Question

Skeletal system locomotion and movement

Answer 1

Skeletal System

$\textbf{Skeletal System is a framework of bones and Cartilage which helps in movement and locomotion.}$

$\textit{In humans skeletons are divided into two parts}$

$\textbf{1. Axial Skeleton}$

Skeleton which lies in the line of axis of body is called as $\textit{Axial Skeleton}$

- There are 80 bones are present in Axial Skeleton.

- Axial Skeleton consist of Skull, Vertebral Column, Ribs and Sternum.

$\textbf{1. Appendicular Skeleton}$

Skeleton which lies in lateral side of axis of body.

- There are 126 bones are present in Appendicular Skeleton.

- Appendicular Skeleton consist of bones of limbs and girdles.

$\textbf{Skull :}$ It provides protection to Brain. It consist of Cranium and Facial Bones. A U-shaped bone is present at the base of oral cavity known as Hyoid. Each ear contains three bones. Skull connects with vertebral column at superior reason with the help of two Occipital condyles that's why known as $\textbf{Dicondylic Skull}$

There are 29 bones are present in Skull.

(i) Cranium - 8 : It provides covering of brain. The opening from where spinal cord, Nevers, Blood vessels and Lymph vessels enters into brain is known as $\textbf{Foramen magnum}$

- Frontal (1) : It is present in anterior (front) part of top of Cranium.

- Perital (2) : It is present behind the frontal and forms roof of Cranium.

- Temporal (2) : Present at the lower side of Cranium.

- Occipital (1) : Present just behind the Perital. Foramen magnum (an opening) is present here.

- Sphenoid (1) : It is present in the base (anterior and middle) of the Cranium. Pituitary gland is present in its cavity. It is of butterfly shaped.

- Ethmoid (1) : It is an irregular shaped bone present just behind the nose.

Total = 8

(ii) Facial Bones - 14 : These bones are present in front side of skull.

- Nasal Bones (2) : They are small rectangular shaped bone which forms nasal chamber.

- Inferior Turbinalis (2) : These are situated at lateral side of nose.

- Vomer (1) : It is a thin disc like bone present at posterior part of nasal chamber.

- Lacrimal (2) : It forms eye socket and are located at lateral sides of nasal bones.

- Zygomatic (2) : These bones are also known as Cheek bones as they forms base of cheek.

- Palatine (2) : They are present at the hard posterior part of hard palate.

- Maxillary (2) : It forms upper jaw. It forms a large part of face. They are immovable.

- Mandible (1) : It is a the largest jaw bone. They are movable and $\textbf{strongest}$bone.

(iii) Ear Ossicles - 6 :

- Malleus (2)
- Inchus (2)
- Stapes (2) $\textbf{smallest}$

(iv) Hyoid - 1 : It is not attached to any other bone.

$\textbf{Ribs :}$ Ribs are flat thin bones which forms a cage like cavity.

There are 12 pairs of Ribs are present in Humans.

- Ribs are attached to vertebral column dorsally and sternum ventrally.

It forms a cage like structure known as Rib Cage.

- 7 pairs ribs are called $\textbf{True Ribs}$

- Rest 5 pairs are known as $\textbf{False Ribs}$ because they are not connected directly to sternum. Last two pairs are not connected ventrally therefore known as $\textbf{Floating Ribs.}$

$\textbf{Sternum :}$

It's a single bone of about 15 cm long.
$\textbf{Vertebral Column :}$

There are 26 units are arranged serially known as $\textbf{Vertebrae.}$

- Formula for vertebral column is $\bold{C_{7}T_{12}L_{5} S_{5} Co_{4}}$

- There are four curves in Vertebral Column which are Cervical, Thoracic, Lumber and Pelvic Curvature.

- Cervical vertebrae are present in almost all mammals so, considered as Significant feature of mammals.

- Atlas (C1) : It is the first vertebrae which connects Occipital condyles of skull. Neural Spines are less developed here.

- Axis (C2) : It is the second vertebrae which contains well developed neural spines.

- Lumber Vertebrae has two parts.
(i) Sacrum : These are large flat triangular shaped vertebrae formed by fusion of 5 sacral vertebrae.

(ii) Coccyx : These are formed by fusion of 4 coccygeal vertebrae and considered as Vestigial in humans.

Bones of vertebral column -
- Cervical (7)
- Thoracic (12)
- Lumbar (5)
- Sacral (1 - fused)
- Coccygeal (1 - fused)

$\textbf{Fore Limbs :}$ :

Total bones = 30 × 2 fore limbs = 60 bones

- Humerus (1)
- Radius (1)
- Ulna (1)
- Carpals (8)
- Metacarpals (5)
- Phalanges (14)

$\textbf{Hind Limbs :}$

- Femur (1) $\textbf{Longest}$
- Patella (1)
- Tibia (1)
- Tibula (1)
- Tarsals (7)
- Metatarsals (5)
- Phalanges (14)

Total bones = 30 × 2 hind limbs = 60 bones.

These are all Bones in Human Body.

$\textit{Total number of bones in late foetal stage is 306}$

$\textit{Total number of bones at the time of birth is 270}$

$\textit{Total number of bones after birth is 206}$

This is all about Skeletal System (Mainly about Bones).

$\textbf{BeBrainly.LoveBrainly}$

Answer 2

The two components of skeletal system making up the body are consisting of tough external structures and hard internal structures of a typical animal or an organism's body framework which altogether conserves a highly complex system called the $\textbf{Skeletal System}$.

Skeleton which constitutes the internally made structures are called as $\textbf{Endoskeleton}$ presenting inside the body framework of an animal "internally". these contains all the bones, cartilages, ligaments, tendons, etc. Skeleton which constitutes the externally made organ structures is called as $\textbf{Exoskeleton}$ these contain Hairs, nails, dead skin cells, etc.

The Skeletal system serves many functions for it's body:

1) They're supporting the organism, protecting them from internal and external damages from environment.

2) Attaching those muscles needed for locomotion and movement of body parts.

3) Assist in the functioning of hearing by attachment of bones in internal ear and Breathing by the help of cartilaginous structures supporting larynx or the voice box, breastbone or sternum and tracheal wall.

4) Reserving most important mineral components in Bones as the form of Calcium and also phosphorous and meeting the demands for it.

5) Maintains Body formations and Body shape of an organism, Assist in formation of Blood cells inside bone marrow as RBCs and WBCs.

6) Helps in movement and locomotion.

Talking about the Skeletal system it constitutes two parts of Skeletal Or Skeleton system, that is,

A) Axial Skeleton System: This system is found mainly on the median or middle of a longitude Axial plane in an organism it'll definitely contain the Rib structures, Breastbone, Skull as a whole and the Vertebrae column (or vertebral column).

B) Appendicular Skeleton System: This system is found mainly on the laterally inclined regions that're moving forward and outwards (or out of it) from a axis called the Principle Axial planar formations. It's containment would've been of Pectoral Girdle, Pelvic Girdle or the Hip bone along with constituting All the bones for Arms including the Legs.

Axial Skeleton Systems consists of a grand total of 80 Bones, as follows:

1) A Skull that further has 8 Number of Bones Namely, Cranial Bones that're containing the $\textbf{2 Parietal Bones}$, $\textbf{2 Temporal Bones}$, $\textbf{1 Occipital Bone}$, $\textbf{1 Frontal Bone}$, $\textbf{1 Ethmoid Bone}$ and the $\textbf{1 Sphenoid Bone}$.

2) Our Face consists of 14 bones in a gist, Namely, 1 Vomer, 2 Maxillae, 2 Palatine Bones, 2 Zygomatic Bones, 1 Dentary Mandible, 2 Nasal or Nose Bones, 2 Lacrimal Bones and one last facial Bone called as Inferior Nasal Conchae present in Nasal chambers or also called as Turbinating Bones or Inferior Turbinate Bones.

3) Just above our voice box or larynx there consist a Hyoid Bone which's one in number. A Hyoid bone when simply said is sitting in the uppermost part of the anterior region of throat and is into a consideration as a part of the Skull in a part of of the Skeletal system that joins muscular structures of our tongue and basal floor of our mouth which'll not show any articulation with bones of other parts.

4) Ossciles of the bones present in our ears three in number for each bones. Total 6 Bones that is, Stapes, 2 in number, Incus, 2 in number and Malleus, 2 in number.

5) Column of Vertebrae are having 26 Bones in total, namely, Cervical Vertebrae, total 7 bones, Thoracic and Lumbar Vertebrae, 12 and the bones respectively, Sacrum and Coccyx, 5 and 4 Vertebrae or bones respectively.

6) Thoracic parts contain two components namely, Breastbone or Sternum, 1 on number and all the 24 Ribs which have True and False Ribs (7 and 5 in pairs, respectively).

Appendicular Skeleton System consists of a grand total of 126 bones, as follows:

1) Pectoral Or Shoulder Girdles have two Bones, Clavicle and Scapula, both are one in number.

2) Arms or basically the extremities in the upper regions are 60 in number. They contain 1 Humerus, 1 Ulna, 1 Radius, 8 Bones of Carpal, 5 Bones of Metacarpal, 14 bones of Phalanges in digits of 5 for each arm. $\bf{30 \times 2 = 60}$ in both arms.

3) Pelvic Girdle or Pelvis are containing Innominate or Hip Bones that are 2 in number

4) The legs or extremities in the lower regions contain Femur, Tibia, Fibula, Patella, Tarsals, Metatarsals and Phalanges which are 2, 2, 2, 2, 14, 10 and 28 in numbers for both the legs respectively.

Number of bones in Infantile Stage is about 306 and decreases to 270 at first stage of Parturition and maintains a total of 206 Bones in adult stage or form. Formula for calculating vertebral column or Vertebral formula is $\bf{C_7 T_{12} L_S S_{(1 - 5)} C_{(1 - 4)}}$, where, alphabetical letters represent the Vertebrae present in a typical Vertebral column.

Disorders like Osteoarthritis and Rheumatoid Arthritis cause Joint Inflammations in synovial membranes.