A vertebrate skeleton is divided into an
axial and appendicular skeleton.
The axial skeleton protects the organs of
the head, neck and chest.
The appendicular skeleton includes the
bones of the limbs
.
diagram of the axial skeleton
The axial skeleton consists of the 80 bones
in the head and trunk of the human body.
It is composed of five parts;
the human skull, the ossicles of the middle ear,
the hyoid bone of the throat, the rib cage,
and the vertebral column.
The axial skeleton and the appendicular skeleton
together form the complete
skeleton and the sternum
.
Overview
Flat bones house the brain, spinal cord, and other
vital organs.
This article mainly deals with the axial skeletons of
humans; however, it is important to understand the
evolutionary lineage of the axial skeleton.
The human axial skeleton consists of 80 different
bones.
As the skeleton grows older the bones get weaker
with the exception of the skull.
The skull remains strong so as to protect the brain
from injury.
Skull
Human skull
•Facial Bones (14)
Skull (22)
•Cranial Bones (8) Maxilla (2)
Zygomatic (2)
Parietal (2)
Mandible (1)
Temporal (2)
Nasal (2)
Frontal (1)
Palatine (2)
Occipital (1)
Inferior nasal concha (2)
Ethmoid (1)
Lacrimal (2)
Sphenoid (1)
Vomer (1
Auditory Ossicles
Ossicles (6 )
•Malleus (2)
•Incus (2)
•Stapes (2)
Hyoid bone
Hyoid bone (1) U-shape bone located in the
neck.
It anchors the tongue and is associated with
swallowing
.
Vertebral column
Main article: Vertebral column
Vertebral Column (26)
•Cervical vertebrae (7)
•Thoracic vertebrae (12)
•Lumbar vertebrae (5)
•Sacrum (1) (they are 5 but fused in adult
stage)
•Coccyx (1) (they are 4 but fused to form
one single bone, varies between 3-5)
Chest
Main article: Chest
Thoracic cage (25)
•Sternum (1)
•Ribs (24)
Appendicular skeleton
Appendicular skeleton
Appendicular skeleton diagram
The appendicular skeleton is composed of 126
bones in the human body.
The word appendicular is the adjective of the
noun appendage,
hich itself means a part that is joined to
something larger.
Functionally it is involved in locomotion (Lower
limbs) of the axial skeleton
and manipulation of objects in the environment
(Upper limbs).
The appendicular skeleton is divided into six major regions:
1) Pectoral Girdles (4 bones) - Left and right
Clavicle (2) and Scapula (2).
2) Arm and Forearm (6 bones) - Left and right Humerus (2)
(Arm), Ulna (2) and Radius (2) (Fore Arm).
3) Hands (58 bones) - Left and right Carpal (16) (wrist),
Metacarpal (10),
Proximal phalanges (10), Middle phalanges (8), distal
phalanges (10), and sesamoid (4).
4) Pelvis (2 bones) - Left and right os coxae (2) (ilium).
5) Thigh and leg (8 bones) - Femur (2) (thigh), Tibia (2),
Patella (2) (knee), and Fibula (2) (leg).
6) Feet (56 bones) - Tarsals (14) (ankle), Metatarsals (10),
Proximal phalanges (10), middle phalanges (8), distal
phalanges (10), and sesamoid (4).
It is important to realize that through
anatomical variation it is common
for the skeleton to have many extra bones
(sutural bones in the skull, cervical ribs,
lumbar ribs and even extra lumbar vertebrae)
The appendicular skeleton of 126 bones and the
axial skeleton of 80 bones together
form the complete skeleton of 206 bones in the
human body. Unlike the axial skeleton,
the appendicular skeleton is unfused. This
allows for a much greater range of motion