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Questions and Answers
What condition can result from a deficiency in certain nutrients, leading to ulceration and hemorrhage?
What is the effect of excessive growth hormone secretion in individuals?
Which hormone is required for normal growth of all tissues, including cartilage?
What is the main process by which new bone is created to replace resorbed bone?
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Which stage of bone remodeling follows the resorption of bone?
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What significant event occurs 2-3 days after a bone is fractured?
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What factor does NOT contribute to the process of bone remodeling?
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What happens to the epiphyseal plate during puberty due to increased hormone levels?
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What type of fracture is defined as a break that completely separates the bone into at least two fragments?
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Which cells are responsible for building new bone and facilitating calcium movement into the bone?
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Which type of cartilage is characterized by being much more flexible and tolerating repeated bending?
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What is the primary role of parathyroid hormone (PTH) in calcium homeostasis?
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What type of fracture occurs due to excessive use and is classified as an incomplete fracture?
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What hormone is released when blood calcium levels increase, inhibiting osteoclasts?
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Which type of bone fracture involves the bone collapsing, often related to conditions like osteoporosis?
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Which type of fracture is also known as a fracture that breaks the bone into multiple fragments?
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Which foramen allows the passage of the maxillary division of cranial nerve V?
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What structure forms part of the medial wall of the orbit?
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Where do the left and right parietal bones meet superiorly in the midline of the cranium?
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Which facial bone is known as the keystone of the facial skeleton?
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What type of cartilage provides support to the external nose?
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What does the foramen spinosum provide passageway for?
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Which of the following bones is part of the cranial vault?
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Which of the following bones forms the inferior nasal septum?
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How many bones are present in an adult human skeleton?
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Which bone is described as the keystone bone of the cranium?
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Which suture occurs between the parietal bones and the occipital bone?
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What is the primary function of the inferior nasal concha?
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What is the function of the foramen magnum in the occipital bone?
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Which type of cartilage serves as a cushion between vertebrae?
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What major part of the human skeleton is responsible for protecting the brain, spinal cord, heart, and lungs?
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Which of the following bones is NOT part of the facial bones?
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What is the primary function of the vertebra prominens?
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How many thoracic vertebrae are there?
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Which feature distinguishes lumbar vertebrae from cervical and thoracic vertebrae?
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What structure does the sacrum articulate with superiorly?
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What does the thoracic cage primarily protect?
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Which component is NOT part of the thoracic cage?
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What is the primary function of the transverse processes of cervical vertebrae?
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Which bones fuse to form the coccyx?
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Study Notes
Vitamin C Deficiency
- Deficiency of vitamin C in both children and adults can result in SCURVY, which is characterized by ulceration and hemorrhage in almost any area of the body
Hormones Affecting Bone Growth
- GROWTH HORMONE from the anterior pituitary increases general tissue growth, including overall bone growth.
- Excessive growth hormone secretion can lead to GIGANTISM.
- Insufficient growth hormone secretion results in DWARFISM.
- THYROID HORMONE is necessary for normal growth of all tissues, including cartilage.
- A decrease in this hormone can lead to a smaller individual.
- ESTROGEN AND TESTOSTERONE contribute to increased bone growth and closure of the epiphyseal plate.
- During puberty, the levels of these hormones increase dramatically.
Bone Remodeling
- Bone Remodeling refers to the ongoing process where existing bone is removed by osteoclasts and replaced with new bone by osteoblasts.
- This dynamic process is essential for maintaining normal bone proportions and strength, particularly during long-bone growth as the body grows larger and heavier.
- Bone remodeling allows for the thickening of bones and the formation of projections to enhance strength in areas where large muscles are attached.
Bone Remodeling Stages
- RESORPTION: Osteoclasts break down bone mineral and matrix, creating an erosion cavity (duration: 3-4 weeks).
- REVERSAL: Mononuclear cells prepare the bone surface for new osteoblasts to begin bone formation.
- FORMATION: Osteoblasts synthesize a new matrix to replace the resorbed bone (duration: 3-4 months).
- RESTING: A prolonged resting period follows until a new remodeling cycle initiates.
Bone Repair
- When a bone is broken, blood vessels inside the bone are typically damaged.
- Bleeding occurs, forming a clot (hematoma) at the site of the injury.
- Within 2-3 days, blood vessels and cells from surrounding tissues start to invade the clot.
Bone Fractures
- INCOMPLETE Fracture: A fracture that only partially traverses the bone.
- COMPLETE Fracture: A fracture that completely separates the bone into at least two fragments.
- COMMINUTED Fracture: A fracture where the bone breaks into multiple fragments.
- STRESS (Hairline) Fracture: Incomplete fracture caused by overuse of the bone.
- COMPRESSION Fracture: The bone collapses, common in spongy bones due to bone weakening (e.g., osteoporosis).
Calcium Homeostasis
- Bone acts as the primary storage site for calcium in the body.
- Calcium movement into and out of bone influences blood calcium levels.
- Osteoblasts build new bone, leading to calcium deposition, while osteoclasts break down bone, releasing calcium into the bloodstream.
- Balanced osteoblast and osteoclast activity maintains equal calcium movement.
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Decreased blood Ca2+: Stimulates parathyroid hormone (PTH) secretion.
- PTH promotes bone breakdown by osteoclasts, releasing Ca2+ into the blood.
- PTH increases Ca2+ reabsorption from the urine in the kidneys.
- PTH stimulates Vitamin D formation, which enhances Ca2+ absorption from the small intestine into the blood.
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Increased blood Ca2+: Stimulates calcitonin secretion from the thyroid gland.
- Calcitonin inhibits osteoclasts, allowing for increased osteoblast uptake of Ca2+ from the blood for bone deposition.
Cartilages of the Skeleton
- Three main types of cartilage tissue exist: hyaline, elastic, and fibrocartilage.
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HYALINE CARTILAGE: Provides sturdy support with some flexibility.
- Most skeletal cartilages are composed of hyaline cartilage.
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ELASTIC CARTILAGE: More flexible than hyaline cartilage, tolerating repeated bending.
- Found in the external ear and epiglottis.
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FIBROCARTILAGE: Offers high tensile strength and resistance to compression.
- Present in intervertebral discs and the knee joint.
Important Adult Skeletal Cartilages
- ARTICULAR CARTILAGES: Cover the ends of bones at movable joints.
- COSTAL CARTILAGES: Connect the ribs to the sternum (breastbone).
- NASAL CARTILAGES: Support the external nose.
- INTERVERTEBRAL DISCS: Separate and cushion the vertebrae.
General Considerations of Bone Anatomy
- A newborn human has approximately 350 bones.
- An adult human has 206 bones.
Bone Markings: Projections for Joint Formation
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Projections for Muscle or Ligament Attachment:
- Tuberosity: Large, rounded projection
- Crest: Narrow, prominent ridge
- Trochanter: Very large, blunt projection
- Line: Narrow ridge
- Tubercle: Small, rounded projection
- Spine: Sharp, slender projection
- Epicondyle: Projection above a condyle
Bone Markings: Depressions and Openings
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Depressions and Openings:
- Fissure: Narrow, slit-like opening
- Foramen: Round or oval opening
- Fossa: Shallow depression
- Meatus: Canal-like passageway
- Sulcus: Groove
Axial Skeleton
- The AXIAL SKELETON includes the SKULL, the VERTEBRAL COLUMN, and the THORACIC CAGE.
- It forms the longitudinal axis of the body and protects the brain, spinal cord, heart, and lungs.
Skull
- Sits atop the vertebral column.
- Composed of two sets of bones:
- Cranium (8 bones)
- Facial bones (14 bones)
- Bones are joined by sutures, except for the mandible, which is attached by a freely movable joint.
Cranium
- Divided into two major areas:
- CRANIAL VAULT (CALVARIA): Forms the superior, lateral, and posterior walls of the skull.
- CRANIAL BASE: Forms the skull bottom.
Cranial Bones:
- FRONTAL BONE (1): Forms the forehead, superior part of the orbit, and the floor of the anterior cranial fossa.
- PARIETAL BONES (2): Form the superior and lateral aspects of the skull.
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TEMPORAL BONES (2): Form the inferolateral aspects of the skull, sides of the head near the ears.
- Include the EXTERNAL AUDITORY MEATUS (ear opening).
- Include the ZYGOMATIC PROCESS (part of the cheekbone).
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OCCIPITAL BONE (1): Forms the posterior aspect and most of the base of the skull (back and base of the cranium).
- Includes the FORAMEN MAGNUM, a large opening allowing the spinal cord to connect with the brain stem.
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SPHENOID BONE (1): Bat-shaped bone; the keystone bone of the cranium, articulating with all other cranial bones.
- Forms parts of eye orbits.
- Contains the SELLA TURCICA, where the pituitary gland sits.
Sphenoid Bone Openings:
- OPTIC CANALS: Pass cranial nerve II (optic nerve) serving the eye.
- FORAMEN ROTUNDUM: Allows passage for a branch of cranial nerve V (maxillary division).
- FORAMEN OVALE: Facilitates passage for a branch of cranial nerve V (mandibular division).
- FORAMEN SPINOSUM: Provides a pathway for the middle meningeal artery.
Ethmoid Bone (1):
- Contributes to the anterior cranial fossa.
- Forms part of the nasal septum and nasal cavity.
- Forms part of the medial wall of the orbit.
Major Sutures:
- SAGITTAL SUTURE: Joins the left and right parietal bones superiorly at the midline of the cranium.
- LAMBDOID SUTURE: Joins the parietal bones with the occipital bone posteriorly.
- SQUAMOUS SUTURE: Joins each parietal bone with the temporal bone on each lateral aspect of the skull.
- CORONAL SUTURE: Runs in the frontal plane and joins the parietal bones with the frontal bone anteriorly.
Cranial Base:
- Possesses three depressions:
- ANTERIOR CRANIAL FOSSA
- MIDDLE CRANIAL FOSSA
- POSTERIOR CRANIAL FOSSA
- These fossae house the brain.
Facial Bones:
- NASAL BONES (2): Small, rectangular bones forming the bridge of the nose.
- LACRIMAL BONES (2): Form part of the medial orbit between the maxilla and ethmoid bone.
- ZYGOMATIC BONES (2): Cheekbones; each forms part of the lateral orbit.
- INFERIOR NASAL CONCHA (2): Form part of the lateral walls of the nasal cavities, improving airflow through the nasal cavity.
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MAXILLA (2): Keystone facial bones articulating with all other facial bones except the mandible.
- Form the upper jaw and parts of the hard palate, orbits, and nasal cavity.
- PALATINE BONES (2): Form the posterior hard palate, part of the nasal cavity, and part of the orbit.
- VOMER (1): Thin, blade-shaped bone forming the inferior nasal septum.
Vertebral Column:
-
CERVICAL VERTEBRAE (7):
- C1 (Atlas): Supports the skull.
- C2 (Axis): Permits head rotation.
- Vertebra Prominens (C7): Spinous process visible through the skin at the base of the neck, useful for counting vertebrae.
- Transverse processes are wide, containing foramina through which vertebral arteries pass to the brain.
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THORACIC VERTEBRAE (12):
- Larger body than cervical vertebrae, somewhat heart-shaped.
- Vertebral foramen is oval or round.
- Spinous process has a long, sharp downward hook.
- Only vertebrae articulating with ribs.
- Articular facets on transverse processes articulate with the tubercles of the ribs.
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LUMBAR VERTEBRAE (5):
- Support the majority of body weight.
- Have massive bodies and heavy, rectangular transverse and spinous processes.
- Superior articular facets face posteromedially, inferior ones face anterolaterally.
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SACRUM (Composite bone formed by fusion of 5 vertebrae):
- Articulates superiorly with L5 and inferiorly with the coccyx.
- Connects with hip bones through auricular surfaces, forming the sacroiliac joint.
- Part of the pelvic girdle, provides stable support for lower limbs.
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COCCYX (Fusion of 3-5 irregularly shaped vertebrae):
- Also known as the tailbone.
- Attached to the sacrum by ligaments.
Thoracic Cage:
- Composed of bony thorax (sternum, ribs, thoracic vertebrae, and costal cartilages).
- Protects organs of the thoracic cavity, including heart and lungs.
Sternum (Breastbone):
- Flat bone formed by fusion of three bones:
- MANUBRIUM: Superior, resembles a tie knot, articulates with clavicle (collarbone) laterally.
- BODY: Articulates with ribs 2-7.
- XIPHOID PROCESS (Smallest part): Located at the inferior end, point of attachment for abdominal muscles.
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Description
Test your knowledge on vitamin C deficiency, bone growth hormones, and the bone remodeling process. This quiz covers important concepts related to nutrition and endocrine factors affecting bone health in children and adults.
