may be an option for severe cases that do not respond to conservative treatment.

Prevention

There are a number of things you can do to prevent hip flexor tendinitis, including:

• Warm up properly before exercising.
• Stretch your hip flexor muscles regularly.
• Gradually increase your training intensity and duration.
• Use proper technique when exercising.
• Strengthen the muscles around your hips and pelvis.

Hip Flexor Bursitis: Fluid Accumulation and Discomfort

Hip Flexor Bursitis: Fluid Accumulation and Discomfort

Hip flexor bursitis is a condition characterized by inflammation and fluid accumulation in the bursa sacs that surround the hip flexor muscles. Bursa sacs are small, fluid-filled sacs that help to reduce friction between bones, muscles, and tendons. When these sacs become inflamed, they can cause pain and discomfort.

Causes

Hip flexor bursitis is commonly caused by overuse of the hip flexor muscles. This can occur due to:

• Excessive training
• Sudden increases in activity level
• Poor technique
• Trauma
• Other conditions, such as rheumatoid arthritis or gout

Symptoms

The most common symptom of hip flexor bursitis is pain in the hip area. The pain may be worse with activity, particularly activities that involve hip flexion. Other symptoms may include:

• Tenderness to the touch
• Stiffness
• Swelling in the hip area
• Warmth and redness in the hip area
• Creaking or popping sounds in the hip

Treatment

Treatment for hip flexor bursitis typically involves rest, ice, compression, and elevation (RICE) protocol. Other treatments may include:

• Physical therapy: A physical therapist can help to improve range of motion, strength, and flexibility in the hip flexor muscles. They can also teach you exercises to help prevent future injuries.
• Corticosteroid injections: Corticosteroid injections can help to reduce inflammation and pain. However, they should be used sparingly, as they can weaken the tendons over time.
• Surgery: Surgery is rarely necessary for hip flexor bursitis. However, it may be an option for severe cases that do not respond to conservative treatment.

Prevention

There are a number of things you can do to prevent hip flexor bursitis, including:

• Warm up properly before exercising.
• Stretch your hip flexor muscles regularly.
• Gradually increase your training intensity and duration.
• Use proper technique when exercising.
• Strengthen the muscles around your hips and pelvis.

4. Strengthening Exercises: Boosting Hip Flexor Power

Strengthening Exercises: Boosting Hip Flexor Power

Strong hip flexors are essential for a wide range of activities, from walking and running to sports and fitness activities. By strengthening your hip flexors, you can improve your hip mobility, stability, and overall performance.

** Exercises**

Here are a few exercises to help you strengthen your hip flexors:

1. Leg Raises

Leg raises are a simple but effective exercise that can be done anywhere. Lie on your back with your knees bent and your feet flat on the floor. Lift your right leg straight up, keeping your knee straight. Hold for a few seconds, then slowly lower your leg back down. Repeat with your left leg.

2. Standing Hip Flexor Stretch

This stretch helps to improve hip flexor flexibility and reduce tightness. Stand with your feet shoulder-width apart. Step forward with your right leg and bend your knee so that your thigh is parallel to the floor. Keep your left leg straight. Lean forward and reach your right arm towards your right foot. Hold for 30 seconds, then repeat with your left leg.

3. Weighted Hip Thrusts

Weighted hip thrusts are a great way to build explosive power in your hip flexors. Sit on the floor with your knees bent and your feet flat on the floor. Place a weight on your lap. Lean back slightly and lift your hips up until your body is in a straight line from your shoulders to your knees. Hold for a few seconds, then slowly lower your hips back down.

4. Cable Knee Drives

Cable knee drives are a dynamic exercise that helps to strengthen your hip flexors and improve your range of motion. Attach a cable to a low pulley. Stand facing the pulley with your feet shoulder-width apart. Grab the handles of the cable with your hands and step forward with your right leg. Bend your right knee and drive your right leg up towards your chest. Hold for a few seconds, then slowly lower your leg back down. Repeat with your left leg.

5. Lunge with Overhead Press

This exercise combines a lunge with an overhead press to target multiple muscle groups, including the hip flexors. Hold a dumbbell or kettlebell in each hand and stand with your feet shoulder-width apart. Step forward with your right leg and bend your knees so that your right thigh is parallel to the floor. Simultaneously, press the weights overhead until your arms are fully extended. Hold for a few seconds, then slowly lower the weights back down and return to the starting position. Repeat with your left leg.

Leg Raises: Core Engagement and Hip Flexion

Leg Raises: Core Engagement and Hip Flexion

Leg raises are a simple yet effective exercise that targets the hip flexor muscles. They are also a great way to engage your core and improve your overall stability. Leg raises can be done with or without weight, and there are several variations to suit different fitness levels.

Benefits

Leg raises offer a number of benefits, including:

• Strengthened hip flexors
• Improved core stability
• Increased range of motion in the hips
• Reduced risk of hip pain and injuries
• Improved athletic performance

How to Perform Leg Raises

To perform a basic leg raise, lie on your back with your knees bent and your feet flat on the floor. Lift your right leg straight up, keeping your knee straight. Hold for a few seconds, then slowly lower your leg back down. Repeat with your left leg.

There are several variations of leg raises that you can try to increase the challenge. For example, you can:

• Hold a weight on your foot or ankle
• Raise both legs at the same time
• Hold your leg up for a longer period of time
• Perform leg raises with a resistance band

Tips

Here are a few tips to help you get the most out of leg raises:

• Keep your core engaged throughout the exercise.
• Focus on lifting your leg with your hip flexors, not your lower back.
• Don’t swing your leg up. Control the movement and slowly lower your leg back down.
• If you have any pain in your hips or lower back, stop doing leg raises and consult with a healthcare professional.

Standing Hip Flexor Stretch: Lengthening and Flexibility

Standing Hip Flexor Stretch: Lengthening and Flexibility

The standing hip flexor stretch is a simple yet effective way to improve hip flexor flexibility and reduce tightness. It is a great stretch to do before and after exercise, or anytime you feel your hip flexors are feeling tight.

Benefits

The standing hip flexor stretch offers a number of benefits, including:

• Improved hip flexor flexibility
• Reduced hip flexor tightness
• Increased range of motion in the hips
• Reduced risk of hip pain and injuries
• Improved athletic performance

How to Perform the Standing Hip Flexor Stretch

To perform the standing hip flexor stretch, follow these steps:

1. Stand with your feet shoulder-width apart.
2. Step forward with your right leg and bend your knee so that your thigh is parallel to the floor.
3. Keep your left leg straight and your right heel on the ground.
4. Lean forward and reach your right arm towards your right foot.
5. Hold this stretch for 30 seconds, then repeat with your left leg.

Tips

Here are a few tips to help you get the most out of the standing hip flexor stretch:

• Keep your core engaged throughout the stretch.
• Focus on stretching your hip flexors, not your lower back.
• Don’t overstretch. Only go as far as you feel comfortable.
• If you have any pain in your hips or lower back, stop doing the stretch and consult with a healthcare professional.

Weighted Hip Thrusts: Power and Performance

Weighted Hip Thrusts: Power and Performance

Weighted hip thrusts are a powerful exercise that targets the hip flexors, glutes, and hamstrings. They are a great way to build explosive power and strength in the lower body. Weighted hip thrusts are commonly used by athletes and fitness enthusiasts to improve their performance in a variety of sports and activities.

Benefits

Weighted hip thrusts offer a number of benefits, including:

• Increased hip flexor strength and power
• Improved glute and hamstring strength
• Enhanced athletic performance
• Reduced risk of hip and knee injuries
• Improved posture

How to Perform Weighted Hip Thrusts

To perform weighted hip thrusts, you will need a weight bench and a barbell or dumbbells. Follow these steps:

1. Sit on the edge of a weight bench with your feet flat on the floor. Place a barbell or dumbbells across your hips.
2. Lie back on the bench and position the barbell or dumbbells so that they are resting on your hips. Your feet should be shoulder-width apart and your knees should be bent at a 90-degree angle.
3. Press your feet into the floor and lift your hips up until your body is in a straight line from your shoulders to your knees. Hold this position for a few seconds, then slowly lower your hips back down to the starting position.

Tips

Here are a few tips to help you get the most out of weighted hip thrusts:

• Keep your core engaged throughout the exercise.
• Focus on driving your hips up with your glutes and hamstrings, not your lower back.
• Don’t overextend your hips. Only go as far as you feel comfortable.
• If you have any pain in your hips or lower back, stop doing the exercise and consult with a healthcare professional.

5. Conclusion: Mastering Hip Flexor Anatomy and Function

Conclusion: Mastering Hip Flexor Anatomy and Function

The hip flexor muscle group is a complex and important part of the human musculoskeletal system. These muscles are responsible for a wide range of movements, including walking, running, and kicking. Understanding the anatomy and function of the hip flexors is essential for maintaining optimal hip health and mobility.

In this article, we have explored the muscular components, clinical significance, and practical exercises related to the hip flexor complex. We have discussed the three primary hip flexors (iliacus, psoas major, and psoas minor) and their individual functions. We have also examined the secondary hip flexors (tensor fasciae latae, sartorius, and rectus femoris) and their contributions to hip movement.

In addition to their anatomical and functional roles, we have also highlighted the clinical significance of hip flexor injuries and dysfunctions. Common conditions such as hip flexor strains, tendinitis, and bursitis can cause pain and discomfort, and it is important to understand the causes, symptoms, and treatment options for these conditions.

Finally, we have provided a range of strengthening exercises that can help to improve hip flexor strength and flexibility. These exercises can be tailored to different fitness levels and can be incorporated into any exercise routine. By following the tips and advice in this article, you can master hip flexor anatomy and function and improve your overall hip health and performance.

Quiz

Multiple Choice

1. Which of the following is NOT a primary hip flexor muscle?

(a) Iliacus (b) Psoas major (c) Psoas minor (d) Rectus femoris

1. What is the function of the tensor fasciae latae muscle?

(a) Hip flexion (b) Hip extension (c) Hip abduction (d) Hip adduction

1. Which of the following is a common symptom of hip flexor tendinitis?

(a) Pain in the hip area (b) Stiffness (c) Reduced range of motion (d) All of the above

True/False

1. The sartorius muscle is the longest muscle in the body. (True/False)

2. Hip flexor bursitis is caused by inflammation of the tendons that attach the hip flexor muscles to the bones. (True/False)

3. Weighted hip thrusts are a good exercise for improving hip flexor flexibility. (True/False)

Answer Key

Multiple Choice

1. (d) Rectus femoris
2. (a) Hip flexion
3. (d) All of the above

True/False

1. True
2. False
3. False