CORE MUSCLE GROUPS
PILATES-Kinesiology #347 - Mission College/Carla Lubow: Instructor
The core is a muscular system that provides the force to stabilize and move body segments. The
core could be considered the link between the upper and lower extremities. They also assist in
the breathing process, especially during exhale when they help force air out of the lungs by depressing
the thorax. Identifying the various muscles that make up the core and understanding how they
function can facilitate your own strength building regimen.
Abdominals: The abdominal muscles are a key part of the core and can be broken down into: the
abdominal muscle group--or abs, as they commonly are called--as comprising the rectus abdominus, the
transverse abdominus and the internal and external obliques. Abdominal muscles are special because they
provide postural support. They also play a role defining the form. For example, the most superficial
abdominal muscle, the rectus abdominus, gives the 6-pack ab effect when it is worked to a high degree of
fitness. More structurally, the deeper and closer to the spine the particular abdominal muscle is, the more
effect over body posture it will have, and this often contributes significantly to a healthy back. From deep
to superficial the abdominal muscles are:
Transversus Abdominis - The Deepest Ab Muscle:
The transverse abdominus muscle is the deepest of the 6 ab muscles. It can have a tremendous effect on
body posture. You cannot touch this muscle from the outside. It wraps around the torso, creating an effect
similar to a back support belt.
The Internal Oblique Muscles - Strong Effect on Posture:
The internal obliques are a pair of ab muscles, residing on each side of the torso. They are the next
deepest, after the transversus. Just like the transversus, they affect body posture tremendously, only
slightly less, because of their more superficial position. The internal obliques are involved in, among
other things, rotation and lateral flexion of the spine.
External Obliques:
The external obliques are another pair of ab muscles that are located on either side of the torso. The
external obliques are more superficial than the transversus and the internal obliques. Consequently the
external obliques have less effect (but certainly not none) on body posture. Like the internal obliques, the
external obliques are involved in, among other things, rotation and lateral flexion of the spine.
Rectus Abdominus:
The rectus abdominus muscle is the most superficial of the abdominal muscles. It and the external
obliques affect body posture, just not as much as the deeper interal obliques and transversus. The rectus
abdominis muscle is responsible for the 6-pack ab look in very fit people.
Hips: The lumbo-pelvic-hip area is a complex conglomeration of 29 muscles that attach to the core.
This musculature is responsible for stabilizing, transferring, reducing and producing force when your feet
are in contact with a solid surface.
Back: The muscles of the back--such as the erector spinae, quadratus lumborum, paraspinals and the
psoas major, to name a few--are included in the muscles of the core.
Erector Spinae is not just one muscle, but a bundle of muscles and tendons. It is paired and runs more or
less vertically. It extends throughout the lumbar, thoracic vertebral column.and cervical regions, and lies
in the groove to the side of the vertebral column.
Quadratus Lumborum is irregular and quadrilateral in shape, and broader below than above. It assists
in the rotation of your torso; in lateral flexion of your torso (i.e., side-bending); and when your left and
right quadratus lumborum muscles contract at the same time, they assist in back extension (i.e.,
straightening your back when you stand up, or perform a good morning lift).
Paraspinal Muscles are the muscles that run next to, and roughly parallel with, the spine. They consist of
many small muscles that are attached to the vertebrae and control the motion of the individual bones, as
well as assist with the larger motions of the whole trunk, or core, area. Together with other muscles, they
help support the spine and keep it in proper alignment. They also limit the range of motion of the spine,
which helps to prevent injuries to the disks and spinal cord caused by overextension.
The Psoas Major is a large muscle that attaches at the bottom of the thoracic spine and along the lumbar
spine, then runs through the pelvic bowl, down over the front of the hip joint, and attaches at the top of
the femur (thigh bone). It is the only muscle connecting the spine to the leg. These muscles are
responsible for supporting postures, creating motion, coordinating muscle actions, and for maintaining
stability.
Core Responsibility
Regardless of the type of movement or activity, the center of the body, or core, is responsible for the
process and outcome. Based on the overall responsibility of the musculature, the need for appropriate and
adequate training for your core should be a fundamental part of your exercise program.