Bio 150 week 4 notes

• Bones perform several important functions:


  ◼Support

  ◼Protection

  ◼Movement

  ◼Mineral storage (calcium, phosphorous, and others)

  ◼Hematopoiesis (blood cell formation)
• ◼Homeostasis


  Store long-term energy (fat) in the yellow marrow

  Regulates blood calcium levels

  Produces the hormone osteocalcin, which regulates bone formation and blood sugar levels
• Long Bones


  - Longer than they are wide

  - Compact bone exterior, with spongy bone marrow interior

  - Support weight and facilitate movement

  - Examples: tibia, fibula, metatarsals
• Short Bones


  - Roughly cubelike, long as they are wide

  - Thin layer of compact bone surrounding spongy bone interior

  - Help provide stability and movement

  - Examples: tarsals, carpals
• Flat Bones


  - Thin, flattened and usually curved, like a shield

  - Parallel layer of compact bone with spongy bone layer between

  - Help protect internal organs

  - Skull, sternum and ribs are examples
• Irregular Bones


  - Irregular bones don't fit into the previous categories

  - Complicated shapes that help protect internal organs

  - Consist of spongy bone surrounded by a thin layer of compact bone

  - Examples are hip bones & vertabrae
• Compact bone


  - smooth, hard outer shell

  - Consists of hardened calcium phosphate, tightly-packed collagen fibers, and bone cells
• Spongy bone


  - Interior layer

  - Contains cross-hatched areas called trabeculae that help the bone to resist stress

  - Trabeculae give strength to the bone without the added weight of being solid
• Bone marrow:


  - Found within spongy bone and medullary cavities

  - Red marrow produces blood cells

  - Yellow bone marrow stores fat
• The osteon


  - is the fundamental functional unit of compact bone

  - Roughly cylindrical structures made up of concentric rings called lamellae, filled with collagen fibers and hardened calcium phosphate

  - In each lamella, collagen fibers run in different directions

  - This reinforced structure helps your bones

  - is a central canal that hold nerves and blood vessels

  - The gaps between each lamella (ring) are called lacuna

  - Individual bone cells, or osteocytes, are found within the lacuna

  - Osteocytes make contact with each-other through a network of even smaller canals, called canaliculi
• Epiphyses:


  flared ends of the bone
• Diaphysis:

  shaft of the bone
• Periosteum:

  vascular layer of connective tissue that envelops the bone
• Articular cartilage:


  covers the epiphyses in joints, allows the bones to glide over each other with very little friction
• Important note


  Yellow marrow is found in the medullary cavity of long bones, but red marrow is found in the spongy bone of flat bones, parts of irregular bones, and the proximal heads of some long bones.
• Skeletal system


  - The human skeleton is the internal framework of the body.

  - The skeletal system comprises of bones, associated cartilages and joints of human body.
• The skeletal system is divided into two major parts:


  - axial skeleton

  - appendicular skeleton
• axial skeleton


  - skull

  - laryngeal skeleton

  - vertebral column

  - thoracic cage
• Appendicular skeleton


  - shoulder girdle

  -upper limbs

  - pelvic girdle

  - lower limbs

  - arm

  - forearm

  -wrist and hand
• The skull consists of:


  - 8 cranial bones that surround and protect the brain

  - 14 facial bones that form the underlying structure of the face

  - Skull bones are tightly interlocked by joints called sutures
• The 8 Cranial bones

  - parietal,

  - temporal,

  - frontal,

  - occipital,

  -sphenoid,

  -ethmoid
• Sphenoid bone


  - Wedged between several other bones in the front of the cranium.

  - Helps form the base of the cranium, the sides of the skull, and the floors and sides of the orbits (eye sockets).
• ethmoid bone


  - Found between the eyes at the roof of the nose

  - Separates your nasal cavity from your brain
• facial bones


  bones of the face: lacrimal, mandibular, maxillary, nasal, vomer, and zygomatic
• Ossicle bones

  - The auditory ossicles consist of three small bones found within a space (the tympanic cavity) in the temporal bone of the skull.

  - Smallest bones in the body

  - Together, the ossicles amplify and transmit sound-induced vibrations of the tympanic membrane to the inner ear, where they are interpreted as sound.
• Tympanic cavity


  The tympanic cavity is a small cavity in the temporal bone that surrounds

  the ossicle bones of the middle ear.
• Skull sinuses

  - The sinuses are a connected system of hollow cavities in the skull, lined with mucosa - mucus-producing epithelial tissue.

  - Normally empty except for a thin layer of mucus

  - Help lighten the skull, humidify inhaled air, and amplify the voice

  - Sinus headaches are usually due to infection or inflammation of the sinuses, leading to congestion
• Vertebral column

  - The vertebral column is made of 26 segmented bones, called vertebrae

  - Vertebrae are separated by intervertebral discs made of tough, fibrous cartilage
• Atlas and Axis

  Atlas (C1)

  - Cervical vertebra 1

  - Holds up the skull

  
  

  Axis (C2)

  - Cervical vertebra 2

  - Enables rotation of the head
• Spinal cord


  - The spinal cord is a bundle of nerves that runs down the vertebral column.

  - Carries signals back and forth between your body and your brain

  - Protected by the vertebrae
• Spinal curves


  - Natural spinal curves help the spine absorb stress from body movement and gravity.

  - Abnormal curves, occur when the spine curves incorrectly

  - Usually due to a birth defect or injury
• Foramen:

  Hole through which spinal cord nerves pass through
• Spinous process:


  - Sticks out of the back

  - Site of attachment for muscles and ligaments of the back
• Transverse process:

  - Sticks out of the sides

  - Site of attachment for muscles and ligaments of the back

  - Point of articulation (attachment) of the ribs (in the thoracic spine).
• Gross anatomy of a vertebrae

  Spinous and transverse processes are sites of attachments for muscles and ligaments of the back.
• Spinal discs


  - Spinal discs (intervertebral discs) are found in between the vertebrae

  - Act as shock absorbers between adjacent vertebrae

  - Also act as ligaments that hold the vertebrae of the spine together

  - Cartilaginous joints allow for slight mobility in the spine
• slipped dis


  - Injury or weakness can cause the inner nucleus of the disc to protrude outward

  - This is known as a slipped, herniated, or prolapsed disk.

  - This causes pain and discomfort if the slipped disk compresses a spinal nerve
• Rib bones


  - Rib bones protect the heart and lungs

  - Thoracic vertebrae have transverse processes to which the rib bones attach

  - 12 pairs of ribs, corresponding to 12 thoracic vertebrae

  - 1-7 are true ribs (connect to sternum), ribs 8-10 are false ribs (connect to rib 7), and ribs 11-12 are floating ribs (no anterior connection).
• sternum


  - The sternum, or breastbone , is a flat bone at the front center of the chest

  - Protects the vital organs lying behind it, primarily the heart and lungs

  - Serves as a central point where the ribs and shoulder bones (clavicle) connect
• the pectoral (shoulder) grille


  - Set of bones which connects the arm to the axial skeleton on each side

  - Consists of the clavicle and scapula

  - The clavicle has a s shaped bone