Human Anatomy: The Musculoskeletal System

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Questions and Answers

What is the primary function of the axial skeleton?

To store energy reserves

To provide mobility to the body

To protect the vital organs and central nervous system (correct)

To produce blood cells

What is the main characteristic of bones in the appendicular skeleton?

They are responsible for haemopoiesis

They are designed for protection

They provide mobility and flexibility (correct)

They are responsible for mineral storage

What is the general shape of bones in the limbs?

Flat bones

Irregular bones

Short bones

Long bones (correct)

Which of the following is a physiological function of bones?

Haemopoiesis Signup and view all the answers

What is the proportion of organic to inorganic constituents in the bones of a child?

50% organic and 50% inorganic Signup and view all the answers

What is the primary function of the bones in the appendicular skeleton?

To sustain weight of the trunk and enable locomotion Signup and view all the answers

Which of the following bones is NOT a location where red marrow is typically found in adults?

Fibula Signup and view all the answers

Which type of bone is characterized by a tubular shaft and usually an epiphysis at each end?

Long bones Signup and view all the answers

What is the main reason for the presence of surface markings on bones?

To respond to the pull of fibrous structures such as fascia, ligaments, tendons, or aponeuroses Signup and view all the answers

What is the name of the fibers that firmly attach the periosteum to the bone at sites where muscles, tendons, and ligaments are attached?

Sharpey's fibers Signup and view all the answers

Which type of bone is typically found in the hand and feet?

Short bones Signup and view all the answers

Which type of joint is characterized by the presence of a fibrocartilage disc?

Interosseous joint Signup and view all the answers

What is the composition of flat bones?

Two thin layers of compact bone enclosing a layer of spongy bone Signup and view all the answers

What is the term for the bony protrusion that serves as an attachment point for muscles, tendons, and ligaments?

Tuberosity Signup and view all the answers

Which of the following fractures is classified as an extracapsular fracture?

Intertrochanteric fracture Signup and view all the answers

Study Notes

The Skeleton - General Points

The adult skeleton consists of 206 bones, categorized into 8 cranial bones, 6 auditory ossicles, 14 facial bones, 26 vertebral column bones, 26 hyoid, sternum, and rib bones, 64 upper limb bones, and 62 lower limb bones.
Each bone links with others to form a sturdy, flexible framework that provides shape, supports soft tissues, and protects vital organs.
The skeleton enables a wide range of coordinated movements through the action of attached muscles.

Bones - Points of Practical Interest

Bones are composed of 35% organic and 65% inorganic materials, with varying proportions at different periods of life.
In children, bones are more elastic due to the equal proportion of organic and inorganic materials, making them more prone to bending or partial fractures.
In adults, bones are more brittle due to the dominant proportion of inorganic materials.
The proportion of organic and inorganic materials differs between bones, with more inorganic material in the petrous part of the temporal bone and more organic material in the squamous part.

The Skeleton - Divisions

The skeleton is bilaterally symmetrical and divided into two main parts: the axial skeleton and the appendicular skeleton.
The axial skeleton provides protective and supporting functions, while the appendicular skeleton enables mobility.

The Axial Skeleton

The axial skeleton consists of bones in the central part of the body, including the skull, vertebral column, ribs, and sternum.
The skull encases the brain, the vertebral column encases the spinal cord, and the ribs form a cage around the heart and lungs.

The Appendicular Skeleton

The appendicular skeleton includes bones of the upper and lower limbs, as well as linking structures like the scapulae and pelvis.
The scapulae and pelvis connect the limbs to the axial skeleton.

Functions of Bone

Bones perform mechanical functions of support, protection, and movement, as well as physiological functions of haemopoiesis and mineral storage.
Bones provide a rigid framework for support, enclose vital structures and viscera for protection, and act as levers for movement.
Bones are also responsible for haemopoiesis in the red marrow and mineral storage in the bone matrix.

Types of Bones - General Shape

Bones can be classified into four types based on their shape: long bones, short bones, flat bones, and irregular bones.
Long bones are found in the limbs and are characterized by a length greater than width, with a tubular shaft and epiphyses at each end.
Short bones are found in the hands and feet and are roughly cuboidal in shape, with a thin compact crust and mainly spongy interior.
Flat bones are found in the skull and are composed of two thin layers of compact bone enclosing a layer of spongy bone.
Irregular bones have an external layer of compact bone and a spongy interior, and are found in the facial skeleton, vertebrae, and pelvis.
Sesamoid bones are found in tendons where they rub over bony surfaces.

Surface Markings of Bones

Surface markings on bones are found where fascia, ligaments, tendons, or aponeuroses are attached to bone.
These markings appear at puberty and become more prominent in adult life.
The pull of fibrous structures causes the periosteum to be raised, and new bone is deposited beneath.

Bone Marrow and Periosteum

Bone marrow is found in the marrow cavities of long and short bones and in between bony trabeculae of cancellous bone in flat and irregular bones.
At birth, marrow is red and responsible for haemopoiesis, but gradually becomes less active with age, replaced by yellow (fatty) marrow.
In adults, red marrow is restricted to certain bones, including those of the skull, vertebral column, thoracic cage, and pectoral and pelvic girdle bones.
Periosteum covers all bone surfaces, except at joints, and has a rich vascular and nerve supply.
Periosteum is firmly fixed at sites where muscles, tendons, and ligaments are attached to bone, with Sharpey's fibers.

Injuries to Bone - Common Fractures

Common fractures in the upper limb include clavicular fracture, fracture of the surgical neck of humerus, fracture of the shaft of the humerus, supracondylar fracture of the humerus, fracture of the olecranon process, fracture of the distal end of the radius (Colles' fracture), and fracture of the scaphoid bone.
Common fractures in the lower limb include fracture of the femoral neck (intracapsular), intertrochanteric/pertrochanteric fracture (extracapsular), fracture of the femoral shaft, tibial shaft fracture, fracture of the fibular neck and shaft, and fracture of the lower end of the tibia and fibula.

Joints

A joint is a point where two bones meet, whether or not movement occurs between them.
Joints can be classified according to the tissues that lie between them (by structure) or by the way they move.
There are three main types of joints: fibrous joints (no movement), cartilaginous joints (primary and secondary), and synovial joints (freely moveable).

Structures that Form Joints

Bone is the fundamental element of all joints, with the extremities in long bones, edges in flat bones, and various parts in short bones.
Cartilage is found at the articular surfaces in long bones and all around the surfaces of short bones.
Fibrocartilage is composed of white fibrous and cartilaginous tissues, with varying arrangements in different joints.
Ligaments are found in nearly all moveable joints, and are composed of bundles of collagen fibers that are pliable and flexible but strong and inextensible.
Synovial membrane is a thin, secretory membrane found in freely moveable joints, with articular and bursal types.