Includes bones, cartilage, and joints The SKELETAL System Includes bones, cartilage, and joints

Functions of the Skeletal System Support Protection Movement Facilitation Mineral Storage and Homeostasis Storage of energy Hematopoiesis

Support Bones are as strong or stronger than reinforced concrete. The skeletal system provides structural support for the entire body. Protection Delicate tissues and organs are surrounded by skeletal elements

Movement The bones serves as points of attachment for muscle tendons. Bones act as levers that convert muscle action to movement. Storage Bones store minerals that can be distributed to other parts of the body upon demand.

Hemopoiesis Energy storage Red bone marrow produces red blood cells, white blood cells, and platelets. Energy storage Yellow bone marrow stores fats for energy

Types of Bone Cells Osteogenic Cells = bone stem cells Osteoblasts = deposit Ca+ & P & collagen fibers--bone builders Osteocytes = mature bone cells-maintain tissue Osteoclasts = break down bone tissue

Bone Growth aka Ossification Bone formation (Osteogenesis) Replacement of pre-existing connective tissue with bone

Intramembraneous ossification Intramembranous Ossification Membranes ----> Bone (Periosteum - Width-wise Growth)

Endochondral ossification Cartilage ----> Bone Epiphyseal (growth) Plate - Length-wise Growth

Bone Structure Periosteum – outside membrane --Fibrous Layer-protection --Osteogenic Layer-stem cells Diaphysis = shaft of a long bone Epiphysis = ends of long bones

Bone Structure Medullary Cavity or Canal Yellow Marrow-in cavity--fat storage Articular (joint) Cartilage (Hyaline Cartilage) Red marrow--blood cell forming tissue (where hematopoiesis takes place) Endosteum

Compact Bone Structure Dense & organized Lamellae: layers of bone circular or interstial Osteons (Haversian canals)--contains, vertical canals - blood vessels and circular lamellae with lacunae

Compact bone structure Perforating or Volkman’s Canals - horizontal canals with blood vessels Lacunae: spaces that hold osteocytes Canaliculi: minute canals where osteocytes stretch out FYI: connect to other Lacunae and eventually with Central or Perforating Canals Gives bone strength

Spongy bone Spongy Bone (Trabecular Bone) irregular network thin plates of bone with lots of intercellular space Spaces filled with Red Bone Marrow Responsible for Hematopoiesis

Types of Bones Long Bones: Longer than wide, have a shaft, slightly curved –spongy bone on ends Short Bones: cube shaped, near equal in length and width, spongy bone on inside Flat Bones: thin and flat, compact bone outside & spongy bone inside, provide protection

Types of Bones Irregular Bones: various shapes Sesmoid Bones: Embedded in tendons

Bone Markings Foramen= a hole for blood vessels, nerves, or ligaments

Bone Markings Meatus= canal or passageway through bone

Sinuses Sinus= cavity or space in a bone, lightens the skull Frontal Sphenoid Ethmoid Maxillary

Fossa A fairly deep pit or depression Examples include the olecranon fossa of the humerus mandibular fossa of the temporal bone

Bone Markings Process = any projection from the surface of a bone EX spinous processes Condyle = “Knuckle” - a large rounded prominence on a bone EX Found in femur

Bone Markings cont Trochanter = a large blunt process found only on the femur Tubercle = a small rounded process

Bone Markings cont Tuberosity = an elevated, rounded, usually roughened area of a bone Facet = a smooth articular surface

Bone Markings Head= proximal end of bone, rounded projection

Sutures Immovable joint Saggital: separates parietal bones Coronal: separates frontal from parietal Lamdoid: separates occipital from parietal Squamous: Separates temporal from parietal

Fontanels Provide room for rapid brain growth Make childbirth easier Move during childbirth Used for access to blood sampling and IV’s

Axial vs. Appendicular Appendicular Axial Appendages Axis of the body Connected to trunk Shoulder girdle Pelvic girdle Upper limbs Lower limbs Axial Axis of the body Three regions Skull Vertebral column Bony thorax

Axial Skeleton Axis of the body--through the midline Three regions Skull Vertebral column Bony thorax

Skull Cranial Bones: six external bones and two internal bones Facial Bones: 14 Facial bones

Vertebral Column Divided into five regions Cervical (7 bones) Thoracic (12) Lumbar (5) Sacrum Coccyx

Intervertebral Disks Made of fibrocartilage Provide cushioning and shock absorption for vertebrae

Vertebral Column Vertebrae can be identified by three criteria: 1. Shape and angle of the spinous process 2. Size of the vertebral body 3. Presence or absence of transverse foramen

Hyoid Bone Does not articulate with any other bones Tongue muscles attach here Aids in swallowing

Bony Thorax (freehand notes) Sternum--Manubrium, body and xiphoid process 12 pair of ribs 7 pair of true ribs 5 pair of false ribs 2 pair of floating ribs

Appendicular Skeleton Attached to Axial Three regions Pectoral girdle Pelvic Girdle Upper and Lower Extremities

Exercise and Bones Wolff’s Law says that function determines form. Bone responds to physical stresses or the lack of them. Bone is deposited on areas subjected to stress and reabsorbed from areas where little stress is present.

Take freehand notes on back of note paper

The Pectoral Girdle attaches the bones of the upper extremities to the axial skeleton Clavicle & scapula

Upper extremities

The Pelvic girdle (Hip girdle) attaches the bones of the lower extremities to the axial skeleton Pelvic bone or coxal

Female Vs. Male Pelvis Light and thin Wide illium Pubic arch greater than 90o Wide sciatic notch Pelvic outlet wide Coccyx more moveable Heavy and thick Narrow illium Pubic arch less than 90o Narrow sciatic notch Narrow pelvic outlet Coccyx less moveable and less curved

Names for thumb and big toe Thumb: Pollex Big toe: Hallux

Lower Extremities

Medial and Lateral Malleolus Medial malleolus on the tibia Lateral malleolus on the fibula Make the ankle bones

END OF SKELETAL Stop! we will continue this part of the notes on a new notes sheet, on a different day!

JOINTS

Fibrous Joints Immovable Thin layer of fibrous connective tissue Sutures Gomphosis

Cartilaginous Joints Bones connected by cartilage Slightly moveable Pubic Symphysis Intervertebral joints

Synovial Joints Contain synovial cavity Ligaments Freely moveable Several different kinds based on degree of motion

Supporting structures in synovial joints Bursa: small sack filled with synovial fluid Meniscus: Pad of cartilage in the knee joint

Types of Synovial Joints Saddle / Ball and Socket Gliding /Hinge Pivot / Condyloid Ligaments