Anatomy and Physiology - Skeletal System (Part 1)

Anatomy and Physiology - Skeletal System (Part 1)

• Learning Outcomes: Students will understand the functions of the skeletal system, describe the structure of compact and spongy bone, understand osteogenesis, the structure and types of axial and appendicular skeletons, and describe joint types and movement.

The Skeletal System: An Introduction

• The skeletal system comprises bones, major bone cells, cartilages, ligaments, and connective tissues stabilizing and connecting bones.

Functions of the Skeletal System

• Support: Provides structural framework for the body.
• Movement: Works with muscles for locomotion.
• Protection: Shields internal organs.
• Storage of Minerals and Lipids: Stores calcium and phosphorus; stores energy as fat.
• Blood Cell Production: Red bone marrow produces blood cells.

Structures of Bone

• Diaphysis: Bone shaft.
• Epiphyses: Ends of long bones.
• Metaphysis: Region between diaphysis and epiphyses.
• Articular Cartilage: Smooth, covering bone ends at joints.
• Marrow Cavity: Space inside the diaphysis filled with bone marrow.
• Bone Marrow: Red (blood cell formation) or yellow (fat storage).

Compact Bone and Spongy Bone

• Compact bone: Organized into osteons (Haversian systems). Osteocytes arranged around a central canal (Haversian canal).
• Lamellae: Layers of compact bone.
• Canaliculi: Channels connecting osteocytes.
• Perforating canals (Volkmann's canals): Channels connecting central canals.
• Trabeculae: Network of bony rods in spongy bone (no central canal)

Bone Histology

• Outer lamellae: Layers of compact bone surrounding bone.
• Osteon: Functional unit of compact bone.
• Haversian canal: Central canal of osteon containing blood vessels.
• Periosteum: Outer covering of bone.
• Endosteum: Inner covering of bone.
• Lacunae: Small spaces containing osteocytes.
• Perforating canals: Channels connecting osteons.
• Trabeculae: Network of bony rods in spongy bone.

Osseous Tissue and Bone Cells

• Osseous tissue: Supporting tissue with a solid matrix, hydroxyapatite crystals, and minerals in lamellae. Covered by periosteum.
• Osteoprogenitor cells: Immature bone cells, differentiate into osteoblasts.
• Osteoblasts: Synthesize new bone matrix (osteoid). Involved in osteogenesis.
• Osteocytes: Mature bone cells in lacunae, connected by canaliculi.
• Osteoclasts: Dissolve bone matrix (osteolysis).

Bone Development and Growth

• Ossification: Converting cartilage to bone tissue.
• Calcification: Depositing calcium salts within tissues (hardening).

Ossification Types

• Intramembranous ossification: Begins with osteoblast differentiation, forming dermal bones at ossification centers. Typical for flat bones.
• Endochondral ossification: Cartilage model gradually replaced by bone at metaphysis, increasing bone length. Appositional growth increases bone diameter.

The Skeleton as a Calcium Reserve

• 99% of the body's calcium is in the skeleton.
• Calcium ion concentration is regulated by the GI tract and kidneys (which produce calcitriol).
• Calcitonin (thyroid gland) and PTH (parathyroid hormone) regulate blood calcium levels.
• Calcitonin decreases blood calcium levels. PTH increases blood calcium levels.

Fracture Repair

• Fracture hematoma: Blood clot forms at break site.
• External callus: Cartilaginous tissue forms around fracture.
• Internal callus: Bone tissue forms within fracture.

Bone Classification

• Long bones: Longer than wide (e.g., humerus, femur).
• Short bones: Roughly cube-shaped (e.g., carpals, tarsals).
• Flat bones: Thin, flattened (e.g., skull bones, ribs).
• Irregular bones: Complex shapes (e.g., vertebrae, facial bones).
• Sesamoid bones: Small, flat, embedded in tendons (e.g., patella).
• Sutural bones: Small bones within sutures of skull.

Division of Skeleton

• Axial Skeleton: Skull, vertebral column, ribs, sternum (80 bones)
• Appendicular Skeleton: Pectoral girdle, upper limbs, pelvic girdle, lower limbs (126 bones)

Openings and Features in Bone

• Fissure: Narrow slit between adjacent bones.
• Foramen: Round opening for blood vessels and nerves.
• Fossa: Shallow depression.
• Sulcus: Furrow along a bone surface.
• Meatus: Tubelike opening.

Processes Forming Joints

• Condyle: Large rounded projection
• Facet: Smooth flat articular surface
• Head: Rounded articular projection

Processes for Attachment Points of Connective Tissue

• Crest: Prominent elongated projection.
• Epicondyle: Projection above condyle.
• Line: Long and narrow ridge.
• Trochanter: Very large projection.
• Tubercle: Knob or rounded projection
• Tuberosity: Large, rounded, and roughened projection.

Cranium Bones

• Parietal (2): Sides and roof of the skull
• Temporal (2): Inferior to parietal, contain auditory meatus
• Frontal (1): Forehead, anterior cranium, orbits
• Occipital (1): Posterior cranium, foramen magnum
• Sphenoid (1): Middle part of skull base.
• Ethmoid (1): Anterior to sphenoid, supports nasal cavity.

Face Bones

• Nasal (2): Superior border of external areas, bridge of the nose.
• Maxillae (2): Largest facial bones, upper jaw and hard palate.
• Zygomatic (2): Cheekbones, temporal process.
• Lacrimal (2): Medial in orbit, posterior/lateral to nasal bone.
• Palatine (2): L-shaped bones, posterior hard palate.
• Mandible (1): Strongest facebone, lower jaw.
• Vomer (1): Inferior portion of the nasal septum.

Hyoid Bones

• Unpaired U-shaped bone.
• Suspended from styloid processes of temporal bone via ligaments and muscles.
• Supports the larynx.
• Auditory ossicles: 6 (Malleus, Incus, Stapes) in the middle ear.

Vertebral Column

• Composed of vertebrae, sacrum, and coccyx.
• Regions: Cervical (7), Thoracic (12), Lumbar (5), Sacrum (1), Coccyx (1).
• Sacrum and coccyx are fused vertebrae.

Spinal Curvatures

• Four spinal curves: Cervical and lumbar are convex, Thoracic and sacral are concave.
• Abnormal curves include scoliosis, kyphosis, and lordosis.

Vertebral Anatomy

• Body and vertebral arch.
• Pedicle and roof (arch) of vertebral arch
• Superior and inferior articular processes
• Transverse process
• Separated by intervertebral discs.

Ligaments of Vertebral Column

• Ligamentum flavum
• Intertransverse ligament
• Posterior longitudinal ligament
• Anterior longitudinal ligament
• Supraspinous ligament
• Interspinous ligaments

Cervical Vertebrae

• Atlas (C1): Distinctive shape, no body.
• Axis (C2): Large vertebral foramen, dens (odontoid process) that protrudes superiorly.
• Notched (v shape) spinous processes
• Transverse processes with transverse foramina (vertebral arteries passing toward the brain).

Thoracic Vertebrae

• Heart-shaped body
• Long, slender spinous processes
• Extra articular facets on transverse process for rib attachment
• Small vertebral foramen compared to spinal vertebrae.

Lumbar Vertebrae

• Large, thick body
• Most massive of vertebrae
• Least mobile
• Superior articular facets face medially, subjected to great stress

Sacrum & Coccyx

• Fused sacral vertebrae.
• Protects reproductive, digestive, and urinary organs.
• Articulates with the pelvic girdle.
• Spinous processes from the first to fourth sacral vertebrae form a medial sacral crest.

Thoracic Cage

• Ribs (1-7 true ribs, 8-10 false ribs, 11-12 floating ribs).
• Sternum (manubrium, body, xiphoid process).

Appendicular Skeleton

• Pectoral girdle: Scapula and clavicle (shoulder).
• Upper limbs: Humerus, ulna, radius, carpals, metacarpals, phalanges.
• Pelvic girdle: Hip bones (ilium, ischium, pubis).
• Lower limbs: Femur, tibia, fibula, patella, tarsals, metatarsals, phalanges.

Pectoral Girdle (Shoulder Girdle)

• Articulates the upper limbs with the trunk.
• Consists of the clavicle and scapula.
• Clavicle and scapula position the shoulder joint.
• Scapula markings are attachment sites for tendons and ligaments of shoulder joint

The Upper Limbs

• Humerus (arm)
• Radius and Ulna (forearm)
• Carpals (wrist)
• Metacarpals (palm)
• Phalanges (fingers)

The Pelvic Girdle and Lower Limbs

• More massive than the pectoral girdle.
• Two coxal bones.
• Fusion of the ilium, ischium, and pubis.
• Subdivided into the false (greater) and true (lesser) pelvis.
• Ilium: Largest hip bone, within acetabulum. Fused to the ischium (posteriorly) and pubis (anteriorly).
• Pubic: Pubic symphysis limits left to right movement.
• Pelvis: Composed of the hip bones, sacrum and coccyx.

The Lower Limbs

• Femur: Longest bone in the body, articulates with tibia at the knee.
• Patella: Large sesamoid bone.
• Fibula: Parallels tibia laterally.

The Knee Joint

• Hinge joint with an incomplete articular capsule.
• Formed by the condyles of the femur and the condylar surfaces of the tibia.
• Accessory structures stabilize lateral movements.
• Permits flexion/extension, limited rotation.
• Supported by ligaments.

Joint Problems with Aging

• Joint problems associated with aging.
• Rheumatism: General term for pain and stiffness in muscular and skeletal elements.
• Arthritis: All rheumatic diseases affecting synovial joints

Aging and the Skeletal System

• Osteopenia: Decreased bone density.
• Osteoporosis: Loss of bone density, increased risk of fracture.

Joint Movements

• Flexion: Decreasing the angle between two bones.
• Extension: Increasing the angle between two bones.
• Adduction: Movement toward the midline of the body.
• Abduction: Movement away from the midline of the body.
• Circumduction: Movement in a circular path.
• Rotation: Movement around a longitudinal axis.
• Supination: Palm faces anteriorly
• Pronation: Palm faces posteriorly
• Right/Left rotation: Rotation of head/spinal column to the right or left
• Medial/Lateral rotation: Rotation of leg/foot medially or laterally.
• Inversion: Sole of foot inward
• Eversion: Sole of foot outward
• Dorsiflexion: Ankle joint flexion upward
• Plantarflexion: Ankle joint flexion downward
• Opposition: Moving thumb across the palm to touch fingertips of other fingers.
• Reposition: Returning thumb to anatomical position.
• Protraction: Forward movement of body part.
• Retraction: Backward movement of body part.
• Elevation: Movement that raises a body part.
• Depression: Movement that lowers a body part.

Ligaments

• Connect two bones at a joint; they are elastic, strong, and tough.
• They strengthen the joint and limit movement to certain directions.

Tendons

• Connect muscles to bones; they are inelastic, strong, and tough.
• They help in joint movements and limit the movement of the muscle.

Intervertebral Articulations

• Gliding joints.
• Vertebral bodies form symphyseal joints cushioned by intervertebral discs (anulus fibrosus and nucleus pulposus).
• Stabilized by ligaments.

Elbow Joint

• Hinge diarthroses (permits only flexion and extension).
• Reinforced with strong ligaments.

Hip Joint

• Ball and socket diarthroses.
• Acetabulum and head of femur.
• Permits flexion/extension, abduction/adduction, circumduction, rotation.
• Stabilized by numerous ligaments.

Additional Notes:

• Pages 8-9, diagrams showing different bone structures.

This quiz covers the fundamental aspects of the skeletal system, including its functions, structures, and the types of skeletons. Students will explore the roles of bones, joints, and the processes involved in bone development. Perfect for those studying anatomy and physiology in detail.