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Questions and Answers
How many bones are found in the adult human skeleton?
How many bones are found in the adult human skeleton?
The axial skeleton contains more bones than the appendicular skeleton.
The axial skeleton contains more bones than the appendicular skeleton.
False
What type of bone is primarily found in the interiors of short bones?
What type of bone is primarily found in the interiors of short bones?
spongy
The bones that attach limbs to the axial skeleton are called girdles.
The bones that attach limbs to the axial skeleton are called girdles.
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Match the following bone types with their descriptions:
Match the following bone types with their descriptions:
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Which of the following is a sign of unequal leg length?
Which of the following is a sign of unequal leg length?
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Supplementation of folic acid during pregnancy can decrease the risk of spina bifida.
Supplementation of folic acid during pregnancy can decrease the risk of spina bifida.
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What is the term for the condition where the spinal cord may protrude due to incomplete closing of the vertebral column?
What is the term for the condition where the spinal cord may protrude due to incomplete closing of the vertebral column?
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Treatment options for spina bifida include therapy and surgery.
Treatment options for spina bifida include therapy and surgery.
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Match the following components of the axial skeleton with their respective descriptions:
Match the following components of the axial skeleton with their respective descriptions:
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What is the primary function of the skull?
What is the primary function of the skull?
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The mandible is the only immovable bone of the skull.
The mandible is the only immovable bone of the skull.
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Name the three auditory ossicles.
Name the three auditory ossicles.
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The _____ bone forms the forehead at the anterior of the skull.
The _____ bone forms the forehead at the anterior of the skull.
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Match the bone with its description.
Match the bone with its description.
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Which bone is known as the 'keystone' of the cranial floor?
Which bone is known as the 'keystone' of the cranial floor?
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The paranasal sinuses make the skull heavier.
The paranasal sinuses make the skull heavier.
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What provides passage for the spinal cord to connect with the brain?
What provides passage for the spinal cord to connect with the brain?
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The _____ bone forms the lower jaw.
The _____ bone forms the lower jaw.
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Which of the following bones forms part of the nasal septum?
Which of the following bones forms part of the nasal septum?
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The lacrimal bones are located in the cheeks.
The lacrimal bones are located in the cheeks.
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List the 8 bones that form the cranial cavity.
List the 8 bones that form the cranial cavity.
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The _____ process forms a cavity that accommodates the mandibular condyle.
The _____ process forms a cavity that accommodates the mandibular condyle.
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Match the bones forming the orbits with the corresponding bone names.
Match the bones forming the orbits with the corresponding bone names.
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What is the primary function of intervertebral discs?
What is the primary function of intervertebral discs?
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The hyoid bone articulates with several other bones in the body.
The hyoid bone articulates with several other bones in the body.
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What is the name of the first cervical vertebra?
What is the name of the first cervical vertebra?
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The thoracic vertebrae are numbered from ______ to ______.
The thoracic vertebrae are numbered from ______ to ______.
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Match the type of rib with its characteristics:
Match the type of rib with its characteristics:
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Which part of the sternum is the most superior?
Which part of the sternum is the most superior?
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Scoliosis is characterized by a lateral bending of the vertebral column.
Scoliosis is characterized by a lateral bending of the vertebral column.
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What type of cartilage is the costal cartilage made of?
What type of cartilage is the costal cartilage made of?
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The large vertebral foramen provides passage for the ________ cord.
The large vertebral foramen provides passage for the ________ cord.
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What is the purpose of the curve of the cervical vertebrae?
What is the purpose of the curve of the cervical vertebrae?
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The coccyx consists of five fused vertebrae.
The coccyx consists of five fused vertebrae.
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What is a unique feature of cervical vertebrae compared to other vertebrae?
What is a unique feature of cervical vertebrae compared to other vertebrae?
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The lumbar vertebrae are numbered L1 to L______.
The lumbar vertebrae are numbered L1 to L______.
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What distinguishes C1 from C2 vertebrae?
What distinguishes C1 from C2 vertebrae?
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Study Notes
The Skeletal System
- The adult human skeleton is made up of 206 bones.
- The skeleton can be divided into two main groups: the axial skeleton (80 bones) and the appendicular skeleton (126 bones).
- The axial skeleton includes the bones that run from the head to the bottom of the vertebral column.
- The appendicular skeleton includes the bones of the limbs and the girdles (shoulder and pelvic) that attach the limbs to the axial skeleton.
- The muscular and skeletal systems work together as the musculoskeletal system.
Types of Bones
- Long Bones: Longer than they are wide, curved to absorb shock. Compact bone tissue in the diaphysis, spongy bone tissue in the epiphyses.
- Short Bones: Nearly as long as they are wide, mostly composed of spongy bone tissue surrounded by a thin layer of compact bone.
- Flat Bones: Thin plates of compact bone with spongy bone interiors.
- Sesamoid Bones: Thin, small bones that develop in areas of high mechanical stress.
- Irregular Bones: Irregularly shaped or distributed.
Bone Surface Markings
- Depressions and Openings: Provide passage for blood vessels and nerves. Foramina, fossae, and meati.
- Processes, Projections, or Outgrowths: Attachment points for ligaments and tendons. Condyles, facets, heads, crests, and processes.
The Human Skull: Cranial and Facial Bones
- The skull protects the brain, serves as a point of attachment for facial muscles, forms portions of the orbits, nasal, and oral cavities, and includes the auditory ossicles.
Cranial Bones
- There are 22 bones in the skull, some are paired.
- Frontal Bone: Forms the forehead and contains the supraorbital foramen (passage for supraorbital artery and nerve).
- Ethmoid Bone: Forms the medial portion of the orbits, the anterior portion of the cranial floor, and contains the cribriform plate (provides passage for olfactory foramina).
- Sphenoid Bone: "Keystone" of the cranial floor, contains the optic foramen (allows passage of the ophthalmic artery and the optic nerve).
- Temporal Bones: Form the lateral and inferior portions of the cranium. Contain the zygomatic arch, the mandibular fossa, the styloid process, the mastoid process, and the external auditory meatus.
- Auditory Ossicles: Malleus (hammer), Incus (anvil), Stapes (stirrup). Involved in hearing.
- Occipital Bone: Forms the posterior and inferior portion of the skull. Contains the occipital condyles (form joints with the atlas), and the foramen magnum (passage for the spinal cord).
- Parietal Bones: Form the superior and lateral portions of the skull.
Facial Bones
- There are 14 facial bones that form the anterior portion of the skull.
- Mandible: Forms the lower jaw, largest and strongest bone of the skull, only moveable bone of the skull.
- Maxillae: Forms the upper jaw.
- Palatine Bones: L-shaped bones that complete the posterior portion of the hard palate.
- Zygomatic Bones: Form the anterior portion of the cheekbones and the inferior and lateral walls of the orbits.
- Vomer: Forms the inferior portion of the nasal septum.
- Inferior Nasal Conchae: Form the lateral walls of the nasal cavity, swirl air around nasal passages to trap airborne invaders.
- Nasal Bones: Form the bridge of the nose.
- Lacrimal Bones: Smallest of the facial bones, lie near the tear ducts.
Special Features of the Skull
- Orbits: Composed of seven bones: frontal, lacrimal, ethmoid, zygomatic, sphenoid, maxilla, palatine.
- Sutures: Incomplete ossification at birth, called fontanels (mesenchymal tissue). Function: Allow the cranium to grow with the brain and facilitate passage through the birth canal.
- Coronal Suture: Connects the frontal and parietal bones.
- Sagittal Suture: Connects the parietal bones superiorly.
- Lambdoid Suture: Connects parietal and occipital bone.
- Squamous Suture: Connects parietal and temporal bone.
- Zygomatic Arch: Prominent bony portion that runs laterally and posteriorly from the zygomatic bone; formed by the zygomatic bone and the temporal bone.
- Sinuses: Cavities lined with mucous membranes, trap invaders, make the skull lighter.
The Hyoid Bone
- Does not articulate with any other bone.
- Floats on tendon and ligaments.
- Muscles of the tongue attach to the hyoid bone.
- Not the Adam's apple (formed by thyroid cartilage).
The Vertebral Column
- Supports and moves the skull, protects the spinal cord, provides points of attachment for muscles, contains intervertebral discs for cushioning.
- Divided into subregions, curved to improve shock absorption.
- The cervical curve develops as the infant learns to hold its head up, the lumbar curve develops as the infant begins to walk.
- The intervertebral discs are made of fibrocartilage and compress throughout the day.
Vertebral Anatomy
- The body bears weight and contains nutrient foramina.
- Large vertebral foramen provides passage for the spinal cord.
- Superior articular processes articulate with the inferior articular processes of the vertebrae above.
- Facets are the surfaces on which bones connect at joints.
Cervical Vertebrae
- C1-C7 (the atlas and the axis)
- Atlas (C1): No body or spinous process, distinct anterior arch, large vertebral foramen to accommodate the dens of axis.
- Axis (C2): Dens (superior and anterior projection), passes through the vertebral foramen of the atlas, forms the atlanto-axial joint.
- Other Cervical Vertebrae: Bifid spinous processes and transverse foramina (passage for the vertebral artery).
Thoracic Vertebrae
- T1-T12
- Large transverse processes for articulations with the ribs.
- Demifacets (surfaces where the head of one rib connects with two vertebrae), facets (surfaces where the tubercle of ribs connect to the vertebral column).
Rib Anatomy
- Head: Articulates with demifacets on vertebral bodies.
- Neck: Narrowed region adjacent to the head.
- Tubercle: Posterior and lateral projection that articulates with facets on transverse processes.
Lumbar Vertebrae
- L1-L5
- Short & thick spinous processes, points of attachment for back muscles.
Sacrum
- Five fused vertebrae.
- Articulates with the pelvic girdle at the sacroiliac joints.
- Vertebral canal becomes the sacral canal.
- Ends at the sacral hiatus.
Coccyx
- Tailbone, four fused coccygeal vertebrae.
The Thoracic Cage
- Forms the ribcage and breastbone.
- Sternum: Breastbone, medial bone to which the ribs attach. Composed of the manibrium, body, and xiphoid process.
- True Ribs: First seven ribs, articulate with thoracic vertebrae and sternum.
- False Ribs: Ribs 8-10 articulate with costal cartilage of the 7th rib.
- Floating Ribs: Ribs 11-12 do not articulate anteriorly.
Disorders of the Axial Skeleton
- Scoliosis: Abnormal lateral curvature of the vertebral column, usually at the thoracic vertebrae, may be inherited or compensatory. Signs: Uneven shoulders and waist, difficulty breathing. Symptoms: Chronic back pain and arthritis. Treatment: Braces, physical therapy, or surgery.
- Spina Bifida: Incomplete closure of the vertebral column during fetal development, spinal cord may protrude (meningocele). Folic acid supplementation during pregnancy decreases risk. Treatments include physical therapy and surgery.
Summary
- The axial skeleton comprises the cranium, face, vertebral column, and thoracic cage.
- These bones protect the brain, spinal cord, and viscera of the thoracic cavity.
- They are a source of red bone marrow.
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Description
Explore the intricate structure of the adult human skeletal system, which is comprised of 206 bones divided into the axial and appendicular skeletons. This quiz covers the different types of bones, their characteristics, and how they contribute to the musculoskeletal system. Test your knowledge and understanding of human anatomy!
