Ch. 7 The Skeleton

Marieb - Human Anatomy & Physiology 7th Edition

Marieb, Hoehn7th EditionHuman Anatomy & PhysiologyISBN: 9780805359091Not the one you use?Change textbook

Marieb, Hoehn 7th Edition

Ch. 7 The Skeleton

Problem 7

Chapter 7, Problem 7

How do the relative proportions of the cranium and face of a fetus compare with those of an adult skull?

Verified step by step guidance

Step 1: Understand the basic anatomy of the skull, which is divided into two main parts: the cranium (which houses the brain) and the face (which includes the jaw, nose, and other facial bones).

Step 2: Recognize that during fetal development, the cranium is proportionally much larger compared to the face because the brain grows rapidly and requires more space early on.

Step 3: Note that in a fetus, the face is relatively small and underdeveloped compared to the cranium, reflecting the priority of brain growth over facial bone growth at this stage.

Step 4: Contrast this with the adult skull, where the face has grown significantly and the proportions between the cranium and face are more balanced, with the face being larger relative to the cranium than in the fetus.

Step 5: Summarize that the relative proportion of the cranium to the face decreases from fetus to adult, meaning the cranium is larger relative to the face in the fetus, while in adults, the face is proportionally larger compared to the cranium.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Cranial and Facial Proportions in Fetal Development

In fetal development, the cranium is proportionally larger compared to the face, reflecting early brain growth. This results in a relatively large forehead and small facial bones. Understanding this helps explain the distinct skull shape differences between fetuses and adults.

Postnatal Growth Patterns of the Skull

After birth, the face grows more rapidly than the cranium, especially during childhood and adolescence. This differential growth changes the relative proportions, making the adult skull have a larger face relative to the cranium compared to the fetal skull.

Functional and Evolutionary Implications of Skull Proportions

The larger fetal cranium accommodates rapid brain development, while the smaller face reflects less developed jaws and sensory structures. In adults, increased facial size supports functions like mastication and respiration, illustrating how skull proportions relate to developmental and functional needs.

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What is the function of the intervertebral discs?

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Distinguish between the anulus fibrosus and nucleus pulposus regions of a disc. Which provides durability and strength? Which provides resilience? Which part is involved in a 'slipped' disc?

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Textbook Question

Use key choices to identify the bone descriptions that follow.

Key:

a. carpals

b. femur

c. fibula

d. humerus

e. radius

f. tarsals

g. tibia

h. ulna

______ (1) articulates with the acetabulum and the tibia

______ (2) forms the lateral aspect of the ankle

______ (3) bone that 'carries' the hand

______ (4) the wrist bones

______ (5) end shaped like a monkey wrench

______ (6) articulates with the capitulum of the humerus

______ (7) largest bone of this 'group' is the calcaneus

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Which ribs are floating ribs and why are they called that?

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Textbook Question

Justiniano worked in a poultry-packing plant where his job was cutting open chickens and stripping out their visceral organs. After work, he typed for long hours on his computer keyboard, writing a book about his work in the plant. Soon, his wrist and hand began to hurt whenever he flexed it, and he began to awaken at night with pain and tingling on the thumb half of his hand. What condition did he probably have?

Name the cranial and facial bones and compare and contrast the functions of the cranial and facial skeletons.

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