Skelton system, Axial and appendicular Skelton . Function of Skelton system . About bones

1. Skeletal system
ANANYA GIRISH BABU
LECTURE

2. Human skeleton, the internal skeleton that serves as a framework for the body. This framework
consists of many individual bones and cartilages
It is composed of around 270 bones at birth – this total decreases to around 206 bones by
adulthood after some bones get fused together.[1] The bone mass in the skeleton makes up about
14% of the total body weight (ca. 10–11 kg for an average person) and reaches maximum mass
between the ages of 25 and 30
Parts of Skelton system are
 bones
Joints
Cartilage
Ligaments
Skelton system
Appendicular
skelton
Axial Skelton

3. The human skeleton, like that of other vertebrates, consists of two principal subdivisions,
each with origins distinct from the others and each presenting certain individual features. These are
(1) the axial, comprising the vertebral column—the spine—and much of the skull, and (2)
the appendicular, to which the pelvic (hip) and pectoral (shoulder) girdles and the bones and
cartilages of the limbs belong.
It is composed of around 270 bones at birth – this total decreases to around 206 bones by
adulthood after some bones get fused together. The bone mass in the skeleton makes up about 14%
of the total body weight (ca. 10–11 kg for an average person) and reaches maximum mass between
the ages of 25 and 30.

5. Major functions
SUPPORT
The skeleton provides the framework which supports the body and maintains its shape.
The pelvis, associated ligaments and muscles provide a floor for the pelvic structures. Without
the rib cages, costal cartilages, and intercostal muscles, the lungs would collapse
MOVEMENT
The joints between bones allow movement, some allowing a wider range of movement
than others, e.g. the ball and socket joint allows a greater range of movement than the pivot joint at
the neck. Movement is powered by skeletal muscles, which are attached to the skeleton at various
sites on bones. Muscles, bones, and joints provide the principal mechanics for movement, all
coordinated by the nervous system.
PROTECTION
The skeleton helps to protect many vital internal organs from being damaged.

6. PRODUCTION OF BLOOD CELLS
The skeleton is the site of haematopoiesis, the development of blood cells that takes place in
the bone marrow. In children, haematopoiesis occurs primarily in the marrow of the long bones
such as the femur and tibia. In adults, it occurs mainly in the pelvis, cranium, vertebrae, and
sternum.
STORAGE OF MINERALS
The bone matrix can store calcium and is involved in calcium metabolism, and bone marrow can
store iron in ferritin and is involved in iron metabolism.
ENDOCRINE REGULATION.
Bone cells release a hormone called osteocalcin, which contributes to the regulation of blood
sugar (glucose) and fat deposition. Osteocalcin increases both insulin secretion and sensitivity, in
addition to boosting the number of insulin-producing cells and reducing stores of fat.

7. AXIAL BONES
Found in the head and torso –skull, vertebrae and
Thoracic cage
APPENDICULAR BONES
Found in appendages or limbs – arms legs pelvis
And shoulder's

8. What’s the difference between the axial and appendicular
skeleton?
axial skeleton is made up of the bones in your head, neck, back and chest. Your appendicular
skeleton is made up of everything else — the bones that attach (append) to your axial skeleton.
Your appendicular skeleton includes the bones in your shoulders, pelvis and limbs, including your
arms, hands, legs and feet.

9. Axial Skelton
Your axial skeleton is made up of the 80 bones within the central core of your body.
 This includes bones in your skull (cranial and facial bones), ears, neck, back (vertebrae, sacrum
and tailbone) and ribcage (sternum and ribs). Your axial skeleton protects your brain, spinal cord,
heart, lungs and other important organs.
axial skeleton is made up of the bones along your vertical axis. Axial comes from the word
“axis,” which means line. The bones line up along the central core of your body.

11. SKULL contain 22 bone
CRANIAL BONE
PROTECT THE
BRAIN
FACIALBONE
GIVE
STRUCTURE TO
FACE

12. CRANIAL BONES
•Parietal (2)
•Temporal (2)
•Frontal (1)
•Occipital (1)
•Ethmoid (1)
•Sphenoid (1)

13. There are eight cranial bones, each with a unique shape:
•Frontal bone. This is the flat bone that makes up your forehead. It also forms the upper
portion of your eye sockets.
•Parietal bones. This a pair of flat bones located on either side of your head, behind the
frontal bone.
•Temporal bones. This is a pair of irregular bones located under each of the parietal bones.
•Occipital bone. This is a flat bone located in the very back of your skull. It has an opening
that allows your spinal cord to connect to your brain.
•Sphenoid bone. This is an irregular bone that sits below the frontal bone. It spans the width
of your skull and forms a large part of the base of your skull.
•Ethmoid bone. This is an irregular bone located in front of the sphenoid bone. It makes up
part of your nasal cavity.

14. FACIAL BONES
Another anatomical name is VISCEROCRANIUM
The names of the 14 facial bones are:
•Inferior nasal concha x 2
•Lacrimal bones x 2
•Mandible
•Maxilla x 2
•Nasal bones x 2
•Palatine bones x 2
•Vomer
•Zygomatic bones, or zygoma, x 2

15. NASAL BONES – They are long rectangular bone made up the bridge of the nose and cover nasal
cavity .it protect the arteries and nerves and give structure to the face
LACRIMAL BONE -Main function is to support the eye and make space for lacrimal duct tube and
tears travel through
MAXILLARY BONE -It’s a part of jaw in human. Their function is to hold upper teeth in place and
support the facial structure along with mandible. Also important in chewing, sinus drainage
smiling etc
MANDIBLE BONE –also known as jaw bones . It is the largest bone in the skull which is
responsible for biting chewing and it forms the structure of mouth . TMJ is the only joint in the
skull
VOMER – its larger than it appear [ it looks tiny in the image ]located bottom of the nasal cavity.
the main function of vomer is to separate the nasal cavity to right and left

16. ZYGOMATIC BONES –to the side of the eye socket the cheek region bone is zygomatic bones ,
it’s a pair of bones. These bones make cheeks and outside edge of the eye
LACRIMAL BONES-it’s the smallest bone of the skull which help to form the eye orbut and
relatable to tear duct

18. STRUCTURE OF SPINE
CERVICAL SPINE
(c1-c7)
THORACIC VERTEBRA
(T1-T12)
LUMBAR SPINE
(L1-L5)
SACRUM
(five fused vertebrae )
COCCYX
(tall bone)

19. The bone ,muscle ,tendon and other tissues that reach from the base of the skull to the tail bone
It is our central supporting system
Key part of spine includes vertebrae, disc ,nerves and spinal cord
It keep upright and connect the different part of the skelton like brain ,chest pelvic etc
It is flexible due to the elastic ligaments and spinal disc

20. Cervical spine /cervical vertebrae
•They are 7 in numbers
•The first cervical vertebrae is called ATLAS
•Second cervical vertebra is called the AXIS
•It provide support and protect spinal cord and allow the head motion

22. Thoracic vertebrae
They are 12 in number ,the body is heart shape
It is the back bone ,long flexible column of the bone that protect the spinal cord
It is the middle section of ypur spine ,consist of 12 vertebrae labeled as T1-T12
Between the vertebrae bones are disc that provide cushion for your vertebrae and make flexible
for you
Thoracic spine is also surrounded by muscles nerves tendons nad ligaments that help the
movement and flexibility

24. LUMBAR SPINE

25. DISC
SPINOUS PROCESS
VERTEBRAL BODY
SPINE NERVE ROOT

27. THORASIC CAGE
The vital organ of the thorax [heart and lung ] are protected inside the bony thoracic cage
It is formed anteriorly by the sternum on the either side by the ribs and costal cartilage and
posteriorly by the thoracic vertebrae
STERNUM –flat bone present in the front of the thoracic cage
RIBS- there are 12 pair of ribs in the body ,each ribs are anteriorly articulate with the sternum
through the costal cartilage ,the anterior end on the last 2 ribs are free and posteriorly
connected to thoracic vertebrae
PECTOTRAL GRIDLE –attaches the upper limbs to the axial skelton

29. APENDICULAR SKELTON

30. UPPER LIMP
CLAVICLE –Your clavicle (collarbone) is a long, thin, slightly curved bone that connects your arm to your
body. It sits below your neck and is part of the front of your shoulder. It runs horizontally . subcutaneous
bone present on either side of the neck connecting the trunk with the upper limb. The clavicle (collarbone) is
a part of the skeletal system that connects the arm to the body. Ligaments connect this long, thin bone to the
sternum and shoulder.
SCAPULA [shoulder blade]-scapula, also called shoulder blade, either of two large bones of
the shoulder girdle in vertebrates. In humans they are triangular and lie on the upper back between the levels
of the second and eighth ribs. bone is placed in the scapular region behind the upper 7 ribs which gives
attachment to many muscles ,it have 2 surface and 3 boarders
HUMERUS –bone of the arm , it have upper end ,lower end and shaft [in between the upper and lower end]
The humerus is a long bone of the upper arm. It is one of the longest bones in the bodyThe humerus bone is
located in the upper arm, between the shoulder joint and the elbow joint. The shoulder joint, also known as
the glenohumeral joint, is a ball and socket joint. The ball is the humeral head, and the socket is the glenoid
fossa of the scapula.

32. RADIUS AND ULNA
RADIUS – lateral bone of the forearm ,it have upper end and lower end with a shaft .
The proximal end has a head which articulates with both the distal humerus and the proximal
ulna, while the distal end articulates with the head of the ulna and carpal bones at the wrist
ULNA –medial bone of the forearm ,fracture in ulna may be associated with fracture in radius.
Like the radius, the ulna also has three main parts: a proximal end, shaft and a distal end. The
proximal end articulates with the distal humerus and the head of the radius. The distal end, on the
other hand, has a head which articulates with the distal radius
The radius and ulna are long bones that make up the forearm, extending from the elbow to the
wrist. In the anatomical position, the radius is found in the lateral forearm, while the ulna is found
in the medial forearm.
The radius is shorter than the ulna and has a small proximal end that articulates with the humerus,
and a broad distal end that articulates with the carpal bones at the wrist.

34. Carpel bones
The skelton f the hand is made up of carpel , metacarpal and phalangeal bone
Carpal bones are 8 in number ad are arranged in proximal and distal row
PROXIMAL ROW CONSIST OF :-
1. Scaphoid
2. Lunate
3. Triquetral
4. Pistiform
DISTAL ROW
1. Trapezium
2. Trapezoid
3. Capitate
4. Hamate

35. Metacarpal and phalanges
METACARPAL
These are five metacarpal each one related to digits ,they articulate proximally with the carpal
and distally with the proximal phalanges
Each metacarpal consist of base shaft and head ,it is attached to interossei muscles
PHALANGES
The bones of the fingers ,each finger has 3 phalanges except for the thumb which has 2[ thumb
has proximal and distal phalanges while the rest have proximal ,distal and middle phalanges ]

37. LOWER EXTREMITY
Bones of lower limb is to support the weight of entire body
Lower limb consist of :-
Pelvic gridle
Thigh
Leg
Foot
Each lower limb is formed by 31 bones
These bones are longer and thicker and stronger than upper limb

38. PELVIC
It is attached to the axial skelton by strong ligaments
Support visceral organs
Acetabulum is a deep cup that hold the head of the femur

39. Female pelvis Male pelvis
Support child bearing Support heavy body build
Larger and broader Taller , narrow and more compact
Iliac crest is lower, it makes pelvic shorter and
larger
Iliac crest is higher
Female pelvis is Larger and wider than male pelvic

41. FEMUR
Its also known as thigh bone.
The head of the femur articulates with the acetabulum
in the pelvic bone forming hip joint while distal end
with tibia and patella which forming the knee

42. TIBIAAND FIBULA

43. TIBIA
•It is the second longest bone in the body
•It play an important role in standing ,move and keep our balance
FIBULA
•The head of fibula is joined to the head of tibia by the ligaments [not part of knee]
•The base of fibula is joined to outer projection of ankle joint.

44. TARSAL BONE
Tarsal bones are any of seven short angular bones that in human make up the ankle
There are 7 tarsal bones which articulate above with the bone of lower leg forming ankle joint
It is made up of
1. MID FOOT [cuboid, medial, intermediate and lateral cuneiform and navicular]
2. HIND FOOT [ talus and calcaneum ]
Calcaneus or heel bone is the largest tarsal forms the prominent in the back of the foot

46. METATARSALAND PHALANGES

47. METATARSAL BONES
It’s a group of 5 bones in the foot located between tarsal bone of the hind and mid foot and
phalanges and toe
The length of metatarsal bone in human is in the descending odder
PHALENGES
The bones of the fingers ,each finger has 3 phalanges except for the thumb which has 2[ thumb
has proximal and distal phalanges while the rest have proximal ,distal and middle phalanges ]

48. END