Skeletal System 1-2 October 2015

Our bones are window to our health, revealing secrets about our lives past & current. Relate to overall unit question: Our bodies require care to function properly. Our bones keep a record of the care we provide, across our lifetime. For this reason, they are often used by forensic biologists and medical examiners.

What do our bones reveal about us? Our health, past and current Trauma, past and current Age Gender Race By the end of the mini unit, you will know how our bones change due to sex hormones, age, and disease.

What are the functions of the bones? Support - support and anchor the body and organs Protection – protect organs Examples:

What are the functions of the bones? Support Protection Examples: Skull protects brain. Ribs protect heart and lungs. Vertebrae protect spinal cord. Movement – bones serve as an attachment site for muscles; muscles use bones like levers for movement Storage – fat, calcium, and phosphorus storage Blood cell formation – Red and white blood cells develop within the red marrow of long bones and flat bones

What are the functions of the bones? Storage – fat, calcium, and phosphorus storage Blood cell formation – Red and white blood cells develop within the red marrow of long bones and flat bones

Classifying Bones by Shape Sesamoid bones are bones embedded within tendons. The patella is the largest example. Sesamoid bones are a type of short bone. Fun fact: The number and size of sesamoid bones vary in different people. Short bones = cube shaped (wrist, ankles), patella flat are flat, thin, usually curved (sternum, ribs, skull Irregular: vertebrae, hip

Classifying Bones by Shape 4 corners Determine which type of bone you have & move to the appropriate corner of the room.

Classifying Bones by Shape 4 corners Examine all the bones in your group. Do you all agree about the type? Can you guess which bones any of them are?

Structure of a Long Bone The diaphysis is the shaft. The epiphyses are the ends Epiphyseal plates are plates of hyaline cartilage found near the ends of growing bones. In adults, this cartilage is completely replaced by bone, forming the epiphyseal line. The epiphyses are covered with articular cartilage – provides a smooth, surface for joints. 25 min to start of structure

Structure of a Long Bone The diaphysis is covered with the periosteum, a fibrous connective tissue Inside the diaphysis is the medullary cavity. In adults, the medullary cavity is filled with yellow marrow (function: to store fats) In infants, the medullary cavity is filled with red marrow (function: to produce blood) Fun fact: In adults, the yellow marrow of the medullary cavity can convert to red marrow in cases of severe anemia.

Structure of a Long Bone Think, Pair, Share: Name two ways the structure of the long bone varies by age. Infants have red marrow in medullary cavity – converts to yellow in adults Growing individuals have epiphyseal plates (cartilage); adults have epiphyseal lines

Classifying Bones by Tissue Type There are two types of bone tissue: spongy bone and compact bone.

Classifying Bones by Tissue Type There are two types of bone tissue: spongy bone and compact bone. Most bones contain both tissues types, in different locations. In irregular, flat, and short bones, the compact bone is exterior and the spongy bone is interior.

Classifying Bones by Tissue Type There are two types of bone tissue: spongy bone and compact bone. Most bones contain both tissues types, in different locations. Long bones are mostly compact; in long bones the spongy tissue is found only in the ephiphyses (ends) of the bones.

Microscopic Structure: Compact Bone Even compact bone is not solid! It has many, many channels for blood vessels, nerves, nutrients and wastes.

Microscopic Structure: Compact Bone Basic unit of structure: Osteon Consists of a central (Haversian) canal and lamellae (rings of calcium salts) Between lamellae are cavities called lacunae. The osteocytes (mature bone cells) are found in the lacunae.

Microscopic Structure: Compact Bone Transport system: Blood vessels and nerves grow through central canals (long axis) and perforating canals (short axis) Canaliculi (tiny channels) branch from central canals to all lacunae

Microscopic Structure: Compact Bone Think, Pair, Share: Explain why an excellent transport system is vital to the functioning of bone.

Microscopic Structure: Compact Bone

Microscopic Structure: Compact Bone

Microscopic Structure: Compact Bone lamellae Osteon

Microscopic Structure: Spongy Bone All you need to know is that Spongy bone is much less dense Spongy bone contains red marrow, which functions to produce blood.

Which ones do you need to know? Bones of the skeletal system Which ones do you need to know? Diagram 5.6 (page 125) Diagram 5.7 (page 126) Diagram 5.11 (page 129) Diagram 5.14 (page 131) Diagram 5.19 (page 135) Diagram 5.23 (page 142)

Human Skeleton Some hints for memory .. . Radius is thumb side; ulna is pinky side Its tibia and fibula The cuff of your sleeve is by your carpals. The tarsals are in your foot. Knowing the major bones will help you learn the muscle names!

Lateral view of human skull Sutures are immovable fibrous joints that connect the bones of the skull. Processes are projections that act as sites for muscle and ligament attachment. A meatus is a canal. External auditory meatus leads to the ear drum. Knowing the bones of the skull will help you learn the lobes of the brain!

anterior view of human skull Foramen are small openings in bone for the passage of nerves and blood vessels. A ramus is an arm-like projection of a bone that helps form a joint.

The vertebral column The vertebral column consists of 33 bones that protect the spinal cord and bear the weight of the body. The vertebral column is divided into different regions. The regions have different curves and different shapes to the vertebrae. The individual cervical, thoracic, and lumbar vertebrae are separated by fibrocartilage pads called intervertebral discs A slipped (herniated) disc occurs when an intervertebral disc slides out of place, pressing on a nerve

The bony thorax What bone shape is the sternum? Flat … so what kind of marrow does it have? red In order to diagnose certain blood disorders, doctors perform a sternal puncture by inserting a needle into the sternum to obtain red marrow. Consists of ribs, sternum, and thoracic vertebrae Sternum is three bones fused together. Has important ‘landmarks’ Jugular notch Sternal angle Have students palpate jugular notch. Its at level of third thoracic vertebrae. Sternal angle can also be palpated. Helps doctors count ribs so know where to listen for different heart sounds.

The bony thorax There are three types of ribs. True ribs connect directly to the sternum by a cartilaginous joint. False ribs connect indirectly to the sternum (or not at all). The last two false ribs are called ‘floating ribs’ because they do not connect to the sternum at all.

Pelvic Girdle The pelvic girdle is composed of two hip bones, sacrum, and coccyx. Each hip bone is composed of three different bones: Ilium (most lateral bone – the ‘hips’) Pubis (most anterior – these fuse at a joint called pubic symphysis Ischium – most inferior

Male vs Female Pelvic Girdle WHY? Female pelvises… have a larger, more circular inlet Is shallower / more spread out Has a larger pubic arch (80-85o) Male pelvises… have a smaller, heart shaped inlet Is deeper / more upright Has a smallerr pubic arch (50-60o)

How do you know? Thumbs up for girls! Male! Pelvis is deep Inlet is heart-shaped & narrow Pubic arch is 50-60 degrees How do you know?

How do you know? Thumbs up for girls! Male! Inlet is heart-shaped & narrow Pubic arch is 50-60 degrees How do you know?

How do you know? Thumbs up for girls! Female! Inlet is large and round Pubic arch is 80-85 degrees How do you know?