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The Skeletal System Chapter 5 Functions of Bones Support – supports the body and organs Protection – protect soft organs and brain Movement – bones are the point of attachment for skeletal muscles. Storage – Stores minerals, Ca and P Blood Cell Formation – in the marrow. Bones 206 bones in the adult body. Bones can be compact of spongy Can also be classified by shape: • Long bones – limbs • Short bones – generally cube shaped, wrist • Flat bones – skull, ribs and sternum • Irregular bones – vertebrae. Spongy vs. Compact Long, Short, Flat, Irregular Bone Anatomy Diaphysis is the shaft of the bone. Mostly compact. Interior of diaphysis is usually a storage place, yellow or red marrow for example. Yellow marrow is fat storage, red is blood production Bone Anatomy Epiphyses are the ends of the bone. A thin layer of compact bone, enclosing an area of spongy bone. Spongy bone contains red marrow Externally, the epiphyses is covered by articular cartilage. Smooth and slippery – decreases friction in joints. Bone Anatomy Bones change over time/growth. They grow from the epiphyseal plate. Cartilage plate that makes new bone cells When the bone is mature, this cartilage turns to bone and stops growing. Bone Growth and Remodeling Fetal skeletons are mostly cartilage and very flexible. As the fetus gestates these cartilage bones go through ossification – the process of bone formation. A bone shell is produced around the cartilage by osteoblasts – bone making cells The cartilage is digested away, leaving a hallow core that can be filled with yellow or red marrow. stop Axial vs. Appendicular The skeleton as a whole can be broken into two sections. • The Axial Skeleton includes the skull, vertebrae, and the bony thorax cavity. • The Appendicular Skeleton includes the limbs and their attachment points. Axial - Skull The skull is comprised of two sets of bones, the cranium and the facial bones. The cranium encloses the brain Facial bones hold the eyes and are connection points for facial muscles Cranium Cranium comprised of 8 large, flat bones. Frontal bone (yellow) forms the forehead and superior ridge of your eye sockets. Cranium Behind the frontal bone we find two parietal bones. They make up the majority of the superior and lateral walls of the cranium. Cranium Temporal bones are inferior to the parietal bones and appear on the lateral sides of the skull. The temporal bones have a number of very important markings. Connection points of your lower jaw. Cranium Temporal Continued. Extermal acoustic meatus – canal that leads to the eardrum Jugular foramen and carotid canal – canals on the inferior side of the skull where the veins and arteries respectively enter the brain cavity. Cranium Occipital bone forms the posterior and inferior floor of the cranium. It contains the foramen magnum – the canal through which the spinal cord enters the cranium. Stop Cranium Sphenoid bone – butterfly shaped bone (pink) that forms the anterior floor of the cranium. Ethmoid Bone – Forms the roof of the nasal cavity. Facial Bones Maxillae – two bones that make the upper jaw (green). The palatine processes make up your hard palate (roof of your mouth) Facial Bones Maxillae also contain the paranasal sinuses. These cavities are there to lighten the skull as well as amplify our voice, however can become infected – sinusitis. Headache and upper jaw pain. Facial Bones Palatine bones form the posterior section of the hard palate. If not formed correctly called a cleft palate. Zygomatic bones form the cheeks and eye sockets. Facial Bones Mandible – the lower jaw. Connects with the temporal bone, forming the only moveable joint in the skull. Hyoid Bone Hyoid Bone – suspended above the larynx. Becomes the attachment for our tongue. Also helps in muscle movement of speech. Broken Bone? Fetal Skull Face is smaller. Fontanels (soft spots) areas where the skull has not fused together yet. Made up of fibrous membranes. Allow for brain growth after birth. Solidify after 22 24 months Pelvis Girdle Pelvis bone makes up our hips and upper leg joints. Bone shape is different in males and females to allow for birth. stop Column Vertebral (spine) Made up of 26 irregularly shaped bones with ligaments and cartilage. Spinal cord runs through the middle of these bones, protecting it. The first seven vertebrae, starting at the base of the skull make up the cervical Curvature. Known as C1-C7 Spine Vertebrae 8-19 are part of the thoracic curve. T1-T12. These are followed by the five lumbar vertebrae L1-L5. The final two bones of the spine are the sacrum and the coccyx Bony Thorax (Thoracic Cage) Includes the sternum, ribs and thoracic vertebrae making a cage for the thoracic organs. Heart lungs etc. Sternum is the flat bone on the anterior side (breastbone). Extreme inferior section is called xiphoid, can be broken off during CPR. Ribs Humans have 12 pairs of ribs. The first seven pairs are called true ribs because they attach directly to the sternum. The next five either attach indirectly or not at all, called false ribs. Appendicular Skeleton Shoulder Girdle Clavicle – holds the shoulder away from the thoracic cavity Scapula – flat bone that extends behind thoracic cavity and contains the shoulder joint. Shoulder Girdle Shoulder has exceptional movement because it is only attached to the axial skeleton at one place, the scapula can actually slide behind the ribs. This however allows for easy dislocation. Arm Bones The upper arm is one bone, the humerus. Forearm is the radius (lateral) and the ulna (medial) Hand 8 carpal bones make up the wrist. 5 metacarpals make up the palm Your fingers are called the phalanges. They are broken into distal, intermediate and proximal phalanges. Lower Limbs Femur is the bone that makes up our thigh. Strongest, longest, and heaviest bone. Trochanters – connection points of muscles. Lower Leg The lower leg is made of two bones Tibia is medial and is the bone that we call the shin. The fibula is lateral and smaller Foot Just like the hand, the foot can be broken into three distinct sections. Tarsals make up your heel and ankle Metatarsals make up the arch of your foot, Phalanges make up your toes. Foot Arch vs. Flat Feet There are three natural arches to the foot. Tendons keep this arch in place. The arch gives our feet “springiness” and allows it to absorb the shock of walking. Flat feet is a condition where this arch does not exist. Osteoporosis Bones do not stop changing when we are adults. Calcium levels and gravity take a toll on our bones as we age. Low calcium levels in our blood trigger osteoclasts – bone eating cells, to digest bone and release stored calcium. This however can ruin the structural integrity of the bone Bones will get stronger or thicker when muscles connected to them get stronger Osteoporosis stop Fracture Types Comminuted – when the bone breaks into many fragments. Occurs in severe accidents or with brittle bones. Fracture Types Compression – bone is crushed Fracture Types Depressed – Portion of bone is pressed inward Typical of skull fractures Fracture Types Impacted – Broken bone ends are forced into each other Typically occurs when one attempts to break a fall with outstretched arms Fracture Types Spiral – Ragged break, usually occurs when an excessive twisting force is applied to a bone. Common sports fracture Fracture Types Greenstick – Bone break is incomplete. Common in children whose bones are more flexible then adults. Closed vs. Open Fractures Closed fractures do not pierce the skin Open fractures are when bones do protrude from the skin. A fracture is treated with reduction – a realignment of the bones. Closed usually can be done with just manipulation, open requires surgery and bones are usually secured with pins and plates. stop Fracture Repair Once a fracture is reduced, it is immobilized by a cast so that the healing process can begin. Healing time is about 6-8 weeks depending on the bone and the age of the patient. Bone Healing When first broke, blood vessels that are broken will leak blood into the area forming a hematoma. Any unnourished cells will die. Bone Healing The Break is splinted by fibrocartilage callus – Capillaries invade the area (granulation) bringing nutrients. Cartilage forms and acts as a splint. Callus Bone Healing The fibrocartilage callus begins to solidify into spongy bone. Now called the bony callus. Bone Healing Over the next few months, this bony callus is restructured to form a permanent patch that is just as strong as the original bone. A small callus will forever remain. Joints Joints occur when any two bones come in contact. The only bone that does not form at least one joint is the Hyoid Bone. Not all joints allow for movement. Suture joints in the skull simply connect different skull bones to make a solid cranium. No Movement! Movable Joints Plane Joint – Two bones can slide or glide past each other to some extent. Found in the ankle and wrist bones. Stop Movable Joints Hinge Joint – movement is along one plane. Phalanges, knees, elbows. Movable Joints Saddle joints – both bones have a convex and concave feature, much like a saddle you would put on a horse. Allows for larger range of motions Thumb Movable Joints Ball and Socket – a spherical head of one bone fits into the round socket of another. Allows for movement on three axes Shoulders and hips Movable Joints Pivot – one rounded bone fits into a sleeve or ring and can rotate. Forearm or shin Movable Joints Condyloid Knuckle/egg shaped joint. Tend to be oval Synovial Joint The bones are covered in cartilage. A synovial membrane fills the space and is filled with fluid. Tendons reinforce the structure. Joint Pain The synovial membrane can become inflamed. Or it could fill with too much fluid. Arthritis is a general term for when the joint is inflamed, causing pain. Gout – uric acid forms sharp crystals joints which cause pain. Joint Replacement
