CORE MUSCLES

GENERAL INFORMATION

The core muscles include a group of muscles responsible for stabilising the trunk and spine, facilitating movement, and maintaining posture. Core muscles are essential for transferring force between the upper and lower body, contributing to balance, coordination, and overall body strength. Core stability helps prevent injuries, enhances athletic performance, and supports everyday activities like lifting, bending, and twisting.

ORIGIN OF CORE MUSCLES

• Rectus Abdominis: Pubic symphysis and pubic crest.
• Transversus Abdominis: Iliac crest, thoracolumbar fascia, cartilage of ribs 7-12, and the inguinal ligament.
• External Obliques: Outer surfaces of ribs 5-12.
• Internal Obliques: Iliac crest, thoracolumbar fascia, and inguinal ligament.
• Multifidus: Sacrum, posterior superior iliac spine, and transverse processes of lumbar, thoracic, and cervical vertebrae.
• Diaphragm: Xiphoid process, lower six ribs, and lumbar vertebrae.

INSERTION POINT

• Rectus Abdominis: Xiphoid process and costal cartilages of ribs 5-7.
• Transversus Abdominis: Linea alba, pubic crest, and lower ribs.
• External Obliques: Linea alba, pubic tubercle, and anterior half of the iliac crest.
• Internal Obliques: Linea alba, pubic crest, and ribs 10-12.
• Multifidus: Spinous processes of vertebrae.
• Diaphragm: Central tendon.

MAJOR ARTERIES OF CORE MUSCLES

• Superior Epigastric Artery: Supplies the rectus abdominis.
• Inferior Epigastric Artery: Supplies the lower abdominal muscles.
• Intercostal Arteries: Provide blood flow to the obliques and transverse muscles.
• Lumbar Arteries: Supply the multifidus and surrounding structures.

NEURAL INNERVATION

• Rectus Abdominis, External Obliques, Internal Obliques, Transversus Abdominis: Innervated by the lower six thoracoabdominal nerves (T7-T11) and the subcostal nerve (T12).
• Multifidus: Innervated by the posterior rami of spinal nerves.
• Diaphragm: Innervated by the phrenic nerve (C3-C5).

TRIGGER POINT

Trigger points in the core muscles, especially in the obliques and rectus abdominis, can cause referred pain in the lower back, pelvis, or abdomen. They often result from poor posture, overuse, or inadequate core stability during physical activities.

CONCENTRIC FUNCTION

• Rectus Abdominis: Flexes the trunk, as in sit-ups or crunches.
• Transversus Abdominis: Compresses the abdominal contents, stabilising the core.
• External Obliques and Internal Obliques: Rotate and laterally flex the trunk.
• Multifidus: Extends and stabilises the vertebral column.
• Diaphragm: Contracts to enable inhalation by increasing the thoracic cavity volume.

ECCENTRIC FUNCTION

• Rectus Abdominis: Controls trunk extension during movements such as lowering the body from a crunch position.
• Transversus Abdominis: Resists abdominal distension and maintains pressure during movements like lifting.
• External and Internal Obliques: Control trunk rotation and lateral flexion, preventing excessive movement.
• Multifidus: Controls trunk flexion and prevents excessive forward bending.
• Diaphragm: Gradually relaxes during exhalation to decrease thoracic cavity volume.

ISOMETRIC FUNCTION

The core muscles work together to stabilise the spine and pelvis during static positions, such as during planks or while maintaining posture during heavy lifting. Transversus abdominis and multifidus play critical roles in maintaining tension and spinal stability.

RELATED MUSCLE – SCIENTIFIC NAMES

• Erector Spinae: Extends the spine and works with the multifidus for spinal stability.
• Quadratus Lumborum: Assists in lateral flexion of the spine.
• Psoas Major: Flexes the hip and contributes to lumbar spine stability.
• Gluteus Maximus: Supports the pelvis and lower back during movements.
• Diaphragm: Essential for breathing and core stability, coordinating with the abdominal muscles.

ANTAGONIST

• Erector Spinae: Opposes the rectus abdominis by extending the spine.
• Hip Flexors (Iliopsoas): Work against the rectus abdominis during hip flexion movements.
• Gluteus Maximus: Stabilises the pelvis in opposition to the internal obliques during trunk rotation.
• Latissimus Dorsi: Assists in upper body movements that oppose core flexion and rotation.
• Diaphragm (as it relaxes): Antagonistic to abdominal muscles during forced expiration.

COMMON INJURIES OF CORE MUSCLES

• Abdominal Strains: Overstretching or tearing of the abdominal muscles, often caused by sudden or forceful twisting or lifting.
• Hernia: A weakness in the abdominal wall that allows internal organs to protrude, typically caused by heavy lifting or overexertion.
• Lower Back Pain: Often due to weak core muscles, leading to improper spinal alignment and overuse of other muscles.
• Oblique Strain: An injury to the external or internal obliques, common in sports that involve twisting motions, like golf or tennis.
• Diastasis Recti: Separation of the rectus abdominis muscles, often occurring postpartum due to the stretching of the abdominal wall.

EXERCISES FOR CORE MUSCLES

• Plank: A static exercise that strengthens the transversus abdominis and multifidus by maintaining a rigid body position, improving core stability.
• Bicycle Crunches: Targets the rectus abdominis and obliques by performing a crunch while alternating knee-to-elbow movements, enhancing rotational strength.
• Russian Twists: Seated and rotating the torso side to side, this exercise targets the obliques and improves trunk rotation strength.
• Dead Bug: Lying on the back, alternating arm and leg movements while keeping the core engaged, improving coordination and core stabilisation.
• Superman: Lying face down and lifting arms and legs simultaneously. This exercise strengthens the multifidus and lower back muscles for spinal extension.

STRETCHES FOR CORE MUSCLES

• Cat-Cow Stretch: A dynamic yoga pose that alternates between flexing and extending the spine, stretching the rectus abdominis and multifidus.
• Child’s Pose: Stretches the lower back and abdominal muscles by sitting back on the heels with arms extended forward, promoting relaxation and core flexibility.
• Cobra Stretch: Lying face down and extending the spine upward, this stretch lengthens the rectus abdominis and opens up the chest.
• Side Bend Stretch: While standing or sitting, reach one arm overhead and lean to the opposite side to stretch the external and internal obliques.
• Seated Forward Bend: Sitting with legs extended, reaching towards the toes, stretches the lower back and engages the multifidus and hamstrings.