GENERAL INFORMATION
The abdomen is a region of the body located between the thorax (chest) and the pelvis. It contains various organs, including the stomach, liver, intestines, kidneys, and reproductive organs. Additionally, the abdomen is surrounded by several layers of muscles, including the internal oblique muscles, which play a crucial role in core stability and movement.
INTERNAL OBLIQUE MUSCLES
It is a pair of broad, deep muscles located on the sides of the abdomen. They contribute significantly to core stability, trunk rotation, and lateral flexion of the spine, thereby playing a pivotal role in daily movements and athletic activities.
ORIGIN
Internal oblique muscles originate from several vital structures, including:
- Thoracolumbar fascia: A sheet of connective tissue on the lower back.
- Anterior iliac crest: The upper edge of the hip bone.
- Inguinal ligament: A band of connective tissue in the groin area.
INSERTION POINT
The internal oblique muscles are inserted into the following critical areas:
- The Lower three or four ribs provide support for the upper body.
- The Linea alba is a fibrous structure running vertically down the midline of the abdomen, which serves as a central tendon for abdominal muscles.
- The Pubic crest, a ridge of bone located on the front side of the pubic bone, is essential for pelvic stability.
MAJOR ARTERIES
The internal oblique muscles receive their blood supply from branches of the following arteries, ensuring they are well-nourished:
- Superior and inferior epigastric arteries
- Lumbar arteries
- Deep circumflex iliac artery
NEURAL INNERVATION
The internal oblique muscles are innervated by the lower intercostal nerves (T7-T12) and the first lumbar nerve (L1). Therefore, proper nerve function is essential for their activation and control.
TRIGGER POINT
Trigger points in the internal oblique muscles can cause localised pain in the abdominal region and may refer to pain in the lower back, hips, or groin. Thus, addressing these trigger points through massage or other therapies can alleviate discomfort and improve muscle function.
CONCENTRIC FUNCTION
The internal oblique muscles’ concentric function involves contracting its fibres, resulting in trunk rotation to the same side and lateral flexion of the spine. Consequently, they are essential for dynamic trunk movements.
ECCENTRIC FUNCTION
The eccentric function of the internal oblique muscles refers to the controlled lengthening of the muscle fibres. It assists in the smooth lowering of the trunk during rotation and lateral flexion movements, and therefore, it plays a critical role in maintaining stability during these movements.
ISOMETRIC FUNCTION
The isometric function of the internal oblique muscles involves maintaining a static contraction without any change in muscle length. This helps stabilise the trunk and maintain core stability during various movements, which is crucial for posture and load-bearing activities.
RELATED MUSCLES (SCIENTIFIC NAMES)
- External oblique: Located above the internal oblique, it also assists in trunk rotation and lateral flexion, providing superficial support.
- Rectus abdominis: Runs vertically on the front of the abdomen, crucial for flexing the spine and maintaining posture.
- Transversus abdominis: The deepest abdominal muscle, essential for core stability as well as compressing the abdominal contents.
- Quadratus lumborum: Located in the lower back, it is important for lateral flexion and maintaining an upright posture.
ANTAGONIST MUSCLES
- Erector spinae muscles (iliocostalis, longissimus, spinalis): Extend and rotate the spine, opposing the flexion and rotation actions of the obliques, vital for back strength.
- Rectus abdominis: Flexes the spine, opposing the extension function of the erector spinae, which is also key for abdominal strength and stability.
COMMON INJURIES
- Muscle strains or tears: Caused by overstretching or overuse, leading to pain and limited movement, often from sudden or intense activities.
- Overuse injuries: Result from repetitive motions, causing muscle fatigue and discomfort, common in athletes and highly active individuals.
- Abdominal hernias: Occur when an organ pushes through a weak spot in the abdominal muscles, often due to heavy lifting or strain.
- Postural imbalances: Arise from weak or tight oblique muscles, affecting overall posture and alignment, potentially leading to chronic pain and discomfort.
EXERCISES FOR INTERNAL OBLIQUE MUSCLES
- Russian twists: Sit on the floor, lean back slightly, and rotate the torso from side to side, engaging the obliques. This exercise improves rotational strength and core stability.
- Side plank variations: Elevate the body on one arm and foot, strengthening the obliques and core. Variations can include leg lifts or reaching movements to increase difficulty.
- Bicycle crunches: Lie on your back, and alternate elbow-to-knee touches, targeting the obliques and rectus abdominis. This dynamic movement enhances overall core strength.
- Woodchoppers: Stand with feet shoulder-width apart, hold weight as well as mimic chopping wood, rotating from high to low. This motion effectively works the obliques and shoulders.
- Standing side bends: Stand upright and bend sideways at the waist, stretching and strengthening the obliques. Adding weights can increase resistance and effectiveness.
STRETCHES
- Standing side bends: Stand and reach overhead with one arm, twisting the torso to the opposite side to stretch the obliques. This stretch can be deepened by holding a lightweight.
- Seated side bends: Sit with legs crossed, reach one arm overhead, and bend sideways to stretch the obliques. This position provides a stable base for a deeper stretch.
- Supine spinal twists: Lie on your back, cross one leg over the other, and twist the torso to stretch the obliques and spine. Holding the stretch for longer periods can increase flexibility.
- Sphinx pose: Lie on your stomach, lift your upper body with your forearms, stretching the abdominal muscles. This gentle backbend can help open up the front body.
- Seated forward folds with a side reach: Sit with legs extended, reach one arm overhead, and bend towards the opposite leg. This stretch targets the sides of the body and improves flexibility.