Download bone

SKELETAL SYSTEM
The skeletal system is formed of bones and cartilages
The bones are connected together by joints to form the skeleton
Functions of bones
• They form the skeleton which gives the body
shape and form
• They provide attachment for muscles & ligaments
• They allow movements of the body
• They provide protection for vital organs
• They provide storage places for calcium salts
• Production of blood cells in the red bone marrow
Structure of Bone
• The bone is a type of connective tissue
• It is hard because of its high content of
calcium salts
• There are 2 types of bone tissue:
Compact bone: which is dense & hard. It
forms the shaft of long bones and outer
shell of other bones.
It consists of cylindrical units of closely
packed lamellae (Haversian system)
Cancellous (spongy) bone: a delicate
bony meshwork that fills the inside of
bones.
Compact
Haversian system
Types of Bones (according to shape)
• Long bones: these are longer than wide, and are found in limbs, e.g.
humerus.
• Short bones: they are cuboidal in shape, and found in the hand and
foot (carpal & tarsal bones)
• Flat bones: thin and flattened, e.g. scapula & skull bones
• Irregular bones: they are irregular in shape, e.g. vertebrae
• Pneumatic bones: they contain air-filled cavities, e.g. ethmoid bone
• Sesamoid bones: embedded within certain tendons, e.g. patella
• Sutural bones: found between the skull sutures
Remember!! Metatarsal & metacarpal bones and phalanges are
considered long bones
Short bones
Long bones
Long bone
Flat bone
Pneumatic bone
Sutural bones
Irregular bone
Patella
Sesamoid bone
Features of Long Bones: Long bones consist of a “shaft” and 2 “ends”
Shaft (Diaphysis):
• This is the tubular part of the long bone. It is formed of compact bone and
contains a central cavity called “medullary” or “bone marrow cavity”.
• The shaft is lined by a membrane called “endosteum” and covered by a vascular
membrane called “periosteum”
• The periosteum contains osteoblasts and causes the increase in width of the
bones, it is also needed for repair of bone fractures.
Ends (Epiphysis):
• These are the expanded ends of the long bone.
• They are formed of cancellous bone covered by a thin layer of compact bone.
Note!! the diaphysis is separated from the epiphysis by the “epiphyseal cartilage”
The Metaphysis: is the part of the diaphysis adjacent to the epiphyseal line
Ossification of bone
• This is the process of bone formation from specialized mesenchymal tissue
• It starts by the appearance of certain points (1ry ossification centers) which are
responsible for ossification of the central parts of the bone.
• After birth, 2ry ossification centers appear in the peripheral parts of the bone and
complete the process of ossification.
Types of Ossification
Cartilaginous ossification:
The bone is formed by replacement
of the cartilaginous model by
bone tissue (like in long bones)
Membranous ossification:
The bone is formed directly from connective
tissue membrane (like in flat bones)
Blood supply of bone
Bones receive blood from:
•Nutrient arteries, which enter the diaphysis through a nutrient foramen
•Periosteal arteries
•Metaphyseal and epiphyseal arteries
Epiphyseal & metaphyseal
arteries
Nutrient artery
Surface Features of Bones
Elevations & projections
• Process: elongated projection
• Spine: pointed (or sharp) projection
• Tubercle: a small rounded elevation
• Tuberosity: large tubercle
• Trochanter: large tuberosity
• Line: faint linear elevation
• Ridge: raised line
• Crest: thick ridge
Temporal lines
process
spine
Perforations
• Foramen: a hole connecting two surfaces
• Fissure: a cleft between two bones
• Canal: a passage between two openings
• Hiatus: a narrow passage with one opening seen
fissure
foramen
Carotid canal
Depressions:
•Fossa: depression below the surface
•Sulcus: elongated depression
•Notch: deficient part of bone
•Meatus: a tube-like passage
head
Articular surfaces
• Head: a rounded end
• Condyle: round or oval projection
• Trochlea: pulley-shaped projection
• Capitulum: like a small head
• Facet: small smooth flat (or slightly
concave) surface
trochlea
capitulum
facet
condyle
SKELETON
Axial skeleton:
• Skull
• Sternum
• Ribs
• Vertebrae
Appendicular skeleton:
• Bones of upper limb & Shoulder girdle
• Bones of lower limb & Pelvic girdle
Shoulder
girdle
SKULL
The skull is formed of two parts:
•Brain box: the upper & posterior part of the skull
•Facial skeleton: the anterior part of the skull
The skull is made up of 22 bones
• 1 movable bone, the mandible
• 21 immovable bones articulating
by fibrous joints (sutures)
Single bones of the skull
Paired bones of the skull
•Frontal bone
•Occipital bone
•Ethmoid bone
•Sphenoid bone
•Vomer
•Mandible
•Parietal bone
•Temporal bone
•Maxilla
•Zygomatic bone
•Nasal bone
•Lacrimal bone
•Palatine bone
•Inferior nasal concha
Features of the Skull
Norma Frontalis, shows:
• Frontal bone
• Nasal bones
• Maxillae
• Zygomatic bones
• Mandible
Orbit opening
• Orbital openings
• Anterior nasal aperture
• Mental foramen
Anterior nasal
aperture
Mental foramen
Norma verticalis, shows:
• Frontal bone
• Parietal bones
• Occipital bone
• Coronal, sagittal and lambdoid sutures
• Parietal foramen
Frontal bone
Coronal suture
Sagittal suture
Lambdoid suture
Parietal foramen
Occipital bone
Norma lateralis, shows:
• Frontal, Parietal, Temporal, Occipital and Zygomatic bones
• Zygomatic arch
• Temporal lines & temporal fossa
• External auditory meatus
Temporal lines
Zygomatic
bone
Zygomatic
arch
External auditory
meatus
Norma occipitalis, shows:
• Occipital bone
• Parietal bones
• External occipital protuberence & crest
• Nuchal lines
Parietal
External occipital
protuberence
Superior & inferior
Nuchal lines
bones
Occipital bone
Norma basalis externa, shows:
• Alveolar arch
• Hard palate
• Posterior nasal apertures
• Foramina and canals which give
passage to structures which enter
or leave the skull
• foramen ovale
• foramen magnum
• carotid canal
Posterior nasal
aperture
• jugular foramen
Hard palate
Alveolar arch
Foramen
ovale
Carotid
canal
Foramen
magnum
Jugular
foramen
Norma basalis interna, shows
• Anterior, middle & posterior cranial fossae
• Frontal, ethmoid, sphenoid, temporal & occipital bones
• Foramina:
• Foramen rotundum
• Foramen ovale
• Foramen lacerum
Frontal bone
• Jugular foramen
• Foramen magnum
Ethmoid bone
Foramen rotundum
Sphenoid bone
Foramen ovale
Foramen lacerum
Temporal bone
Jugular foramen
Occipital bone
Foramen
magnum
Vertebral Column (Spine)
•The vertebral column (spine) consists of:
•7 cervical vertebrae
•12 thoracic vertebrae
•5 lumbar vertebrae
•5 sacral vertebrae (fused together to form the sacrum)
•4 coccygeal vertebrae (fused together to form the coccyx)
•The vertebral column provides support for the head and trunk
•It provides protection for the spinal cord
Basic Structure a Vertebra
• Body: disc shaped and anterior in position
• Vertebral arch: a bony ring behind the body. It is formed of 2 pedicles and 2 laminae
• Vertebral foramen: the ring bound by the vertebral arch. The vertebral canal is formed
by the succession of vertebral foramina
• 7 Processes: They project from the vertebral arch
• A Spinous process, projects posteriorly
• 2 Transverse processes, one projecting on each side
• 2 Superior articular processes projecting up to articulate with the inferior articular
processes of the vertebra above.
• 2 Inferior articular processes projecting down to articulate with the superior
articular processes of the vertebra blow.
Characteristics of Vertebrae
Cervical
Thoracic
Lumbar
Body
Small & oval
Heart-shaped with
articular demifacets
Large & kidney-shaped
Spinous
process
Short & bifid
Long & directed down
Short & thick
Transverse
processes
Show a foramen
transversarium
Have articular facets
Long & slender
Vertebral
foramen
Large & triangular
Small & circular
Large & circular
Foramen
transversarium
Cervical Vertebra
Bifid spine
Thoracic Vertebra
Lumbar Vertebra
1st & 2nd Cervical Vertebrae
Sacrum:
It is formed of 5 vertebrae that are fused together
Intervertebral foramina
• These are notches in the upper and
lower borders of each pedicle of the
vertebral arch
• Adjacent notches from an intervertebral
foramen for the passage of spinal nerves
Curves of the vertebral column
• The vertebral column presents 4 curves that are termed
cervical, thoracic, lumbar and pelvic.
• At birth, the vertebral column forms one C-shaped curve
(1ry curve) which is convex backward
• Later in life, 2 curves (2ry curves) appear in the cervical and
lumbar regions and are convex forward.
• Thus, the cervical & lumbar curves are convex forward, while
the thoracic & pelvic curves are convex backward
Cervical
curve
Thoracic
curve
Lumbar
curve
C-shaped curve
of fetal spine
Pelvic
curve
Abnormal curves of the vertebral column
Lordosis: increased forward curvature of the lumbar region
Kyphosis: increased backward curvature of the thoracic region
Scoliosis: lateral curvature usually in the thoracic region.
Kyphosis
Lordosis
Scoliosis
Sternum & Ribs
The sternum is composed of 3 fused pieces
•manubrium sterni
•body
•ziphoid process
Sternal angle: is the junction between the
manubrium and the body
Ribs
• There are 12 pairs of ribs
• All the ribs are attached at their posterior ends
to the vertebrae.
• Anteriorly:
• The upper 7 pairs (true ribs) are attached
directly to the sternum by their costal
cartilages
• The 8th, 9th, and 10th ribs (false ribs) are
attached to the 7th costal cartilage.
• The 11th and 12th ribs (floating ribs) have
no anterior attachment.
Basic features of ribs
• Head: articulates with the thoracic vertebrae
• Neck: the constriction just beyond the head
• Tubercle: articulates with the transverse process of its corresponding vertebra
• Angle: the sharp turn in the rib
• Shaft: thin and flattened, its lower border is sharp and shows a groove for intercostal
nerves & vessels.
APPENDICULAR SKELETON
Skeleton of the Upper Limb consists of:
Shoulder girdle: 2 bones
• Clavicle, anteriorly
• Scapula, posteriorly
Upper arm, one bone
• Humerus
Forearm, 2 bones
• Radius, laterally
• Ulna, medially
Hand, formed of:
• Carpus (8 bones)
• Metacarpus (5 bones)
• Phalanges (3 in each finger, except the
thumb which contains 2 phalanges)
APPENDICULAR SKELETON
Skeleton of the Lower Limb consists of:
Hip bone
Pelvic girdle: 1 bone
• Hip bone
Thigh, 1 bone
• Femur
Leg, 2 bones
• Fibula, laterally
• Tibia, medially
Foot, formed of:
• Tarsus (7 bones)
• Metatarsus (5 bones)
• Phalanges (3 in each toe, except the big
toe which contains 2 phalanges)