MUSCULOSKETAL SYSTEM Windsor University School of Medicine Premed Biology September 2014

Pre Med – Biology Chapter 13 Musculoskeletal System There is more to lectures than the power point slides! Engage your mind

SKELETON Animals have a framework similar to the framework of a home. The framework in animals is called the skeleton. In animals or man, the framework has muscles attached to it instead of walls or roof. “Endoskeleton” Protection, support, and movement of the body

EXOSKELETON ENDOSKELETON

The Skeletal System Gives form to the body Protects vital organs Consists of 206 bones Acts as a framework for attachment of muscles Designed to permit motion of the body

Bones serve the following functions: - Protect the vital organs inside the body Provide anchor or support to the muscles Produce blood cells Bones

Functions of Bone  Support and protection  Blood cell formation  Mineral storage (calcium especially)  Site for muscle attachment  body movement

Bone cells are living, they can reproduce resulting in the hardening of the bones called “ossification” and bone growth Not only does bone size change, their number also changes. As you grow the number of your bones increases although some bones fuse

Skeletal system includes the bones, cartilage, ligaments, and tendons. These are tissues that make up the skeleton. A bone is a hard, living tissue and contains blood vessels, nerves and dividing cells Bones are hollow or spongy inside Hollow portion of the bone is made of “Marrow” The marrow produces red and white blood cells and stores some of the body’s excess fat

Cartilage – Tough, flexible tissue that functions as cushioning Found in lower nose, earlobes, trachea, voicebox Ligaments – Tough, connective tissue that connect one bone to another bone E.g. Hurt when sprain an ankle Tendons – Connect a bone to a muscle

Anatomy Muscles- provide movement & generate heat. Ligaments- connect bone to bone injury = sprain Tendons- connect bone to muscle injury = strain Bones- protection & shape

Skeletal System Bone types Bone structure Bone function Bone growth and metabolism affected by calcium and phosphorous, calcitonin, vitamin D, parathyroid, growth hormone, glucocorticoids, estrogens and androgens, thyroxine, and insulin.

Bones are of two types: Compact Bone--- Represent the shaft of long bones and have lamellae arranged in “Haversian system” (Central haversian canal carrying blood vessels and nerves) Spongy Bone--- Found in vertebrae, ribs, skull and epiphysis of long bones Lamellae contain red bone marrow

“Epiphysis” = Articular cartilage end of bones Tissue near the joints is called the spongy layer, absorbs mechanical shock Spongy layer contains the red bone marrow producing red blood cells and white blood cells Between the joint ends of the bone is the shaft = “Diaphysis” Shaft is location of the medullary canal containing of the yellow marrow (fat cells) During bone growth the diaphysis and epiphysis are separated by the epiphyseal line (growth plate) which fuses later in life

Bones classified by shape: long, short, flat, irregular, round Bone enclosed in periosteum, which is continuous with tendons and ligaments blood vessels in periosteum Epiphysis- ends spongy bone contains red marrow compact bone, articular cartilage Diaphysis- middle compact bone medullary cavity- contains yellow marrow (fat) lined with endosteum (squamous epithelium)

Adults continually break down and build up bone Osteoclasts: Remove damaged cells and release calcium into blood (bone resorption) Osteoblasts: Build new bone matrix and remove calcium from blood. They become trapped  osteocyte

Osteoclast reabsorbing bone tissue

There are 3 main parts of the AXIAL skeleton – Skull Rib cage Back bone or spinal cord Appendages which includes the hands, arms, shoulders and collar bone and the back appendages composed of the feet, legs, knees and hip bone.

Axial skeleton supports and protects organs of head, neck and trunk Appendicular skeleton Appendicular skeleton - bones of limbs and bones that anchor them to the axial skeleton

VERTEBRAE BACKBONE is made up of thirty-three small bones called vertebrae Neck to tailbone 33 bones Total: 1. Cervical = 7 2. Thoracic = Lumbar = 5 4. Sacral = 5 5. Coccyx = 4

Joints Joint is a place where two bones meet. Contain synovial fluids and cartilage at ends of the bones Most are movable joints HINGE JOINTS – Move in one direction E.g. Knee and Elbow joints PIVOT JOINTS – Allow Rotation E.g. Head attached to spinal chord and wrist BALL-and-SOCKET JOINTS – Allow you to turn hands and arms in a complete circle. Knob at one end of one bone and a socket at end of another bone E.g. Shoulder joints and Hip joints GLIDING JOINTS – Allow bones to move over one another E.g. Vertebrae bones in the backbone FIXED JOINTS – Bones are tightly joined together and cannot move E.g. Skull bones

Joints

Synovial Fluid Fluid found in the joint which helps to reduce friction when bones move with respect to one another

The Skull

The Spinal Column

The Thorax

The Pelvis

The Lower Extremity Hip Thigh Knee Leg Ankle Foot

The Upper Extremity Shoulder girdle Arm Elbow Forearm Wrist Hand

Muscular System

THE MUSCULOSKELETAL SYSTEM The musculoskeletal system includes all of the bones in a body and the muscles that make them move.musculoskeletal system It supports the body and protects delicate organs.

Functions of the Musculoskeletal System – Gives the body shape – Protects internal organs – Provides for movement – Consists of more than 600 muscles

Muscles contract causing movement Heat production and maintain body temperature

Types of Muscle 1. Skeletal Muscle – Attached to the bones of the body – Striated and Voluntary 2. Smooth Muscle – Carry out the automatic muscular functions of the body – Involuntary – Muscle of digestive and other internal organs

Types of Muscle 3. Cardiac Muscle – Involuntary muscle E.g. Heart Muscle – Has own blood supply and electrical system – Can tolerate interruptions of blood supply for only very short periods

THE MUSCULOSKELETAL SYSTEM Muscle tissue consists of bundles of long cells called muscle fibres, which contain specialized proteins. These proteins cause muscles to contract when signalled by nerve cells.

Muscle consist largely of muscle cells that are specialized to undergo contraction During contraction, muscles pull causing action When muscle contracts, it shortens and causes movement Flexor muscles and extensor muscles act on the same joint to produce opposite actions or Antagonists

The two muscles of your arms are called biceps and triceps: The biceps is a flexor muscle. It produces a flexing or bending action by pulling the lower arm bone at the joint towards the body. The triceps is an extensor muscle. It produces an extending or straightening action by returning the bone to the relaxed position

THE MUSCULOSKELETAL SYSTEM Skeletal muscles are attached to the bone at each end by tendons. Insertion- Attachment site to more movable bone Origin- Attachment site that is less movable

Fracture Most common disorder of musculo-skeletal system are different types of fractures: 1. Green stick fracture (E.g. Children) 2. Comminuted Fracture 3. Compound Fracture – Greenstick or Simple - skin is not pierced – Comminuted – bone fragments – Compound- skin is pierced Occur due to osteoporosis, trauma, bone cancer, complication of prolonged therapy

Dislocation The bone ends are moved out of place at the joint, and the ligaments holding them are severely stretched or torn

THE MUSCULOSKELETAL SYSTEM Similar to other organ systems, the musculoskeletal system is susceptible to disease. Osteoporosis is a common disease that involves the loss of bone tissue, which makes bones weak and brittle. It is common among older women. As well, extreme movements can fracture bones and damage muscles, ligaments, and cartilage. Some invertebrates have no rigid frame to give them structure, while others have their skeletal system on the outside (exoskeleton).

Osteoporosis Bone remodeling - The coordination of osteoclasts and osteoblasts maintains bone Eventually, this coordination can break down, and the osteoclasts begin to remove more bone than the osteoblasts can create.

ARTHRITIS Disease of bone joints Inflammation of bone at the joints resulting in pain and swelling

Homeostatic Calcium

PTH (Parathyroid hormone) Parathyroid hormone is secreted by the parathyroid glands (posterior side of the thyroid) Parathyroid hormone inhibits osteoblasts, stimulates osteoclasts, reduces the output of calcium by the kidneys and promotes the absorption of calcium by the small intestines, thus increasing blood calcium levels.

Calcitonin Calcitonin, secreted by the thyroid gland inhibits osteoclasts and stimulates osteoblasts, thus decreasing blood calcium levels

Growth hormone regulates skeletal growth stimulates cell division in epiphyseal disks in long bones Growth stops when epiphyseal disks are converted to bone When excess growth hormone is produced in childhood  gigantism In adulthood- acromegaly. Bones can’t growbut soft tissue can

Axial skeleton skull (cranium and facial bones) hyoid bone (anchors tongue and muscles hyoid bone (anchors tongue and muscles associated with swallowing) vertebral column (vertebrae and disks) vertebral column (vertebrae and disks) thoracic cage (ribs and sternum) thoracic cage (ribs and sternum) Appendicular skeleton pectoral girdle (clavicles and scapulae) upper limbs (arms) pelvic girdle (coxal bones, sacrum, coccyx) lower limbs (legs)

22 bones in skull 6 in middle ears 1 hyoid bone 26 in vertebral column 25 in thoracic cage 4 in pectoral girdle 60 in upper limbs 60 in lower limbs 2 in pelvic girdle 206 bones in all

The skull 8 sutured bones in cranium Facial bones: 13 sutured bones, 1 mandible Cranium encases brain attachments for muscles sinuses

Allows for growth

Vertebral column 7 cervial vertebrae 12 thoracic 5 lumbar 1 sacrum (5 fused 1 coccyx (4 fused) Vertebrae vary in size and morphology

Thoracic cage ribs thoracic vertebrae sternum costal cartilages True ribs are directly attached to the sternum (first seven pairs) Three false ribs are joined to the 7 th rib Two pairs of floating ribs

Clavicles and scapulae Help brace shoulders Attachment sites for muscles

Bones of upper limb Humerus (upper arm) Radius; ulna Carpals, metacarpals, phalanges Bones of lower limb FemurPatella Tibia, fibula Tarsals, metatarslas, phalanges

Joints Immovable (synarthoses) bones sutured together by connective tissue: skull Slightly movable (amphiarthoses) connected by fibrocartilage or hyaline cartilage: vertebrae, rib/sternum joint, pubic symphysis Freely movable (diarthroses)- separated ligaments- hold bones together tendons- muscle to bone lined by synovial membrane

Types of freely movable joints Saddle: carpal and metacarpal bones of thumb Ball and socket: shoulder and hip joints Pivot- rotation only: proximal end of radius and ulna Hinge- up and own movement in one plane: knee and elbow Gliding- sliding and twisting: wrist and ankle Condyloid- movement in different planes but not rotations: btw metacarpals and phalanges

Types of movement and examples (with muscles) flexion- move lower leg toward upper extension- straightening the leg abduction- moving leg away from body adduction- movong leg toward the body rotation- around its axis supination- rotation of arm to palm-up position pronation- palm down circumduction- swinging arms in circles inversion- turning foot so sole is inward eversion- sole is out

Elevation and depression- raising body part up or down Aging and bones both bone and cartilage tend to deteriorate cartilage: chondrocytes die, cartilage becomes calcified osteoporosis; bone is broken down faster than it can be built bones get weak and brittle; tend to fracture easily

Skeleton and other systems Skin makes vitamin D which enhances calcium absorption Skeleton stores calcium for muscle contraction, nervous stimulation, blood clot formation Red marrow- site of blood cell formation Calcium levels regulated by parathyroid hormone and calcitonin kidneys (can help provide vitamin D) digestive system (can release calcium into blood