Lesson 3 Ecorche

The hip and thigh

-The fatty pads of the knee

-The Adductor group

-The Quadriceps group

-The Hamstrings group

-The Sartorius

-The Gluteus medius

-The Gluteus maximus

-The Tensor fascia Latae

-The Iliotibial Band


Knee fatty pads

-These form noticeable masses below on either side of the patella, making the knee bulkier and squarer 

Colour on your model: 

Cream 


Attachments on the Femur

Left: Posterior surface

Right: Anterior surface

These diagrams from an early copy of Gray's Anatomy can be particularly useful for understand how the muscles of the thigh wrap around the femur. (These diagrams are among many available through Wikipedia because the edition is now out of copyright.  Wikipedia is often a great resource for anatomical information)

 


Grouped Adductors

Grouped adductors (Gracilis, Adductor Magnus, Adductor Longus, Adductor brevis, Pectineus)    

 

-Think of the adductor group as a thick volume that begins at the pubis and ischial tuberosities (sitting bones) and fans out onto the inside of the femur, right down to the inside of the knee    

-The hamstrings muscles originate behind the adductor group, on the posterior surface of the ischial tuberosities, thus limiting the attachment of the adductors to the inferior surface of these bones.  That is to say: in a standing figure with a neutral pelvis, the very lowest point on the sitting bones will be furthest back your attachment for the Adductor mass can go.

 

Origin:

From top of pubis to bottom of ischial tuberosity    

 

Insertion:

Posterior face of femur (on the Linea aspera) and the superior surface of the medial side of the head of the femur (the Adductor tubercle)

The Gracilis inserts onto the medial surface of shaft of the tibia, beside the Sartorius and medial part of the hamstrings group, which together are sometimes refered to as the “goose's foot” as it is three tendons webbing out together     

 

Colour on your model:

Blue


Quadriceps

Quadriceps Group (vastus lateralis, v. Intermedius, v. medialis, Rectus femoris)    

-As the name suggests, there are four muscles in this group, all of which insert via a common tendon onto the patella, which is then anchored to the tibia via the patella ligament    

-The Vastus Medialis is most inferior (lowest) of the group, followed by the Vastus Lateralis and V. Intermedius, with the rectus femoris being the most superior.  This arrangement contributes to the characteristic “flame shape” pattern of the the thigh.

-The “Band of Richer” crosses the vastus medialis and creates a characteristic channel here, most visible when the knee is locked and the vastus medialis is relaxed

-As the knee is bent, the shelf of the superior surface of the tibia slides around the curved surface of the end of the femur, and the Patella, onto which the common Quandriceps tendon inserts is pulled downwards with it.  As the Patella is pull around the knee, the mass of the quadriceps is pull down with it, shifting the relationship of the masses of the front and back of the knee (see the diagrams labeled ""Generalised patterns of the thigh" at the bottom of this page).

 

Origin:

-Three of the four muscles orginate along the femur - the Vastus Lateralis, V. Intermedius, V. Medialis    

-The fourth muscle, the Rectus Femoris, originates at the front of the pelvis, at and near the Anterior Superior Iliac Spine (ASIS)

 

Insertion:

The four muscles of the Quadriceps group insert onto the patella via the common Quadriceps tendon.  The Patella is anchored to the Tibia via the Patellar ligament, which inserts on the Tuberosity of the Tibia (the lump at the top of the shin).      

 

Colour on your model:

Green


Sartorius

-The sartorius lies in the diagonal valley between the masses of the adductors and the quadriceps.            

-It is like a belt, flat and shallow, and in terms of observable surface anatomy, is usually only visible as the valley between the leg masses listed above, and sometimes at the top.  It also contributes volume to the convexity of the inner knee that flows into the depression of the shin.

 

Origin:

Inferior surface of the Anterior superior iliac spine (ASIS) of the pelvis.

 

Insertion:

Below the medial condyle of the Tibia - with the insertions of the Gracilis and medial part of the hamstrings (Semitendinosus) to form the “Goose’s foot” that lays on the inside of the top of the shin (upper anteriomedial surface oof the tibia)

 

Colour on your model:

Red


Surface forms of the Sartorius

In the image to right, the model is lean enough to reveal the edge of the Sartorius up near his hip.

In the right image, the approximate path of the sartorius along the groove between the Adductor group and the Quadriceps group is shown.


Hamstrings Group

Hamstrings Group (Biceps femoris, Semimembranosus, Semitendinosus)    

-They lie side by side for most of the length down the femur and then divide and insert onto either side of the bones of the lower leg at the knee, providing a space for the gastrocnemius (calf muscle) to insert between.

-They emerge from under the gluteus maximus that lies diagonally across them

-The insertions on or towards the back of the knee mean the the tendons lie across the back surface of the joint, more than the side

-The medial hamstring tendons lie further towards the mid line of the knee than the lateral ones- this contributes to the greater bulk of the medial part of the knee, while providing space for the Soleus and Gastrocnemius to sweep out laterally as they descend.

-The hamstrings group is in two parts, both of which begin on the rear face of the ischial tuberosities of the pelvis (sitting bones.)      

 

Origin:

Most of the hamstring group: Posterior face of ischial tuberosity

Exception of: Biceps femoris short head: Middle third of the Linea aspera (posterior surface of femur)    

 

Insertion:

The lateral hamstring group attaches to the head of the fibula    

The medial hamstring group attaches to the back of the head of the tibia and the rear of the inside of the shaft of the tibia near the head (at the Goose’s foot).

 

Colour on your model:

Orange


Gluteus Medius

-The Gluteus Medius is the mass of muscle hanging from the iliac crest to the side of and higher than the Gluteus Maximus     

-An important stabilising muscle, as it engages on a standing leg side, it will lift the relaxed side up.  On dancers and athletes, who are running and jumping, these muscles are often quite developed, contributing to a squaring of the buttock form.

-See the diagram below the Gluteus Maximus section (next muscle on this page) for how the G. medius contributes to the overall surface form of the buttocks.

Origin:

Outside of the iliac crest, beginning right up under the lip of the crest    

 

Insertion:

Top and side surfaces of the Greater Trocanter    

 

Colour on your model:

Orange


Gluteus Maximus

-The largest of the Gluteal muscles, it provides most of the mass of the buttocks    

-See the diagram below for some generalisations of how this muscle contributes to the overall surface form of the buttocks.

Origin:

Posterior inferior surface of the sacrum and coccyx, posterior region of iliac crest    

 

Insertion:

Posterior surface of the shaft of the femur, about the top 1/4 to 1/3, and also the Ilio-tibial band (see section on the Ilio-tibial Band below the section on Tensor Fasica Latae on this page)    

 

Colour on your model:

Red


General buttock form

Notice how the form of the Gluteus medius and Gluteus maximus radiating around the axis of the Greater trocanter creates spiralling upwards and inwards movement. 

Also notice that the fold where the buttock meets the back of the thigh does not exactly follow the shape of the Gluteus maximus - fat pads under this muscle create a squarer (more horizontal  shape.


Tensor Fascia Latae

-The Tensor of the Fascia Latae and the Sartorius descend from the anterior iliac crest, like slightly parted curtains that the Rectus Femoris emerges from

-The Tensor fascia latae makes an important contribution to the form of the pelvis: it provides “front corners” for this mass.  This is often an important plane break to observe.    

-Along with the Gluteus maximus and Gluteus medius, these three muscles make an inverted horseshoe around the Greater Trocanter of the Femur.

Origin:

Lateral surface of the anterior superior iliac spine (lateral to the origin of the sartorious)

 

Insertion:

Iliotibial tract (ITB), anteriorly to the greater trocanter of the femur

 

Colour on your model:

Purple


TFL plane break and the Frustum of the pelvis

The pelvis can be a difficult area to make sense of, often more so than the ribcage mass.  This is because of the amount of soft tissue that surrounds the bony, structural part of the pelvis, and that the upper part of the thigh is actually part of the pelvis volume (as it is conceived here) - in other words the volumes overlap conceptually.

 

Several bony landmarks remain visible all the time though, and these can be used to work out what is going on.  These are:

- The anterior superior iliac spines (ASIS) on the front or the posterior superior iliac spines (PSIS) on the back

- The pubic bone/ symphysis pubis (just below where the line of the pubic hair is) (Note that the crotch is below this point)

- The greater trocanters (These points do move relative to the pelvis, but in most poses will be located approximately in line with the pubic bone as in the diagram above). 


Ilio-Tibial Band

-This is a thickenning of the fascia latae (the heavy connective tissue of the side of the thigh)

-It provides insertion points for the Tensor Fascia Latae as well as the Gluteus maximus    

-It is not visible in the living model at the topof the     leg, but can be quite pronounced in a thin or athletic model adjacent to the inferior part of the Vastus lateralis of the Quadriceps.  Together, there is a characteristic L-shaped depression when the quadricep contracted, the ITB notch (see diagram below labeled "ITB Notch").

 

Insertion:

Inserts onto the Lateral condyle of the Tibia    

 

Colour on your model:

Blue


ITB Notch

These images of an athletic male leg reveal the L-shaped notch between thebottom part of the Vastus lateralis and the front edge of the Ilitotibial band (ITB)


Generalised patterns of the thigh

We will go into more detail about the patterns of the leg as a whole in the next lesson, when the lower leg has been added.  This is because the patterns flow along the length of the whole leg so they are difficult to discuss without the lower leg being completed.

Therefore, for this lesson, I will leave you with these simplified diagrams the show how the thigh counterbalance changes between a flexed and an extended posture.