Download Kinesiology of Exercise Muscle Groups – The Hamstrings

Kinesiology of Exercise Muscle Groups – The Hamstrings
The hamstring muscle group includes the semitendinosus, semimembranosus, and the biceps femoris. These muscles
flex the knee. The biceps femoris is the largest muscle of the hamstring group and has two heads. At the upper end
the long head is attached to the tuberosity of the ischium bone of the pelvic girdle . The short head is attached to the
middle and central area of the femur bone of the thigh. At the lower end the biceps femoris is attached to the lateral
condyle of the tibia and the head of the fibula bones of the shin. The tendon of insertion (which attaches to the bone)
forms the lateral hamstring. It is important in providing lateral stability to the knee.
The semitendinosus runs from the tuberosity of the ischium (on a common tendon with the biceps femoris) to the
upper medial condyle of the tibia. The semimembranosus also attaches to the tuberosity of the ischium at the upper
end and to the posterior medial condyle of the tibia at the lower end.
Both the semimembranosus and semitendinosus extend the thigh at the hip joint and assist in hip joint medial rotation .
Because their tendon of insertion is on the medial side of the knee joint, they are known as the medial hamstrings.
They provide lateral stability to the knee joint.
The semimembranosus and semitendinosus muscles lie side by side on the inside back of the thigh . They are much
thinner than the biceps femoris and have a unique relationship. The semimembranosus has a long upper tendon and a
short lower tendon, and the semitendinosus has a short upper tendon and a long lower tendon. Because of this, the
muscle masses of each of these muscles are in line with one another and form a cylindrical mass. Therefore, when
well-developed they appear as one long muscle.
The hamstring muscle is a two-joint muscle having an action at the knee and hip joints. These actions can be
separated - in other words, the knee can act independently of the hip joint and the muscles can act to produce
movement in only one of the joints. It is interesting to note that when both ends of the muscle act simultaneously, the
contraction of the muscle is weaker than when only one end is involved. The hamstring muscle can also be contracted
in sequence, as for example in the glute-ham-gastroc raise when the hip end contracts first followed by the knee end
while the hip end remains under isometric contraction.
Legs (Upper, Posterior)
Biceps Femoris
Semimembranosus
Semitendinosus
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Kinesiology of Exercise ebooks based on the work of Dr. Michael Yessis
Volume 1 - The Ankle Joint
Volume 2 - The Knee Joint
Volume 3 - The Hip Joint and Pelvic Girdle
Volume 4 - Combination Exercises
Volume 5 - The Spine: The Abdominals
Volume 6 - The Spine: Lower Back Muscles
Volume 7 - The Shoulder Joint
Volume 8 - The Elbow Joint
Volume 9 - The Radio-Ulnar Joint
Volume 10 - The Wrist Joint
Volume 11 - Combined Shoulder and Arm Exercises
Bonus 1 – Introduction to Biomechanics
Bonus 2 – Training Factors
Bonus 3 – Training Recommendations
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Copyright © 2016 KinX Learning Inc. All Rights Reserved