Mammalian Skeleton - SS1 Biology Lesson Note

The mammalian skeleton can be divided into two main parts: the axial skeleton and the appendicular skeleton.

1.     Axial Skeleton: The axial skeleton includes the bones that form the central axis of the body. It provides support and protection for vital organs and helps maintain the body's overall structure. The main components of the axial skeleton include:

a.     Skull: The skull protects the brain and supports the structures of the face.

b.     Vertebral Column: The vertebral column, or spine, consists of individual vertebrae that provide support and protection for the spinal cord.

c.      Ribs: The ribs are curved bones that surround the thoracic cavity, providing protection for the heart and lungs.

d.     Sternum: The sternum, or breastbone, is a flat bone located in the center of the chest. It serves as a point of attachment for the ribs.

e.     Hyoid Bone: The hyoid bone is a U-shaped bone located in the neck. It plays a role in supporting the tongue and aiding in swallowing.

2.     Appendicular Skeleton: The appendicular skeleton includes the bones of the limbs and the structures that connect them to the axial skeleton. It is involved in movement and locomotion. The main components of the appendicular skeleton include:

f.       Pectoral Girdle: The pectoral girdle consists of the clavicles (collarbones) and scapulae (shoulder blades). It connects the upper limbs to the axial skeleton.

g.     Upper Limbs: The upper limbs consist of the humerus (upper arm bone), radius and ulna (forearm bones), carpals (wrist bones), metacarpals (palm bones), and phalanges (finger bones).

h.     Pelvic Girdle: The pelvic girdle, or hip girdle, consists of the hip bones (ilium, ischium, and pubis). It connects the lower limbs to the axial skeleton.

i.        Lower Limbs: The lower limbs consist of the femur (thigh bone), tibia and fibula (leg bones), tarsals (ankle bones), metatarsals (foot bones), and phalanges (toe bones).

The axial skeleton provides support and protection for vital organs, while the appendicular skeleton allows for movement and locomotion. Together, they form the complete skeletal system of mammals, including humans.

The human body has a total of 206 bones. However, it is important to note that the number of bones can vary slightly among individuals due to differences in the fusion of certain bones during development. This number represents the average adult skeleton and includes bones of the axial and appendicular skeleton.

(images from istockphoto.com)