Skeleton and the Names – Axial and Appendicular

Skeleton and all the names

Axial Skeleton:

Is made up of 80 bones and lies along the longitudinal axis of the body. It includes the:

v  Skull – cranial (cranium) (8 bones and 14 bones of the face)

  • Forms a cranial cavity and smaller cavities = nasal and eye
  • Some contain a mucus membrane lined cavity (paranasal sinuses)
    • Cavity that connect to the nasal cavity, lines by mucous membranes and serve to lighten the skull as well as something to do with speech (resonating chambers).
    • The frontal, sphenoid, maxilla and ethmoid  (all cranial bones) are containing the sinuses.
    • Sinusitis is the inflammation of the membrane due to an allergy
    • Sutures: are immovable joints that are between skull bones. They hold the skull bones together. They include: Coronal (front), sagital (top), lambodial (back of skull), squamous sutures and others.
    • Cranial Bones:
      • Frontal = above the bridge of the nose, across the eye socket half way and up to the crown of the head (only one of these)
      • Occipital = the bottom of the skull (follow the bones up your neck until you get under your skull, I would describe it as being there, it is single)
      • Parietal = between the frontal and the occipital (there is a right and left) sides and roof of the cranial cavity
      • Temporal = (has a right and left) sides of the head.

¨      Has many parts : temporal squama, zygomatic process. ect

  • Sphenoid = think of where your sinuses are, behind the eye socket and nose.
  • Ethmoid = is behind the nose, still covered  by frontal.

 

  • The cranial bones protects and is home to the brain and the ear bones, the outer surface provides muscle attachments for jaw, neck and facial muscles. The inner surface attachments stabilize the brain, blood vessels and nerves.

 

  • Fontanels are the top of the skull, it is what allows baby’s to be birthed, it is connective tissue membrane filled space between the cranial bones of a infant, they allow the skull to modify its size as it passes through the birth canal.  It also permits rapid growth. Eventually it will close up and ossify, although this is not always the case. During WW2, men in Australia whose scull hadn’t closed at the top were not allowed to fight even if they were healthy, willing and able. The fontanels that are the main ones are the anterior, posterior, anterolaterals and porterolaterals.

 

  • Facial bones:
    • Nasal (2 bones)
    • Mandible – Only the ear and the lower jaw (mandible) are movable
    • Maxillae (2 bones) – upper jaw
    • Zygomatic (2 bones)
    • Lacrimal (2 bones)
    • Palatine (2 bones)
    • Vomer
    • Inferiour nasal conchae (2 Bones)

 

  • Facial Bones protect the sense organs and soft tissue (taste, smell and sight). Which in turn support the entrance for the digestive and respiratory system.
  • Facial bones provide the framework of the face as well as provide support and house the blood vessels and nerves.

 

v  Hyiod (that is the loose bone in the throat)

  • It is that u shaped bone that just kind of floats around (it doesn’t exactly float though!) it is held in place by muscles and ligaments from the skull.
  • It is under your jaw and above the larynx.

v  Vertebrae – 26 bones

  • The vertebral column (along with the sternum and ribs) makes up the trunk of the skeleton.
  • The bones are arranged in 5 segments:
    • Cervical (looking at the back of the body, it would be in the area of the neck)
    • Thoracic (looking at the shoulders, it is the area from the shoulders down midway of the back. Thorax refers to the entire chest, a bony cage consists of the sternum, costal cartilages, ribs and the bodies of the thoratic vertebrae, it protects the organs and provides support for shoulder and upper limbs)
    • Lumbar (Lower back region)
    • Sacral (fused part of the low lower back)
    • Cocygeal (coccyx – fused sitting bones – lowest of the lower back)
    • Intervertebreal Disks: they absorb the weight shock,
    • All four curves of the spine are developed by 10 years old. The primary curves are formed in the womb, the secondary curves are formed when the baby first lifts it’s head and the lumbar forms during the sitting up and walking stage.
    • A herniated disk is a slipped sidk, the nerve becomes tra[[ed and eventually you will lose it.

v  Ribs –  24 bones

  • 1-7 are true ribs, attached with own cartilage towards the sternum, the other 8-12 are false and don’t attach directly. (11-12 are floating – don’t attach to anything)
  • 12 ribs are the structural support to the sides of the thoratic cavity.

v  Sternum 1 bone

  • Located in the anterior midline of the thoratic wall

v  Ear Ossicles (3 ear bones each ear (6 all up))

 

Appendicular Skeleton:

The remaining 126 bones, it is involved in the upper and lower extremities and the pelvic (hip) and  pectoral (shoulder) girdles that link the upper and lower extremities.

v  Pectoral (shoulder) girdle consists of:

  • Scapula and clavicle, the clavicle is attached to the sternum and the scapula, the scapula is held in place by muscle only under ribs.

v  Humerus (long bone of upper arm)

v  Ulna and Radius, (ulna on the medial side of the forarm and radius on the lateral side of the forarm) –thumbs pointing away. (ulna runs to little finger (each finger has 3 bones and thumb has 2) and the radium runs to thumb)

v  Carpals, Metacaples and Phalanges (wrist, palm and finger bones in laymans terms):

  • 8 carple bones are bound together by ligaments to make the wrist (proximal row –lateral to medial : Scaphoid, Lunate, Triqentrum, Pisiform (she looks too pretty))(distal row – lateral to medial : Traperzium, Trapezoid, Capitate, Hamate (try to catch her))
  • 5 metacarples in the palm of the hand
  • 14 phalanges, three in each finger, and two in each thumb, one is called : phalanx.

v  Pelvic Girdle:

  • Pelvic girdle is made up of two hipbones coming together at pubic, the hip bones (ilium, pubis and ischium) fuse after the baby is born.
  • Sacrum, coccyx and 2 hipbones make the pelvis. The pelvic brim separate false (houses the abdominal organs)and true pelvis.
  • The size of the pelvic rim determines gender:
    • Male: Larger, heavier, bigger surface area, large muscle attachment. Circle narrow, higher hips, the arch is small.
    • Female: wide and shallower, has larger inlet and outlet, more space in true pelvis and the pubic arch is >90degrees. Women have : lower hips (designed for childbearing) and a more round and wider.

v  Femur: largest and heaviest bone in the body, the neck of the bone is the most common fracture site.

v  Patella: kneecap. A sesamoid bone located anterior to the knee joint, it increases leverage and protect the knee joint

v  fibula = less dense, parallel/lateral to the tibia

v  tibia = really dense, (shin bone) medial weight bearing bone of leg

v  Tarsals, Metatarsals and Phalanges:

  • 7  tarsal bones make up the ankle (Talus = ankle, calcaneous =heel, Navicular = like a boat, Third Cuneiform = wedge shape –lateral ) (second cuneiform = wedge shaped – intermediate, first cuneiform – medial, cuboid = cube)
  • 5 metatarsal bones are in the foot
  • Phalanges in the toes are laid out like that in the fingers, 14 bones in each foot.

 

 

Types of Bones:

v  Long = compact (humorous)

v  Short =spongy except for the surface, which is a thin layer of compact bone (wrist and fingers, trapiziodal)

v  Flat =plates of compact enclosing the spongy, 2 layers. (Shoulder blade and sternum)

v  Irregular =variable (vertebra)

v  Sesamoid = development of tendons or ligaments (patella in knee)

v  Structural = in joint between the skull bones

 

SURFACE MARKINGS:

If you have ever watched a crime show where they identify a dead body that is only bone, or mostly bone, they are using the surface markers.

Look Out For:

v  Depressions and openings in joints or that allow the passage of soft tissue.

  • Fissures = narrow slit between the neighboring part of the bone
  • Foramen =an opening
  • Fossa = a shallow depression
  • Sulcus = a groove
  • Meatus = a canal (like inner ear)

v  Projections and outgrowth that are either attachment points for connective tissue/muscle or help form joints.

  • Condyle = large round bump that protrudes
  • Facet = smooth and flat articular
  • Head = round articular projection supported on the neck of a bone.
  • Crest = ridge or long projection
  • Epicondyle = projection above condyle
  • Line = long narrow ridge
  • Spinous Process = sharp and slender projection
  • Trochanter = very large projection
  • Tubercle = small and round projection
  • Tuberosity = large and round rough projection

Next Post on joints 🙂 hope you are excited!

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