Lesson 1 Basic Ecorche 

Activity 2

Summary

- Filling in abdominal cavity

  1. Inguinal ligament 
  2. Underlying volume of abdominal cavity
  3. Internal Oblique

- The inner neck volumes 

  1. Plane under jaw
  2. "Inner Neck Volume" group

  3. Throat


1. Inguinal Ligament

-Runs from the Anterior Superior Iliac Spines to the top surface of the pelvis beside the Symphysis Pubis

-It provides an attachment for the adominal muscles.

- Notice the triangular shape it defines between the bony landmarks of the ASIS and pubic bone - these points are critical for orienting the pelvis when drawing.

- From a practical perspective on the small figures in this course, it is probably difficult to sculpt them in, and they are largely hidden by abdominal muscles.  However, it is important to know that they are there and the function they serve.

-Two muscles that flex the thigh (bring the knee towards the chest) the Iliacus and Psoas Major pass under the inguinal ligament as they connect the pelvis and lumbar spine to the femur.  This course does not include sculpting these muscles because they are not distinct in the surface anatomy.


2: The underlying volume of the abdominal cavity

-In this section, you will be adding clay to the inside of the ribcage, filling out the volume to allow the surface anatomy to be added.  The anatomical forms that are subsumed by this volume include:

-The viscera - the internal organs and tissues

- The internal and external intercostal muscles (between the ribs - note the intercostalsreach about halfway out on each rib - not projecting outside the ribcage.

-The Transversus abdominis (the deepest level of the abdominal muscles).  This muscle causes the form seen in the diagram of the abdominal region, with the body of the muscles on the sides of the region and a sheet of connective tissue stretching across between them.  In the centre is the Linea alba and on that line the umbilicus (belly button).

-The Quadratus lumborum, filling out the space on the dorsal (back) surface of the body between the 12th (very bottom) rib and the pelvis.

-Various other small muscles on the sides of the vertebral column.

 

- Note that the volume of the mass we are making extends about halfway to the outer surface of the pelvis and ribcage.

- Note also the projection of this form, swelling out from the ASIS (Anterior Superior Iliac Spines) of the Pelvis. Notice how the swelling of the abdomen is a little larger below the umbilicus.


3: Internal oblique 

This muscle creates the form of the semi circular “apron” of muscle below the Rectus abdominis (the “six pack” muscles”.  The upper body that you can see above the iliac crest will be hidden under the External Oblique.  Notice the shape of the bottom of the armour in the statue of the roman emperor below - the arc is a stylisation of the Internal Oblique.

 

Origin: 

Middle part of the iliac crest

Lateral (ie. away from the middle of the body) 1/3 of the inguinal ligament 

Thoracolumbar Fascia (connective tissue to the sides of the lumber vertebrae (small of the back)

 

Insertion:

Costal cartilage of ribs 9 and 10 (the medial, ie innermost section of the rib cage is cartilage not bone, allowing the flexibility for breathing).

The inferior (ie underneath, lowest surface) of ribs 11 and 12

The linea alba and aponeurosis (connective tissue of the abdominals


4: The plane under the jaw

On your model this volume is already filled in for practical reasons of the casting process. It still merits discussion though:

The Hyoid bone is suspended by various muscles and other soft tissues at the top of the throat, at the position that the throat meets the underplane of the the jaw.

Notice how this plane gently curves with the jaw, wrapping like the letter C around the hyoid bone and throat.  

This plane is very important for drawing the head in any position where we can see under the chin, and often receives a gentle reflected light.

 


5: "Inner Neck Volume" group

This volume is a simplification designed for this course.  Colour on your model: Red

It has two purposes:

1. To provide the physical support for the more superficial muscles we will be adding over the top.  The volume we are making here will lie underneath that of the Sternocleidomastoid and the Trapezius muscles, as well as the throat volume.  

2. To group together a great complexity of small muscles that fill the inner part of the neck, as well as a variety of other tissues within the neck region, so as not to get lost in detail and focus instead on the superficial form we will actually see.  The point of the exercise is to consider the form of the neck as four masses: The inner neck volume, the throat volume, the Sternocleidomastoid and the Trapezius  

The volume that we are building here has borders on the first rib on the front and stretches out to the superior border of the scapula and flattens out as far down as the 4th rib on the back. It will reach up to the base of the skull, nearly the whole inferior surface of the Occipital bone of the skull. You will see a raised line following the centre of the back of the neck between the base of the skull and spine of the last of the neck vertebrae - the 7th Cervical spine. This is the Nuchal Ligament.

The volume includes, amongst others, the following muscles: 

-the top part of the Multifidus, 

-the Semispinalis capitis, 

-the top parts of the Longissimus capitis, the Longissimus cervicis, the Splenius cervicis, the Splenius capitis, and the Serratus posterior superior, 

-the Levator scapulae

-the Scalenus anterior


Remember: It is not a simple muscle but a grouping of volumes of soft tissue that underly more superficial volumes for purposes of simplification.


Once the volumes of the Sternocleidomastoid, the throat and the Trapezius are added, the inner neck volume will be largely hidden, but this column is key to adding the other forms.


6: The Throat

Next, model a cylindrical volume for the throat onto the Inner Neck Volume you have already added, beginning at the hyoid bone and descending to the space just in front of the Manubrium (the large bone at the top of the sternum).  The Throat consists of the trachea and esophagus, as well as various muscles and blood vessels. 

At the top of the throat volume, the larynx (or voice box) is located.  This structure contains various cartilages and other tissues that produce the form of the “Adam’s apple”, the prominence not far below the Hyoid bone, which is usually larger in males.