The skeletal system is that in which is related with the different bones present in our body and the gives protection of the internal organs of the body, movement of the body and attachment of different muscles of the body.
The skeletal system is of two types:
Axial skeletal system: It contains bones of ribs, skull, vertebral column, sternum, scapula, clavicle and hyoid bone.
Appendicular skeletal system: It contains bones of upper and lower limbs and pelvis.
Hyoid bone is also included in skeletal system total number of bones in body are 212 (3 of each middle ear). There is no muscle attachment with these six bones of middle ears that’s why they are not taken in skeletal system.
Skull-22 (8 cranial and 14 facial)
Bones of upper limb-60
Bones of lower limb-60
Total – 206
Longest bone of body is femur (Thigh bone)
Shortest bone of body is stapes (Present in middle ear)
Bones can be classifies according to their shape and the formation. There are different types of bones:
Example: Humerus, radio-ulna of upper limb and femur, tibia-fibula of lower limb.
The long bones functions as the lever in the body.
Example: Tarsals and carpals
They give strength and support example: Wrist and ankle.
Example: Bones of vertebral column and some bones of face.
1. Patella bone (present in knee joint)
Function of skeletal system:
Joint: The joint is a point where two or more bone unites.
Types of joints:
Example: Joints of skull
Example: Shoulder joint, elbow joint, wrist joint, hip etc.
The ankle, knee and elbow joints are hinge joint (movement in single direction)
Skull: The skull is bony frame work of the head arranged in two parts:
The bones of skull are paired and unpaired. The bones of skull are present as under.
Cranial bones: Frontal (1), sphenoid (1), ethmoid (1), occipital (1), perital (2), temporal (2)
Facial bones: Nasal (2), Lacrimal (2), inferior nasal concha (2), maxilla (2), palatine (2), zygomatic (2), mandible (1), vomer (1)
Structure of skull:
Vertebral column (Backbone): The backbone contains 33 bones it starts from the base of the skull and ends at the pelvis bone. It contains the following bones.
The single bone is called as vertebra. Length of the vertebral column in male is about 70 cm in female 60 cm.
The ATLAS rotates like a white around the axis.
Divided into two groups:
Features: The body is heart shaped; vertebra foramen is small and circular
Lumber vertebra: Size of the vertebra increase from top to bottom. Upper four are typical and 5th is atypical features. Kidney shaped body.
Sacrum: This is a large flat triangular bone formed by the fusion of the five bones. The upper part is broad and lower part is narrow. The sacrum articulates with the hip bone.
Features: Divide into base and apex and four surfaces.
Coccyx formed by fusion of lowers four bones of the back bone. This is broader upward and pointed in lower direction.
Ribs: There are 12 pairs of ribs in the body each rib articulates with the sternum. The anterior ends of the last two ribs are free-posteriorly each rib articulates with the thoracic vertebrae.
Upper 7 ribs are called as true ribs the next 3 are called as false ribs and 11th and 12th are called as floating ribs.
Sternum: Single bone present in thoracic region and makes the thoracic cage.
The sternum contains the following parts:
Clavicle (collar bone): These are 2 in number
The clavicle bone helps to attract the some of the muscles of head and neck and shoulder.
Bones of upper limb
The radius is the lateral and long bone present towards the thumb.
The ulna is present just opposite to the radius bone. It is wide from the upper side and rounded from lower side the upper ends of the radius and ulna helps to makes the elbow joint
Bones of lower limb: There are present 30 bones in lower limbs which are as following:
The upper head of the femur makes the hip joint. There are maximum important muscles of the thigh are attached on the femur bone.
The lower and is joined with the upper ends of tibia fibula and makes the knee joint.
The lower ends of these bones are joints with the 7 short bones (Tarsals)
Patella: The patella bone is present in the knee joint.
Pelvis bone (Hip bone)
This is also called as the hip bone. The hip bone is large irregular bone made of three parts.
These parts fuse at a depressed area which is acetabulum.
There are two hip bones in our body.
|Male Pelvis||Female pelvis|
|There are following differences between male and female pelvis bones.||The obdurate foramen is oval shaped with more diameters.|
|The pelvic inlet is triangular. The obdurate foramen is triangular in male with short diameter, The pelvic cavity is narrow and funnel shaped||The pelvis cavity is milder and the side walls are parallel.|
|The male pelvis is narrow with the public arch (75-80)||The public arch is 90 or more|
Joints of upper limb:
It is formed by the lower head of the humerus and upper heads of radius and ulna.
Nerve supply – Radial and ulnar nerves
Nerve supply – anterosseus and interosseus nerves
Hip joint: This is the synovial joint of ball and rocket variety. It is very simple joint. The hip joint is formed by the upper head of femur and the acetabulum of the pelvis bone.
It is much similar to shoulder joint it can also move in different direction. This is more stable as compare to shoulder joint. The head of the femur is thickest in the center and thin at the periphery.
The hip joint transmits the body weight in the lower direction of body.
Blood supply – Branches from the superior obturator and femoral, gluteal arteries
Nerve supply – Femoral obtutrator and superior gluteal nerve
Knee joint: It is synovial joint of hinge variety, compound joint formed by the lower ends of the femur and upper ends of the tibia fibula.
Patella bane is present in front of 3 tones. The synovial membrane covers all the structures within the joints
Blood supply – Branches of descending genicular, popliteal and tibial artery.
Nerve supply – Obturator femoral and tibia nerves
Ankle joint: This is also the synovial joint of hinge variety movement is in single direction. This joint is formed by the lower ends of tibia fibula and talus bone (bore of heels)
Blood supply – anterior tibial and perineal arteries.
Nerve supply – Perineal and tibia nerves
Example: Sternoclavicular joint.
Example: Elbow, knee and ankle joints.
Example: Superior radio-ulnar joint.
Example: Meta carpo-phalangial.
Example: Wrist joint
Example: Carpo metacarpal joint of thumb
Example: Shoulder and hip joint.
Functions of periosteum:
The microscopic structure of compact bone is as following.
The bone formation is called as the osteo-genesis by two different methods the formation of bone take place:
The intramembranous ossification takes place within the connection tissue membrane.
The cement substances and the collagen fibers make the bone matrix after this the deposition of the calcium salt takes place.
First of all periosteum is formed then the ring of bone is formed.
After this the calcification of the hyaline cartilage takes place.
The progress takes place from diaphysis to epiphysis and the bone grows.
The bone marrow is the vascular connective tissue present in the medullary cavity of the bone. At the birth the bone marrow is red with active haemopoises. The parts of the developing long bone:
Example: The ends of the long bone.
Example: Shaft of long bone.
Structurally the bones contain the outer covering periosteum just below this part there is compact bone present which is made up of lamellae which contains the bony plates of fibers.
Blood supply of long bone image
It is also called as the bone metabolism. The bone metabolism is a lifelong process where the mature bone tissue is removed from the skeleton and the new bone tissue is formed. These processes are also controls the reshaping of the bone or the fractures
In 1st year of life 100% of skeleton is replaced.
In adults remolding is 10% per year only.
The cartilage is the special connection tissue present in the body. The cartilages are rigid structure; they are supportive and protective in function.
Blood supply to long bone: The long bone is supplied by four sets of long vessels.
There are three types of cartilages:
Skeletal frame work of larynx:
Example: Thyroid, cricoid and arytenoid cartilage. It is present in the tracheal rings.
1) Pinna of ear
2) Epiglottis of pharynx.
Important features of cartilage:
Many cartilage masses are linked with cartilage canal which convey the blood vessel.
These cartilage canals supply the nutrition to the deepest part of the cartilage.
Synovial fluid: It is the fluid filled in the synovial cavity and helps in the movement of the joints.
Synovial membrane: This is a pink smooth shiny cellular connective tissue membrane which lines the fibrous capsule from outside.
Functions of synovial membrane:
Difference between newly born skill and adult skull:
Cause: The common cause is bacterial infection, gout, wear and tear of articular cartilage of joint due to age factor.