Skeletal System

Part 1 — Skeletal System Answer Review 1. Axial vs. appendicular skeleton Axial skeleton: Bones along the body's central axis, including the skull, vertebral column, ribs, and sternum. It supports the body and protects the brain, spinal cord, and organs in the chest. Appendicular skeleton: Bones of the upper and lower limbs, plus the pectoral (shoulder) and pelvic girdles. It supports movement and connects the limbs to the axial skeleton. 2. Bones of the axial skeleton • Skull bones • Auditory ossicles: malleus, incus, and stapes • Hyoid bone • Vertebral column: cervical, thoracic, and lumbar vertebrae, sacrum, and coccyx • Ribs and sternum 3. Bones of the appendicular skeleton • Pectoral girdle: clavicles and scapulae • Upper limbs: humerus, radius, ulna, carpals, metacarpals, and phalanges • Pelvic girdle: right and left hip bones; each hip bone forms from the ilium, ischium, and pubis • Lower limbs: femur, patella, tibia, fibula, tarsals, metatarsals, and phalanges 4. Number of bones The typical adult human skeleton has 206 bones. 5. Articular bone markings: condyle, facet, head Condyle: A rounded articular projection at the end of a bone. Facet: A smooth, flat or slightly curved surface where bones articulate. Head: A rounded, expanded end of a bone, often supported by a narrower neck. 6. Bone markings associated with projections Crest: A prominent ridge of bone. Epicondyle: A projection located above or near a condyle. Line: A narrow, low ridge of bone. Process: A projection or prominence of bone. Protuberance: A bone projection that sticks out. Spine: A sharp, slender projection. Trochanter: A large, blunt projection found on the femur. Tubercle: A small, rounded projection. Tuberosity: A large, roughened projection, often for muscle or ligament attachment. 7. Bone markings associated with passages and cavities Canal: A tubular passage through a bone. Page 2 Chapter 8 — Skeletal System Review Fissure: A narrow, slit-like opening. Foramen: An opening through a bone for nerves or blood vessels. Meatus: A canal-like passageway. Sinus: An air-filled cavity within a bone, usually lined with mucous membrane. 8. Skull structures to review for figures 8.4–8.17 The referenced textbook figures were not included in the upload, so exact figure labels cannot be confirmed. Use this review list: • Ethmoid: cribriform plate, crista galli, olfactory foramina, superior and middle nasal conchae, perpendicular plate, ethmoid air cells. • Sphenoid: sphenoid sinus, sella turcica, greater and lesser wings, body, medial and lateral pterygoid plates, optic foramen, foramen rotundum, foramen ovale, foramen spinosum. • Temporal: squamous, petrous, and mastoid portions; internal and external acoustic meatuses; styloid, zygomatic, and mastoid processes. • Occipital: foramen magnum, occipital protuberances, occipital condyles. • Frontal: glabella, supraorbital margin, supraorbital foramen, frontal sinus. • Maxilla: infraorbital foramen, alveolar margin, maxillary sinus. • Mandible: alveolar margin, mental foramen, mandibular condyle, mandibular notch, coronoid process, ramus, angle, body, mandibular foramen. • Auditory ossicles: malleus, incus, stapes. 9. Vertebral column and curvatures The vertebral column has 33 vertebrae early in life; the sacral and coccygeal vertebrae typically fuse in adulthood. • Cervical: 7 vertebrae (C1–C7). • Thoracic: 12 vertebrae (T1–T12). • Lumbar: 5 vertebrae (L1–L5). • Sacrum: usually 5 fused vertebrae. • Coccyx: usually 4 fused vertebrae. Normal curves: cervical lordosis (inward), thoracic kyphosis (outward), lumbar lordosis (inward), and sacral kyphosis (outward). Abnormal curves: scoliosis is a sideways curvature; excessive kyphosis is an exaggerated outward curve of the upper back; excessive lordosis is an exaggerated inward curve of the lower back. 10. Lumbar vertebra and intervertebral disk Lumbar vertebra: vertebral body, vertebral foramen, pedicles, laminae, spinous process, transverse processes, superior articular processes/facets, and inferior articular processes/facets. Intervertebral disk: annulus fibrosus (tough outer ring of fibrocartilage) and nucleus pulposus (soft, gel-like center that helps absorb compression). 11. Atlas (C1), axis (C2), and atlantoaxial joint Atlas (C1): supports the skull; includes anterior and posterior arches, lateral masses, and superior articular facets. Axis (C2): has the dens (odontoid process), which projects upward. Page 3 Chapter 8 — Skeletal System Review Atlantoaxial joint: between C1 and C2; allows rotation of the head from side to side. 12. Cervical, thoracic, and lumbar vertebrae Cervical: small body, large triangular vertebral foramen, transverse foramina, and often a bifid spinous process. Thoracic: costal facets for rib articulation, relatively circular vertebral foramen, and a long spinous process that angles downward. Lumbar: large, thick body for weight-bearing, triangular vertebral foramen, and short, thick spinous process. 13. Differences among cervical, thoracic, and lumbar vertebrae Cervical vertebrae are smaller and have transverse foramina for blood vessels. Thoracic vertebrae have costal facets for rib attachment. Lumbar vertebrae have large bodies and thick processes adapted for supporting body weight. 14. Sacrum and coccyx Sacrum: sacral promontory, base, apex, sacral canal, anterior and posterior sacral foramina, median sacral crest, and auricular surfaces. Coccyx: terminal bone of the vertebral column, usually made of four fused vertebrae; includes a base, apex, and coccygeal cornua. 15. Thoracic cage and pectoral girdle Thoracic cage: thoracic vertebrae, ribs, costal cartilages, and sternum. Pectoral girdle: clavicle and scapula. Scapular landmarks include the spine, acromion, coracoid process, glenoid cavity, and borders. Clavicle landmarks include the sternal and acromial ends. 16–17. Sternum and costal cartilage The three parts of the sternum are the manubrium, body, and xiphoid process. Ribs attach to the sternum through hyaline cartilage, called costal cartilage. 18–19. Rib anatomy and rib groups Rib landmarks: head, neck, tubercle, angle, shaft/body, and costal groove. The head articulates with vertebral bodies; the tubercle articulates with the transverse process of a thoracic vertebra. Rib 1: short, broad, strongly curved; has grooves for subclavian vessels and a scalene tubercle. Ribs 2–10: generally have a head, neck, tubercle, angle, and shaft; most connect to the sternum directly or indirectly through costal cartilage. Ribs 11–12: floating ribs; have no anterior attachment to the sternum and generally lack a neck and tubercle. 20–23. Floating ribs and rib articulation Ribs 11 and 12 are floating ribs because their anterior ends do not attach to the sternum or to another rib's costal cartilage. Humans typically have 12 pairs of ribs, though anatomical variations occur. A typical rib, such as rib 6, articulates posteriorly with the bodies of two adjacent thoracic vertebrae and the transverse process of its corresponding vertebra. Anteriorly, rib 6 connects to the sternum through its own costal cartilage. 24–25. Additional figures and textbook review questions Figures 8.30–8.42 and the “Before You Go On” questions on pages 232, 245, 255, 259, and 268 were not visible in the uploaded file. The following structures are useful review targets, but exact labels and answers should be checked against the original figures/pages. Page 4 Chapter 8 — Skeletal System Review Major bones: clavicle, scapula, humerus, radius, ulna, carpals, metacarpals, phalanges, ilium, ischium, pubis, femur, patella, tibia, fibula, tarsals, and metatarsals. Important landmarks: greater and lesser tubercles of the humerus, olecranon of the ulna, head of the radius, acetabulum, obturator foramen, greater trochanter, tibial tuberosity, and malleoli. 26–27. Male and female skeleton; pelvis The male skeleton is generally larger, heavier, and more robust, with more prominent muscle attachment markings. The pelvis is typically narrower and deeper. The female skeleton is generally lighter, with a broader, shallower pelvis. These are general patterns, not universal differences. The female pelvis typically has a wider, more circular pelvic inlet; larger pelvic outlet; broader subpubic angle; shorter, wider, less curved sacrum; more laterally oriented ischial spines; and a wider pelvic cavity. These features provide more space for childbirth. Part 2 — Joints, Ligaments, and Tendons Types of joints Structural type Functional classification Fibrous Usually synarthrotic (immovable) Example Skull sutures Cartilaginous Synovial Parts of a synovial joint Often amphiarthrotic (slightly movable) Diarthrotic (freely movable) • Articular cartilage: smooth cartilage covering bone ends. • Joint cavity: space containing synovial fluid. • Joint capsule: encloses the joint. • Fibrous capsule: tough outer layer of the joint capsule. • Synovial membrane: inner layer that produces synovial fluid. • Synovial fluid: lubricates the joint and helps nourish articular cartilage. • Ligaments: connect bone to bone. • Bursae: small fluid-filled sacs that reduce friction between moving tissues. Pubic symphysis Knee joint • Tendon sheaths: tubular coverings around certain tendons that reduce friction. Ligaments vs. tendons Ligaments connect bone to bone. Tendons connect muscle to bone. Rotator cuff muscles — SITS Supraspinatus, Infraspinatus, Teres minor, Subscapularis. These muscles stabilize the shoulder joint and help control shoulder movement. Important ligaments and structures • Hip: ligamentum teres femoris. • Knee: anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), lateral collateral ligament (LCL), menisci, and patellar tendon. Page 5 Chapter 8 — Skeletal System Review • Foot: Achilles (calcaneal) tendon. • Vertebral column: anterior longitudinal ligament, posterior longitudinal ligament, ligamentum flavum, interspinous ligament, supraspinous ligament, and ligamentum nuchae.