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206 bones in an adult (~ 350 cartilaginous bones as a developing baby)
Skeleton reaches full maturity by age 25Supports the body and protects vital organsManufactures blood cells at a rate of 1.2
million per secondAllows body movement by connecting with
skeletal muscles
SKELETAL SYSTEM FACTS
Stores excess minerals – primarily calcium and phosphorous
Ligaments connect bone to boneTendons connect bone to muscle2 broad divisions – axial and appendicular
SKELETAL SYSTEM FACTS
Includes the head (cranial and facial), spine, and thorax
80 bones totalPrimary function is to
support and protect the internal organs
AXIAL SKELETON
Cranial BonesMade of 8 bones – parietal (2), temporal (2), frontal, occipital, sphenoid, ethmoid
Fit tightly together without moveable jointsOne purpose is to protect the brain and other organs located in the cranium
BONES OF THE HEAD
Cranial BonesWhen born, joints are not fused – instead connected by cartilage called fontanels (makes the “softspot”)
Skull growth is not complete until age fourAreas where bones join are the sutures Jagged edge of sutures gives added strength
BONES OF THE HEAD
Facial BonesMade of 14 bones – maxilla (2), zygomatic (2), palatine (2), nasal (2), lacrimal (2), inferial nasal concha (2), mandible, vomer
Maxilla and palatine form upper jaw and the roof of the mouthMandible forms the lower jaw – only moveable bone in the skull
BONES OF THE HEAD
Auditory BonesMade of 6 bones – malleus (2), incus (2), stapes (2)
Also known as the hammer, anvil, and stirrupSmallest bones in the bodyNecessary for hearing
BONES OF THE HEAD
Hyoid (1)Only bone that does not articulate with another bone
U-shapedA point of articulation for many muscles (ex: tongue, pharynx)
Found just above the larynx
BONES OF THE HEAD
Vertebral Column (general information)Vertebrae – plural; vertebra – singularMade of 26 vertebrae (originally 34, but 5 sacral
bones fuse together and 4-5 coccygeal bones fuse together.
Intervertebral disks allow the spine to bend and act as shock absorbers – made of cartilage
Have a hollow area for the spinal cord to pass through
BONES OF THE SPINE
Cervical VertebraeFirst 7 vertebrae – make up the neck (C1-C7)C1 – atlas
Point where the head is connected to the spineAllows the head to pivot up and down
C2 – axisLocated right below the atlasAllows the head to swivel left to right
Other cervical vertebrae allow the head to tilt and move in other directions
BONES OF THE SPINE
Thoracic VertebraeMade of 12 vertebrae (T1-T12)
Larger than the cervical vertebrae
Attachment point for the ribs
BONES OF THE SPINE
Lumbar VertebraeMade of 5 vertebrae (L1-L5)Largest vertebraeForm the lower backSupport the weight of the entire upper body
BONES OF THE SPINE
Sacral Vertebrae (or Pelvic Vertebrae)Made of 5 vertebrae fused together (in adults)Also called the sacrum Joined to the hips to form the base of the spine
BONES OF THE SPINE
CoccyxMade of 4-5 vertebrae fused together (in adults)Also called the tailbone or coccygeal vertebraeUsed for muscle attachment and a shock absorber for the spine
BONES OF THE SPINE
Four curvesCervical lordosisThoracic kyphosisLumbar lordosisSacral/coccygeal curve
CURVATURE OF THE SPINE
Provide additional strength and flexibility
Can have excess curvatureScoliosis – excessive lateral curvature
Kyphosis – excessive thoracic curvature (humpback)
Lordosis – excessive lumbar curvature (swayback)
CURVATURE OF THE SPINE
RibsMade of 24 bones (12 pairs)Attaches to the thoracic vertebrae in the back and by cartilage to the sternum in front (the first 7 pairs)
Cartilage is flexible so the ribs can expand and contract during breathing
BONES OF THE CHEST
3 types of ribsTrue ribs- first 7 pairs, attach directly to the sternum
False ribs – next 3 pairs, attaches to the lowest true rib by cartilage
Floating ribs – last 2 pairs, do not attach to the sternum at all, also considered false ribs
BONES OF THE CHEST
SternumKnown as the breast boneContains the manubrium, body, and xiphoid process
Last bone to ossify
BONES OF THE CHEST
General InformationIncludes the shoulders, hips,
arms, and legs126 bones totalPrimary function is support
and to enable movement
APPENDICULAR SKELETON
Scapulae (2)Singular is scapulaAlso known as the shoulder bladesContains sockets for the armsDon’t rigidly attach to the axial skeletonOnly articulate with the humerus and clavicle
Clavicle (2)Also known as the collar boneArticulates with the scapula and the sternum
BONES OF THE SHOULDER
Consists of 60 bones
Only 6 are in the arms with the rest in the wrists, hands, and fingers
BONES OF THE UPPER EXTREMITIES
Humerus (2)Makes the upper armArticulates with the scapula, ulna, and radius
BONES OF THE UPPER EXTREMITIES
ForearmConsists of 4 bonesRadius (2)
Located on the lateral side of the forearm (thumb side)
Rotates over the ulnaUlna (2)
Locaed on the medial side of the forearm (little finger side)
Does not move when the arm is rotated
Has a “hook” to attach to the humerus
BONES OF THE UPPER EXTREMITIES
WristThe bones as a group are known as the carpalsConsists of 16 bones (8 on each side) – pisiform, lunate, scaphoid, trapezium, trapezoid, capitate, hamate, triquetrium
The bones are arranged in two rows of 4This allows the wrist to bend in various directions
BONES OF THE UPPER EXTREMITIES
Hands and FingersConsists of 38 bonesMetacarpals
These make up the palm of the handThere are 10 of these bones (5 per side)The metacarpal that makes up the thumb is held by ligaments that give it great mobility
Phalanges28 phalanges make up the fingers (14 per side)3 in each finger, 2 for each thumb
BONES OF THE UPPER EXTREMITIES
The pelvic girdle is made of a ring of bones: the sacrum makes up the back and the sides are made up of a pair of bones called the coxae
Each coxae is really three bones fused together: ilium, ischium, pubis
Coxae, coxal bone, and pelvic bone all refer to the same thing
BONES OF THE PELVIC GIRDLE
Similar in basic layout to the upper extremities
Bones are thicker and stronger than in the upper extremities
Each lower limb has 30 bones – 4 in the leg and 26 in the foot and ankle
BONES OF THE LOWER EXTREMITIES
Bones of the LegFemur
Makes up the thighLongest bone in the body
Strongest bone in the body
Attaches to the pelvic girdle at the hip joint
BONES OF THE LOWER EXTREMITIES
TibiaOne of the bones in the lower leg
The main weight bearing bone of the leg
Extends from the knee to the ankle
FibulaMuch thinner than the tibiaFound on the lateral sideDoes not attach to the femur
BONES OF THE LOWER EXTREMITIES
PatellaKneecapFound on top of the joint between the femur and the tibia
Serves as a brace for the patellar tendon to increase leverage on the joint
Also helps to protect the joint from injury
BONES OF THE LOWER EXTREMITIES
Bones of the Ankle and Foot
TarsalsMake up the ankle14 bones (7 per side): talus, calcaneus (heel bone), navicular, cuboid, and 3 cuneiform
Thick and strong to support the weight of the body
Talus connects with the tibia
BONES OF THE LOWER EXTREMITIES
MetatarsalsMake up the base of the footMade of 10 bones (5 per side)Forms the framework of the arches of the foot
PhalangesMade of 28 bones (14 per side)Makes up the toesArranged like the phalanges in the fingers: 2 in each big toe, 3 in every other toe
BONES OF THE LOWER EXTREMITIES