Human Skeletal System

Skeletal System

• It's made of bones and cartilage that forms your body's framework
• It allows movement and structure
• Babies have approximately 300 bones
• Adults have 206 bones

Bone Structure

• Bones consist of salts, water, and tissue
• Bone marrow, a jelly-like substance inside bones, produces blood cells

Skeletal System Functions

• Protects the entire body
• Provides the body's shape
• Protects internal organs
• Serves as a frame for muscles that enable movement
• Stores minerals
• Produces blood cells

Skeletal System Structures

• Axial
• Appendicular

Bone Types

• Flat
• Long
• Short
• Irregular

Connective Tissues

• Cartilage
• Joints
• Ligaments
• Tendons

Axial Skeleton

• Consists of 80 bones including the skull, spine, ribs, and sternum
• Functions of the vertebrae include protecting the spinal cord
• Protects the rib cage
• Protects the heart and lungs

Axial - Skull

• The human skull is generally composed of the eight cranial bones and fourteen facial skeleton bones
• The neurocranium includes the:
  • Occipital bone
  • Two temporal bones
  • Two parietal bones
  • Sphenoid
  • Ethmoid
  • Frontal bones

Axial - Spine

• Vertebrae, composed of 33 individual bones, interlock to form the spinal column.
• Vertebrae are numbered and divided into:
  • Cervical
  • Thoracic
  • Lumbar
  • Sacrum
  • Coccyx
• Only the top 24 vertebrae are moveable
• The sacrum and coccyx vertebrae are fused

Axial - Ribs

• Includes twelve bones that form the thorax's protective 'cage'
• They connect to the vertebral column posteriorly
• Terminate anteriorly as cartilage called costal cartilage
• Ribs contribute to the bony thorax protecting the internal thoracic organs

Axial - Sternum

• A long, flat bone, aka the "breastbone"
• Located in the central part of the chest
• Connects with the cartilage of the ribs, forming the ribcage front
• Shields the heart, lungs, and major blood vessels from injury

Appendicular Skeleton

• Consists of 126 bones in the shoulder, arms, hands, hips, legs, and feet
• Facilitates a wide range of bodily movements

Appendicular - Pectoral Girdle

• A set of bones in the appendicular skeleton that connects to the arm
• Consists of "the clavicle and scapula"

Appendicular - Clavicle

• The clavicle, or collarbone, serves as a strut between the shoulder blade and the sternum (breastbone).
• Includes two clavicles, one on each side
• The body's only horizontal long bone

Appendicular - Scapula

• Known as the shoulder blade or wing bone
• Connects the humerus (upper arm bone) and clavicle (collar bone)

Appendicular - Pelvic Girdle

• Functions as the "bone of the hip."
• Composed of the fused bones:
  • Ilium
  • Ischium
  • Pubis

Appendicular - Humerus

• A long arm bone that runs from the shoulder to the elbow
• Connects the scapula with radius and ulna

Appendicular - Radius

• Forearm bone that extends from the elbow's lateral side to the wrist on the thumb side
• Runs parallel to the ulna in the forearm

Appendicular - Ulna

• Forearm bone that stretches from the elbow to the smallest finger on the medial side
• Runs parallel to the other long bone in the forearm, the radius

Appendicular - Carpals

• Consists of eight small bones that make up the wrist
• Connect the hand to the forearm
• "Carpus" comes from the Latin term carpus
• The Greek word karpós, means "wrist"

Appendicular - Metacarpals

• Metacarpals form the skeletal hand intermediate
• Located between the finger phalanges and wrist carpals
• The bones connect to the forearm
• The metacarpal bones are analogous to the metatarsal bones in the foot.

Appendicular - Phalanges

• Bones that make up the fingers and toes
• The human body consists of 56 phalanges, with 14 on each hand and foot
• Every finger and toe has 3 phalanges, except for the thumb and large toe, each possessing 2

Appendicular - Femur

• The only bone within the human thigh
• The body's strongest and longest bone
• Extends from hip to knee

Appendicular - Patella

• Also called the kneecap
• A flat, circular-triangular bone that articulates with the femur (thigh bone)
• Covers and protects the knee joint's anterior articular surface

Appendicular - Tibia

• Shin bone, the larger of the two lower leg bones
• The top of the tibia connects to the knee joint
• The bottom of the tibia connects to the ankle joint
• Carries all the body's weight
• Supported by the fibula

Appendicular - Fibula

• A leg bone, also known as the calf bone
• Located on the tibia's lateral side, connecting to it above and below
• The smaller of the two bones and the slenderest of all the long bones, relatively

Appendicular - Tarsal/Metatarsal/Phalanges

• Tarsals refer to seven irregularly shaped ankle bones in the foot's proximal area
• Metatarsals connect the phalanges to the tarsals, numbering five in total with one for each toe
• Phalanges are the bones forming the toes.

Bone Types

• Long
• Short
• Flat
• Irregular

Long bones

• Located in the arms and legs
• Very strong
• Includes:
  • Femur
  • Tibia
  • Fibula
  • Humerus
  • Radius
  • Ulna
  • Metacarpals
  • Metatarsal
  • Phalanges
  • Clavicle

Short Bones

• Cubed shape
• Made mostly of spongy bone
• The outside surface is comprised of a thin layer of compact bone
• Found in the hands and feet

Concise notes on the axial and appendicular skeleton. Key functions of the vertebral column, sternum, and bone marrow are described. Includes the number of bones in newborns and details on pectoral girdle composition.