Core Muscles

The core muscles are the central group of muscles in the body that aid in stabilizing the spine, pelvis, and trunk during movement. These muscles are crucial for maintaining posture, balance, strength, and overall bodily function. Regardless of whether you’re an athlete, an office worker, a fitness lover, or in recovery from an injury, having a strong core is vital for everyday tasks and physical performance.

A robust core enhances athletic performance and lowers the likelihood of injuries, particularly in the lower back. Core muscles play a role in nearly every body movement, including walking, bending, lifting, and twisting. Knowing the anatomy and function of core muscles can enable you to train them efficiently and boost your overall health.

The muscles that surround the abdomen, pelvis, lower back, and hips are known as core muscles. Together, these muscles support the spine and keep the body stable when moving.

Although the abdominal “six-pack” muscles are frequently the only muscles connected with the core, the core actually consists of some deep and superficial muscles that support stability and strength.

Anatomy of Core Muscles

The complex collection of muscles that surround the lower back, hips, pelvis, and abdomen is known as the core muscles. Together, these muscles assist movement, preserve posture, stabilize the spine, and transfer force between the upper and lower bodies. Almost all physical activities require the core, which serves as the body’s primary support system.

Depending on where they are located and what they do, core muscles are separated into deep and superficial categories.

Layers of Core Muscles

The core muscles can be categorized into:

1. Deep Core Muscles

These muscles are located close to the spine and provide stability and support.

Main Deep Core Muscles:

• Transverse Abdominis
• Multifidus
• Diaphragm
• Pelvic Floor Muscles

2. Superficial Core Muscles

These muscles are larger and responsible for movement and power generation.

Main Superficial Core Muscles:

• Rectus Abdominis
• External Obliques
• Internal Obliques
• Erector Spinae
• Quadratus Lumborum

1. Rectus Abdominis

The rectus abdominis is the most recognizable abdominal muscle, often called the “six-pack” muscle.

Location

• Extends vertically along the front of the abdomen
• Runs from the pubic bone to the ribs and sternum

Origin

• Pubic crest
• Pubic symphysis

Insertion

• Xiphoid process of the sternum
• Costal cartilages of ribs 5–7

Nerve Supply

• Thoracoabdominal nerves (T7–T12)

Functions

• Flexes the trunk
• Assists in forced expiration
• Stabilizes the pelvis
• Supports posture

2. Transverse Abdominis

The transverse abdominis is the deepest abdominal muscle.

Position

• Located beneath the internal oblique muscle
• Wraps horizontally around the abdomen

Origin

• Thoracolumbar fascia
• Iliac crest
• Lower six ribs
• Inguinal ligament

Insertion

• Linea alba
• Pubic crest

Nerve Supply

• Thoracoabdominal nerves
• Iliohypogastric nerve
• Ilioinguinal nerve

Blood Supply

• Intercostal arteries
• Deep circumflex iliac artery

Functions

• Stabilizes the lumbar spine
• Compresses abdominal contents
• Increases intra-abdominal pressure
• Supports posture

3. External Oblique

The external oblique is the largest superficial lateral abdominal muscle.

Position

• Located on the sides of the abdomen
• Superficial to internal oblique

Origin

• External surfaces of ribs 5–12

Insertion

• Iliac crest
• Linea alba
• Pubic tubercle

Fiber Direction

• Downward and medially

Nerve Supply

• Thoracoabdominal nerves

Blood Supply

• Lower posterior intercostal arteries

Functions

• Contralateral trunk rotation
• Trunk flexion
• Side bending
• Abdominal compression

4. Internal Oblique

The internal oblique lies beneath the external oblique.

Position

• Middle abdominal muscle layer

Origin

• Thoracolumbar fascia
• Iliac crest
• Inguinal ligament

Insertion

• Lower ribs
• Linea alba
• Pubic crest

Nerve Supply

• Thoracoabdominal nerves
• Iliohypogastric nerve
• Ilioinguinal nerve

Blood Supply

• Lumbar arteries
• Deep circumflex iliac artery

Functions

• Ipsilateral trunk rotation
• Lateral flexion
• Core stabilization

5. Multifidus

The multifidus is a deep spinal stabilizing muscle.

Position

• Deep to erector spinae
• Along the vertebral column

Origin

• Sacrum
• Transverse processes
• Mammillary processes

Insertion

• Spinous processes of vertebrae

Nerve Supply

• Dorsal rami of spinal nerves

Blood Supply

• Lumbar arteries

Functions

• Stabilizes vertebrae
• Controls spinal movement
• Supports posture

6. Erector Spinae

The erector spinae group consists of:

• Iliocostalis
• Longissimus
• Spinalis

Position

• Runs vertically along the spine

Origin

• Sacrum
• Iliac crest
• Lumbar vertebrae

Insertion

• Ribs
• Cervical vertebrae
• Skull

Nerve Supply

• Posterior spinal nerves

Blood Supply

• Posterior intercostal arteries
• Lumbar arteries

Functions

• Extends spine
• Maintains upright posture
• Assists side bending

7. Quadratus Lumborum

The quadratus lumborum is a deep posterior abdominal wall muscle.

Position

• Between the iliac crest and the 12th rib

Origin

• Iliac crest
• Iliolumbar ligament

Insertion

• 12th rib
• Lumbar transverse processes

Nerve Supply

• T12–L4 spinal nerves

Blood Supply

• Lumbar arteries

Functions

• Lateral trunk flexion
• Pelvic stabilization
• Rib stabilization during breathing

8. Diaphragm

The diaphragm is the main respiratory muscle and an essential component of the core.

Position

• Separates the thoracic and abdominal cavities

Parts

• Sternal part
• Costal part
• Lumbar part

Origin

• Xiphoid process
• Lower ribs
• Lumbar vertebrae

Insertion

• Central tendon

Nerve Supply

• Phrenic nerve (C3–C5)

Blood Supply

• Pericardiophrenic artery
• Musculophrenic artery

Functions

• Inspiration
• Core stabilization
• Intra-abdominal pressure regulation

9. Pelvic Floor Muscles

Main Muscles

• Levator ani
• Coccygeus

Levator Ani Components

• Pubococcygeus
• Puborectalis
• Iliococcygeus

Position

• Bottom of the pelvic cavity

Nerve Supply

• Pudendal nerve

Blood Supply

• Internal pudendal artery

Functional Roles of Core Muscles

1. Spinal Stability:
   Ensures proper alignment of the vertebrae.
2. Posture Control:
   Maintains an upright and balanced body position.
3. Force Transfer:
   Facilitates the transfer of power between the upper and lower body.
4. Balance and Coordination:
   Aids in maintaining stability during movement.
5. Breathing Support:
   Collaborates with the diaphragm in the process of breathing.
6. Protection of Internal Organs:
   Offers support and safeguards abdominal organs.

Core strengthening exercise

You must focus on strengthening both the smaller, deep (Local) muscles and the outer (global) muscles. All these muscles work together to help stabilize your spine and pelvis, which in turn reduces low back pain, stabilizes your spine, and prevents injuries.

• Abdominal crunch
• Bridge
• Single-leg abdominal press
• Double-leg abdominal press
• Quadruped
• Modified plank
• Side plank
• Opposite arm and leg raise

1. Abdominal crunches

FAQs

References

• Nitesh Dhameliya. (2023). List of Core muscles: Major, Minor Muscles List, Function. Mobile Physiotherapy Clinic. https://mobilephysiotherapyclinic.in/list-of-core-muscles/
• Turetsky, L., & Turetsky, L. (2023, November 1). 6 Exercises to strengthen lower back and core muscles. Back Intelligence (Creators of PostureFlow App). https://backintelligence.com/exercises-to-strengthen-lower-back/
• Neumann DA.
  Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation and Research. 4th Edition. St. Louis: Elsevier; 2024.
• Kisner C, Colby LA, Borstad J.
  Therapeutic Exercise: Foundations and Techniques. 8th Edition. Philadelphia: F.A. Davis; 2023.
• Magee DJ.
  Orthopedic Physical Assessment. 7th Edition. St. Louis: Elsevier; 2021.
• MedlinePlus – Exercise and Physical Fitness