Human Skeletal System

Divisions of the Skeleton The skeleton is divided into two parts because it organizes the skeleton and makes it easier to distinguish the central and outer parts of the skeleton. The skeleton is divided into two parts because it organizes the skeleton and makes it easier to distinguish the central and outer parts of the skeleton.

Divisions of the Skeleton The axial skeleton forms the "axis" of the central body. It consists of 80 bones including the skull, the vertebral column, pelvis, ribs, and breastbone. The skull protects the brain, the vertebral column protects the spinal cord and the ribs protect the heart and lungs, and help in breathing. The appendicular skeleton consists of 126 bones including the bones of the arms, legs, shoulders, and the hip.

Axial Skeleton A. Skull 1. Cranial Bones 1. Cranial Bones a. Frontal bone a. Frontal bone b. Parietal bones b. Parietal bones c. Temporal bones c. Temporal bones d. Occipital bone d. Occipital bone e. Sphenoid bone e. Sphenoid bone f. Ethmoid bone f. Ethmoid bone

Cranial Bones

Facial Bones 2. Facial Bones a. Maxilla a. Maxilla b. Mandible b. Mandible c. Zygomatic bone c. Zygomatic bone d. Nasal bone d. Nasal bone *e. Lacrimal bone *e. Lacrimal bone *f. Palatine bone *f. Palatine bone *g. Inferior nasal conchae *g. Inferior nasal conchae h. Vomer bone h. Vomer bone  * (Do not have to label)

Facial Bones

Facial Bones (side view)

Cranial and Facial Bones

Infant’s Skull  Fontanels or soft spots permit the skull to undergo changes in shape during childbirth and allow for growth of the brain. Ossification of the fontanels is usually complete between 18 and 24 months of age.  1-sagittal suture; 2-anterior fontanel; 3-coronal suture; 4- frontal bones

B. Hyoid bone – only bone in the body that articulates with no other bones

C. Vertebral Column a. Cervical vertebrae – 7 a. Cervical vertebrae – 7 b. Thoracic vertebrae – 12 b. Thoracic vertebrae – 12 c. Lumbar vertebrae – 5 c. Lumbar vertebrae – 5 d. Sacrum – five separate vertebrae until about the age of 25 when they fuse d. Sacrum – five separate vertebrae until about the age of 25 when they fuse e. Coccyx – four or five separate vertebrae in a child but fused in an adult e. Coccyx – four or five separate vertebrae in a child but fused in an adult

Vertebral Column

D. Sternum - breastbone; three main parts are the manubrium, body, and the xiphoid process

E. Ribs a.True ribs – upper seven pairs; fasten to sternum by costal cartilages a.True ribs – upper seven pairs; fasten to sternum by costal cartilages b. False ribs – pairs 8-10; attach to the lowest true rib and not to sternum directly b. False ribs – pairs 8-10; attach to the lowest true rib and not to sternum directly c. Floating ribs – pairs 11 and 12; only attach to the spine c. Floating ribs – pairs 11 and 12; only attach to the spine

Ribs

Bones of the Middle Ear 1. Incus 2. Stapes 3. Malleus

Appendicular Skeleton Upper Extremity = bones of shoulder girdle, upper arm, lower arm, wrist, and hand Upper Extremity = bones of shoulder girdle, upper arm, lower arm, wrist, and hand Pectoral Girdle (shoulder girdle) = scapula and clavicle Pectoral Girdle (shoulder girdle) = scapula and clavicle Humerus = long bone of upper arm Humerus = long bone of upper arm Radius = long bone of the top side of the forearm Radius = long bone of the top side of the forearm Ulna = long bone on the underside of the forearm Ulna = long bone on the underside of the forearm Carpal bones = 8 small bones of wrist Carpal bones = 8 small bones of wrist Metacarpals = form framework of hand Metacarpals = form framework of hand Phalanges = finger bones Phalanges = finger bones

Upper Extremity

Lower Extremity = bones of the hip, thigh, lower leg, ankle, and foot Lower Extremity = bones of the hip, thigh, lower leg, ankle, and foot Pelvic girdle = sacrum and the two coxal bones Pelvic girdle = sacrum and the two coxal bones (Each coxal bone is made up of the ilium, ischium and pubis which are fused together) (Each coxal bone is made up of the ilium, ischium and pubis which are fused together) *Sacrum may or may not be included in appendicular Femur = longest and heaviest bone of the body Femur = longest and heaviest bone of the body Patella = knee cap; largest sesamoid bone in the body Patella = knee cap; largest sesamoid bone in the body Tibia = larger, stronger bone of the lower leg Tibia = larger, stronger bone of the lower leg Fibula = smaller, more laterally and deeply placed of the two leg bones Fibula = smaller, more laterally and deeply placed of the two leg bones Tarsals = ankle bones Tarsals = ankle bones Metatarsals = bones of the foot Metatarsals = bones of the foot Phalanges = toe bones Phalanges = toe bones

Lower Extremity

Skeletal Differences in Men and Women FEMALEMALE flared iliumstraight ilium greater angle on the public arch smaller angle on the pubic arch wide pelvic cavitynarrow pelvic cavity

BROKEN BONES GENERAL SYMPTOMS: 1. Exquisite pain when you move or touch the broken area. 2. Bruising and edema of the skin over the area of the break. 3. Shortening of the limb. 4. Snapping sound at injury. 5. Unable to support your weight standing in fractures from the waist down. 6. Something hard pushing up the skin or through it. ** The shortening of broken limbs happens because your bones are connected to muscles. When a bone snaps, the two ends can be pulled past each other by the muscles still attached.

BROKEN BONES (cont’d) Bone fractures are potentially serious injuries. As well as damaging the bone they often injure the tissues around the bone such as tendons, ligaments, muscles and even the skin.

Multiple types of fractures exist. These are just a few examples of the different types:  Transverse - Straight across bone  Oblique - Diagonal break across bone  Spiral - Around the bone  Comminuted - Bone is shattered  Compound – bone fragments break through the skin from the inside. (susceptible to infection)

Guide to broken bones:

BROKEN BONES

SURGICAL REPAIR

REPAIR OF BONE FRACTURES  Complex bone tissue repair is apparently initiated by bone death or by damage to periosteal and Haversian system blood vessels.  A fracture invariably tears and destroys blood vessels that carry nutrients to osteocytes, and this vascular damage initiates the repair sequence.

STEPS IN THE REPAIR PROCESS Fracture  Vascular Damage  Hemorrhage  Fracture Hematoma (blood clot) formed  Hematoma resorbed  Callus tissue deposited (specialized repair tissue)  Callus tissue “collars” the broken ends, stabilizing them  Callus tissue “modeled” and eventually replaced with normal bone tissue ** The last step (when callus tissue is “modeled” and replaced with normal bone tissue) occurs when the fracture is properly aligned and immobilized - and if complications do not develop.

The End Anatomy and Physiology