The Locomotor System
The locomotor system is also known as the musculoskeletal system. It is made up of the
skeleton, the skeletal muscles, tendons, ligaments, joints, cartilage and other connective
tissue. These parts work together to allow movement.
The Skeleton
Functions of Bones :
The average human adult has 206 bones. They have four main functions that are support,
protection, movement and store minerals. The skeleton is divided into two different parts.
The axial and the appendicular skeleton.
Support : The body is supported and shaped by the skeleton – for example upright posture
would be impossible without a spine.
Protection : Our internal organs are protected by our skeleton, such as the brain inside the
skull and the heart and lungs inside the ribcage.
Movement : The skeleton allows movement of the body as a whole and its individual parts.
The bones act as levers and form joints that allow muscles to pull on them and produce joint
movements.
Stores of Minerals : The skeleton also stores minerals (such as calcium) and lipids (fats) and
produces blood cells in the bone marrow.
Classification :
Appendicular Skeleton : The bones of the upper and
lower limbs and their girdles that join to the axial skeleton.
Axial Skeleton : This forms the long axis of the body and
includes the bones of the skull , spine and rib cage .
Ligament : A tough band of fibrous, slightly elastic
connective tissue that attaches one bone to another. It
brings the ends of the bones together to prevent
dislocation.
,Tendon : A very strong connective tissue that attaches skeletal muscle to bone
Important to remember :
The clavicle , scapula and pelvis belong to the appendicular skeleton. It is a common error to
link them to the axial skeleton .
The bones of the human skeleton are classified by their shape: long bones, short bones, flat
bones, sutural bones, sesamoid bones, and irregular bones.
Long bones
Are longer than they are wide and have a shaft and two
ends. The diaphysis, or central
shaft, contains bone marrow in a marrow cavity. The
rounded ends, the epiphyses, are covered with articular
cartilage and are filled with red bone marrow, which
produces blood cells . Most of the limb bones are long
bones—for example, the femur, tibia, ulna, and radius.
Exceptions to this include the patella and the bones of the
wrist and ankle.
Long bones function to support the weight of the body and
facilitate movement.
, Structure of long bones
The structure of a long bone allows for the best visualization of all of the parts of a bone . A
long bone has two parts: the diaphysis and the epiphysis. The diaphysis is the tubular shaft
that runs between the proximal and distal ends of the bone. The hollow region in the
diaphysis is called the medullary cavity, which is filled with yellow marrow. The walls of the
diaphysis are composed of dense and hard compact bone.
The wider section at each end of the bone is called the epiphysis (plural = epiphyses), which
is filled with spongy bone. Red marrow fills the spaces in the spongy bone. Each epiphysis
meets the diaphysis at the metaphysis, the narrow area that contains the epiphyseal plate
(growth plate), a layer of hyaline (transparent) cartilage in a growing bone. When the bone
stops growing in early adulthood (approximately 18–21 years), the cartilage is replaced by
osseous tissue and the epiphyseal plate becomes an epiphyseal line.
The medullary cavity has a delicate membranous lining called the endosteum (end– =
“inside”; oste– = “bone”), where bone growth, repair, and remodeling occur. The outer
surface of the bone is covered with a fibrous membrane called the periosteum (peri– =
“around” or “surrounding”). The periosteum contains blood vessels, nerves, and lymphatic
vessels that nourish compact bone. Tendons and ligaments also attach to bones at the
periosteum. The periosteum covers the entire outer surface except where the epiphyses meet
other bones to form joints . In this region, the epiphyses are covered with articular cartilage, a
thin layer of cartilage that reduces friction and acts as a shock absorber.
Short bones
or cuboidal bones, are bones that are the same width and length, giving them a cube-like
shape. For example, the bones of the wrist (carpals) and ankle (tarsals) are short bones
Short bones provide stability to the wrist and ankle joints and help facilitate some movements
The locomotor system is also known as the musculoskeletal system. It is made up of the
skeleton, the skeletal muscles, tendons, ligaments, joints, cartilage and other connective
tissue. These parts work together to allow movement.
The Skeleton
Functions of Bones :
The average human adult has 206 bones. They have four main functions that are support,
protection, movement and store minerals. The skeleton is divided into two different parts.
The axial and the appendicular skeleton.
Support : The body is supported and shaped by the skeleton – for example upright posture
would be impossible without a spine.
Protection : Our internal organs are protected by our skeleton, such as the brain inside the
skull and the heart and lungs inside the ribcage.
Movement : The skeleton allows movement of the body as a whole and its individual parts.
The bones act as levers and form joints that allow muscles to pull on them and produce joint
movements.
Stores of Minerals : The skeleton also stores minerals (such as calcium) and lipids (fats) and
produces blood cells in the bone marrow.
Classification :
Appendicular Skeleton : The bones of the upper and
lower limbs and their girdles that join to the axial skeleton.
Axial Skeleton : This forms the long axis of the body and
includes the bones of the skull , spine and rib cage .
Ligament : A tough band of fibrous, slightly elastic
connective tissue that attaches one bone to another. It
brings the ends of the bones together to prevent
dislocation.
,Tendon : A very strong connective tissue that attaches skeletal muscle to bone
Important to remember :
The clavicle , scapula and pelvis belong to the appendicular skeleton. It is a common error to
link them to the axial skeleton .
The bones of the human skeleton are classified by their shape: long bones, short bones, flat
bones, sutural bones, sesamoid bones, and irregular bones.
Long bones
Are longer than they are wide and have a shaft and two
ends. The diaphysis, or central
shaft, contains bone marrow in a marrow cavity. The
rounded ends, the epiphyses, are covered with articular
cartilage and are filled with red bone marrow, which
produces blood cells . Most of the limb bones are long
bones—for example, the femur, tibia, ulna, and radius.
Exceptions to this include the patella and the bones of the
wrist and ankle.
Long bones function to support the weight of the body and
facilitate movement.
, Structure of long bones
The structure of a long bone allows for the best visualization of all of the parts of a bone . A
long bone has two parts: the diaphysis and the epiphysis. The diaphysis is the tubular shaft
that runs between the proximal and distal ends of the bone. The hollow region in the
diaphysis is called the medullary cavity, which is filled with yellow marrow. The walls of the
diaphysis are composed of dense and hard compact bone.
The wider section at each end of the bone is called the epiphysis (plural = epiphyses), which
is filled with spongy bone. Red marrow fills the spaces in the spongy bone. Each epiphysis
meets the diaphysis at the metaphysis, the narrow area that contains the epiphyseal plate
(growth plate), a layer of hyaline (transparent) cartilage in a growing bone. When the bone
stops growing in early adulthood (approximately 18–21 years), the cartilage is replaced by
osseous tissue and the epiphyseal plate becomes an epiphyseal line.
The medullary cavity has a delicate membranous lining called the endosteum (end– =
“inside”; oste– = “bone”), where bone growth, repair, and remodeling occur. The outer
surface of the bone is covered with a fibrous membrane called the periosteum (peri– =
“around” or “surrounding”). The periosteum contains blood vessels, nerves, and lymphatic
vessels that nourish compact bone. Tendons and ligaments also attach to bones at the
periosteum. The periosteum covers the entire outer surface except where the epiphyses meet
other bones to form joints . In this region, the epiphyses are covered with articular cartilage, a
thin layer of cartilage that reduces friction and acts as a shock absorber.
Short bones
or cuboidal bones, are bones that are the same width and length, giving them a cube-like
shape. For example, the bones of the wrist (carpals) and ankle (tarsals) are short bones
Short bones provide stability to the wrist and ankle joints and help facilitate some movements
