<< Chapter < Page Chapter >> Page >
Photo shows a human skeleton riding a bucking horse skeleton.
The skeletons of humans and horses are examples of endoskeletons. (credit: Ross Murphy)

The human skeleton is an endoskeleton that consists of 206 bones in the adult. It has five main functions: providing support to the body, storing minerals and lipids, producing blood cells, protecting internal organs, and allowing for movement. The skeletal system in vertebrates is divided into the axial skeleton (which consists of the skull, vertebral column, and rib cage), and the appendicular skeleton (which consists of the shoulders, limb bones, the pectoral girdle, and the pelvic girdle).

Visit the interactive body site to build a virtual skeleton: select "skeleton" and click through the activity to place each bone.

Human axial skeleton

The axial skeleton    forms the central axis of the body and includes the bones of the skull, ossicles of the middle ear, hyoid bone of the throat, vertebral column, and the thoracic cage (ribcage) ( [link] ). The function of the axial skeleton is to provide support and protection for the brain, the spinal cord, and the organs in the ventral body cavity. It provides a surface for the attachment of muscles that move the head, neck, and trunk, performs respiratory movements, and stabilizes parts of the appendicular skeleton.

On a human skeleton, the parts of the axial skeleton are highlighted.
The axial skeleton consists of the bones of the skull, ossicles of the middle ear, hyoid bone, vertebral column, and rib cage. (credit: modification of work by Mariana Ruiz Villareal)

The skull

The bones of the skull    support the structures of the face and protect the brain. The skull consists of 22 bones, which are divided into two categories: cranial bones and facial bones. The cranial bones are eight bones that form the cranial cavity, which encloses the brain and serves as an attachment site for the muscles of the head and neck. The eight cranial bones are the frontal bone, two parietal bones, two temporal bones, occipital bone, sphenoid bone, and the ethmoid bone. Although the bones developed separately in the embryo and fetus, in the adult, they are tightly fused with connective tissue and adjoining bones do not move ( [link] ).

The eight cranial bones of the skull are shown.
The bones of the skull support the structures of the face and protect the brain. (credit: modification of work by Mariana Ruiz Villareal)

The auditory ossicles of the middle ear transmit sounds from the air as vibrations to the fluid-filled cochlea. The auditory ossicles consist of six bones: two malleus bones, two incus bones, and two stapes on each side. These are the smallest bones in the body and are unique to mammals.

Fourteen facial bones form the face, provide cavities for the sense organs (eyes, mouth, and nose), protect the entrances to the digestive and respiratory tracts, and serve as attachment points for facial muscles. The 14 facial bones are the nasal bones, the maxillary bones, zygomatic bones, palatine, vomer, lacrimal bones, the inferior nasal conchae, and the mandible. All of these bones occur in pairs except for the mandible and the vomer ( [link] ).

Illustration shows a front-end view of a skull. The frontal bone is the prominent bone that makes up most of the top of the skull. The parietal bone sphenoid bones make up the side of the skull. Two nasal bones make up the bridge of the nose. The zygomatic bone is the cheek bone. The vomer is a single bone in the middle of the nose. The maxilla makes up the upper jaw, and the mandible is the lower jaw. The lacrimal is a bone on the inner center of they eye. The nasal conchae are bones inside the nose.
The cranial bones, including the frontal, parietal, and sphenoid bones, cover the top of the head. The facial bones of the skull form the face and provide cavities for the eyes, nose, and mouth.

Questions & Answers

what is abiotic?
Williams Reply
state 2 abiotic factors that affect the rate of transpiration in plants?
Benenge
non living things
Chris
what is a cell
Esther Reply
what is contained in a smooth endoplasmic reticulum?
Bleyd Reply
sperm
Chris
cool
Jo
sorry i meant the structure within the smooth endoplasmic reticulum
Bleyd
what is cell made of
Jo Reply
what is sponge
Joseph Reply
what is a photometer
Abigail Reply
what is respiration
Alao Reply
Is the release of energy from food substance in a living organism
innocent
What is cytoplasm
Nitta Reply
Parasitic adaptation of tapeworm
Angela Reply
Describe osmoregulator or osmoconformers and how these tools allow animals to adapt to different environment.
Alick Reply
describe the secondary function of a leaf to a plant.
Twizera Reply
hi I'm asking a question about HIV infection, can HIV infection transmitted from Mother to unbron child? please help me I So confused.
Khushboy Reply
no it can't
Ahmad
yes it can but their is an injection that can be used to prevent it.
Gift
Ahmad how no?
Khushboy
Hi im new
innocent
no, unless when giving birth
Bright
YES
Kaole
it is can be transmitted but there is an injection that the mother is injected to prevent the disease
Nia
OK
Kaole
I agree with nia
peter
but I think HIV infection can be transmitted through blood so the unborn baby can be affected by HIV when a slight mistake occurred that what i think
Salim
yes, but there is a treatment however, using a retroviral therapy and injection to prevent the unborn child unscathed from the infection
Gula
what is the difference between primary and secondary active transport in detail? I didn't understand the steps in the textbook specifically
Fathima Reply
you are a doctor?
Mohammed
what is the meaning of connective tissue?
Mohammed Reply
what are the characteristics of living things
Owolo Reply
hi
Mohammed
what's the meaning of connective tissue?
Mohammed
Reproduction, adaptation, interaction, movement, growth, respiration, made of cells, responsive to environment (homeostasis), metabolic action (consumption of food converted into energy)
garret
Movement, reproduction, nutrition, irritability, growth, excretion, respiration, death, adaptation, competition
peter

Get the best Biology course in your pocket!





Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Biology' conversation and receive update notifications?

Ask