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Questions and Answers
What is the bulk of the sternum called?
What is the bulk of the sternum called?
Body
The xiphoid process is the superior bone of the sternum.
The xiphoid process is the superior bone of the sternum.
False
Which of the following are landmarks seen on the sternum? (Select all that apply)
Which of the following are landmarks seen on the sternum? (Select all that apply)
How many pairs of ribs form the walls of the thoracic cage?
How many pairs of ribs form the walls of the thoracic cage?
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What are the first seven pairs of ribs called?
What are the first seven pairs of ribs called?
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What do we call the fibrous membranes between the bones of the fetal skull?
What do we call the fibrous membranes between the bones of the fetal skull?
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Which canal is the passage for the internal carotid artery?
Which canal is the passage for the internal carotid artery?
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Match the following skull features with their descriptions:
Match the following skull features with their descriptions:
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The ______ forms the chin.
The ______ forms the chin.
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What are the nasal conchae?
What are the nasal conchae?
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What are the two main tissues that make up the skeleton?
What are the two main tissues that make up the skeleton?
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Which part of the skeleton consists of the Skull, Sternum, and Vertebral Column?
Which part of the skeleton consists of the Skull, Sternum, and Vertebral Column?
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How many bones are there in the human body?
How many bones are there in the human body?
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Compact bone is smooth looking and homogenous.
Compact bone is smooth looking and homogenous.
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What type of bone is the femur?
What type of bone is the femur?
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What are osteoblasts?
What are osteoblasts?
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What does the periosteum cover?
What does the periosteum cover?
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Match the following terms with their correct definitions:
Match the following terms with their correct definitions:
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Which type of cartilage is known for its elasticity?
Which type of cartilage is known for its elasticity?
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Osteoporosis results in an increase in bone mass.
Osteoporosis results in an increase in bone mass.
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What are vertebrae?
What are vertebrae?
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What is the function of intervertebral discs?
What is the function of intervertebral discs?
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Study Notes
The Skeleton: Bone & Cartilage
- Two main tissues: Bone and Cartilage
- Cartilage more prevalent in embryos, bone in adults
- Cartilage found in nose bridge, larynx, trachea, joints, ribcage, and ear
Skeleton Functions
- Support
- Protection
- Movement lever system
- Storage
- Blood cell production
Subdivisions
- Axial Skeleton: Central torso, Skull, Sternum, Vertebral Column
- Appendicular Skeleton: Limbs, Pelvic & Pectoral Girdles
Bone Markings
- Areas where ligaments, tendons, nerves, blood vessels attach, joints form
- Projections: Tuberosity, Crest, Trochanter, Line, Tubercle, Epicondyle, Spine, Process, Head, Facet, Condyle, Ramus
- Depressions & Cavities: Groove, Fissure, Foramen, Notch, Meatus, Sinus, Fossa
Bone Types
- Compact Bone: Smooth, dense, homogeneous
- Spongy Bone: Open, lattice-like structure with trabeculae (bars of bone) & spaces
- Long bones: Femur, longer than wide, shaft & heads, mostly compact bone
- Short bones: Tarsals, cube-shaped, more spongy than compact bone
- Flat bones: Skull bones, thin compact layers with spongy in between, often curved
- Irregular bones: Vertebrae, uniquely shaped
- Sesamoid bones: Inside tendons, ex: Patella
- Wormian/Sutural bones: Small bones between cranial bones
Anatomy of a Long Bone
- Shaft/Diaphysis: Long axis, mainly compact bone
- Periosteum: Fibrous membrane covering the outside of bone, Sharpey's fibers anchor it
- Osteoblasts: Bone-forming cells in periosteum
- Osteoclasts: Bone-destroying cells in endosteum
- Epiphysis: Ends of long bones, mostly spongy bone with thin compact layer
- Articular Cartilage: Hyaline cartilage covering epiphyseal surface, smooth, friction-reducing
- Epiphyseal Plate: Hyaline cartilage allowing growth in young animals, replaced by Epiphyseal Line in adults
- Central Cavity/Medullary Cavity: In shaft, stores fat, red marrow in infant epiphyses
Microscopic Bone Structure
- Haversian Canal: Central channel running parallel to bone's long axis, contains blood vessels, nerves, lymph vessels
- Osteocytes: Mature bone cells in lacunae (chambers) arranged in concentric circles (lamallae) around Haversian Canal
- Osteon/Haversian System: Central canal and all concentric lamallae
- Canaliculi: Tiny canals radiating from Haversian Canal, nutrient transport network
- Volksmann's Canals: Perpendicular to shaft, connect central cavities to periosteum and bone marrow cavity
Ossification of Bone
- Endochondral Ossification: Hyaline cartilage as template for bone
-
Primary Ossification Center:
- Periosteum replaces perichondrium
- Osteoblasts secrete bone around cartilage model
- Shaft center cartilage calcifies & hollows forming a cavity
- Periosteal bud (containing osteoblasts, osteoclasts, etc.) invades cavity, forming medullary cavity
- Medullary cavity grows & lengthens during bone growth
- Epiphyseal plate replaced by calcified Epiphyseal Line after adolescence
Cartilage
- Mostly water with varying amounts of elastic, reticular, or collagen fibers
- Outer covering: Perichondrium, growth & repair
- No nerves, relatively avascular
- Types: Elastic, Hyaline, Fibrocartilage
Cartilages of the Skeleton
- Articular cartilage: Hyaline, at epiphysis of long bones
- Costal cartilage: Hyaline, connects ribs to sternum
- Laryngeal cartilage: Hyaline, constructs voice box in larynx
- Tracheal & Bronchial cartilages: Hyaline, reinforce respiratory passageways
- Nasal cartilage: Hyaline, supports external nose
- Intervertebral disc cartilage: Fibrocartilage, separates & cushions vertebrae
- Ear cartilage: Elastic, supports external ear
Osteoporosis
- Gradual loss of bone mass, weakening bones, increasing fracture risk
- Causes: Hormone deficiency, Calcium & Vitamin deficiency, Physical inactivity, vices
The Axial Skeleton
- Skull, Vertebral Column, Bony Thorax
- 80 bones
The Skull
- Cranium: Encloses brain
- Facial Bones: Support eyes, facial muscles
- Bones connected by immovable sutures except for mandible (freely moving joint)
Cranium/Cranial Bones
- Cranial Vault/Calvaria: Superior portion
- Cranial Floor/Base: Inferior portion, 3 concavities for brain (Anterior, Middle, Posterior fossa)
- Bones: Frontal, Parietal (paired), Temporal (paired), Occipital
The Frontal Bone
- Anterior cranium, forehead, superior orbit, Anterior Fossa floor
- Supraorbital foramens (notch): Openings above each orbit for blood vessels & nerves
Parietal Bones
- Superior sides of cranium
- Sagittal Suture: Midline articulation of parietal bones
Temporal Bones
- Inferior sides of cranium
- Squamous Suture: Articulation with parietal bones
- Zygomatic process: Forms cheekbone
- Mandibular fossa: Articulation with mandible
- External Acoustic Meatus: Canal to eardrum & middle ear
- Styloid process: Muscle & ligament attachment
- Mastoid process: Muscle attachment, Mastoiditis (infection)
- Stylomastoid foramen: Cranial Nerve VII passage
- Jugular foramen: Internal jugular vein & Cranial Nerves IX, X, XI passage
- Carotid canal: Internal carotid artery passage
- Internal acoustic meatus: Cranial Nerves VII & VIII passage
- Foramen Lacerum: Internal carotid artery & small nerves passage
The Occipital Bone
- Posterior cranium, joins sphenoid anteriorly
- Lambdoid Suture: Articulation with parietal bones
- Foramen Magnum: Opening for spinal cord
- Hypoglossal Canal: Hypoglossal nerve (Cranial Nerve XII) passage
- Occipital Condyles: Articulate with Atlas (C1)
The Sphenoid Bone
- Bat-shaped, anterior plateau of middle cranial fossa, across skull width
- Greater wings: Part of orbital socket
- Superior Orbital Fissures: Jagged openings for cranial nerves III, IV, V, VI to orbit for eye
- Inferior Orbital Fissures: Infraorbital vessels & Cranial Nerve V passage
- Sella Turcica: Central portion, "Turk's Saddle"
- Hypophyseal fossa: Seat of Sella Turcica, holds pituitary gland
- Optic canals: Optic nerves passage
- Foramen Rotundum & Ovale: Branches of 5th Cranial Nerve passage
- Foramen Spinosum: Middle Meningeal Artery passage
The Ethmoid Bone
- Anterior to sphenoid, roof of nasal cavity, upper nasal septum, medial orbital wall
- Crista Galli: Vertical projection, Dura Mater attachment point
- Cribiform plates: Lateral to Crista Galli, contain Olfactory foramina (for olfactory fibers)
- Horizontal plate: Formed by Crista Galli and cribiform plates
- Perpendicular plate: Forms superior nasal septum
- Lateral masses: Part of medial orbital walls
- Superior & Middle Nasal Conchae: Turbinates, warm & humidify incoming air
Facial Bones
- 7 paired bones (14), 2 single bones (Vomer & Mandible)
The Mandible
- Lower jawbone, articulates with temporal bone via only freely moving skull joint
- Mandibular Body: Forms chin
- Mandibular condyles: Articulation points with temporal bone
- Coronoid process: Muscle attachment
- Mental Foramen: Opening for mental blood vessels & nerves
- Alveolar margin: Superior sockets for teeth
- Mandibular symphysis: Point of mandibular fusion
- Mandibular Foramen: Cranial Nerve V passage
The Maxillae
- Two bones fused to form upper jaw, other facial bones (except mandible) attached here
- Alveolar margin: Inferior sockets for teeth
- Palatine processes: Form anterior hard palate
- Infraorbital foramen: Opening for infraorbital nerves & blood vessels
- Incisive fossa: Transmits nasopalatine arteries & blood vessels
Lacrimal Bones
- Medial wall of orbit, between maxilla & ethmoid
- Pierced by Lacrimal fossa: Passageway for tears
Palatine Bones
- Posterior hard palate & part of orbit
Zygomatic Bones
- Lateral to maxillae, part of cheekbones & lateral orbit
Nasal Bones
- Small, rectangular, form bridge of nose
Vomer
- Blade-shaped, medial plane, posterior & inferior nasal septum
Hyoid Bone
- Throat, above larynx, attachment for neck & tongue muscles
- Not articulated to any other bone
Paranasal Sinuses
- In maxillary, sphenoid, ethmoid, & frontal bones (maxillary is largest)
- Resonance chambers & lighten facial bones
- Sinusitis: Inflammation of sinuses, caused by allergy or bacterial infection, blockage with mucus, sinus headache
The Vertebral Column
- Skull to pelvis, major axial support
- Protects spinal cord, allows nerves to exit
- 24 vertebrae, sacrum, coccyx
- Cervical vertebrae: 7 (neck)
- Thoracic vertebrae: 12 (upper back)
- Lumbar vertebrae: 5 (lower back)
- Intervertebral discs: Fibrocartilage between vertebrae,クッション＆衝撃吸収
- Nucleus pulposus: Inner gelatinous mass
- Annulus fibrosus: Outer collagen ring
- Ruptured discs: Nucleus pulposus herniation through annulus fibrosus, spinal nerve compression
- S-shape prevents shock & allows flexibility
- Primary Curvature: Thoracic & Sacral, present at birth
- Secondary Curvature: Cervical & Lumbar, develop later
Spinal Curvature Abnormalities
- Scoliosis: Excessive lateral curvature
- Kyphosis: Excessive dorsal (backwards) curvature
- Lordosis: Excessive anterior (forward) curvature
Structure of a Vertebra
- Body/Centrum: Rounded central portion facing anteriorly
-
Vertebral arch: Pedicles, Laminae, Spinous process
- Pedicles: Connect body to laminae
- Laminae: Connect spinous & transverse processes
- Vertebral foramen: Opening between arch & body, for spinal cord
- Transverse process: Lateral projection of arch
- Spinous process: Medial/posterior projection of arch
-
Superior & Inferior articular processes: Paired projections lateral to vertebral foramen, articulate between vertebrae
- Superior process faces towards spinous process, inferior faces away
- Intervertebral Foramina: Spaces in pedicels for spinal nerves to exit
Cervical Vertebrae
- C1 & C2 have special functions & names
- Atlas (C1): No body, lateral processes with depressions for occipital condyles
- Axis (C2): Pivot for atlas rotation, odontoid process/dens is the pivot
- Vertebral prominence: C7, visible through skin
- Costal demifacets: On thoracic vertebrae bodies, articulate with ribs
- Superior & inferior articular processes reduce mobility
Spinal Cord & Lumbar Puncture
- Spinal cord ends at L2, coverings continue & filled with spinal fluid
- Lumbar puncture/Spinal tap: Between L3-L4 & L4-L5, Saddle Block (anesthesia for childbirth) to avoid cord damage
The Sacrum
- 5 fused vertebrae, articulates with L5
- Medial Sacral crest: Fused spinous processes
- Alae: Fused transverse processes, articulate with pelvic girdle
- Sacral foramina: Blood vessels & nerves passage at fusion ridges
- Sacral canal: Holds spinal coverings, enters coccyx at Sacral Hiatus
- Sacral promontory: Anterior border of S1, landmark for obstetricians
The Coccyx
- 3-5 fused small vertebrae, vestigial tail
The Bony Thorax
- Ribs, Sternum, Thoracic Vertebrae
- Also called thoracic cage
The Sternum
- Breastbone, flat bone, fusion of 3 bones
- Manubrium: Triangular, articulates with clavicles
- Body: Bulk of sternum
- Xiphoid process: Most inferior, can cause trauma to heart/liver if struck
- Landmarks:
- Jugular notch: Concave upper border of manubrium
- Sternal angle: Manubrium & body meet
- Xiphisternal joint: Body & xiphoid process meet
- Clavicular Notches: Articulation sites with clavicles
Ribs
- 12 pairs, form thoracic cage walls
- Vertebrosternal (True ribs): Pairs 1-7, attached directly to sternum & vertebral column
- Vertebrochondral/False ribs: Pairs 8-10, indirectly attached to sternum by hyaline cartilage
- Floating/Vertebral ribs: Pairs 11 & 12, not attached to sternum
The Fetal Skeleton
- Indentations between fetal skull bones: Fontanels, fibrous membranes
- Ossify by 20-22 months after birth
- Allow for skull compression during birth & brain growth
- Fontanels: Anterior, Posterior, Sphenoid, Mastoid
Skull Depressions and Projections Summary
- Frontal Bone*
- *Supraorbital foramens (notch)**: Openings above each orbit for blood vessels & nerves
- Coronal Suture*: Articulation point between Frontal & Parietal bones
- Parietal Bones*
- Sagittal Suture*: Articulation point between Parietal bones
- Temporal Bone*
- Squamous Suture*: Articulation point between Temporal & Parietal bones
Cranial Bones
- Zygomatic process: Forms the cheekbone.
- Stylomastoid foramen: Allows passage of the facial nerve (CN VII).
- Jugular foramen: Allows passage of the internal jugular vein and cranial nerves IX, X, and XI.
- Carotid canal: Allows passage of the internal carotid artery.
- Mandibular fossa: A rounded depression that articulates with the mandible.
- Styloid process: An attachment site for muscles and ligaments of the neck.
- Mastoid process: An attachment site for muscles.
- External acoustic canal: Passage for sound to the middle ear.
- Internal acoustic canal: Passage for cranial nerves VII and VIII.
- Foramen lacerum: Allows passage of the internal carotid artery.
Occipital Bone
- Lambdoid suture: Articulation point of the occipital and parietal bones.
- Foramen magnum: Passage for the spinal cord.
- Hypoglossal canal: Passage for the hypoglossal nerve (CN XII).
- Occipital condyles: Articulation point of the occipital bone and the atlas (C1).
Sphenoid Bone (Cranial Keystone)
- Greater wings: Part of the eye orbit/socket.
- Superior orbital fissure: Passage for cranial nerves III, IV, V, and VI.
- Inferior orbital fissure: Passage for infraorbital blood vessels and the maxillary nerve (CN V).
- Hypophyseal fossa: Holds the pituitary gland.
- Optic canal: Passage for the optic nerve (CN II).
- Foramen rotundum and ovale: Passage for the maxillary nerve (CN V).
- Foramen spinosum: Passage for the middle meningeal artery.
Ethmoid Bone
- Lateral masses: Part of the eye orbit/socket.
- Crista Galli: Attachment for the dura mater to the skull.
- Cribriform plates: Contain olfactory foramina, which are passageways for the olfactory nerve (CN I).
- Horizontal plate: Houses the crista galli and the two cribriform plates.
- Perpendicular plate: Forms the superior nasal septum.
- Superior and inferior nasal conchae: Also known as turbinates, structures that increase surface area within the nasal cavity.
Mandible
- Mandibular body: Forms the chin.
- Mandibular condyle: Articulates with the mandibular fossa.
- Conoid process: A site for muscle attachment.
- Mental foramen: Passage for the mental blood vessels.
- Alveolar margin: Site of the inferior teeth sockets.
- Mandibular symphysis: Site of mandibular fusion.
- Mandibular foramen: Passage for the mandibular nerve (CN V).
Maxillae (Facial Keystone)
- Alveolar margin: Site of the superior teeth sockets.
- Palatine processes: Anterior portion of the hard palate.
- Infraorbital foramen: Passage for infraorbital blood vessels.
- Incisive fossa: Passage for the nasopalatine artery and nerve.
Lacrimal Bone
- Lacrimal fossa: Passage for tears, also part of the eye orbit/socket.
Palatine Bone
- Forms the posterior portion of the hard palate.
Zygomatic Bone
- Forms cheeks and part of the eye orbit/socket.
Nasal Bones
- Forms the bridge of the nose and part of the eye orbit/socket.
Hyoid Bone
- Attachment site for neck and tongue muscles.
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Description
Test your knowledge on the human skeletal system with this quiz that covers various aspects including the sternum, ribs, skull features, and bone types. Match terms with definitions and answer questions about bone structure and function. Perfect for anatomy students or anyone interested in human biology!
