8.7: Muscles

Most muscles in our body operate voluntarily. Some muscles are involuntary like swallowing and breathing (controlled without conscious thought). For the purposes of our learning here, we will only discuss a few muscles that are voluntary skeletal muscles – the muscles that move your joints. There are different types of muscles, and these include power muscles, rotator cuff muscles, foot, leg, and ankle muscles, calf muscles, oblique muscles, hip to knee muscles, hip muscles, deep rotators in the hip, inward rotators in the hip. There are more than listed below, but this reasonable scope for our learning material will provide a succinct look at some of the main muscles we use as dancers.

Power Muscles

• Pectoralis Major
• Deltoid Group
• Latissimus Dorsi

Figure 8.13. Power Muscles

(OpenStax College. (2017, Nov 23). File:1119 Muscles that Move the Humerus b.png. https://commons.wikimedia.org/wiki/File:1119_Muscles_that_Move_the_Humerus_b.png)

Rotator Cuff Muscles

• Supraspinatus
• Teres minor
• Infraspinatus
• Subscapularis

Foot, Leg, Ankle Muscles

The anterior muscles that dorsiflex the foot/ankle include the extensor digitorum longus. The extensor digitorum longus is important when a dancer wishes to achieve a winged, or beveled foot, which is considered correct and aesthetically pleasing in techniques such as ballet and jazz dance.

Figure 8.14. Extensor Digitorum Longus

(Polygon data were generated by Database Center for Life Science (DBCLS). (2019, Nov 27). Extensor Digitorum Longus muscle. https://commons.wikimedia.org/wiki/File:Extensor_digitorum_longus_muscle_-_anteriror_view.png)

Calf Muscles

The posterior muscles that plantar flex the foot/ankle include the gastrocnemius (superficial) and the soleus (inner, deep calf muscle). Pointing the foot and going into relevé are examples of plantar flexion.

Figure 8.15. The anatomy of the calf muscles

(Source: Injurymap; https://injurymap.com/free-human-anatomy-illustrations/)

Oblique Muscles

Your oblique muscles are a key component of the abdomen as they let you bend sideways and twist your trunk, moving in the transverse plane. They also help somewhat with breathing. The top of the obliques connects with the ribs while the lower end connects with the hip bone.

Hip to Knee Muscles

The Quadricep muscle group is anterior (in the front). The Hamstring muscle group is posterior (in the back). The Sartorius is the longest muscle in the human body. It wraps around the femur and attaches to the Anterior Tibia. The knee only moves on the Sagittal Plane.

Figure 8.16. The Sartorius Muscle

(BodyParts3D/Anatomography. (2014, July 7). Rotating image of the anatomy of muscles of the upper leg. https://commons.wikimedia.org/wiki/File:Sartorius_3D.gif)

Hip Muscles

• The Iliopsoas is comprised of the psoas and the iliacus muscles.
• The psoas starts in the spine and meets at the iliacus on the crest of the ilium.
• The iliopsoas is the only hip flexor muscle that is deep in the abdominal.

Deep Rotators in the Hip

6 deep outward rotators

• Piriformis
• Gemellus inferior
• Gemellus superior
• Obturator internus
• Obturator externus
• Quadratus femoris

Figure 8.17. Representation of some hip muscles used in dance that can become strained with improper technical training. The hip flexors are a muscle group responsible for flexing the hip and raising the legs, and depicted on the right side, the psoas major is strained (InjuryMap. (2019, April 25). Medical illustration of the bones and muscles of the pelvic region, with a focus on the hip flexors, a muscle group responsible for flexing the hip and raising the legs. On the right side the psoas major is strained. https://commons.wikimedia.org/wiki/File:Hip_flexor_strain.svg)

Inward Rotators of the Hip

• Gluteus Medius
• Gluteus Minimus
• Tensor Fasciae Latae (TFL)