Skeletal System Overview

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Questions and Answers

What term describes bones that are roughly cube-shaped and nearly equal in length and width?

Sesamoid bones

Irregular bones

Short bones (correct)

Flat bones

Which of the following is NOT a type of bone according to shape?

Irregular bones

Sesamoid bones

Compact bones (correct)

Flat bones

Which part of a typical long bone is described as the hollow, cylindrical space that contains fat yellow bone marrow?

Epiphysis

Medullary cavity (correct)

Metaphysis

Diaphysis

What is the primary function of the periosteum?

Protects the bone and assists in fracture repair Signup and view all the answers

What are small bones located in the sutures between certain cranial bones called?

Sutural bones Signup and view all the answers

What are the two major types of surface markings on bones?

Processes and openings Signup and view all the answers

The trabeculae in spongy bone refer to what structure?

Flat pieces of bone Signup and view all the answers

Where is red bone marrow primarily found in adults?

In the epiphyses of long bones Signup and view all the answers

What is the term used for the regions located between the diaphysis and the epiphyses of a long bone?

Metaphysis Signup and view all the answers

Which type of bone has a design that includes an outer thin plate of compact bone and inner spongy bone without a diaphysis?

Flat bones Signup and view all the answers

Which of the following options correctly describes the functions of bones?

Store fat in the medullary cavity Signup and view all the answers

What role do processes and projections of bones serve?

They provide attachment points for ligaments and tendons Signup and view all the answers

What type of bone is specifically formed within a tendon?

Sesamoid bones Signup and view all the answers

Which type of markings on a bone are characterized by depressions such as fossae, fissures, and grooves?

Depressions Signup and view all the answers

In newborn infants, where is red bone marrow predominantly located?

The medullary cavity and spongy bone cavities Signup and view all the answers

What is the primary function of the axial skeleton?

Supports and protects vital organs Signup and view all the answers

How does red bone marrow change from infancy to adulthood?

It diminishes significantly and is replaced by fat. Signup and view all the answers

Which of the following is NOT a function of bones?

Protect the body from pathogens Signup and view all the answers

How many bones are found in the adult human skeletal system?

206 Signup and view all the answers

What is the role of depressions and openings in bones?

Facilitate the passage of soft tissues Signup and view all the answers

Which bones are included in the auditory ossicles?

6 bones Signup and view all the answers

Which of the following is NOT a part of the appendicular skeleton?

Skull Signup and view all the answers

What distinguishes long bones from other types of bones?

Greater length than width Signup and view all the answers

What is the function of yellow marrow in bones?

Stores fat Signup and view all the answers

How many cranial bones are there in the human skull?

8 Signup and view all the answers

Which bone is part of the axial skeleton?

Sternum Signup and view all the answers

What is the primary role of bone markings?

To facilitate muscle attachment Signup and view all the answers

Which best describes the function of articular cartilage?

Provides a smooth surface for joint movement Signup and view all the answers

What is the primary function of cranial bones?

Protect the brain Signup and view all the answers

Which of the following functions is NOT performed by bones?

Enhancing visual acuity Signup and view all the answers

Which cranial bone is known as the keystone of the cranial floor?

Sphenoid bone Signup and view all the answers

What is the role of yellow bone marrow?

Storing triglycerides Signup and view all the answers

Which bone forms the forehead and roofs of the orbits?

Frontal bone Signup and view all the answers

What structure allows the passage of the spinal cord through the skull?

Foramen magnum Signup and view all the answers

Which of the following bones is NOT considered a paired cranial bone?

Frontal bone Signup and view all the answers

How do skeletal muscles interact with bones to assist movement?

Muscles pull directly on tendons attached to bones. Signup and view all the answers

What is formed by the facial bones?

Framework of the face Signup and view all the answers

Which function involves the release of stored minerals into the bloodstream?

Mineral homeostasis Signup and view all the answers

Which bone is primarily responsible for forming the base and anterior aspect of the skull?

Ethmoid bone Signup and view all the answers

What is the main function of the nasal cavity?

Provide passage for air Signup and view all the answers

Which of the following bones is NOT part of the orbit's bony structure?

Nasal bone Signup and view all the answers

Which cavity is lined with mucous membranes and serves to warm and humidify air?

Nasal cavity Signup and view all the answers

What do the paranasal sinuses primarily drain into?

Nasal cavity Signup and view all the answers

Which bone is the only mobile bone in the skull?

Mandible Signup and view all the answers

Which suture unites the two parietal bones at the superior midline of the skull?

Sagittal suture Signup and view all the answers

Which of the following is a marking found on the mandible?

Coronoid process Signup and view all the answers

What structure in the skull provides a passage for the spinal cord?

Foramen magnum Signup and view all the answers

Which of the following bones forms the inferior portion of the bony nasal septum?

Vomer Signup and view all the answers

Which bones contribute to the formation of the hard palate?

Maxilla and palatine bones Signup and view all the answers

Which of the following is known as the smallest bone in the human body?

Stapes Signup and view all the answers

What is the primary purpose of the temporal process of the zygomatic bone?

Formation of the zygomatic arch Signup and view all the answers

Study Notes

Skeletal System

The skeletal system is comprised of 206 named bones, mostly paired.
The adult skeleton can be divided into the axial and appendicular skeletons.
The axial skeleton includes the skull, vertebral column, and rib cage, and its functions include protection, support, and carrying other body parts.
The appendicular skeleton consists of the bones of the upper and lower limbs and girdles, responsible for the locomotion of the body.

Divisions of the Skeletal System

The axial skeleton contains 80 bones, including
- The skull, with 8 cranial bones and 14 facial bones.
- The hyoid bone (1 bone).
- The auditory ossicles (6 bones).
- The vertebral column (26 bones).
- The thorax, consisting of the sternum (1 bone) and ribs (24 bones).
The appendicular skeleton contains 126 bones, including
- The pectoral or shoulder girdles (clavicle (2) and scapula (2)), pelvic or hip girdle (pelvic or coxal (2), lower limbs (femur (2), patella (2), fibula (2), tibia (2), tarsals (14), metatarsals (10), phalanges (28), upper limbs (humerus (2), ulna (2), radius (2), carpals (16), metacarpals (10), phalanges (28).

Types of Bones

Long bones have greater length than width, with a shaft and two expanded ends (e.g., all limb bones except patella, wrist, and ankle bones).
Short bones are roughly cube-shaped, with nearly equal length and width (e.g., bones of the wrist and ankle).
Flat bones are thin, flattened, and usually curved (e.g., sternum, scapulae, ribs, and most skull bones).
Irregular bones have complex shapes (e.g., vertebrae and hip bones).
Sesamoid bones are special short bones that form within a tendon, varying in size and number (e.g., patella, pisiform).
Sutural bones are small bones located in sutures between certain cranial bones.

Gross Anatomy: Bone Textures

Bones contain two layers:
- Compact bone: The dense outer layer that appears smooth and solid to the naked eye.
- Spongy bone: The inner layer containing small needle-like or flat pieces called trabeculae, with spaces filled with red or yellow bone marrow (in living bone).

Structure of a Typical Long Bone

Diaphysis: The bone's shaft or body, long, cylindrical, and the main portion of the bone.
Epiphysis: The proximal and distal ends of the bone.
Metaphysis: The regions between the diaphysis and the epiphyses.
Articular cartilage: A thin layer of hyaline cartilage covering the part of the epiphysis, reducing friction at movable joints.
Periosteum: A tough connective tissue sheath associated with blood supply, protecting the bone, assisting in fracture repair, helping nourish bone tissue, and serving as an attachment point for ligaments and tendons.
Medullary cavity or marrow cavity: A hollow cylindrical space within the diaphysis, containing fat yellow bone marrow and blood vessels.
Endosteum: A thin membrane lining the medullary cavity, containing a single layer of bone-forming cells and a small amount of connective tissue.

Structure of Short, Irregular, and Flat Bones

Share a simple design: outer thin plate of compact bone covered by periosteum, inner spongy bone covered by endosteum, with no diaphysis, epiphyses, or medullary cavity.
Spongy bone in a flat bone is called the diploë.

Bone Surface Markings

Projections: Heads, trochanter, spine, tubercle, crest, line, tuberosity, condyle, ramus.
Depressions: Fossae, fissure, groove.
Openings: Foramina, sinus, meatus.

Location of Hematopoietic Tissue

Red bone marrow: Hematopoietic tissue found within the red marrow cavities, trabecular cavities of spongy bone in long bones, and the diploë of flat bones.
In newborns, red marrow is located in the medullary cavity and spongy bone cavities.
In adult long bones, the fat-containing medullary cavity extends, and hemopoiesis occurs only in the heads of the femur and humerus, diploë of flat bones, and some irregular bones.

Functions of Bones

Support: Provides a structural framework supporting the body and attachment points for tendons.
Protection: Protects internal organs from injury.
Assistance in movement: Skeletal muscles attach to bones via tendons, using bones as levers for movement.
Mineral homeostasis: Serves as a reservoir for minerals like calcium and phosphate, releasing them into the bloodstream to maintain balance.
Blood cell production: Blood cell formation (hemopoiesis) occurs in the red marrow of specific bones.
Triglyceride (fat) storage: Yellow bone marrow stores potential energy reserves of triglycerides in bone cavities.
Hormone production: Bones produce osteocalcin, which regulates bone formation and protects against obesity and glucose intolerance.

The Skull

The bony framework of the head, resting on the superior end of the vertebral column.
Cranial bones: Form the cranial cavity, enclosing and protecting the brain, and providing attachments for head and neck muscles.
Facial bones: Form the framework of the face, containing cavities for special senses, providing openings for air and food passages, securing teeth, and anchoring the facial muscles of expression.

Cranial Bones

Paired cranial bones:
- Parietal bones: Form the superior and lateral aspects of the skull.
- Temporal bones: Form the inferolateral aspects of the skull and part of the cranial floor; the zygomatic process forms the cheek prominence.
Unpaired cranial bones:
- Frontal bone: Forms the forehead, roofs of the orbits, part of the cranial floor, and has supraorbital foramina allowing for the passage of arteries and nerves.
- Occipital bone: Forms the posterior aspect and base of the skull, with the foramen magnum allowing passage of the spinal cord.
- Sphenoid bone: Forms the posterior aspect and base of the skull, called the "keystone" because it articulates with all other cranial bones, holding them together.

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Description

Test your knowledge of the skeletal system, including its structure and functions. This quiz covers the major divisions, axial and appendicular skeletons, and the number and types of bones involved. Perfect for students studying anatomy!