HAP Chapter 4

HUMAN ANATOMY & PHISIOLOGY
CHAPTER 4
Osseous System/Skeletal System
The human skeleton is the internal framework of the human body and
composed of Bone, cartilage, joints, ligaments, and tendons which
supporting structure of the body. It helps to stand straight to move to
perform any physical activity.
 Bone—Bone is rigid connective tissue that constitutes the

minerals, calcium phosphate, collagen. Bone protects the various
organs of the body, produce the blood cells, store minerals, provide
structure and support for the body. It is composed of around 270
bones and reduces to around 206 bones by adulthood after some
bones get fused together.
 Cartilage—Cartilage is the non vascular type or supporting
connective tissue which provide the flexibility to the body organs
and joining the one organ to another. Cartilage occurs only in
isolated areas, such as the nose, parts of ribs, and joints.
 Ligaments—Ligament is also a fibrous type of connective tissue
and connects the one bone to another bone.
 Joints—joint or articulation is connect the one bone to another and
provide the bending ability.
 Tendons— Tendon is a cord of strong flexible connective tissue,
which joins the bone to the body muscle.
Human skeleton system divided into two parts—
1. The Axial skeleton.
2. The Appendicular skeleton.
Function:
1) Shape and support : Bones act as a structural framework which
provides support and keeps the body in shape
2) Protection: Many vital organs of the body are protected by the
skeletal system as it helps in holding the organs at their places.
3) Movement: Bone and muscle interaction helps in different body
movements. Various parts like bones, skeletal muscles, ligaments, joints,
and tendons altogether generate and transfer forces to aid in physical
movements of the whole body or that of some parts in three-dimensional
space.
4) Acid-Base Balance: The alkalines bones, which helps in buffering of
the pH of blood.
5) Mineral Storage: Bones also act as a mineral reservoir especially for
calcium and phosphorus.
6) Blood Production: Bones also participate in the erythrocytes are
produced by marrow present in the medullary cavity of long bones and
interstitial spaces of cancellous bone.
7) Detoxification: Heavy metals and foreign elements are also absorbed
by bone tissues, i.e., they are removed from the blood and thus, the
impact of such foreign elements and heavy metals on other tissues is
also decreased. These absorbed toxins can be eliminated gradually by
the process of excretion.
1. The Axial skeleton:
Axial skeleton includes those bones which help in the formation of body
axis. It supports and protects the skull, neck, and the torso (or trunk)
region. Axial skeleton is composed by the 80 bones segregated into three
major regions.
 Skull:
Most of skull bone are flatted and firmly united by interlocking joints
called sutures but mandible bone which is connected to the rest of the
skull freely movable bones.
The skull is the most complex structure of the human body. It consists of
22 bones and forms the hard protective outer covering for brain tissue. It
is further divided into two parts.
1. The cranial bone— Cranial bone consists of 8 number of bones.
Frontal bone(1), Parietal bone(2), Temporal bone(2), Occipital bone(1),
Sphenoid(1), Ethmoid (1).
2. The facial bone—It consists of 14 number of bones.
Mandible(1), Vomer (1), maxilla(2), Zygomatic bone(2), palatine
bone(2), Nasal bone (2), Lacrimal bone(2), inferior nasal concha(2).
Functions of Skull bone—
➢ It provides the framework for the face and cranial.
➢ Provide the opening for food and air passage.
➢ Socket formation for the teeth
➢ Protect the most important processing unit of brain.
 Vertebral column:
Vertebral column also called as spine or spinal column, it consists of 26
irregular serially arranged unit called as vertebrae and dorsally placed. In
the fetus and infants, the vertebral column consists of 33 separate bones
or vertebrae. In adult age, nine of these eventually fuse to form two
composites bones.
The Vertebral column differentiated into— Cervical (7), Thoracic (12),
Lumber (5), Sacral (1-Fused), Coccygeal (1- Fused).
Functions of vertebral column—
➢ It maintains the erect body posture.
➢ It maintains the body balance.
➢ It supports the upper limbs and head to make them freely movable.
➢ It acts as a point of attachment for various muscles, ribs, and some
organs.
➢It forms the site of attachment for muscles, tendons, and ligaments.
 Thoracic Cage/Thorax:
The thoracic cage or thorax is a region of the human body that lies
between the head and the abdomen, excluding upper limbs. It consists
of-
1. Sternum:
It is also called breast bone. Sternum is a flat bone about 15cm long
present on the anterior position of the thoracic cage.
2. Ribs:
12 pairs of ribs present in the human body. Each rib is posteriorly
connected with vertebral column and anteriorly sternum.
True Ribs: These ribs are directly attached to the sternum (via
cartilages). First seven pair of ribs are called true ribs.
False Ribs: The 8th, 9th and 10th pairs of ribs which are not directly
attached to the sternum.
Floating Ribs: Last 2 pair (11th and 12th), these ribs are not attached to
the sternum.
Function of thoracic cage:

 It protects the vital organs (Heart, lungs, and blood vessels).
 It provide the support for shoulder , upper limbs and also provide
attachment points for many muscle of the neck, back, chest, shoulder.
2. The Appendicular skeleton:

Appendicular skeleton is the bony framework of upper and lower limbs
and their supporting girdles including 126 bones.
 Pectoral Girdle:
Each pectoral girdle consists of a clavicle bone (anterior) and a scapula
(posterior). Clavicles or Collar bone are slender S-shaped bone. Scapula
is a large triangular flat bone.
 Upper limbs:
Each upper limbs consists 30 bones. It is categories into three parts.
1. Arm—Humerus is sole bone of arm.
2. Fore arm— Forearm consists of two parallel bone Radius and Ulna.
3. Hand— it consists of 3 types of bone. e.g. Carpel, Metacarpal and
Phalanges.
 Pelvic Girdle/Hip girdle:
Pelvic girdle consists of irregularly shaped 3 separated bones during
childhood, the Ileum, Ischium, and Pubis. In adults, these bones are
firmly fused.
 Lower Limbs:
Each Lower limb consists of 30 bones. It is divided into three segments.
1. Thigh— the Femur is the sole bone of the thigh, it is the longest,
largest bone of the body. It length is roughly ¼ of a person height.
2. Leg—Leg consists of the two parallel bones, the Tibia and Fibula.
3. Foot— It consists of the three bones. Tarsal, Metatarsal and
Phalanges.
JOINTS
Joints are point of contact between bones or between bones and
cartilage. More than 100 types of joints are present in the human body.
Classification of Joints:
1. Functional Classification: Functionally, joints are classified into
three types, based on the degree of mobility of the joint.
2. Structural Classification:
Structural classification mainly based on the material binding the bone
together.
These joints are of three types:
i) Fibrous joint. ii) Cartilaginous joint, iii) Synovial joint
Synovial joint are characterized by the presence of a fluid filled synovial
cavity between the articulating surfaces of the two bones.
Types of synovial joint:
Ball and socket joint— between humerus and pectoral girdle, between
femur and pelvic girdle.
Hinge joint— Knee joint, Elbow joint, Ankle joint.
Pivot joint— between atlas and axis of cervical vertebrae.
Disorders of Joint:
 Arthritis—Inflammation of the joint.
 Rheumatoid Arthritis— Rheumatoid arthritis is progressive a
inflammatory, musculoskeletal disorder which affects multiple
joints, connective tissues, muscles, tendons, and fibrous tissues
Joint Dislocation.
 Gout: Gout is painful arthritis formed on the joints. It is usually
caused by the presence of high level of uric acid in the blood,
which crystallizes and settles in the joint.
 Osteoporosis: Age related disorder characterized by decreased
bone mass and increased chances of fractures.

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HUMAN ANATOMY & PHISIOLOGY

 Bone—Bone is rigid connective tissue that constitutes the

➢ It provides the framework for the face and cranial.

➢ Provide the opening for food and air passage.

➢ Socket formation for the teeth

➢ Protect the most important processing unit of brain.

➢ It maintains the erect body posture.

➢ It maintains the body balance.

Function of thoracic cage:

2. The Appendicular skeleton:

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