Human skeleton: 50 cards on bones and joints

All 50 cards

1. 1
   How many bones are in the adult human skeleton?
   206

   Babies are born with more separate bones, around 270, many of which fuse during childhood.
2. 2
   Axial vs appendicular skeleton
   Axial (80 bones): the skull, ear ossicles, hyoid, vertebral column, ribs and sternum. Appendicular (126 bones): the limbs plus the shoulder and pelvic girdles
3. 3
   Functions of the skeleton
   Support, protection of organs, movement together with muscles, blood cell production in red marrow, and storage of minerals such as calcium and phosphate

   Yellow marrow also stores fat.
4. 4
   The five bone shapes, with an example of each
   Long (femur), short (carpals), flat (sternum), irregular (vertebrae) and sesamoid (patella)
5. 5
   Longest and strongest bone in the body
   The femur (thighbone)

   Its length is roughly a quarter of a person’s height.
6. 6
   Hands and feet: how many bones together?
   106, more than half of the 206 in the body

   27 in each hand and 26 in each foot.
7. 7
   How many bones are in the skull?
   22: 8 cranial bones and 14 facial bones

   This count leaves out the six ear ossicles and the hyoid.
8. 8
   The eight cranial bones
   Frontal, occipital, sphenoid and ethmoid, plus two parietal and two temporal bones
9. 9
   The fourteen facial bones
   Two each of the maxilla, zygomatic, nasal, lacrimal, palatine and inferior nasal concha, plus the vomer and the mandible
10. 10
    The only skull bone that moves
    The mandible (lower jaw), which moves at the temporomandibular joint

    It is also the largest and strongest bone of the face.
11. 11
    Upper jaw bone
    The maxilla, a pair of bones fused at the midline

    It holds the upper teeth and forms part of the eye sockets, the nasal cavity and the hard palate.
12. 12
    Cheekbone
    The zygomatic bone
13. 13
    Foramen magnum
    The large opening in the occipital bone where the brainstem continues into the spinal cord
14. 14
    Skull sutures
    Immovable fibrous joints between skull bones: the coronal (frontal and parietals), sagittal (between the parietals) and lambdoid (parietals and occipital) sutures
15. 15
    Fontanelles
    Soft, membrane-covered gaps between a baby’s skull bones that let the skull flex during birth and grow afterward

    The largest, the anterior fontanelle, usually closes by about age 2.
16. 16
    The three ear ossicles
    Malleus (hammer), incus (anvil) and stapes (stirrup), which pass sound vibrations from the eardrum to the inner ear
17. 17
    Smallest bone in the body
    The stapes (stirrup) in the middle ear, about 3 mm long
18. 18
    Hyoid bone
    A U-shaped bone in the neck that anchors the tongue; it is the only bone that doesn’t form a joint with any other bone
19. 19
    Number of vertebrae in each region of the spine
    Cervical 7, thoracic 12, lumbar 5, then the sacrum (5 fused) and the coccyx (usually 4 fused)

    A mnemonic: breakfast at 7, lunch at 12, dinner at 5.
20. 20
    How many bones make up the adult vertebral column?
    26: 24 separate vertebrae plus the sacrum and the coccyx

    Counting the fused pieces separately gives 33.
21. 21
    Atlas (C1)
    The first cervical vertebra, a ring that holds up the skull; it has no body, and nodding happens at its joint with the skull
22. 22
    Axis (C2)
    The second cervical vertebra; the atlas and skull rotate around its peg-like dens, as when you shake your head
23. 23
    Natural curves of the spine
    The cervical and lumbar curves bulge toward the front (lordosis); the thoracic and sacral curves bulge toward the back (kyphosis)
24. 24
    Intervertebral disc
    A pad of fibrocartilage between two vertebrae: a tough outer ring (annulus fibrosus) around a gel-like core (nucleus pulposus) that absorbs shock

    In a herniated (slipped) disc, the core pushes out through a tear in the ring.
25. 25
    Sacrum
    A triangular bone of five fused vertebrae that joins the hip bones at the sacroiliac joints
26. 26
    How many ribs do humans have?
    12 pairs (24 ribs)

    Men and women have the same number.
27. 27
    True, false and floating ribs
    True ribs (pairs 1–7) attach to the sternum by their own cartilage; false ribs (pairs 8–12) don’t; floating ribs (pairs 11–12) don’t reach the sternum at all
28. 28
    The three parts of the sternum
    Manubrium, body and xiphoid process
29. 29
    Bones of the shoulder (pectoral) girdle
    The clavicle (collarbone) and the scapula (shoulder blade) on each side

    The joint between the clavicle and the sternum is the arm’s only bony connection to the axial skeleton.
30. 30
    Upper arm bone
    The humerus

    The “funny bone” is really the ulnar nerve, which runs behind the inner bump of the humerus at the elbow.
31. 31
    Radius vs ulna
    Both are forearm bones: the radius is on the thumb side, the ulna on the little-finger side

    The point of the elbow is the olecranon, part of the ulna.
32. 32
    Bones of the hand
    27: 8 carpals, 5 metacarpals and 14 phalanges
33. 33
    The eight carpal bones
    Scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate and hamate

    Listed from the thumb side, the row nearer the forearm first. Mnemonic: Some Lovers Try Positions That They Can’t Handle.
34. 34
    Most commonly broken carpal bone
    The scaphoid, usually from a fall onto an outstretched hand
35. 35
    Phalanges in the thumb vs the other fingers
    The thumb has two (proximal and distal); each other finger has three (proximal, middle and distal)

    The toes follow the same pattern: two in the big toe, three in each of the others.
36. 36
    The three bones that fuse to form each hip bone
    Ilium, ischium and pubis

    They meet in the acetabulum, the socket for the head of the femur.
37. 37
    The hip bone you sit on
    The ischium, at its ischial tuberosities
38. 38
    Kneecap
    The patella, the largest sesamoid bone (a bone that develops inside a tendon)

    It sits in the tendon of the quadriceps muscle.
39. 39
    Tibia vs fibula
    The tibia (shinbone) is the thick inner bone that carries most of the body’s weight; the fibula is the thin outer bone
40. 40
    The two bony bumps of the ankle
    The medial malleolus (inner ankle) is part of the tibia; the lateral malleolus (outer ankle) is part of the fibula
41. 41
    Bones of the foot
    26: 7 tarsals, 5 metatarsals and 14 phalanges
42. 42
    The seven tarsal bones
    Calcaneus, talus, navicular, cuboid, and the medial, intermediate and lateral cuneiforms
43. 43
    Heel bone
    The calcaneus, the largest bone of the foot
44. 44
    Talus
    The ankle bone that links the leg to the foot, fitting under the tibia and between the malleoli

    No muscles attach to it.
45. 45
    Three structural types of joint
    Fibrous (skull sutures), cartilaginous (intervertebral discs, pubic symphysis) and synovial (knee, shoulder)

    Synovial joints move freely; their bone ends are capped with cartilage and lubricated by synovial fluid.
46. 46
    Ball-and-socket joints
    The shoulder and the hip; they allow movement in every direction, including rotation
47. 47
    Hinge joints
    The elbow, the knee and the joints between finger bones; they bend and straighten in one plane
48. 48
    Pivot joints
    Between the atlas and the axis, which turns the head, and between the radius and ulna near the elbow, which turns the forearm
49. 49
    Saddle joint
    The joint at the base of the thumb (the first carpometacarpal joint), which lets the thumb move across the palm to touch the fingertips
50. 50
    Ligament vs tendon
    Ligaments connect bone to bone; tendons connect muscle to bone