What do comparisons of the skull and pelvic bone of

SAQs 6. The pelvis is a hard ring of bone see Figure 6. The muscles of the legs, back and abdomen are attached to the pelvis, and their strength and power keep the body upright and enable it to bend and twist at the waist, and to walk and run.

The pelvis is composed of pairs of bones, which are fused together so tightly that the joints are difficult to see. We will describe each of the bones in turn, and their major landmarks. It will help you to visualise the anatomy of the pelvis if you keep referring back to Figure 6. The major portion of the pelvis is composed of two bones, each called the ilium — one on either side of the backbone or spinal column and curving towards the front of the body.

When you place your hand on either hip, your hand rests on the iliac crest , which is the upper border of the ilium on that side. Anterior tells you that the iliac spines are at the front of the body, and superior tells you that they are above the main portion of the ilium on each side. The ischium is the thick lower part of the pelvis, formed from two fused bones — one on either side. When a woman is in labour, the descent of the fetal head as it moves down the birth canal is estimated in relation to the ischial spines , which are inward projections of the ischium on each side.

The pubic bones on either side form the front part of the pelvis. The two pubic bones meet in the middle at the pubi c symphysis. A symphysis is a very strong bony joint. When you examine the abdomen of a pregnant woman, feeling for the top of the pubic symphysis with your fingers is a very important landmark. In Study Session 10, you will learn how to measure the height of the uterus from the pubic symphysis to the fundus top of the uterus — see Figure 3. This measurement enables you to estimate the gestational age of the fetus, i.

The sacrum is a tapered, wedge-shaped bone at the back of the pelvis, consisting of five fused vertebrae the small bones that make up the spinal column or backbone. At the bottom of the sacrum is a tail-like bony projection called the coccyx. The upper border of the first vertebra in the sacrum sticks out, and points towards the front of the body; this protuberance is the sacral promontory — an important landmark for labour and delivery.

The roughly circular space enclosed by the pubic bones at the front, and the ischium on either side at the back, is called the pelvic canal — the bony passage through which the baby must pass.

This canal has a curved shape because of the difference in size between the anterior front and posterior back borders of the space created by the pelvic bones.

You can see it from the side view in Figure 6. The size and shape of the pelvis is important for labour and delivery. Well-built healthy women, who had a good diet during their childhood growth period, usually have a broad pelvis that is well adapted for childbirth.

It has a round pelvic brim and short, blunt ischial spines. It gives the least difficulty during childbirth, provided the fetus is a normal size and the birth canal has no abnormal tissue growth causing an obstruction. There is considerable variation in pelvis shapes, some of which create problems in labour and delivery. A narrow pelvis can make it difficult for the baby to pass through the pelvic canal. A deficiency of important minerals like iodine in the diet during childhood may result in abnormal development of the pelvic bones.

As you will see in the next section, the inlet and the outlet of the pelvis are not the same size. The pelvic inlet is formed by the pelvic brim, which you saw in Figure 6. The pelvic brim is rounded, except where the sacral promontory and the ischial spines project into it.

The dimensions in centimetres cm of the pelvic inlet are shown in Figure 6. The long bones , longer than they are wide, include the femur the longest bone in the body as well as relatively small bones in the fingers. Long bones function to support the weight of the body and facilitate movement.

Long bones are mostly located in the appendicular skeleton and include bones in the lower limbs the tibia, fibula, femur, metatarsals, and phalanges and bones in the upper limbs the humerus, radius, ulna, metacarpals, and phalanges.

Short bones are about as long as they are wide. Located in the wrist and ankle joints, short bones provide stability and some movement. The carpals in the wrist scaphoid, lunate, triquetral, hamate, pisiform, capitate, trapezoid, and trapezium and the tarsals in the ankles calcaneus, talus, navicular, cuboid, lateral cuneiform, intermediate cuneiform, and medial cuneiform are examples of short bones.

Irregular bones vary in shape and structure and therefore do not fit into any other category flat, short, long, or sesamoid. They often have a fairly complex shape, which helps protect internal organs. For example, the vertebrae, irregular bones of the vertebral column, protect the spinal cord. The irregular bones of the pelvis pubis, ilium, and ischium protect organs in the pelvic cavity. Sesamoid bones are bones embedded in tendons. Forensic anthropologists will compare this against a database of standard markers to learn the age of the skeleton.

Check if there are any soft marks on the cartilage which are left by childbirth as the bones soften to allow easier birth. To identify gender, assess the pelvis shape; men have a narrow, deep pelvis and women a wider, shallower pelvis, better-suited to carrying a baby.

For a quick identification in the field, a forensic anthropologist will find the notch in the fan-shaped bone of the pelvis and stick their thumb into it. If there's room to wiggle the thumb, then it's a female; if it's a tight fit, it's the skeleton of a man. Examine the wrists, as bones often hold clues to the primary work of the decedent. Bony ridges form where the muscles were attached and pulled over the years. A forensic anthropologist might find a bony ridge on the wrist and decide the dead person may have been someone who used their hands for a living, such as a chef or seamstress.

For example, certain teeth with more attrition can suggest chewing leather to soften it, holding twine during basket weaving, or even smoking a pipe. In addition to dental attrition, many other kinds of dental diseases familiar today are regularly found in historic skeletons. Issues you might spot include:. Evidence of disease is also evident in many parts of the skeleton.

One of the most obvious and disfiguring diseases was syphilis. Syphilis is an infectious disease caused by a bacterium known as Treponema pallidum , and it only became widespread in Europe in the post-medieval period. It is spread through sexual contact and can be passed on from mother to baby. The disease is thankfully now rare, and readily treatable with antibiotics. In the video below, osteologist Linzi Harvey shows how you can spot the tell-tale signs of this disease.

Skeletons across the ages display degenerative bone changes associated with age and wear, and on your skeleton you might find signs of the following diseases:. Although we can tell a lot about a person from their bones, determining how they died can be difficult. It can be tempting to see signs of trauma on a skeleton as evidence of a violent death, but most fractures are not fatal. There are 33 individuals with signs of trauma in the London collection, and of these only two show possible evidence of fatal blows.

When trauma occurs before death, healing can be seen around the edges of the wound. Not all deaths are so violent. Signs have been found in medieval remains from Europe that point to a disease considered to be modern: cancer. Cancer often affects the bone when it metastasises: when it spreads from the soft tissue to the bone, a condition that almost certainly would have been fatal in the past.

Analysing the bones and teeth of individuals can give us insights into the details of their lives, such as whether they smoked a pipe or had a rich diet. But by looking at human remains found across London, researchers can build up a picture of life in the city throughout the ages, from Romans with terrible dental hygiene to post-medieval people struggling with the rising tide of syphilis. Unearth the one-million-year story of humans in Britain and their struggle to survive in a changing land.

Dr Silvia Bello tells us about the gruesome yet fascinating behaviour of people living in a Somerset cave 14, years ago. Get email updates about our news, science, exhibitions, events, products, services and fundraising activities. You must be over the age of Privacy notice.

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