CHAPTER V.

OSTEOLOGY.

=Definition.=—Osteology is the science of the structure and functions of bones.

In regard to the treatment of this subject, it is not our aim to take up all the minute details concerning each bone, all we desire is to explain the form, uses and location of some of the principle bones and sets of bones of the body in so far as they may come to be used as landmarks for the embalmer.

=The Skeleton.=—The entire skeleton in the adult consists of 200 distinct bones.

Spine— Cervical 7 Dorsal 12 Lumbar 5 Coccygeal 1 Sacral 1 —— 26 26 Cranium 8 Face 14 Hyoid 1 Sternum 1 Ribs— True 7 Pair False 3 “ Floating 2 “ ——————— 12 “ 24 Upper Extremities 64 Lower Extremities 62 ——— 200

In the above outline the bones of the ear and the sesamoid bones are not considered. Different anatomists make different computations as to the number of bones in the skeleton. Some authorities add the bones of the ear, thus making 206 in all. If all the little sesamoid bones were added, the number could be greatly augmented.

=The Vertebral or Spinal Column. (The Spine).=—The spine is a flexuous and flexible column formed of a series of bones called vertebrae. There are twenty-six in number and may be divided as follows:

Cervical 7 bones Dorsal 12 “ Lumbar 5 “ Sacral 1 “ Coccygeal 1 “

The cervical vertebrae are smaller than those in any other region of the spine, and may be readily distinguished as they lie in the neck and extend from the base of the skull to the dorsal vertebrae, or the point of attachment of the first rib to the first dorsal.

The dorsal or thoracic vertebrae are the next in rotation down the spine and are intermediate in size between those in the cervical and those in the lumbar region, and increase in size from above downward.

The lumbar vertebrae, the next in rotation, are the largest of the vertebral column and can be distinguished as those lying in the lumbar region or the small of the back.

The sacrum, meaning sacred, so called, because it was the part selected in sacrifices. The sacrum is a large triangular bone, situated at the lower part of the vertebral column, and at the upper and back part of the pelvic cavity.

The coccyx, so called from having been compared to a cuckoo's beak. It is usually formed of four small segments of bones, and gradually diminish in size from above downward, and blend together so as to form a single bone.

The spinal column is situated in the median line, at the posterior part of the trunk. Its average length is about two feet, two or three inches. The female spine is about one inch shorter than the male.

The spinal canal in which runs the spinal cord, follows the different curves of the spine; the opening being the largest in those regions in which the spine enjoys the greatest freedom of movement, and the smallest where motion is more limited.

=The Skull.=—The skull is the bony framework of the head. The cranium is the name applied when we do not consider the mandible (the lower jaw).

The skull is oval in shape, wider behind than in front, and is supported on the summit of the vertebral column.

The skull is composed of twenty-two bones and is divided as the following diagram will show:

{ Occipital { Two parietal { Frontal { Cranium { Two temporal { { Sphenoid { { Ethmoid Skull { { { Two inferior turbinate { { Two nasal { { Two superior maxillary { Face { Two lachrymal { Two malar { Two palate { Inferior maxillary { Vomer

=The Bones of the Cranium.=—_Occipital Bone._—The occipital bone is situated at the back part and base of the cranium.

_Frontal Bone._—The frontal bone is situated at the anterior part of the cranium, and forms the forehead.

_Parietal Bones._—The parietal bones, two in number, form, by their union, the sides and roof of the cranium. They are between the frontal and the occipital bones.

_Temporal Bones._—The temporal bones, two in number, are situated at the sides and base of the skull.

_Sphenoid Bone._—The sphenoid bone is situated at the anterior part of the base of the skull articulating with all the other cranial bones.

_Ethmoid Bone._—The ethmoid is an exceedingly light, spongy bone, which is situated at the anterior part of the base of the cranium.

=The Bones of the Face.=—_Nasal Bone._—The nasal bones, two in number, are placed side by side at the middle and upper part of the face, forming, by their junction, “the bridge” of the nose.

_Superior Maxillary Bones._—The superior maxillae, two in number, are the largest bones of the face, excepting the lower jaw, and form by their junction, the upper jaw.

_Inferior Maxillary Bone._—The inferior maxillary bone is also called the mandible. This bone is the largest and strongest bone of the face. In a great many cases after death this bone drops down, and it becomes one of the first duties of the embalmer, to place this bone in the proper position, so that it will set with the gradual death stiffening. If the lower jaw has already set, in proper position, it is best not to break up the rigor, because, once broken up, it will be hard to set it in proper condition again without the use of stitches.

The upper and lower jaws are the fundamental bones for mastication.

_Lachrymal Bones._—The lachrymal bones, two in number, are the smallest and most fragile bones of the face. They are situated at the front part of the inner wall of the orbit of the eye.

_Malar Bones._—These are the cheek bones. There are two in number, situated at the upper and outer part of the face.

_Palate Bones._—The palate bones, two in number are situated at the back part of the nasal fossae. Each bone assists in the formation of three cavities: the floor and the outer wall of the nose, the roof of the mouth, and the floor of the orbit.

_Inferior Turbinated Bones._—The inferior turbinated bones are situated one on each side of the outer wall of the nasal fossae.

_Vomer._—The vomer, a single bone, is situated vertically at the back part of the nasal fossae, forming part of the septum of the nose. It is thin and somewhat like a ploughshare in form.

=The Hyoid Bone.=—_The hyoid bone_ is named from its resemblance to the Greek letter U. It is also called the lingual bone, because it supports the tongue and gives attachment to its numerous muscles.

The omo-hyoid muscle, which crosses the carotid artery at its middle third, has its insertion with the hyoid bone.

=The Bones of the Thorax.=—_The Sternum_ or _Breast Bone_.—The sternum is a flat, narrow bone, situated in the median line of the front of the chest. The lower end is called the ensiform process, to which the diaphragm has its anterior attachment.

_The Ribs._—The ribs, which are curved arches of bone, form the chief part of the thoracic walls. There are twelve in number on each side, although this number may vary.

The ribs are divided into seven pairs of true ribs, three pairs of false ribs, and two pairs of floating ribs, as the following outline will show:

Ribs

7 true 3 false 2 floating —— 12 pairs in all.

The true ribs are connected behind to the spine and in front to the sternum.

The false ribs are connected behind to the spine, but are called false because they are not attached directly to the sternum, but indirectly, the cartilages attaching to the cartilage of the rib next above.

The floating ribs are so named because they are only attached at one place, which is the spine and are loose or float in front.

=The Bones of the Upper Extremities.=—_The Shoulder girdle_ consists of the _clavicle_ and _scapula_.

_The Clavicle._—The clavicle or key bone, so-called because of its supposed resemblance to the key used by the Romans, forms the anterior portion of the shoulder girdle. It is often commonly called the collar bone.

_The Scapula._—The scapula comes from a Greek word meaning “a spade.” It forms the back part of the shoulder girdle.

_The arm_ is that portion of the upper extremity which is situated between the shoulder and the elbow.

_The Humerus._—This is the largest and strongest bone of the upper extremity and is found in the arm between the shoulder and the elbow. It is the only bone in the arm.

_The fore arm_ is that portion of the upper extremity which is situated between the elbow and the wrist. The fore arm has two bones, the _ulna_ and the _radius_.

_The Ulna._—A long thin bone, but larger than the radius, and situated on the inside of the fore arm.

_The Radius._—So-called because it is the rotary bone of the fore arm. It is situated on the outside of the fore arm and parallel with the ulna.

_The hand_ is subdivided into the wrist or _carpus_ bones, the _metacarpus_ or the bones of the palm, and the _phalanges_ or the bones of the digits. There are twenty-seven bones in each hand.

=The Bones of the Lower Extremities.=—The bones of the lower extremities consist of _the pelvic girdle_, _the thigh_, _the leg_ and _the foot_.

_The pelvic girdle_ consists of three portions, the _ilium_, the _pubis_, and the _ischium_.

_The Ilium._—The ilium is the superior, broad and expanded portion and forms the prominence of the hip. The top part is called _the crest_.

_The Ischium._—The ischium is the lowest portion of the girdle, and is the portion which supports the body when in a sitting position.

_The Pubis._—This bone forms the front of the pelvis, and supports the external organs of generation.

_The thigh_ is that portion of the lower extremity which is situated between the pelvis and the knee. It consists of a single bone called the femur.

_The Femur._—The femur is the largest, longest and strongest bone in the skeleton. It is almost perfectly cylindrical. It extends from the hip to the knee.

The bones of the leg are three in number and are as follows: patella, tibia, and fibula.

_The Patella._—This bone is often called the knee cap or the knee pan. It is a flat triangular bone, situated at the anterior part of the knee joint.

_The Tibia._—The tibia is situated at the front and inner side of the leg, and is next to the femur in strength and size. It is sometimes called the shin bone.

_The Fibula._—The fibula is sometimes called the calf bone. It is situated at the outer side of the leg, and is a quite slender bone.

The foot is divided into the _tarsus_, _metatarsus_, and the _phalanges_. There are seven tarsus bones, five metatarsus bones, and fourteen phalanges bones, making a total of twenty-six bones for each foot.