Core Muscles: Understanding their Anatomy and Function

The core is a family of muscles that surround the pelvis, lower back, hips, and abdomen. Together these muscles provide you with balance and stability. Having a strong core is essential to increasing your fitness and preventing injuries. When you are bending, falling, twisting, or spinning, your core muscles correct the instabilities. Thus, your core reduces the stress our movements put on the spine. A strong core reduces your risk of lower back injuries.

Muscles of the Core

Whether you are picking up a bag or pushing a grocery cart you’re core is helping you. When you hear the word core, you immediately picture six pack abs. However, there are more muscles in this muscle group than just the abs. Your core is composed of seven different muscles: rectus abdominis, external obliques, internal obliques, the transversus abdominis, multifidus, quadratus lumborum, and the lumbar erector spinae. Each of these muscles plays a different role in helping you complete your everyday movements.

Rectus Abdominis

Core muscles, rectus abdominis
The human rectus abdominis muscle1.

The rectus abdominis is the most well known core muscle. Commonly referred to as the abdominal muscle, it is the most forward facing core muscle. This muscle originates on the front of your pubic bone and attaches to your lower ribs. The rectus abdominis is a long flat muscle that extends along the whole length of the abdomen. It is a very important muscle for your overall posture and is responsible for flexing of the spine in a crunching motion. Additionally, it supports our breathing by allowing us to forcefully exhale. Finally, it acts as the protection for out internal organs.

External Obliques

core muscles, external obliques.
Muscles of the core2.

The external obliques, also referred to as the exterior oblique, is on the outer sides of our abdomen. It is the largest of the three outer abdominal muscles. This muscle starts from the 5-12 ribs, and attaches on the outside of your pelvic bone. This muscle helps us pull the chest downwards and compress the abs. Additionally, it helps us with side-bending and sideways rotation.

Internal Obliques

Core muscles, internal obleques.
lnternal obleques3.

The internal oblique muscle, or the interior oblique, is the abdominal muscle that lies below the external oblique. It starts from the base of your hip bone and attaches to the 10-12 ribs. Additionally, it attaches to the midline of the abdomen. This muscle has two major functions. Firstly, it plays a large role in helping us breath. The internal obliques helps compress the chest cavity when we exhale. Secondly, it supports the opposite external oblique muscle during side-bending. For example, the right internal oblique would contract with the left external oblique when we are bending sideways to the left.

Transverse Abdominis

core muscles transverse abdominis
Transverse abdominis4.

The transverse abdominis is the deepest of the three side abdominal wall muscles. It sits below the internal oblique muscle. This muscle starts from your hip bone and inserts on the sternum and on the midline of the abdomen. The transverse abdominis is nicknamed the corset muscle because of how it helps pull in our abdomen. Additionally, this muscle plays a key role in the stabilization of our torso and spine.


core muscles, multifidus muscle.
Multifidus muscle5.

The multifidus is a deep muscle of the back. It is a long muscle that spans the entire length of the spine. This muscle starts from the back of the pelvic bone and attaches to the spine. The length and stiffness of this muscle makes each of your vertebra work more effectively. Additionally, it helps reduces the wear and tear of the joints in our spine caused by friction from our daily activities. Finally, this muscle helps with backward extension of the spine, side-bending, and side rotation.

Quadratus lumborum

core muscles, quadratus lumborum.
The left quadratus lumborum6.

The quadratus lumborum muscle is located on the lower back. It is the deepest of all the abdominal muscles and due to its location can be considered apart of the back muscle family. This muscle originates on the back of our pelvic bone, and attaches on the back of our 12th rib and on the lumbar section of our spine. This muscle is responsible for four actions. first, it helps us when we bend to the side. Second, it plays a role when we extend our back. Third, it fixes the placement of our 12th rib when we forcefully exhale. Finally, it is responsible for allowing us to hike our hip upwards.

lumbar Erector Spinae

core muscles, erector spinae muscle.
The erector spinae muscle group7.

The seventh and final core muscle is the lumbar erector spinae. This is a group of muscles that helps to support and move our spine. It originates at the base of the thoracic vertebrae (the upper section of the spine) and attaches to the base of the thoracic vertebrae and cervical vertebrae. In addition to helping with the support of our spine, it also helps rotate and extend the spine.


The muscles of the core are the central link connecting our upper and lower body. Whether you are carrying groceries or sweeping the floor, the actions are supported by your core muscles. The core muscles are a family of seven muscles the help with our poster and provide us with balance and stability. It is important to develop these muscles to avoid injuries and prevent back pain.

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