A&P Skeletal System Ruben J. Mora P.2
Types of Bones:
Long Bone: Is long with expanded ends; examples: arm and leg bones
Short Bone:Are almost equal in length and width; examples: bones of the wrist and ankles
Sesamoid (round) bones: are small, nodular bones that develop within a tendon; a special type of short bone; example: patella
Flat bones:plate-like shape with broad surface; examples: ribs, scapula, flattened skull bones
Irregular Bones: vary in shape; examples: vertebrae, some facial bones
Structure of the Long Bone:
The ends of a long bone that connect to other bones that form joints are called the epiphysis
Articular cartilage which is made of hyaline cartilage, covers the epiphyses
The long middle part/the shaft of the bone is called the diaphysis
The outer sheet like layer which covers and protects the bone and is continuous with ligaments and tendons is called the perioustrium
The shaft(diaphysis) of the long bone is hollow, this hollow chamber is called the medulary cavity
The medulary cavity is lined up with a thin layer of cells called the endometrium.
Inside the meulary cavity there is a special type of connective tissue called bone marrow.
Compact bone is a very tightly packed tissue, which makes up the wall of the diaphysis
The epiphyses are filled with spongy (cancellous) bone, which reduces the weight of the skeleton.Spongy bone consists of many branching bony plates called trabeculae
Bone Function:
One of the functions of bones is to support and protect. For ex: bones give shape to the head, face, thorax, and limbs. For instance, the bones such as the pelvis and lower limbs provide support for the body’s weight. The bones of the skull protect the eyes, ears, and brain. The bones of the rib cage and shoulder girdle protect the heart and lungs, And the bones of the pelvic girdle protect the lower abdominal and reproductive organs
Bone also helps in movement: Bones act with muscles to cause movement of limbs and other body parts
Blood cell formation (hematopoiesis) Two kinds of marrow occupy the medullary cavities and the larger central canals of bone the red marrow and the yellow marrow. Red marrow occupies the spongy bone of the skull, ribs, sternum, clavicles, vertebrae, and pelvis in adults. Functions in the formation of red blood cells, white blood cells, & platelets. Color comes from the O2-carrying pigment hemoglobin.Yellow marrow stores fat and occupies most cavities of bone in adults :
Bone also functions in the storage of inorganic salts. For instance, the extracellular matrix of bone is rich in calcium salts, mainly calcium phosphate. Bone also stores magnesium, sodium, potassium, & carbonate ions. Bones can also accumulate harmful metallic elements, such as lead, radium, and strontium
Bone remodeling:
Bone remodelling is the continuous metabolic process of bone breakdown (resorption) by specialised cells called osteoclasts, followed by formation of new bone tissue (ossification) by cells called osteoblasts.
Osteoclasts resorb and osteoblasts deposit bone throughout life, in a process called bone remodeling An average of 3% to 5% of bone calcium is exchanged each yearThe remodeling process is controlled by hormones that regulate blood calcium levels
Skeletal Organization and Bones:
The axial skeleton consists of the bony and cartilaginous parts that support the and protect the head, neck and trunk, skull: cranium and facial bones. Hyoid bone: supports the tongue and aids in swallowing. Vertebral column. Thoracic cage: ribs and sternum
The appendicular skeleton consists of the bones of the upper and lower limbs and the bones that anchor the limbs to the axial skeleton: Pectoral girdle, upper limbs, pelvic girdle: 2 hip bones and lower limbs
Middle ear bones; malleus (2), incus (2), stapes (2)
Upper limbs :humerus/upper arm(2),radius/lateral forearm(2), ulna/medial forearm(2), carpal/wrist(16), metacarpal/palms (10), phalanx/fingers(28)
Hyoid: Hyiod bone(1)
Skull: Has 8 cranial bones; frontal bone/forehead (1), parietal bones/top of the head (2), occipital bone/back of head(1), temporal bones/bones side of the head(2). sphenoid bone(1), and ethmoid bone(1). The skull has 14 facial bones; maxilla(holds upper teeth) (2) zygomatic(check bone)(2), palatine( (2),inferior nasal concha (2),mandible(jawbone) (1), lacrimal (2), nasal (2), vomer (1)
Vertebral column; cervical vertebra (7),thoracic vertebra (12), lumbar vertebra (5), sacrum (1), coccyx (1)
Pelvic girdle; coxal(hip) bone 2
Pectoral girdle: scapula/shoulder blades(2), clavicle/collar bones(2)
Lower limbs; femur/thigh(2), tibia/shine bone(2),fibula/lateral lower leg(2), patella/kneecap (2),tarsal/ankle (14),metatarsa/sole of foot (10),phalanx/toes(28)
Thoracic cage; ribs (24), sternum/breast bone(1)
Differences Between male and female bones:
In the pelvic cavity, the female pelvic cavity is wider in all diameters and is shorter, roomier, and less funnel-shaped. The distances between the female ischial spines and ischial tuberosities are greater than in a male.
In the sacrum, the female sacrum is wider, and the sacral curvature is bent more sharply posteriorly than in a male.
In the pelvic girdle, the female hip bones are lighter, thinner, and have less evidence of muscular attachments. The female obturator foramina are triangular, whereas the males are oval. The female acetabula are smaller and the pubic arch is wider than the corresponding structures of a male.
In the coccyx, the females coccyx is more movable than the males.
A female's skeleton is usually much smoother and less knobby than a male's. A male's skeleton is usually thicker, rougher, and appears bumpier. Due to the fact that males have larger muscles and therefore their skeletons require stronger attachment sites.
Differences in the male and female pelvic cavity:
Fractures and Repairs:
Synovial Joints:
Saddle (sellar) joint: Permits a variety of movements, mostly in 2 planes (biaxial). Example: the joint between the trapezium (carpal) and the metacarpal of the thumb
Joints:
Slightly movable, or amphiarthrotic
Bone Repair: Soon after a fracture occurs, the body acts to protect the injured area, and forms a protective blood clot and callus around the fracture. New "threads" of bone cells start to grow on both sides of the fracture line. These threads grow toward each other. The fracture closes and the callus is absorbed.
A fracture is a broken bone, the same as a crack or a break. A bone may be completely fractured or partially fractured in any number of ways (crosswise, lengthwise, in multiple pieces). A fracture can be classified in one of six categories, greenstick, fissured, comminuted, transverse, oblique, or spiral fracture.
Freely movable, or diarthrotic
Immovable, or synarthrotic
Plane (gliding) joint:Allows a sliding or twisting movement (nonaxial). Examples: joints of the wrist and ankle, as well as those between vertebrae, sacroiliac joints
Condylar (ellipsoidal) joint: Permits back and forth and side to side movements within 2 planes (biaxial), but not rotation. Examples: joints between metacarpals and phalanges
Hinge joint: Allows movement in 1 plane (uniaxial), like hinge of a door. Examples: the elbow and joints between phalanges
Ball-and-socket (spheroidal) joint: Allows widest range of motion, including movement in all planes. Ex: shoulder and hip bones
Pivot (trochoid) joint: Allows only rotation around central axis (uniaxial). Examples: joint between the dens of the axis and the atlas
Cartilaginous:composed of cartilage. Intervertebral discs between vertebrae help absorb shock and are slightly movable. Other examples include the pubic symphysis and the first rib with the sternum
Fibrous: composed of dense connective tissue. EX:A few are slightly movable, such as the joint between the distal tibia and fibula
Synovial:having a complex structure. They are diapthrotic. Synovial joints are classified by shape of their parts and the movements they allow
Transverse Fracture: when a bone breaks at a 90-degree angle to the long axis of the bone
Comminuted Fracture: bone is broken into more than two pieces.
Fissured Fracture: a crack extending from a surface into, but not through, a long bone.
Oblique Fracture: complete fractures that occur at a plane oblique to the long axis of the bone
Greenstick Fracture; bone bends and cracks, instead of breaking completely into separate pieces
Spiral Fracture: broken bone resembles a corkscrew or a winding staircase, because the break happens diagonally across a bone that is longer than it is wide