Human Anatomy: Skeletal System and Axial Skeleton

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Questions and Answers

What does the shape and depth of each fossa correspond to?

The location of the brain region it houses

The density of the brain region it houses

The size of the brain region it houses

The shape of the brain region it houses (correct)

What does the frontal bone's anterior portion form?

The orbital portion

The supraorbital margin (correct)

The nasal portion

The zygomatic process

Where is the supraorbital foramen of the orbit located?

Outside the supraorbital margin

At the anterior part of the supraorbital margin

At the posterior part of the supraorbital margin

At the center of the supraorbital margin (correct)

What does the orbital portion of the frontal bone form?

The floor of the anterior cranial fossa Signup and view all the answers

What does the parietal bone form?

The upper lateral sides of the skull Signup and view all the answers

What part of the temporal bone extends laterally and anteriorly to articulate with the zygomatic arch?

The zygomatic process Signup and view all the answers

How many parietal bones are present in the human skull?

2 Signup and view all the answers

Which of the following sutures fuses the occipital bone to the two parietal bones?

Lambdoid suture Signup and view all the answers

Which of the following is NOT one of the three large spaces that subdivide the base of the skull?

Lateral cranial fossa Signup and view all the answers

How many nasal bones are present in the human skull?

2 Signup and view all the answers

Which of the following bones is NOT part of the bones that form the cranium?

Mandible Signup and view all the answers

What is the name of the membranous gap present at the junction of the coronal and sagittal sutures in neonates?

Anterior fontanelle Signup and view all the answers

Which of the following statements about the axial skeleton is correct?

It serves to protect the brain, spinal cord, heart, and lungs. Signup and view all the answers

How many individual bones make up the skull in an adult?

22 Signup and view all the answers

Which of the following is NOT a cranial bone?

Zygomatic bone Signup and view all the answers

What is the function of the sutures in the skull?

To unite the flat bones of the skull at immobile joints Signup and view all the answers

Which of the following statements about the skull is correct?

The internal surface of the skull is thinner and more brittle than the external surface. Signup and view all the answers

How many pairs of ribs are part of the thoracic cage?

12 Signup and view all the answers

Study Notes

Cranial Bones

There are 22 individual bones in the adult skull, including the mandible.
21 bones are immobile and united into a single unit.
The mandible is the only moveable bone in the skull.

Parietal Bones

There are 2 parietal bones, which form most of the upper lateral sides of the skull.
Each parietal bone is bounded anteriorly by the frontal bone (coronal suture).
Each parietal bone is bounded inferiorly by the temporal bone.
Each parietal bone is bounded posteriorly by the occipital bone (lambdoid suture).

Temporal Bones

There are 2 temporal bones, which form the lower lateral side of the skull.
The temporal bone has several regions, including:
- Squamous portion (flattened upper portion and largest one).
- Zygomatic process (extends laterally and anteriorly and articulates with the posterior temporal portion of the zygomatic arch).
- Mastoid portion (posteriorly).

Occipital Bone

There is 1 occipital bone.

Sphenoid Bone

There is 1 sphenoid bone.

Vomer

There is 1 vomer.

Ethmoid Bone

There is 1 ethmoid bone.

Palatine Bones

There are 2 palatine bones.

Inferior Conchae

There are 2 inferior conchae.

Mandible

There is 1 mandible.

Sutures of the Skull

Skull sutures are a type of immovable fibrous joint.
The main sutures in adulthood are:
- Coronal suture (fuses the frontal bone with the two parietal bones).
- Sagittal suture (fuses both parietal bones to each other).
- Lambdoid suture (fuses the occipital bone to the two parietal bones).

Fontanelles

In neonates, the incompletely fused suture joints give rise to membranous gaps between the bones, known as fontanelles.
The two major fontanelles are:
- Anterior fontanelle (located at the junction of the coronal and sagittal sutures).
- Posterior fontanelle (located at the junction of the sagittal and lambdoid sutures).

Cranium

The cranium forms the superior aspect of the skull.
It protects the brain, meninges, and cerebral vasculature by an interior space called the cranial cavity.
Anatomically, the roof and the lateral and posterior sides of the skull are called the vault, and the floor of the cranium is referred to as the base of the skull.
The base is subdivided into three large spaces:
- Anterior cranial fossa.
- Middle cranial fossa.
- Posterior cranial fossa.
From anterior to posterior, the fossae increase in depth.

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Description

Learn about the skeletal system of the body with a focus on the skull, cranial bones, and the axial skeleton. Understand the role of the axial skeleton in protecting vital organs and providing attachment sites for muscles.