Musculoskeletal System –Lower Limb

Movements and Muscles

By Kareem Magar

Introduction – Lesson Agenda Lower Limb components and function Movements and Muscles of the Hip Joint-Flexion, Extension, Abduction, Adduction, Medial and Lateral Rotation. Movements and Muscles of the Leg/Knee-Flexion, Extension, Medial Rotation, Lateral Rotation Movements and Muscles of the Leg/Foot (includes ankle)-Dorsiflexion, Plantarflexion, Eversion, Inversion Walking, not as easy as you think! (The GAIT Cycle)

Brief Introduction on Lower Limb Components and Function The Lower Limb consists of four major parts which includes:

- The hip bones (help to make up the pelvic girdle, 2 hip bones + sacrum) - The thigh (between hip and above the knee) - The leg (between the start of the top of the knee and above the foot) - The foot It’s main function and specialization is to support the weight of the upper body, adapt to

gravity and locomotion (moving from one place to another).

Interesting Facts It contains the strongest bone in the body, the femur which is between the hip and

knee, serving as an attachment point for all the muscles (22 in total originating from the femur) that exert their force over the hip and knee joints.

The ligament that helps to connect the femur to the hip bone is known as the iliofemoral ligament, the strongest ligament in the body.

It also contains the largest and one of the strongest muscles known as the gluteus maximus located on the human buttocks, as well as the longest muscle, the sartorius muscle.

Contains 54 muscles total from the hip to the foot, many of which are used together to conduct one movement and in some scenarios movements not as easy to do on its own such as abducting your digiti minimi (for example moving your right small toe to the right).

Movements and Muscles of the Hip Joint/Thigh – Flexion

Flexion

Primary Hip Flexor is the iliopsoas (psoas major and iliacus).

Iliopsoas also involved in anterior pelvic tilt and trunk flexion with reversed origin. What does this mean?

Other weak hip flexors that assist the iliopsoas include the Sartorius, Pectineus, Tensor Fascia Latae and Rectus Femoris.

Movements and Muscles of the Hip Joint/Thigh – Extension

Extension – Role in stance, forward propulsion, pelvis stabilization.

Main extensors are the gluteus maximus (most powerful hip extensor) and the hamstrings.

Hamstrings include the semitendinosus, semimembranosus and biceps femoris.

The Hamstrings are also involved in flexion of the leg (knee).

Movements and Muscles of the Hip Joint/Thigh – Abduction

Abduction- The thigh is pulled laterally away from the midline

Main Hip Abductors: Gluteus Medius (larger of the two muscles) and Gluteus Minimus (smaller muscle). These muscles keep the hips levelled when walking, running, etc (when weight is placed on that leg).

When these muscles are weakened, hips are no longer even.

These two muscles are assisted by the piriformis muscle, quadriceps femoris (rectus femoris part) and tensor fascia latae.

Movements and Muscles of the Hip Joint/Thigh – Adduction

Adduction- The thigh moves medially toward the midline. Also keeps head of femur in the acetabulum (to help increase hip stability in conjunction with abductors).

Main Adductor muscles: Adductor Longus, Adductor brevis, Adductor Magnus and Gracilis are the powerful hip adductors.

Assisted by pectineus.

Movements and Muscles of the Hip Joint/Thigh – Medial and Lateral Rotation

Medial Rotation- brings the knee and foot medially.

Generally a weak movement where all muscles involved have different primary functions.Medial Rotation Muscles: Gluteus medius and minimus, supported by the adductors (longus, magnus, gracilis), tensor fascia latae, semitendinosus and semimembranosus Lateral Rotation- moves the knee and foot

laterally.Lateral Rotation Muscles: Gluteus maximus is most powerful, assisted by 6 muscles which include piriformis, obturator internus and externus, the gemelli (superior and inferior), and quadratus femoris.The six muscles are also stabilisers of the hip joint (steady the head of the femur into the acetabulum).

Muscles of the Hip Joint/Thigh – Summary

Compartments of the Thigh The thigh is split into different compartments which helps to group muscles

and specific movements.

Movements of the Leg/Knee – Flexion and Medial/Lateral Rotation

Flexion- Flexion of the leg is flexion at the knee. (Only slight rotation can occur at the knee joint)

Main Flexor Muscles: Hamstrings which include semitendinosus, semimembranosus, biceps femoris).

Other Weak Knee Flexors: Sartorius, Gracilis, Gastrocnemius and Deep popliteus.

Biceps Femoris flexes the knee and laterally rotates knee slightly when flexed.

Semimembranous and Semitendinous flex knee and medially rotate it.

Sartorius and Gracilis also help to medially rotate the knee.

Movements of the Leg/Knee – Extension Extension - Extension of the leg is extension at the knee. Main Extensor Muscles: Quadriceps (Rectus Femoris, and Vastus

Lateralis, Vastus Medialis, and Vastus Intermedius).

Genu Valgum and Genu Varus Genu valgum is a clinical term describing ‘knocking of the knee’.

The medial collateral ligament on the knee limits this movement, so a valgus stress is placed on the knee to test the integrity of this ligament.

Genu varus is the clinical term for "bowleg". The lateral collateral ligament limits this movement, so a varus stress is placed on the knee to test the integrity of this ligament.

The knee diagram on the right shows the different components that keeps the knee intact including ligaments and meniscus (you will learn about this in a later presentation!)

Movements of the Ankle and Foot - Dorsiflexion

Dorsiflexion– flexion of the foot in an upward direction where the toes are brought closer to the shin. It could be considered "true" extension at the ankle.

Main Dorsiflexion muscle- Tibilias Anterior Minor Dorsiflexion muscles- Extensor hallucis longus,

Extensor digitorum longus and Fibularis tertius (these three muscles are also involved in extension of the digits/toes).

Movements of the Ankle and Foot - Plantarflexion

Plantarflexion– Movement of the foot that flexes the foot or toes downward toward the sole. It could be considered "true" flexion at the ankle.

The posterior (flexor) compartment has superficial and deep components; the superficial group contains the two large plantarflexors.

Main Plantarflexor muscles- Gastrocnemius (two joint muscle) and Soleus.

Minor Plantarflexor muscles- Popliteus (involved in knee flexion as mentioned before), Tibialis posterior (also inverts foot), Flexor hallucis longus, Flexor digitorum longus (these two muscles are also involved in flexion of the digits/toes) and Plantaris.

Continued Plantaris is a very small member of this group,

and is significant only because the long tendon snaps easily when overstretched.

Movements of the Ankle and Foot – Inversion and Eversion

Inversion– Movement that tilts the sole of the foot towards the midline of the body.

Main Inversion muscles- Mainly Tibialis anterior, assisted by tibialis posterior.

Eversion- Movement that tilts the sole of the foot away from the midline of the body.

Main Eversion muscles- Fibularis Longus, Fibularis Brevis and Fibularis Tertius

NOTE: Fibularis muscles also known as Peroneus muscles, so you may see the names Peroneus longus, brevis, etc instead in some resources you use!

Continuation of Compartment Below the Knee to the Foot

Walking, not as easy as you think! (The GAIT Cycle)

The most complex muscle movement set in the body. Don’t worry, this is just for reference, you do not need to learn this….yet!

Thigh/Hip Movements Leg/Knee

Movements

SUMMARY ON MOVEMENTS

SUMMARY ON MOVEMENTS CONTINUED Leg and foot (ankle)

movement

Lower Limb Movement and Muscle Notes In Detail

Different colours indicate that type of movement

Lower Limb Movement and Muscle Notes Continued

Useful Online Resources 3D Anatomy Model:

https://www.zygotebody.com/zb#nav=1.82,90.72,38.85,0,0,0,0&sel=p:;h:;s:;c:0;o:0&layers=0,0,7500,0,0,10000,10000,10000,10000,10000,10000 (make a free account to use)

Other models and information of everything anatomy.http://www.getbodysmart.com/ap/muscularsystem/menu/menu.html