Introduction to Osteology and Joints

  1. Introduction to the Human Skeleton

    • Total of 206 bones in the human body.

    • Breakdown of Bones:

      • 14 facial bones, most are paired (meaning most have a corresponding bone on the opposite side).

  2. Mandible

    • Definition: The mandible, or lower jaw bone, contains the lower teeth.

    • Notable Feature: It is the only truly movable joint in the skull.

    • Temporomandibular Joint (TMJ):

      • Articulates the temporal bone with the mandible.

      • Movement of the jaw can cause a depression or click at the joint when pressing around the ears.

    • Consequence of a Broken Mandible:

      • When broken, the mandible must be wired for stabilization, restricting movement.

      • Affected individuals may eat or drink solely through straws due to the inability to open the mouth.

  3. Bruxism

    • Definition: A condition characterized by involuntary teeth grinding.

    • Causes: May occur due to pain, stress, or as a response to traumatic brain injuries.

    • Impact of Bruxism:

      • Often occurs alongside conditions like a broken or dislocated mandible.

      • Individuals may not be aware they are grinding their teeth, possibly due to pain or neurological conditions.

  4. Maxilla

    • Definition: Top portion of the mouth formed by two maxillary bones.

    • Functions:

      • Forms the upper jaw and affects the structure of the nasal cavity and eye orbits.

      • Contains the palatine process, which forms the anterior portion of the hard palate.

  5. Palatine Bones

    • Definition: Two palatine bones that form the posterior part of the hard palate and the floor of the nasal cavity.

    • Clinical Connection:

      • Potential congenital conditions such as cleft palate may arise from complications during pregnancy (e.g., alcohol consumption or exposure to certain medications).

      • Cleft palate can hinder a baby 's ability to suckle, leading to nutritional concerns.

  6. Zygomatic Bones

    • Definition: Also known as cheekbones, they are part of the eye orbits.

  7. Nasal Bones

    • Definition: The two nasal bones form the bridge of the nose.

    • The shape of the nose is maintained by cartilage situated above the nasal bones.

  8. Other Facial Bones

    • Glacial bones, glomer, and inferior nasal conchae are additional facial bones with less clinical focus.

    • Hyoid Bone:

      • U-shaped bone located in the upper neck, anchoring the tongue.

      • Susceptible to fracture in cases of hanging.

    • Middle Ear:

      • Contains six ossicles (three in each ear), integral to hearing.

  9. Sinuses

    • Definition: Air-filled cavities within the skull bones.

    • Purpose:

      • Lighten the weight of the skull and modulate voice sound.

    • Types of Sinuses:

      • Frontal, ethmoidal, sphenoidal, and maxillary sinuses.

    • Clinical Condition:

      • Sinusitis: Inflammation of the sinuses that can spread due to interconnected nasal passages.

  10. Sutures

    • Definition: Immovable joints that connect skull bones.

    • Types of Sutures:

      • Coronal: between the frontal and parietal bones.

      • Sagittal: between the left and right parietal bones.

      • Lambdoidal: between occipital and parietal bones.

      • Squamous: between parietal and temporal bones.

    • Infant Skull Characteristics:

      • Fontanels (soft spots) allow for flexibility during childbirth, eventually fusing by age two.

      • Early fusion of sutures can lead to conditions such as microcephaly (impaired brain development) or hydrocephalus (excessive fluid in the brain).

  11. Vertebral Column

    • Definition: Also known as the spine or backbone, consisting of 26 vertebrae separated by intervertebral discs.

    • Functions: Supports the head and torso, protects the spinal cord, provides flexibility.

    • Regions:

      • Cervical (C1-C7): 7 vertebrae

      • Thoracic (T1-T12): 12 vertebrae

      • Lumbar (L1-L5): 5 vertebrae

    • Mnemonic for Remembering the Number of Vertebrae:

      • Breakfast at seven (C), Lunch at twelve (T), Dinner at five (L).

    • Importance of key landmarks (C7: prominent bump in the neck) and other recognizable features.

  12. Curvatures of the Spine

    • Normal Curvatures:

      • Cervical and lumbar curves are anteriorly convex; thoracic and sacral are posteriorly convex.

      • The cervical curvature develops after several months of life; lumbar curvature emerges as the infant begins to stand and walk.

    • Abnormal Curvatures:

      • Scoliosis: Lateral (S-shaped or C-shaped) curvature of the spine, may impair respiratory function if severe.

      • Kyphosis: Abnormal posterior thoracic (hunchback or roundback) curvature, often related to osteoporosis.

      • Lordosis: Abnormal anterior (swayback) curvature, which can occur during pregnancy or due to obesity.

  13. Thoracic Cage

    • Definition: Comprises the sternum and ribs protecting vital organs and facilitating breathing.

    • Components of the Sternum:

      • Manubrium (top part), body, xiphoid process (tip).

    • Ribs:

      • Total = 12 ribs: 7 true ribs (attach directly to the sternum) and 5 false ribs (includes floating ribs).

  14. Appendicular Skeleton

    • Components:

      • Upper limbs and lower limbs, shoulder girdle, and pelvic girdle.

    • Function: Allows for movement and supports weight.

  15. Upper Limb Bones

    • Clavicle: Also known as the collarbone, easily broken.

    • Scapula: Also known as the shoulder blade, connects with the humerus to facilitate movement.

    • Humerus: The upper arm bone.

    • Forearm Bones: Radius (lateral side) and ulna (medial side).

  16. Movements of the Forearm

    • Pronation: The palm faces downward.

    • Supination: The palm faces upward.

  17. Pelvic Girdle

    • Composed of two coxal bones, sacrum, and coccyx.

    • The pelvic girdle supports the body and protects organs in the pelvic cavity.

    • Differences between Male and Female Pelvis:

      • Female pelvis is broader and designed for childbirth; male pelvis is narrower and heavier.

  18. Lower Limb Bones

    • Major Bones:

      • Femur: The largest bone in the body.

      • Tibia: The shinbone, larger and bears weight.

      • Fibula: Thinner bone alongside tibia.

      • Patella: The kneecap, triangular in shape.

  19. Joints

    • Definition: Points where bones articulate; essential for movement and flexibility.

    • Types of Joints:

      • Immovable: (e.g., sutures of the skull)

      • Slightly movable: (e.g., symphysis pubis)

      • Freely movable: (e.g., synovial joints)

    • Synovial Joint Structure:

      • Articular cartilage, joint capsule, synovial fluid for lubrication.

    • Common Movements:

      • Flexion, extension, hyperextension