Anatomy and Skeletal Systems

• Skeleton


  • Movement - Bones act as levers for muscles
  • Hematopoiesis - Blood cell production including immune cells (white blood cells), red blood cells, and platelets. Cells are formed in bone marrow
  • Storage - Calcium and Phosphorous are stored in bone as reserves
• There are typically around 270 bones in human infants, which fuse to become 206 to 213 bones in the human adult
• The reason for variability in the number of bones is because some humans may have a varying number of ribs, vertebrae and digits
• The magic number is 206
• Cartilage and Bone


  • Cartilage is rigid but not mineralised, it gains nutrients by diffusion
  • Bone is mineralised and rigid
• There are no neurovascular elements within cartilage
• Muscular System


  • Muscle cells (fibers) produce contractions (shortenings in length) that result in movement, maintenance of posture, changes in shape or the propulsion of fluids through hollow tissues or organs
  • There are three different types of muscle: Skeletal, Cardiac, Smooth
• Biceps brachii


  • Origin: Short head - Apex of coracoid process of scapula. Long head - Supraglenoid tubercle of scapula
  • Insertion: Radial tuberosity
  • Innervation: Musculocutaneous nerve (C5-C6)
  • Blood Supply: Brachial artery and circumflex arteries
  • Main action: Supinates flexed forearm; flexes forearm at elbow
• Biceps tendon rupture
• Posterior compartment of the thigh (Hamstrings)


  • Origin: Ischial tuberosity (short head of biceps femoris = lateral supracondylar line)
  • Insertion: Semitendinosus = medial aspect of proximal part of tibia. Semimembranosus = medial condyle of tibia. Long and short head(s) of biceps femoris = head of fibula
  • Innervation: Tibial division of sciatic nerve (L5-S2). Biceps femoris (short head): common fibular division of sciatic nerve (L5-S2)
  • Blood Supply: Perforating arteries of deep femoral artery
  • Main action: Flexes and rotates leg
• Ischial tuberosity avulsion