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OVERVIEW OF THE
COMPONENTS OF THE MSS.
Dr. Nabil Khouri, MD, MSc, Ph.D, Anatomy,
First lecture: Objectives: part I
• Discuss the components and functions of the MSS.
• Identify the major regions and compartments of
upper and lower limbs.
• Contrast the structural and functional classification
of joints and identify factors that determine the
degree of movement at a joint.
• Describe the relation between bones and skeletal
muscles in producing body movements.
THE MUSCULOSKELETAL SYSTEM
Major substructure components Are:
Bone.
Muscle.
Tendons.
Ligaments.
Fascia.
Cartilage.
THE SKELETAL SYSTEM
The Human skeletal system consists of a set of 206
bones.
They support and protect the body.
They work with the muscles to provide movement.
The Joints – allow motion between body segments.
The skeleton is divided into 2 parts:
the axial and the appendicular
skeleton.
THE AXIAL SYSTEM
The axial system is made up of the skull bones,
the vertebrae, the ribs and the sternum.
THE APPENDICULAR
SYSTEM
The appendicular system is formed
by the upper and lower limbs
connected to the axial skeleton
through bones of pectoral (shulder)
girdle and pelvic girdle.
THE UPPER LIMBS BONES
THE LOWER LIMBS BONES
Bone: Mechanical properties
• Most important properties are:
– strength and stiffness of bone.
• Fractures occur when the bone is loaded to failure.
– Compression fractures are commonest in cancellous bone
(e.g. fractured skull)
– Bending and torsional fractures are commonest in cortical
bone (e.g. broken tibia).
The following clinical points related to the skeleton of
human body are of interest for medical students.
• Regions of bone sensitive to pain:
• Periosteum is the outer dense membrane that covers the bone that is
particularly sensitive to tearing or tension.
• Fractures, tumors and infections of the bones are very painful.
• The compact bone produces comparatively less sensation of pain as
compared to the Periosteum and Spongy bone.
• Drilling into the compact bone without anesthesia causes only dull pain
or an aching sensation but drilling into spongy bone is much more
painful.
• Profuse blood supply of bone:
• Blood supply of bone is so rich that it is very difficult to interrupt it
sufficiently to kill the bone.
• Passing a metal pin into the medullary cavity hardly interferes with the
blood supply of the bone.
• Bone fractures: Fracture is a breakage of the continuity of bone.
– The fracture which is not connected with skin wound is known as
simple or closed fracture.
– The fracture which communicates with the skin wound is known as
compound or open fracture.
– A fracture requires reduction by which the alignment of broken ends
is restored.
Repair of fracture takes place in three stages;
1.
2.
3.
Repair by granulation tissue
Union by callus
Consolidation by mature bone
• Rickets: In Rickets (deficiency of Vitamin D) calcification of cartilage
fails and ossification of the growth zone of a bone is disturbed.
• Rickets affects the growing bones and therefore the disease develops
during the period of most rapid growth of skeleton that is the period
between the age of 3 months to 3 years
• Scurvy: In Scurvy (deficiency of Vitamin C) formation of collagenous
fibers and matrix is impaired.
Anatomy of The
Musculoskeletal
System
What we will study!
The Muscular and Skeletal system
Skeletal system: is made of Bones that is a hard supporting
tissue
Bones are used to make up the skeleton
Found in many forms including:
“small, large, long, short and flat”
Bones are held together by Joints which allow and/or restrict
movements.
Movements are performed by Muscle upon their contractions
Muscle is made of muscular tissue
Types of Ordinary Body Movements
 Flexion – decreases angle of joint and brings two
bones closer together
 Extension- opposite of flexion
 Rotation- movement of a bone in longitudinal
axis, shaking head “no”
 Abduction/Adduction
 Circumduction
Body Movements
Abduction –
moving the limb
away from the
midline
Circumduction: coneshaped movement,
proximal end doesn’t
move, while distal end
moves in a circleular
aspect
Adductionmoving
toward the
midline
Skeletal system
Objectives
•
•
•
•
Divisions of the Skeleton
Major bony landmarks
Bone functions
Classification of Bones
Bones: Forms In the skeleton and are arranged into
• Vertebral Column
•
•
•
•
•
•
•
•
•
•
•
•
•
appendicular skeleton
Axial skeleton
Skull
Hyoid bone
Ribs and sternum
Appendiclular skeleton
Upper Extremities
Lower Extremities
Auditory bones
The total number of bones
26
22
1
25
------64
62
-------6
-------206
Axial and
Function of Bones
–
–
–
–
–
support (eg: pelvis, legs)
protect (eg: skull, vertebrae)
mineral storage (eg: calcium, phosphate, inorganic component)
movement (eg: walk, grasp objects)
blood-cell formation (eg: red bone marrow)
• Cellular components include
– Osteoblasts: secrete organic part of bone matrix = osteoid
– Osteocytes: mature bone cells, maintain bone matrix
Classification of Bones
Types of Bone
1). Long bones
2). Short bones.
3). Flat bone:
4). Irregular bones
5). Sesamoid bones are special short bones:
Ex: patella
Long Bones
• Long bones are characterized by
having one shaft (the Diaphysis)
that is much greater in length
than width and two extremities
(epiphysis).
• They are comprised mostly of
compact bone and lesser
amounts of marrow, which is
located within the medullary
cavity, and spongy bone.
• Most bones of the limbs,
including those of the fingers and
toes, are long bones.
Short bones
• Short bones are roughly
cube-shaped, and have
only a thin layer of
compact bone
surrounding a spongy
interior .
• The bones of the wrist
and ankle are short
bones, as are the
sesamoid bones .
Flat bones
• Flat bones are thin
and generally curved,
with two parallel
layers of compact
bones sandwiching a
layer of spongy bone .
• Most of the bones of
the skull are flat
bones, as is the
sternum .
Irregular
bones
• Irregular bones do not fit
into the above
categories .
• They consist of thin layers
of compact bone
surrounded by a spongy
interior.
• As implied by the name,
their shapes are irregular
and complicated .
• The bones of the spine
and hips are irregular
bones .
Surface Features of the Bone
• 1). Projections that form joints
• a). Head: The proximal articular end of the bone
• b). Facet: A small, flattened articular surface
• c). Condyle: A large, rounded articular process
• d). Ramus: An arm-like branch off the body of a bone
2). Sites of muscle & ligament attachment.
a). Tuberosity: A projection or bump with a roughened surface
b). Crest: A prominent elevation or ridge
c). Trochanter: A specific tuberosities located on specific bones “
Femur”
d). Line
e). Tubercle: A projection or bump with a roughened surface, generally
smaller than a tuberosity
f). Epicondyle: A projection near to a condyle but not part of the joint.
g). Spine: A relatively long, thin projection or bump
h). Process: A relatively large projection or prominent bump.(gen.)
Surface Features of the Bone
3). Openings that allow blood vessels and nerves to pass
– a). Meatus: A short canal
– b). Fissure: A small or large gap between two parts of one bone
– c). Foramen: An opening through a bone.
– d). Sinus: Pocket (cavity) like structure within the
cranial bone
– e). Canal: A long, tunnel-like foramen, usually a passage for
notable nerves or blood vessels
4). Depressions
– a). Fossa: A broad, shallow depressed area
– b). Grove: A longe depresive mark on one surface of a bone
– c). Notch: A small depression
The Skull
• The skull, the body’s most complex bony structure, is formed
by the cranium and facial bones
• Cranium –
– protects the brain and is the site of attachment for head
and neck muscles
• Facial bones
– Supply the framework of the face, the sense organs, and the
teeth
– Provide openings for the passage of air and food
– Anchor the facial muscles of expression
Anatomy of the Cranium
• Eight cranial bones –
–
–
–
–
–
–
Two parietal
Two temporal
One frontal.
One occipital
One sphenoid
One ethmoid
• Cranial bones are thin and remarkably strong
for their weight
Neonatal (Fetal) Skull
Parietal Bones and Major Associated Sutures
• Four sutures mark the articulations of the parietal
bones
– Coronal suture – articulation between parietal bones and
frontal bone anteriorly
– Sagittal suture – where right and left parietal bones meet
superiorly
– Lambdoid suture – where parietal bones meet the occipital
bone posteriorly
– Squamous suture – where parietal and temporal bones meet
• Parietal Bones: lateral aspects of the skull
Frontal Bone
• Forms the anterior portion of the cranium
• Articulates posteriorly with the parietal bones
via the coronal suture
• Major markings include the supraorbital
margins, the anterior cranial fossa, and the
frontal sinuses (internal and lateral to the
glabella)
Skull – Anterior View
Temporal Bone: Lateral Aspects of the Skull
Temporal Bones
• Form the inferolateral aspects of the skull and parts
of the cranial floor
• Divided into four major regions – squamous,
tympanic, mastoid, and petrous
Occipital Bone: Posterior view of the skull
• Forms most of
skull’s posterior wall
and base
• Major markings
include the
posterior cranial
fossa, foramen
magnum, occipital
condyles, and the
hypoglossal canal
Occipital Bone and Its Major Markings
Superior view of the skull
Sphenoid Bone
• Butterfly-shaped bone that spans the width of the
middle cranial fossa
• Forms the central wedge that articulates with all other
cranial bones
• Consists of a central body, greater wings, lesser wings,
and pterygoid processes
• Major markings: the sella turcica, hypophyseal fossa, and
the pterygoid processes
• Major openings include the foramina rotundum, ovale,
and spinosum; the optic canals; and the superior orbital
fissure
Sphenoid Bone
Inferior Aspect of the Skull base
Med-Sagital aspects of the Skull
Facial Bones
• Fourteen bones of which only the mandible and vomer
are unpaired
• The paired bones are:
–
–
–
–
–
–
Maxillae
Zygomatics
Nasals
Lacrimals
Palatines
Inferior conchae
Maxillary Bones
• Medially fused bones that make up the upper jaw and
the central portion of the facial skeleton
 Facial keystone bones that articulate with all
other facial bones, except the mandible
 Their major markings include palatine, frontal,
and zygomatic processes, the alveolar margins,
inferior orbital fissure, and the maxillary sinuses
Maxilla Bones
Zygomatic Bones
• Irregularly shapes bones
(cheekbones) that form
the prominences of the
cheeks and the inferolateral margins of the
orbits
Mandible Bone
• The mandible (lower
jawbone) is the largest,
strongest bone of the
face
• Its major markings
include the coronoid
process, mandibular
condyle, the alveolar
margin, and the
mandibular and mental
foramina
Other Facial Bones
• Nasal bones – thin medially fused
two bones that form the bridge of
the nose
• Palatine bones – two bone plates
that form portions of the hard
palate, the posterolateral walls of
the nasal cavity, and a small part of
the orbits
Lacrimal bones – contribute to the medial walls of the
orbit and contain a deep groove called the lacrimal
fossa that houses the lacrimal sac
The Orbit
• Bony cavities in which the eyes are firmly encased and cushioned
by fatty tissue
• Formed by parts of seven bones – frontal, sphenoid, zygomatic,
maxilla, palatine, lacrimal, and ethmoid
The Orbit
Figure 7.9b
Ethmoid Bone
• Most deep of the skull bones; lies between the
sphenoid and nasal bones


Forms most of the bony area between the nasal cavity and
the orbits
Major markings include the cribriform plate, crista galli,
perpendicular plate, nasal conchae, and the ethmoid
sinuses
Ethmoid Bone
Other Facial Bones
• Vomer – plow-shaped bone that forms part of the
nasal septum
• Inferior nasal conchae – paired, curved bones in the
nasal cavity that form part of the lateral walls of the
nasal cavity
Nasal Cavity
• Constructed of bone and hyaline cartilage
• Roof – formed by the cribriform plate of the ethmoid
• Lateral walls – formed by the superior and middle
conchae of the ethmoid, the perpendicular plate of
the palatine, and the inferior nasal conchae
• Floor – formed by palatine process of the maxillae
and palatine bone
Nasal Cavity
Paranasal Sinuses
• Mucosa-lined, air-filled sacs found in five skull bones
– the frontal, sphenoid, ethmoid, and paired maxillary
bones
• Air enters the paranasal sinuses from the nasal cavity
and mucus drains into the nasal cavity from the
sinuses
• Lighten the skull and enhance the resonance of the
voice
Paranasal Sinuses
Sinuses connections and drainage
Hyoid Bone
• Not actually part of the skull, but
lies just inferior to the mandible in
the anterior neck
• Only bone of the
body that does not
articulate directly
with another bone
• Attachment point
for neck muscles
that raise and
lower the larynx
during swallowing
and speech