lecture 2 - osteology

STMU DPT 1st Semester (General Anatomy)

Anatomy of skeletal systemDr. SUHAIL KARIMBSPT, PPDPT

Shifa Tameer-E Millat University Islamabad*STMU DPT 1st Semester (General Anatomy)


Topics of DiscussionSKELETAL SYSTEMAXIAL SKELETONAPPENDICULAR SKELETONBONESCOMPOSITION OF BONESFUNCTIONS OF BONESSTRUCTURE OF BONECOMPACT BONECANCELLOUS OR SPONGY BONEBONE MARROWPERIOSTEUMENDOSTEUMCLASSIFICATION OF BONESDEVELOPMENTAL CLASSIFICATIONHISTOLOGICAL CLASSIFICATIONACCORDING TO REGIONACCORDING TO SHAPE & SIZE (LONG, SHORT, FLAT, IRREGULAR)

IRREGULAR BONESPNEUMATIC BONESSESAMOID BONESWORMIAN OR SUTURAL BONESBONE MARKINGSOSSIFICATIONBLOOD SUPPLY OF BONEVENOUS AND LYMPHATIC SUPPLYNERVE SUPPLYCARTILAGECLASSIFICATION

*STMU DPT 1st Semester (General Anatomy)


SKELETAL SYSTEMThe skeleton consists of bone and cartilage. Younger persons have more cartilage in their skeleton, and, as a result, the bones of newborn babies are soft and flexible. The skeletons consist of two parts.1. Axial skeleton2. Appendicular skeleton*STMU DPT 1st Semester (General Anatomy)


SKELETAL SYSTEMAxial skeletonIt consists ofBones of the head SkullBones of the neck Hyoid boneCervical vertebraeBone of the trunk RibsSternumThoracic vertebraeLumbar vertebraSacrum

Appendicular skeletonIt consists of Bones of upper limb Pectoral girdleHumerusRadius UlnaHand bonesBones of lower limb Pelvic girdleFemurTibia FibulaBones of foot*STMU DPT 1st Semester (General Anatomy)


Skeletal systemSTMU DPT 1st Semester (General Anatomy)*


BONESBone is specialized connective tissue. It is very hard and highly vascular connective tissue. They have an organic framework of fibrous tissues and cells, among which inorganic salts phosphates of calcium are deposited. It can grow, it can repair itself and it can change its shape in proportion to the activity and stresses placed on it.The bones of the body taken together are known as the skeleton.



Composition of bonesBones consist of an organic framework of fibrous tissues and cells. These lie in inorganic salts (mainly phosphate of calcium), which have been deposited, in a particular fashion. The fibrous tissue gives the bone resilience and toughness.whereas the salts make it hard and rigid.*STMU DPT 1st Semester (General Anatomy)


Functions of bones1. Protection Bones can serve to protect internal organs, such as the skull Protecting the brain or the ribs protecting the heart and lungs. 2. Shape Bones provide a frame to keep the body supported. 3. Blood production The marrow, located within the medullary cavity of long bones and the cancellous bone, produces blood cells. 4. Mineral storage Bones act as reserves of minerals important for the body, most notably calcium and phosphorus.*STMU DPT 1st Semester (General Anatomy)


Continue..5. MovementBones, skeletal muscles, tendons, ligaments and joints function together so that individual body parts or the whole body can be manipulated in three-dimensional space. 6. Acid-base balance Bone buffers the blood against excessive pH changes by absorbing or releasing alkaline salts. 7. Detoxification Bone tissues can also store heavy metals and other foreign elements, removing them from the blood and reducing their effects on other tissues. These can later be gradually released for excretion.



STRUCTURE OF BONEOn naked eye examination of a section of dried bone, two types of bone can be distinguished.1. Compact2. CancellousThe difference between the two types depends on the relative amount of solid matter and on the number of spaces they contain.All bones have a superficial thin layer of compact bone around a central mass of spongy bone, except in places when medullary (bone marrow) cavity replaces spongy bone.



Compact and cancellous boneSTMU DPT 1st Semester (General Anatomy)*


STMU DPT 1st Semester (General Anatomy)*


Compact boneIt forms the outer shell of bone. It is thicker at the shaft of a long bone and thinner at the ends of a long bone. The compact bone of the body or shaft is known as cortical bone and surrounds the medullary cavity. Compact bone provides strength for weight bearing.Compact bone is surrounded by periosteum and lined by endosteum. It has a lot of connective tissue fibers are arranged in layers. They form connective tissue sheets called lamellae. Between adjacent lamellae osteocytes are embedded.*STMU DPT 1st Semester (General Anatomy)


Most of these lamellae are arranged as concentric cylinders around central canals. These canals contain blood vessels and are also called Haversian canals. This arrangement is known as Haversian system or osteon. Each osteon is surrounded by a cementing line. These systems lie parallel to each other and in the long axis of bone.The osteons communicate with medullary cavity and with each other by canals, which run transversely. Such canals containing anastomosing vessels and are called anastomosing canals. The anastomosing canals communicating the central canals with medullary cavity or outside are called Volkmanns canals.*STMU DPT 1st Semester (General Anatomy)


Cancellous or spongy boneIt is a sponge network of bony trabeculae. It is always in the interior of bones. In long bones it is present at the ends. The spaces between trabeculae are filled with blood vessels and bone marrow. The bony spicules or trabeculae are arranged in a pattern best suited. This arrangements change with any alterations in the strain exerted on the cancellous bone.Spongy bone is always surrounded by a thin shell of compact bone.*STMU DPT 1st Semester (General Anatomy)


Bone marrowIt fills the medullary cavities of long bones and the spaces in cancellous bone. It is of two types.1. Red bone marrow2. Yellow bone marrowAt birth all of the marrow is of the red type and is a factory for making blood cells and blood platelets. This activity is known as heamopoiesis.With the passage of time, the amount of red marrow decreases and is replaced by yellow marrow which has no power of haemopoiesis. This change begins in the distal parts of limbs and gradually involves proximal parts.By young adult life, the limb bones contain red marrow only at their cancellous ends. The bones that contain red marrow throughout life are Ribs Sternum Vertebrae Skull bones Hip bone*STMU DPT 1st Semester (General Anatomy)


Periosteum

The outer surfaces of bone are covered with a thick fibrous layer of connective tissue containing blood vessels. This is known as periosteum. It is responsible for nutrition of the underlying bone.Periosteum is osteogenic. It gives rise to new bone. In a growing person, new bone is laid down under periosteum. After a person attains maturity and the growth has ceased. It still retains the power to produce new bone in the repair of fractures.Periosteum is absent at the articulating (joint) surface of bones.*STMU DPT 1st Semester (General Anatomy)


Structure of boneSTMU DPT 1st Semester (General Anatomy)*


EndosteumIt is single layered epithelium Lining the internal surface (marrow / medullary cavity, vascular canals) of bone. It is also osteogenic and takes part in formation of new bone.*STMU DPT 1st Semester (General Anatomy)


CLASSIFICATION OF BONESBones are classified in different ways.1.Developmental classification. (According to mode of development)

I. MEMBRANOUS BONES.

These bones develop through Intra membranous ossification. Intra membranous ossification is a process of conversion of embryonic mesenchyme directly into bone. The process is seen in the embryo. It is a rapid process.Membranous bones includea. Bones of the vault of the skullb. Bones of the face*STMU DPT 1st Semester (General Anatomy)


ContinueII. CARTILAGINOUS BONES. These develop by the process of intracartilaginous ossification. Here a cartilage model of future bone is formed first which changes into bone. It is a slow process beginning in the intrauterine life ending during adulthood. All long bones of the body (except clavicle) vertebrae & short bones develop by this process.

III. MEMBRANO-CARTILAGINOUS BONES. These develop through both of the above processes. These include bones at the junction of vault and base of skull. For example occipital bone, etc*STMU DPT 1st Semester (General Anatomy)


ContinueHISTOLOGICAL CLASSIFICATION. (According to structure / architecture)COMPACT BONE. It forms the outer shell of the shaft of long bones & vertebrae.

II. CANCELLOUS BONE OR SPONGY BONE. It is seen internal to compact bones and at the ends of long bones. According to regionAxial bones (belonging to axial skeleton)a. Bones of the skullb. Auditory ossiclesc. Vertebraed. Sternume. RibsAppendicular bones (belonging to appendicular skeleton)a. Bones of the limbsb. Bones of the shoulder & pelvis girdle*STMU DPT 1st Semester (General Anatomy)


continue..4. According to shape & size (Long, short, flat, irregular)Long boneShort boneLong bonesThese are usually tubular in shape and found in the limbs. They are verticallyplaced in human body. Their length is greater than the breadth. They act aslevers for muscles. Their length varies from bones of fingers (phalanges) to thighbones.

The anterior aspect of right humerus is shown. Humerus is a long bone. It is present in arm.



ContinueEach long bone has a shaft or body (also called diaphysis) and two ends. The shaft or diaphysis is hollow containing the medullary or marrow cavity filled with bone marrow. This part is responsible for the strength of a bone. The shaft typically has 3 borders, which separates 3 surfaces. It appears triangular in cross section.Long bones have many raised areas (e.g. ridges, crests, tubercles), which provide support where heavy muscles are attached.*STMU DPT 1st Semester (General Anatomy)


ContinueEnds of long bone are composed of cancellous bone with a thin layer of compact bone. The ends are enlarged and smooth and are either convex or concave. In a growing bone the ends are known as epiphyses.The epiphysis is separated from the diaphysis by cartilage (epiphyseal cartilage).The portion of the diaphysis close to the epiphyseal cartilage is known as metaphysis. When growth is complete, the epiphyseal cartilage disappears and epiphysis unites with the diaphysis (shaft).Every long bone does not have the above specifications. The clavicle and ribs do not have a medullary cavity, but fulfill the other criteria of long bones.*STMU DPT 1st Semester (General Anatomy)


ContinueSuperior aspect of right clavicle is shown. Clavicle is a long bone. It is horizontally placed in the human body. It does not have medullary cavity.*STMU DPT 1st Semester (General Anatomy)


Short bones These bones are not long. They are short. They are irregular. They resemble cubes. These are found only in the wrist (carpus) and ankle (tarsus). They have 6 surfaces (like a cube) out of which 4 or less are articular (i.e. take part in the formation of joints) the remaining 2 or more are free for attachments of ligaments and entry of blood vessels.They do not have medullary cavity. They have spongy bone inside with compact bone forming outer shell.Right Hamate bone. Lateral aspect.Right Hamate bone. medial aspect*STMU DPT 1st Semester (General Anatomy)


Continue..FLAT BONESThese resemble sandwiches. They have thin outer layers of compact bone separated by a layer of spongy (cancellous) bone between them. Most of skull bones, sternum scapula and parts of many other bones belong to this group.In flat bones of the skull particularly calvaria (bone forming the roof of skull), spongy bone containing marrow is known as diploe, which appears some years after birth and splits each flat bone into two layers. The outer and inner layers of compact bone are called tables in the flat skull bones while diploe is in the center. The diploe of spongy bone is sandwiched between outer and inner tables of compact bone.Other flat bones (sternum, scapula, ilium of hipbone) are also like flat skull bones. They also have two layers of compact bone and spongy layer is sandwiched between them.



Calvaria of the skull seen from inside showing flat bonesPosterior surface of sternum. Sternum is a flat bone.Sternum and ribs are flat bones.*STMU DPT 1st Semester (General Anatomy)


ContinueAnterior aspect of right scapula shown. Scapula is a flat and irregular bone.*STMU DPT 1st Semester (General Anatomy)


Irregular bonesThese are irregular shaped bones. Most of the facial bones (maxilla and zygomatic bone) are irregular shaped. Other examples are vertebrae, scapulae and hipbones. All of them consist of cancellous bone covered with compact bone of variable thickness. Vertebrae are irregular bones but they are symmetrical bones. We can classifyirregular bones into two subcategories.1. Symmetrical bones Vertebrae are good example2. Asymmetrical bones Scapula, hipbone, maxilla



Pneumatic bones

These bones are found in the skull. The spongy part of the bone is replaced by air- filled cavities, which communicate with the nose. These air- filled cavities are known as paranasal sinuses. These are found in the frontal, maxillary and sphenoid bones.*STMU DPT 1st Semester (General Anatomy)


ContinueSesamoid bonesThese are so named because they resemble sesame seeds.They are usually present where tendons glide over bones.The largest sesamoid bone in human body is patella (knee-cap). It is found in the tendon of Quadriceps femoris.*STMU DPT 1st Semester (General Anatomy)


Wormian or sutural bonesSmall bones are found along the sutures of the skull where flat bones come together. These are called wormian bones or sutural bones.*STMU DPT 1st Semester (General Anatomy)


BONE MARKINGSNormally bone appears smooth in three main areas.1. Where it is covered by articular cartilage (i.e. cartilage on the surface of bone taking part in forming a synovial joint).2. Where it is subcutaneous (covered only by skin).3. Where it gives fleshy attachment to muscle.The bone is rough where it gives attachments to ligaments, aponeurosis and tendons.The bone has grooves for blood vessels. The bones have foramina where arteries, veins and nerves pass through these foramina. *STMU DPT 1st Semester (General Anatomy)


ContinueThe various markings and features of bones are.Line: It is a linear elevation on the surface of bone. Example. Superior nuchal line and inferior nuchal line on the back of skull. Superior and inferior temporal lines of skull. Intertrochanteric line in femur.*STMU DPT 1st Semester (General Anatomy)


Continue.Lateral view of skull showing superior and inferior temporal lines.*STMU DPT 1st Semester (General Anatomy)


2. Condyle: It is a rounded articular area. Example. Condyles of mandibleCondyles of femur3. Epicondyle: It is a raised area above the condyle. Example. Epicondyles of humerus.*STMU DPT 1st Semester (General Anatomy)


Continue4. Crest: It is the ridge of a bone. Example. Iliac crest and Pubic crest in hip bone. Intertrochanteric crest in femur. Medial crest in fibula.*STMU DPT 1st Semester (General Anatomy)


Continue5. Groove: It is an elongated depression in the bone. Example. Infraorbital groove in the orbital cavity.*STMU DPT 1st Semester (General Anatomy)


Continue..6. Facet: It is a flat area, usually covered with cartilage, where bones join each other. Example. Costal facets on vertebral bodies and transverse processes to articulate with ribs.Superior aspect of first cervical vertebra (atlas). Look at the superiorarticular facets. They articulate with overlying skull.*STMU DPT 1st Semester (General Anatomy)


Continue..7. FossaIt is a depressed area in the bone. Example. Anterior cranial fossa, middle cranial fossa and posterior cranial fossa in skull. Temporal fossa of skull. Incisive fossa in palate. Supraspinous fossa of the scapula. Iliac fossa in hip bone.Interior of base of skull. Three main fossae (anterior, middle and posterior) are labeled.*STMU DPT 1st Semester (General Anatomy)


Continue..Lateral view of skull showing temporal fossa. Inferior aspect of palate.*STMU DPT 1st Semester (General Anatomy)


Continue8. ForamenIt is a hole in the bone. Example. Foramen magnum in occipital bone for medulla oblongata.Interior of base of skull. Five foramina are shown.*STMU DPT 1st Semester (General Anatomy)


Continue9. Malleolus It is a rounded process projecting from the end of a bone. Example. Medial malleolus of tibia. Lateral malleolus of fibula. 10. NotchIt is an indentation at the edge of a bone. Example. Greater sciatic notch, lesser sciatic notch and acetabular notch in hip bone. Trochlear notch and radial notch in ulna. 11. ProtuberanceIt is a projection of bone. Example. External occipital protuberance and internal occipital protuberance in skull.*STMU DPT 1st Semester (General Anatomy)


ContinueLateral view of skull. External occipital protuberance have been marked and labeled.

Interior of base of skull. Look at the internal occipital protuberance.*STMU DPT 1st Semester (General Anatomy)


Continue..12. Spine It is a thorn like process from the bone. Example. Spine of scapula.Dorsal aspect of right scapula is shown. Look at the spine of scapula and coracoid process.*STMU DPT 1st Semester (General Anatomy)


Continue13. Process It is a spine like part projecting from the bone. Example Anterior cliniod process and posterior cliniod process in skull. Styloid process on the base of skull. Coronoid process of mandible. Spinous process and Coracoid process of scapula*STMU DPT 1st Semester (General Anatomy)


ContinueLateral view of skull. The processes have been marked and labeled.Right lateral view of typical thoracic vertebra.*STMU DPT 1st Semester (General Anatomy)


Continue14. Trochanter It is a large blunt raised area of a bone. Example. Greater trochanter and lesser trochanter of femur.15. TubercleIt is a small raised area on the surface of bone. Example. Anterior and posterior tubercles of atlas. Greater tubercle and lesser tubercle of humerus. Superior aspect of first cervical vertebra (atlas). Look at the anterior and posterior tubercles.*STMU DPT 1st Semester (General Anatomy)


Continue16. TuberosityIt is large rounded elevation of a bone. Example. Greater tuberosity and lesser tuberosity of humerus. Gluteal tuberosity on femur. Tibial tuberosity on tibia.*STMU DPT 1st Semester (General Anatomy)


BLOOD SUPPLY OF BONEBlood supply of long bonesThe blood vessels supplying long bones come from 3 sources. Nutrient artery which enters the shaft through the nutrient foramen Periosteal arteries Branches of blood vessels supplying the joints. These form an anatomosis called juxta-articular anastomosis from which small twigs supply the epiphysis and the metaphyseal region.*STMU DPT 1st Semester (General Anatomy)


Continue Nutrient arteryUsually one (or two) artery enters the shaft obliquely through an opening called nutrient foramen, which leads into a nutrient canal.In upper limbs, the direction is towards elbow joint, whereas in lower limbs, it is away from the knee joint.So remember this formula to the elbow I go, from the knee I flee.*STMU DPT 1st Semester (General Anatomy)


ContinueSmall branches from the periosteal arteries of the periosteum supply most of the compact bone. Consequently, if the periosteum is removed, the bone will die.Metaphyseal and epiphysial arteries supply the ends of the bones. These vessels arise mainly from the arteries that supply the joints. The metaphyseal arteries come from muscular arteries whereas epiphyseal arteries come from blood vessels around the joints.These blood vessels enter the bone through many foramina. The epiphyseal and metaphyseal arteries supply more blood then the nutrient artery. They can supply the bone if the nutrient artery is blocked.*STMU DPT 1st Semester (General Anatomy)


In the children, there are no anastomoses between epiphyseal and metaphyseal arteries due to the presence of epiphyseal plate between the epiphysis and metaphysis.If the nutrient artery gets blocked due to any reason, the metaphyseal bone dies. This is called necrosis. The dead bone gets infected easily and this condition is called osteomyelitis. This is why the commonest site of osteomyelitis in children is the metaphysis.Once the epiphyseal plate disappears with completion of bone growth, and the epiphysis joins the metaphysis, blood vessels from the epiphysis and metaphysis link up. Now there is no danger of bone death if nutrient artery gets blocked.*STMU DPT 1st Semester (General Anatomy)


Blood supplySTMU DPT 1st Semester (General Anatomy)*


venous and lymphatic supply Veins accompany arteries through the nutrient foramina. Many large veins leave through foramina near the articular ends of the bones. Lymphatic vessels are abundant in the periosteum. *STMU DPT 1st Semester (General Anatomy)


Nerve supply Nerves accompany the blood vessels supplying bones. The periosteum is richly supplied with sensory nerves periosteal nerves that carry pain fibers. The periosteum is especially sensitive to tearing or tension, which explains the acute pain from bone fractures. Bone itself is relatively poorly supplied with sensory endings. Within bones, vasomotor nerves cause constriction or dilation of blood vessels, regulating blood flow through the bone marrow. *STMU DPT 1st Semester (General Anatomy)


Cartilage Cartilage is a resilient, semi rigid, avascular form of connective tissue that forms parts of the skeleton where more flexibility is necessary (e.g., the costal cartilages that attach the ribs to the sternum). The articulating surfaces of bones participating in a Synovial joint are capped with articular cartilage, which provides smooth, low-friction gliding surfaces for free movement of the articulating bones.*STMU DPT 1st Semester (General Anatomy)


ContinueCartilage is avascular and is, therefore, nourished by diffusion. The proportion of bone and cartilage in the skeleton changes as the body grows; the younger a person is, the greater the contribution of cartilage. The bones of a newborn infant are soft and flexible because they are mostly composed of cartilage. *STMU DPT 1st Semester (General Anatomy)


ContinueThe fibrous connective tissue covering that surrounds bone is periosteum; that surrounding cartilage elements, excluding articular cartilage, is perichondrium.The periosteum and perichondrium help nourish the tissue, are capable of laying down more cartilage or bone (particularly during fracture healing), and provide an interface for attachment of tendons and ligaments. *STMU DPT 1st Semester (General Anatomy)


CLASSIFICATION

There are 3 types of cartilage; hyaline, elastic, and fibrocartilage. Hyaline CartilageIt is homogenous, bluish-white and translucent in appearance. It forms temporary cartilage model, from which bones develop.

After birth it is found in following places Articular cartilage of synovial joints Plates of cartilage between separately ossifying parts of a bone during growth. It is called epiphyseal cartilage. Xiphoid process of sternum Costal cartilages or cartilage of ribs Nasal septum Larynx Trachea Bronchi*STMU DPT 1st Semester (General Anatomy)


Continue..Fibrocartilage It is like white fibrous tissue, but contains small islands of chondrocytes and ground substance between collagen bundles.It is found in Intervertebral discs joining adjacent surfaces of vertebral bodies Articular discs in wrist joints, sternoclavicular joints and temporomandibular joints. As a labrum or rim deepening the sockets of shoulder or hip joints As semliunar cartilages (menisci) in knee joints In the plate and disk which unites pubic bones at symphysis pubis.



Continue..Elastic cartilageIt has bundles of yellow elastic fibers.It is found in external ear auditory tube epiglottis cuneiform cartilages of larynx.*STMU DPT 1st Semester (General Anatomy)


THANKS*STMU DPT 1st Semester (General Anatomy)


Buffer: a solution which resist in changes when acid or base is added to a solution, three hearing bones : the malleus, the incus, and the stapes**

lecture 2 - osteology

Documents

shape bones

protection bones

bones of newborn babies

medullary cavity of

individual body parts

mineral storage bones

blood cells

shape size long