The Skeletal System
Functions of the Skeletal System
1. Support – provides a framework for softer tissues and organs
of the body to attach
2. Protection – encloses and protects vital organs; sites for
blood cell production
3. Movement – bones act as levers when attached muscles
contract, causing movement about joints
4. Hemopoiesis – red bone marrow of an adult produces red
and white blood cells and platelets
5. Mineral and Energy Storage – matrix of bone is composed of
calcium and phosphorus, which can be withdrawn in small
amounts to be used elsewhere in the body; small amounts of
magnesium & sodium also stored; yellow bone marrow stores
energy (adipose)
Categorization of Bones
 Long bones: longer than wide
 Found in appendages
 Short bones: more or less cubical
 Found in confined spaces
 Flat bones: Protection
 Found: bones of the skull, ribs
 Irregular bones: odd shapes
 Found: vertebrae, certain skull bones
Structure of a Long Bone
 Diaphysis: shaft
 Epiphysis: ends;
consist of spongy
bone (contains red
bone marrow)
surrounded by
compact bone
 Medullary cavity: in
the diaphysis,
contains fatty yellow
bone marrow
 Endosteum: thin layer of connective tissue that lines the medullary
cavity
 Periosteum: covering made of dense connective tissue where
tendons and muscles attach
Bones of the Axial Skeleton
 Includes:
 Cranium
 Rib cage
 Vertebral column
Bones of the
Cranium
Frontal View
Frontal
Frontal View
Parietal
Frontal View
Temporal
Frontal View
Nasal
Frontal View
Vomer
Frontal View
Zygoma
Frontal View
Maxilla
Frontal View
Mandible
Frontal View
Frontal
Parietal
Temporal
Nasal
Vomer
Zygoma
Maxilla
Mandible
Frontal View
Lateral View
Frontal
Lateral View
Parietal
Lateral View
Temporal
Lateral View
Nasal
Lateral View
Zygoma
Lateral View
Maxilla
Lateral View
Mandible
Lateral View
Sphenoid
Lateral View
Occipital
Lateral View
Mastoid Process
Lateral View
External Auditory Meatus
Lateral View
Parietal
Frontal
Sphenoid
Nasal
Temporal
Zygoma
Maxilla
Occipital
Mastoid Process
Mandible
External Auditory Meatus
Lateral View
Sutures
Sagittal
Sutures
Frontal
(Coronal)
Sutures
Squamous
Sutures
Lambdoid
Sutures
Sagittal
Frontal
(Coronal)
Squamous
Lambdoid
Sutures
Bones of the Rib Cage
Rib Cage
 Sternum (aka breastbone)
 Covers the heart, ribs
attach to it
 12 Pairs of Ribs
 1 – 7: true ribs – cartilage
joins the sternum
 8 – 12 false ribs – do not
connect to sternum
 Pairs 8, 9, & 10 join to cartilage of rib above it and indirectly
to the sternum
 Pairs 11 & 12 are floating ribs – they do not connect to the
sternum in any way
Bones of the Vertebral
Column
Bones of the Vertebral Column
 Composed of 33 vertebra

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7 cervical (neck)
12 thoracic
5 lumbar
4-5 fused sacral
4-5 fused coccyx
Bones of the Appendicular
Skeleton
 Includes:
 Pectoral girdle
 Pelvic girdle
 Upper & lower
extremities
Clavicle
Scapula
Humerus
Ulna
Radius
Clavicle
Scapula
Humerus
Ulna
Radius
Ilium
Ischium
Pubis
Femur
Patella
Tibia
Fibula
Ilium
Ischium
Pubis
Femur
Patella
Fibula
Tibia
Bones of the Hand
Carpels
Bones of the Hand
Metacarpels
Carpels
Bones of the Hand
Phalanges (14)
Metacarpels (5)
Carpels (8)
Bones of the Hand
Bones of the Foot
Tarsals
Bones of the Foot
Metatarsals
Tarsals
Bones of the Foot
Phalanges (14)
Metatarsals (5)
Tarsals (7)
Bones of the Foot
Joints and Fractures
Joints
 Points of contact between 2 bones – classified according to
movement:
 SYNOVIAL FLUID – lubricating substance in joints
 BALL AND SOCKET JOINT – bone with ball- shaped head fits
into concave socket of 2nd bone. Shoulders and hips.
 HINGE JOINTS – move in one direction or plane. Knees, elbows,
outer joints of fingers.
 PIVOT JOINT – those with an extension rotate on a 2nd, arch
shaped bone. Radius and ulna, atlas and axis.
 GLIDING JOINTS – flat surfaces glide across each other.
Vertebrae of spine.
 SADDLE JOINT – one bone is shaped like a saddle, while the
other bone rests on it like a rider on a horse. Base of thumb
 SUTURE – immovable joint. Between bones of skull.
Fractures
 FRACTURE – a break
 Treated by:
 CLOSED REDUCTION – cast or splint applied
 OPEN REDUCTION – surgical intervention with devices such as
wires, metal plates or screws to hold the bones in alignment (internal
fixation)
 TRACTION – pulling force used to hold the bones in place – used
for fractures of long bones
 Types:
 CLOSED or SIMPLE fracture – bone broken, broken ends do not





break the skin
OPEN or COMPOUND – broken bones pierce the skin, can lead to
infection
GREENSTICK – in children, bone bent and splintered but never
completely separates
COMMINUTED – splintered or broken into many pieces
SPIRAL – bone twists, resulting in one or more breaks
DISLOCATION – bone displaced from proper position in joint