The skeletal system consists of both axial and appendicular parts. The axial skeleton includes the skull, vertebral column, ribs, and sternum. The skull contains both single and paired bones that protect the brain and form cavities for sensory organs. The vertebral column is made up of vertebrae which vary based on region. The appendicular skeleton connects the limbs to the axial skeleton and includes the shoulder girdle, upper limbs, pelvic girdle and lower limbs. Long bones have a shaft and two ends, and different bone types serve various protective and movement functions.

1. ‫هللا‬ ‫سبحان‬
‫الرحيم‬ ‫الرحمن‬ ‫هللا‬ ‫بسم‬
‫و‬‫به‬‫نستعين‬

2. General Anatomy
Anatomy Group
Department of Clinical Anatomy
2020

3. SKELETAL
SYSTEM
Dr. Gamal Said

4. 4
List the functions of bone.
Identify the two divisions of the skeleton.
Describe the microscopic structure of bone.
List the different types of bones and give examples.
Identify the parts of a long bone.
Identify the subdivisions of the axial skeleton.
Identify the bones of the skull and the face.
Identify the various regions of the vertebral column.
Identify the subdivisions of the appendicular skeleton.
List the bony components of the pectoral and pelvic girdles and
upper and lower limbs.
Identify the major bony landmarks in the bones of the body.
Upon completion of this lecture, you will be able to:

5.  The skeletal system is formed mostly of bones and
cartilages. The bones are connected together by
number of joints to form the “skeleton of the body”.
Functions of bones:
 They form the skeleton, which gives the general framework
of the body, determining its shape and length.
 They provide attachment of muscles and other ligaments.
 They allow different movements of the body by acting as
levers.
 They have protective function for some vital organs e.g. the
brain is protected by the skull, the heart and lungs are
protected by thoracic wall.
 They are important storage places for calcium salts.
 They have haemopoietic function through the production of
blood cells by the red bone marrow (present in sternum, ribs
and ends of long bones).

6. Types of bones:
 Long bones: are longer than they are wide. They are found in
the limbs e.g. femur, humerus (the metatarsal, metacarpal
bones and phalanges are considered as short long bones).
 Short bones: are cuboidal in shape. They are found in the
hand and foot e.g. carpal and tarsal bones.
 Flat bones: are thin and flattened such as scapula, ribs and
skull bones.
 Irregular bones: they are irregular in shape. They have many
processes such as vertebrae and pelvic bones.
 Pneumatic bones: they have air filled cavities within it e.g.
some facial bones like maxilla).
N.B. the following 2 bone types are usually classified separately:
 Sesamoid bones: are found embedded within certain tendons,
such as the patella and fabella.
 Sutural bones: they occur between the sutures of the skull.

8. Description of a long bone
A long bone consists of shaft and two ends:
 Shaft (diaphysis):
 It is tubular form of compact bone that contains a central cavity
(medullary or bone marrow cavity). This cavity is lined by a
cellular membrane called “endosteum”.
 During growth the diaphysis is separated from the epiphysis by
the epiphyseal cartilage.
 The metaphysis is the part of the diaphysis adjacent to the
epiphyseal cartilage.
 The diaphysis is covered by a vascular membrane "periosteum",
which has an osteogenic power as it contains osteoblasts (bone-
forming cells). It causes the increase in breadth of bones and it is
needed to repair any fractures of bone. It gives attachment to
ligaments and tendons.
 Ends:
 They are the expanded ends of a long bone. Each one is called
“epiphysis”.
 They are formed of spongy bone covered by a thin layer of
compact bone.
 The articular surfaces of the ends are covered by hyaline cart.

10. THE SKELETON
The human skeleton
includes:
 Axial skeleton:
includes the skull,
sternum, ribs and
vertebrae.
 Appendicular
skeleton: includes
the bones of upper
and lower limbs and
their girdles that
connect them to the
axial skeleton.

11.  Skull
 Vertebral column
 Thoracic cage
Remaining 126 bones of
 Pectoral girdle
 Pelvic girdle
 Attached limbs
Axial & Appendicular Skeleton

12. Skull

13. The bones of the skull are either
single or paired:
Single Paired
 Frontal
 Occipital bone
 Ethmoid
 Sphenoid
 Vomer
 Mandible
Parietal
Temporal
Maxilla
Nasal bone
Zygomatic bone
Lacrimal bone
Palatine bone
Inferior nasal concha

14. Vertebral
column

15. The characters of each type of vertebrae:
Vertebra No. Body Spinous
process
Transverse
process
Vertebral
foramen
Cervical 7 relatively small;
oval
short, bifid with transverse
foramen
large,
triangular
Thoracic 12 larger, heart-
shaped; 2 demi-
facets for
articulation with
rib head
long;
directed
down
with facets for
articulation
with rib
tubercle
small,
circular
Lumbar 5 largest of all
vertebrae;
kidney-shaped
short, thick
&
horizontally
Long, slender large,
circular
sacrum 5
Fused
triangular-
shaped bone
with apex
directed
downwards
fuse to
become
median
sacral crest
fuse to become
lateral sacral
crest
becomes
sacral
canal
Coccyx 2-4
Fused
small trianglar
bone attaches to
sacrum
no no no canal

16. Vertebral Column and Spinal Curvatures
Alternating concave and convex curves

17. Thoracic Cage
 Sternum
 12 pairs of ribs
 True vs. false ribs
 Vertebrosternal
 Vertebrochondral
 Vertebral

18. Appendicular Division
 Girdles with their
associated extremities
 Pectoral girdle: clavicle
and scapula
 Upper limb: humerus,
ulna, radius, carpal
bones, hand
 Pelvic girdle: Os coxae
 Lower limb: femur,
patella, tibia, fibula,
tarsal bones, foot

19. Bones of upper limb
 Shoulder girdle: 2 bones
 scapula and clavicle.
 Upper arm: one bone
humerus.
 Forearm: 2 bones 
radius and ulna.
 Hand: carpus (8),
metacarpus (5) and
phalanges (14: 3 in each
finger except thumb,
which contains 2
phalanges only).

25. Bones of lower limb
 Pelvic girdle: one
bone hip bone.
 Thigh: one bone 
femur.
 Leg: 2 bones 
tibia and fibula.
 Foot: tarsus (7),
metatarpus (5) and
phalanges (14: 3 in
each toe except big
toe, which contains
2 phalanges only).