Anatomy of the Musculoskeletal System - … · Anatomy of the Musculoskeletal System The musculoskeletal system consists of bones, muscles, bone marrow, bursae (fluid-filled sacs

Medical Terminology | Musculoskeletal System

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Anatomy of the Musculoskeletal System

The musculoskeletal system consists of bones, muscles, bone marrow, bursae (fluid-filled sacs that enable

movement), cartilage, and joints. Our body has 206 bones and more than 600 muscles. The bones meet each

other at joints. These joints contain cartilage and bursae.

Here are the main functions of the skeletal system.

Creating a framework for the body

Protecting delicate organs such as the brain

Storing calcium

Generating blood cells

And here are the functions of the muscular system.

Enabling movement

Stabilizing joints

Creating heat

Bone Structure

Here is a list of components that make up the bones.

Term Definition

Periosteum Outer layer of fibrous tissue.

Compact bone Hard, dense layer of tissue beneath the periosteum.

Cancellous bone Spongelike layer that contains little space and is contained within the compact

bone.

Endosteum Linear membrane in the hollow cavity of bones.

Diaphysis Shafts of long bones.

Epiphysis Ends of long bones.

Bone marrow

Material inside the cavities of bones. The marrow can be thick and red in color,

as in flat bones and epiphysis, where blood cells are produced. It can be soft

and fatty yellow, as in the medullary cavity of long bones.



Bone structure

Diaphysis

This term is derived from the Greek diaphusis, which means the “state of growing between.”

Epiphysis

This term was first used by a Greco-Roman physician to mean “a portion of bone that is attached for a time

to another bone by a cartilage but later combines with the principal bone.” The term was later used to

simply denote the ends of long bones because they are separated from the main part of the bone by a

cartilage. The term has been used in English since the 1600s.

Periosteum

Compact bone

Cancellous bone

Yellow marrow



The Skeleton

The Vertebral Column

This long, column-like structure is made up of small bones called vertebra (pl. vertebrae). These bones have

holes in the center and are arranged one below the other, creating a canal-like space through which the spinal

cord passes. The vertebral column protects the spinal cord, acts as a point of attachment for various muscles and

the ribs, and supports the head. The vertebral column has the following important components.

Term Definition

Cervical vertebrae First 7 vertebrae that form the neck.

Thoracic vertebrae Next 12 vertebrae that act as a point of attachment for 12 pairs of

ribs. They form the outward curve of the spine.

Lumbar vertebrae The 5 large vertebrae following the thoracic vertebrae. They form

the inward curve of the spine.

Sacrum The 5 vertebrae following the lumbar spine that fuse together to

form a triangular bone between the hip bones.

Coccyx Last 4 vertebrae that fuse together to form the tailbone.

Lamina Portion of the vertebral arch.

Other Parts of the Skeleton

Here is a list of other important skeletal bones.

Term Definition

Cranium Bones of the head

Maxilla Upper jawbone. The lower jaw bone is called mandible

Clavicle Collarbone. The shoulder blade is called scapula

Sternum Breastbone

Humerus Upper arm bone

Ulna and radius Lower arm bones

Carpal bones Wrist bones. Hand bones are called metacarpal bones

Phalanges Finger and toe bones. The singular form is phalanx

Pelvic bone, or hip bone Composed of three bones: ischium, ilium, and pubis



Acetabulum Socket in the pelvic bone where the femur is attached

Femur Upper leg bone

Tibia and fibula Lower leg bones

Patella Kneecap

Tarsal bones Ankle bones

Calcaneus Heel bones

Metatarsal bones Foot bones

Skeletal bones



Joints

Joints hold bones together and enable movement. They are also known as articulations. Here is a list of important

terms related to joints.

Term Definition

Articular cartilage Smooth, firm fibrous tissue that covers the

contacting surface of joints

Meniscus Crescent-shaped cartilage in the knee joint

Intervertebral disk Cartilaginous pad between vertebral disks

Synovia Fluid secreted from the synovial membrane

and found in joint cavities

Bursa

Fluid-filled sac allowing easy movement of

the joints

Ligament Tough, flexible, and fibrous connective tissue

that joins one bone to another

Tendon Fibrous connective tissue that binds muscle

with bone

Intervertebral

disk

Intervertebral disk

Tendon

Synovial cavity

Cartilage

Meniscus

Ligament

Knee joint



Muscles

Here are some of the important muscles.

Term Definition

Skeletal muscles

Also called striated muscles, these are attached to bones by tendons and

are responsible for enabling movement and action. They are called

voluntary muscles because we can control their movement.

Smooth muscles

Also called unstriated muscles, these are located on the walls of internal

organs and enable organ movement. They are called involuntary muscles

because we cannot control their movement.

Cardiac muscles

Also known as the myocardium, these are located on the walls of the heart

and enable the heart to beat. They are also involuntary muscles because

we cannot control their movement.

Movements

Here are some of the different types of body movement.

Abduction

(ab-dŭk′shŭn) Moving away from the midline

Adduction

(ă-dŭk′shŭn) Moving toward the midline

Inversion

(in-vĕr′zhŭn) Turning inward

Eversion

(ē-vĕr′zhŭn) Turning outward

Extension

(eks-ten′shŭn) Movement in which a limb is placed straight

Flexion

(flek′shŭn) Movement in which a limb is bent



Pronation

(prō-nā′shŭn) Downward movement of the palm

Supination

(sū′pi-nā′shŭn) Upward movement of the palm

Rotation

(rō-tā′shŭn) Movement around an axis

Knowledge Check

Here are some statements about bone structure and body movements. Mark each of them as True or False.

When you’re done, scroll down to check your answers.

1. Yellow marrow is found in flat bones.

2. Compact bones are hard layers of bone tissue.

3. The periosteum lies beneath the compact bone.

4. The ends of long bones are called diaphysis.

5. Epiphysis is spongy bone.

6. Endosteum is the hollow cavity inside long bones.

7. Pronation is the motion of turning the palm downward.

8. Adduction means moving toward the midline.

9. Flexion is the movement in which a limb is placed straight.

10. Eversion means turning outward.

11. Red bone marrow produces blood cells.



Answer Key

1. False

2. True

3. False

4. False

5. False

6. False

7. True

8. True

9. False

10. True

11. True

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Anatomy of the Musculoskeletal System - … · Anatomy of the Musculoskeletal System The musculoskeletal system consists of bones, muscles, bone marrow, bursae (fluid-filled sacs