Question

Give ONE example of a: long bone, short bone, flat bone, irregular bone, and sesamoid bone. What is a suture? What is a tubercle? What is the difference between a foramen and a fossa? How many total bones are normally present in humans? How many ribs? How many phalanges? Define true rib, false rib, and floating rib. What is the name of the largest bone in the body? Identify the BONE where the following features can be found: 1) foramen magnum; 2) sella turcica; 3) dens; 4) coracoid process; 5) greater tubercle; 6) trochlear notch; 7) xiphoid process; 8) iliac fossa; 9) lesser trochanter; 10) medial malleolus.

Answer 1

* Example of a long bone is the femur or the thigh bone. It is the longest bone in the body and makes a ball and socket joint with the pelvic girdle in the hip, and a hinge joint at the knee.

* Short bones are cube shaped. The bones of the carpels in the wrist and the tarsals in the ankles are examples of short bones.

* Irregular bones have no definite shape and are mostly found in those skeletal structures which protec a body organ. The best examples of irregular bones in the body are the vertebrae which make the vertebral column.

* Sesamoid bones are found along with tendons, the tissues which attach muscles to bones. A good example of sesamoid bone in our body is the patella or the knee cap.

* A suture is a type of fixed, fibrous joint that is found only in the bones of the skull or the cranium. Although rigid, the sutures allow a miniscule amount of movement which allows a slight compliance and elasticity to the skull.

* A tubercle is a small rounded projection on some bones that serves as a point of attachment for skeletal muscles. For example, the great tubercle at the top of the humerous provides for the attachment of the powerfull rotator cuff muscles.

* Foramen is a hole in the bone while fossa is a shallow depression on the bone surface. Foramen allows for the passage of blood vessels and nerves to pass through. Examples are supraorbital foramen, infraorbital foramen, etc.

Fossa provides a surface to recieve another articulating bone. Example is the mandibular fossa which plays an important part in attaching the lower jaw bone with the temporal bone.

* An adult human skeleton is made up of 206 bones. At birth, the number of bones is 270 but as the person grows, several bones fuse to form one and hence the number of bones decreases.

* The rib cage is made up of 12 pairs or 24 number of ribs.

* The phalanges are the bones which make up the fingers of the hands and the toes of the feet. Altogether, there are 56 phalanges in the human skeleton. There are 14 phalanges on each hand and foot.

* True ribs are the first seven pair of ribs that are directly attached to the sternum by costal cartilages.

The 8th, 9th and 10th pairs do not attach to the sternum and are called false ribs. They are attached to the seventh rib by cartilage.

The two lowermost ribs, that is, the 11th and 12th pair are attached only to the vertebrae and not to the sternum.

* The femur is the largest bone in the body.

1. Foramen magnum - occipital bone on the base of the skull.

2. Sella turcica - sphenoid bone which contains the pituitary gland. It looks like a midline depression on the bone.

3. Dens - axis vertebra. It is used as a pivot for the rotation of the head.

4. Coracoid process - Scapula. It appears like a hook on the lateral edge of the superior anterior portion of the scapula.

5. Greater tubercle - Humerus. It is a prominent, rounded structure at the head of the humerus.

6. Trochlear notch - Ulna. It appears as a large depression in the upper extremity of ulna as part of the elbow joint.

7. Xiphoid process - Sternum. It is the cartilaginous section at the lower end of the sternum where no ribs are attached.

8. Iliac fossa - Concave surface of the ilium. Above it lies the iliac crest and below lies the arcuate line.

9. Lesser trochanter - Femur. It is a small protruberance at the posterior end of the femur.

10. Medial malleolus- Tibia. It appears as a small projection on the innerside of the ankle and provides support for the ankle joint.