Together, these primary muscles of the core make up “the natural belt” that stabilizes the lower back. Tese muscles must be engaged for a stable upper body. Te following muscles and muscle groups also constitute part of the core. Tey play an important role in stabilizing and controlling movements of the upper body, and therefore
play an essential role in balancing movements. ■ Erector spinae: Tis muscle group is responsible for extending the vertebrae, or back extension.
■ Latissimus dorsi: Tis muscle is responsible for arm extension, adduction (lateral flexion), and rotation.
■ Trapezius: Tis muscle primarily affects movements of the arms and shoulders, but can affect movements of the thoracic and cervical spine.
■ Longissimus thoracis: Tis muscle is primarily responsible for movements of the head and extension of the thoracic vertebrae.
Te pelvis is part of the upper body. Te gluteus maximus, among other muscles, helps stabilize both the pelvis and upper body. Many of the muscles in the pelvic area can also be described as part of the core.
FIGURE 4.15: Primary muscles of the pelvis and hip joint
TENSOR FASCIAE LATAE
ILLIOPSOAS SARTORIUS
RECTUS FEMORIS
Pelvis and Hip Joint
Muscles around the pelvis serve to control the hip joint, which moves in all directions in a complex relationship of muscular actions and range of motion. For the sake of simplicity, individual muscles are grouped into categories of movement.
Extension Tese muscles play an important role in all extension movements, and in managing and
resisting pressure coming from the snow. Tey also help control the rate of flexion. ■ Gluteus maximus (butt) ■ Hamstrings (back of thigh)
Flexion Tese muscles play an important role in all flexion movements, and in managing pressure.
Tese muscles also help control the rate of extension. ■ Iliopsoas (front of thigh through top of pelvis) ■ Sartorius (inner thigh) ■ Rectus femoris (part of the quadriceps muscle)
TheSnowPros.org CHAPTER 4: BIOMECHANICS OF SKIING 67
ADDUCTOR MUSCLES
GLUTEUS MEDIUS
GLUTEUS MINIMUS
GLUTEUS MAXIMUS
BICEPS FEMORIS
HAMSTRINGS
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