PELVIS

The Pelvic Assembly: This discussion of the pelvis may seem convoluted because of its complexity as an identifiable subsection and that it is nearly inseparable from the "Spinal Column" and "Hips" topics. The pelvic assembly is the largest of the frame and probably the largest subassembly within the body.

The pelvic girdle by itself would be a very complex casting if it was to be made from one piece. The divisible portions (3 in [Gray]) could make for less complicated castings even though there are more of them. Likewise, symmetrical halves may be as workable.

The pelvic assembly includes all of the bones of the pelvic girdle and the Sacrum and Coccyx. In earlier editions of the handbook, the division of the castings were left up to you, the android maker, because you know your limits and resources for making multifarious castings. For the Third Edition of the Android Makers Handbook, it is suggested to make the pelvic girdle from the seven subassemblies as suggested in the "Frame Elements" subtopic.

Before the "Frame Elements" subtopic, there is a new subtopic for this type of entry. "Designing/Engineering Notes" is a new subtopic to collate information on how to determine the shapes and geometries of the particular topic. It is to include the concept of an "articulation" model, the "stick figure." Of course, that information must be generated and then refined.

[1]    Designing/Engineering Notes:

This is a new subtopic! During the writing process of the first edition of this encyclopedia, it was determined that an extensive change to the modeling process is in order. It seems that a "Stick figure-like" articulation model would be best to describe the basic stature of an individual or an android.

Therefore, this added some terms to the original total model's factors. This "frame model" should describe points so that any android component can be related to it. In a way, a "frame model" would look like an armature for a doll.

The "frame model" for a particular android would describe the geometry of the hip articulation and thus the orientation and dimensions of the acetabulum. Likewise, the top surface of the Sacrum would be described for articulation with the spinal column. From this model, points for describing the frame elements themselves could be determined.

[1.1]    Some facts (and some speculation) related to the acetabulum geometry:

[1.1.1]     Angle between femurs is greater in females than males because of wider pelvis. However, this may only be true if the comparative males and females are of equal height.

    The lower limbs seem to be of similar geometry between a virule male and his nubile female counterpart. The male's mesomorphic upper torso adds to his height and weight to make him larger and heavier. If he is so inclined, this same sizing allows him to wear his sweetheart's knickers and tights.

    Therefore, is it true that the angles are different? Perhaps not between the average male and the average young female. Perhaps continuing maturation does widen female hip spacings, but not by much even though women may grow from "junior" sizes to "misses" or even on to "womens." (See "Q angle.")

[1.1.2]    Neck.shaft angle: 130° in adult (male?). Female "more nearly a right angle with the shaft that in a man." [Gray] Assume related to hip spacings.

[2]    Frame Elements:

The frame elements or classifications of the pelvic assembly (which make up the pelvis) are:

[2.1]    Pubis,

[2.2]    Sacrum,

[2.3]    Coccyx,

[2.4]    Ilium (L&R),

and the
[2.5]    Ischium (L&R)

for a total of seven bones to construct the human pelvis. It is expected that there will be seven elements in an HTA subassembly.

[3]    Articulations:

The Ilium, Ischium, and Pubis converge on both sides in the acetabulum. The ball shaped head of the Femur mates with the socket of the acetabulum to form the hip joint. Also, the Sacrum, at the base of the spinal column, is at the keystone of the spine and both halves of the pelvis.

In general, there is practically no movement within the pelvis itself. However, in a human, the seven parts are connected with ligatures that allow some flexing. Giving birth stretches some of these ligatures to a limit.

The pelvis is where the trunk meets the legs, but, it is in the topic of the lower extremities because it is most common to the legs. Completing the pelvis assembly incorporates some of the body's partially movable joints, (like vertebrae) the "amphiarthrodial" type.

Gray [p.241] defines four classifications or localities of connections (of the deepest layers of ligatures) forming the pelvis from separate bones:

[3.1]    Those connecting between the oval shaped surfaces of the two pubic bones at the pubic arch. This is the first connection because it adheres the symmetrical Ossa pubis and starts forming the pelvis assembly. It is also best completed in one work session. See Gray, page 244 for more detailed information. The particular ligaments which are larger in the female; are:

[3.1.1]    Interpubic disk is made and the bones are connected with from TEFC.

[3.1.2]    and the following similar:

[3.1.2.1]    Anterior Pubic,

[3.1.2.2]    Posterior Pubic,

[3.1.2.3]    Superior Pubic,

and the
[3.1.2.4]    Subpubic ligaments.

    These are made from WhiFt. They are made and applied using the same technique and at the same time.

    Once this connection is made, this subassembly can be mounted in the main jig. The brackets are clamped on the bare bone as attach points.

[3.2]    Connecting the Sacrum and Ilium [Gray, p.241]: This shear weight bearing articulation becomes quite movable (diarthrosis) in human's old age as the fibro-cartilage becomes replaced with a synovia-like fluid. These are the associated specific ligatures making the connection:

[3.2.1]    The interosseous tissues themselves.

[3.2.2]    Posterior Sacro-iliac

[3.2.3]    Anterior Sacro-iliac is made from WhiFt.

And...
[3.2.4]    Oblique Sacro-iliac is made from WhiFt. Each side is applied from the ilium posterior superior spine (near the jig attach point) to the Sacrum posterior third transverse tubercle.

    This connection is temporarily braced stable with clamps to a board. See the last sub-step of this construction for more permanent attachment to the main jig.

[3.3]    Connecting the Sacrum and Ischium is not as much like the connection of the Sacrum and Ilium as the construction could allow (see [Gray, p.242]). The associated ligaments tie to the Ilium, Sacrum, Coccyx, and Ischium. These two associated ligaments are:

[3.3.1]    Great Sacro-sciatic (posterior, L&R) ligament is the specific ligament that makes the tie to four of the pelvis bones. It is made from WhiFt. See [Gray, p.242] for more detailed information about size and shape.

[3.3.2]    Lesser Sacro-sciatic (anterior, L&R) ligament is intermingled with the Great Sacro-sciatic ligament. The path is similar also. It too is made from WhiFt. See [Gray, p.243] for more detailed information about size and shape.

    This connection is also temporarily braced stable with clamps to a board. Again, see the last sub-step of this construction for more permanent attachment to the main jig.

[3.4]    Connecting the Sacrum and coccyx. This articulation is limited to minimal forward and backward. This range is increased during pregnancy. See Gray, page 244 for more detailed information. There is one particular posterior Sacro-coccygeal ligament that is in relation with the Gluteus maximus.

    This connection is listed last because it finishes the pelvis assembly and can be done with the work in the main jig. It could have been second because that would have made a logical subassembly. However, it seemed to make android fabrication more efficient. Doing this step first or second or last probably will not require any rework.

    Perhaps this can be made into one piece in a budget or male android. As of May 3, 1994, the effect of combining these into one assembly is unknown.

Applying these ligatures assembles the pelvis, if not already done in an earlier section. Once this is one piece, the spinal column could be made. However, the spinal column is built on later, so the hips and the legs are the next topics.

The pelvis is ready to be temporarily connected into the main jig. The Posterior spine (not the crests themselves) of both ilium are the attach points.

[4]    Innermost Layer of Muscles and Other Tissues:

These comprise this deepest layer's muscles. A lot of these muscles affect standing, walking, running, and most other activities using the lower body.

Gray's Anatomy's Fig. 221 indicated that this should be a separate topic. The applicable ac tuators for this innermost layer of muscles and fascia of the pelvis are:

[4.1]    Psoas magnus

[4.2]    Psoas parvus

[4.3]    Quadratus lumborum

[4.4]    Iliacus

Gray illustrated many of these muscles in Fig. 253. Notice that they do not fit neatly into one topic. The arrangement of muscle pairs within these sections of the innermost layer of the body probably will and should not affect their order on the timing charts.

These have been listed within the "Hips" topic, but they can be listed as within this topic also:

[4.5]    Obturator internus

[4.6]    Quadratus femoris

[5]    Internal Components:

The respective internal components to the pelvis to be installed are not defined yet. Therefore, this subtopic is not a pure "stub." It is anticipated as of that there must be access to components that can be expected to require service or replacement.

Since the common biology of both sexes has a rectum, the android equivalent could allow access to the elements that require maintenance. Of course, the position of the android may be like a human for a proctologist. Likewise, here is a requirement for very special tools.

[6]    Intermediate Layer of Muscles and Other Tissues:

The applicable actuators for this intermediary layer of muscles and tissues for the pelvis may have been listed under the "Hips," "Legs," or "Trunk" topics.

[7]    Outermost Layer of Muscles and Other Tissues:

The applicable human and android muscles for this last, outermost layer of muscles and tissues for the pelvis may have been listed under the "Hips," "Legs," or "Trunk" topics also.

[8]    Final Layers and Artifacts:

Certain subcutaneous fat is used to protect the skin from articulation abrading. A little more in femdroids with their substantially smaller hands adds to the feminine softness desired.

There are no particular artifacts required on the pelvic area of an HTA. The only possible exception to that statement would be if you desire your android equipped with the male external genitalia or either sex to have pubic hair.

Femdroids of the HTA specifications are not designed to meet the carnal needs of males. That is why there is no specifications for a vagina or female external, yielding genitalia.or even for any pubic hair.

[9]    Inspection Criteria:

The Pelvis is a completed subassembly. Like any other subassembly, it must conform to drawing specifications. Of course, it must be apparent that it is of your desired android's sex.

The shape of the acetabulums should allow for the hips Range of Motion. The interface to the spinal column should fit.

[10]    Trivia:

Surgeons at the Munich-Grosshadern University Clinic with engineers from BMW Research and Development Center in Munich have combined CT scans with stereolithography to create polymer parts. The article shows a female (not stated, but apparent by aspect) pelvis. Apparently, they have made spinal components and jawbones of polymers (or the resultant formed bone) in experimental surgery. What is not clear is: Is the replacement bones the polymers themselves or were the polymer prototypes merely a casting form? [PS, July `95; 10]

INDEX:    See "Engineering the Pelvis," "Femur," "Hips," "Legs," and "Trunk" for more information.