The Musculoskeletal System
Link with the Nervous System
• The nervous system controls and coordinates
movements within our bodies.
• It collects sensory information that is relayed to the
brain, causing our bodies to react.
• The musculoskeletal system is what makes those
movements possible.
• Without our muscles and our bones, we would not be
able to stand, write, or even open our eyes.
The Skeletal System
Basic Information
• The human skeleton is made up of 206 bones. Around
80% of these bones are found in our hands and feet.
• At birth, humans have 270 bones. As we grow, our
bones fuse together until adulthood.
• The bones of the body can be divided into three
anatomical regions:
▫ The head – cranium, mandible, maxilla, etc.
▫ The trunk – sternum, clavicle, scapula, ribs, etc.
▫ The limbs – humerus, femur, tibia, carpals, etc.
The Head
1. The head
a.
Skull (cranium)
⚫ Houses the brain
⚫ Cranial bones are
flat and are
immovable
b.
Face
⚫ All bones are
immovable, except
the jaw (mandible)
The Trunk
2. Trunk (2 main groups of bones)
1. Spinal column
⚫ 33 vertebrae (short
bones joined by
cartilage which allow
only limited
movements)
⚫ It is flexible, mobile
and resists shocks
⚫ 5 parts
⚫ Cervical (neck)
⚫ Thoracic (chest)
⚫ Lumbar
⚫ Sacral (sacrum)
⚫ Coccygeal (coccyx)
2. Thorax or rib cage
• Ribs, sternum,
thoracic vertebrae
• Make a bony cage
that protects organs
and can change in
volume for gas
exchange
• 3 main types of ribs
⚫ True
⚫ False
⚫ Floating
Limbs
• Occur in pairs
• Each has 3 parts (i.e. arm, forearm, hand)
• They are jointed held together by ligaments
Bone Anatomy
• Bones are made up of bone cells. These cells are
constantly renewing, (mitosis), and make up the
hardest material in the human body.
Diaphysis
⚫ middle section of the bone (yellow
marrow)
2 Epiphyses
⚫ ends of the bone (red marrow) =
red blood cells
Periosteum
⚫ Responsible for growth in width
⚫ thin membrane that encloses the
bone
⚫ role in growth of the thickness of
the bone, in healing fractures.
Continually active, but decreases
with age
• Within each bone is a
variable proportion of
spongy bone and compact
bone.
• Spongy bone contains small
cavities. Marrow, (yellow
and red), is found here.
▫ Yellow marrow produces fat
and bone.
▫ Red marrow produces red
and white blood cells and
platelets.
• Compact bone is dense and
hard, giving bones their
durability.
Bone Classification
• Bones come in a variety of shapes and sizes.
• The longest bone in the body is the femur, at around
60 cm long. The smallest bones are the ossicles in the
ear, which are around the size of a pea.
• Bones are classified into four types:
▫
▫
▫
▫
Long bones
Short bones
Irregular bones
Flat bones
Type of bone
Example in body
Main Function in body
Long Bones
Femur, humerus.
work with muscles to move body
parts, storage, support, blood
production.
Short bones
Tarsals, carpals, clavicle
work with muscles to move body
parts, storage
Flat bones
Sternum, cranium,
scapula
Protect organs, blood production
The vertebrae, mandible,
Iliac.
Support, blood production,
movement
Irregular Bones
Bone
Shape
1. Humerus
long
2.Radius
Long
3.Ulna
Long
4.Femur
Long
5.Fibula
Long
6.Tibia
Long
7.Cranium
Flat
8. Mandible
Irregular
9. Clavicle
Short
10.Scapula
Flat
11.Sternum
Flat
12. Rib cage
Long
13. Vertebrae
Irregular
14. Iliac / os coxa
Irregular
15.Carpals
Short
16.Phalanges
Long
17.Patella
Short
Joints
• Any place where two bones meet.
• Because of their rigidity, bones are held together by
cartilage. Cartilage is more elastic and flexible,
allowing movement between bones. It also acts as a
shock absorber.
• Ligaments are tissues that hold bones in their place.
Types of Joints
• Immovable
▫ Pelvis
▫ Skull
• Moveable
▫
▫
▫
▫
Ball and socket
Hinge
Gliding
Pivot
…
• Ball and Socket
▫ When a rounded end of one bone fits into a cup-like
cavity in another bone.
▫ Ex – Humerus in the scapula, femur in the pelvis.
…
• Pivot
▫ When one bone rotates within another.
▫ Ex – Neck, radius and ulna
…
• Hinge
▫ When two bones move back and forth in relation to one
another, like the hinges of a door.
▫ Ex – Elbow joint, (humerus to radius), knee joint, (femur
to tibia).
…
• Gliding
▫ When one bone slides past another.
▫ Ex – carpals and metacarpals, tarsals and metatarsals.