Bones

Hyoid Bone

  • Location: Head and neck area, specifically in the neck.
  • Unique Characteristics:
    • Does not attach to any other bone in the body, akin to the patella.
    • Is held exclusively by tendons and ligaments.
    • Appears as a collar-like structure.
  • Function:
    • Aids in swallowing.
    • Provides structural support to the larynx.
    • Important for breathing.
  • Forensic Relevance:
    • A broken hyoid bone may indicate strangulation or severe neck trauma, requiring intentional force to break.

Soft Spot in Fetal Skull

  • Definition: Areas where the sutures of the fetal skull have not fully formed.
  • Risks:
    • Sensitive area where pressure could lead to brain damage in infants.
  • Development:
    • Sutures close as a person ages, fully formed by early to mid-twenties.

Vertebrae Overview

  • Count:
    • Generally, 24 individual vertebrae.
    • Includes fused vertebrae, totaling 32 to 25 depending on the individual.
  • Regions Divided Into:
    • Cervical (7 vertebrae)
    • Thoracic (12 vertebrae)
    • Lumbar (5 vertebrae)
    • Sacrum (5 fused vertebrae)
    • Coccyx (fused vertebrae).

Cervical Vertebrae

  • Characteristics:
    • Small and easily identifiable.
    • Labeled C1 to C7.
    • C3 to C7 possess transverse foramina for blood vessels.
  • Special Types:
    • C1 (Atlas): Supports the skull, unique in structure with large openings for spinal cord entry.
    • C2 (Axis): Contains the dens allowing head rotation.

Thoracic Vertebrae

  • Count: 12
  • Characteristics:
    • Heart-shaped bodies, costal facets for rib attachment.
    • Distinctly look like a giraffe when viewed from posterior.

Lumbar Vertebrae

  • Count: 5
  • Characteristics:
    • Thick and robust to support body weight.
    • Spinous processes are oriented more horizontally.
    • Resemble a moose when viewed from the side.

Sacrum and Coccyx

  • Sacrum: 5 fused vertebrae; fuses completely by late twenties.
  • Coccyx (Tailbone): Smaller fused vertebrae starting to fuse around puberty.

Basic Structure of Vertebrae

  • All vertebrae share structural similarities:
    • Spinous Process: For muscle attachment.
    • Transverse Process: Various muscles and rib attachments.
    • Intervertebral Foramina: Allowing nerves to exit the spinal column.
    • Vertebral Body: Thick part supporting weight.
    • Vertebral Foramen: Where spinal cord passes through.

Thoracic Cage

  • Components: Ribs and sternum.
  • Vertebrae Articulation: All ribs articulate with thoracic vertebrae.
  • Rib Types:
    • True Ribs (1-7): Attach directly to the sternum.
    • False Ribs (8-12): Do not attach directly to the sternum.
    • Floating Ribs (11-12): No direct cartilage attachment to the sternum.
  • Sternum Anatomy:
    • Manubrium: Top portion.
    • Body: Central portion.
    • Xiphoid Process: Lower point of the sternum.

Clavicle and Scapula

  • Clavicle:
    • Spoon-shaped, attaching to the sternum and scapula.
    • Key parts: Sternal end, acromial end, costal tuberosity.
  • Scapula:
    • Composed of anterior and posterior sides with the spine visible on the back.
    • Key features: Acromion, coracoid process, glenoid cavity.

Humerus

  • Upper Arm Bone: Only bone in the upper arm.
  • Key Features:
    • Head: Rests in the glenoid cavity.
    • Deltoid Tuberosity: Where the deltoid muscle attaches.
    • Capitulum and Trochlea: For articulation with forearm bones.

Radius and Ulna

  • Radius:
    • Located on the thumb side.
    • Features: Head, tuberosity, styloid process.
  • Ulna:
    • Located on the pinky side, shaped like a claw at the top.
    • Features: Trochlear notch, coronoid process, head, styloid process.

Hand Anatomy

  • Metacarpals: 5 long bones in the hand, numbered 1-5 starting from the thumb.
  • Phalanges: Finger bones:
    • For fingers 2-5: Proximal, middle, distal phalanges.
    • For thumb (pollex): Proximal and distal phalanges.

Carpals

  • Names of Carpal Bones:
    1. Proximal Row: Scaphoid, lunate, triangular, pisiform.
    2. Distal Row: Trapezium, trapezoid, capitate, hamate.

Pelvis Structure

  • Components: Comprised of fused bones: ilium, ischium, pubis.
  • Key Features: Acetabulum, pelvic inlet, subpubic angle.
  • Differences in Male and Female Pelvis: Male pelvis is narrower; female pelvis is wider for childbirth.

Development of the Skeleton

  • Begins in week 4 of fetal development as cartilage.
  • Fully developed limbs (including fingers and toes) are formed by week 8.

Review and Practice

  • Engage in drawing and labeling the bones and their structures.
  • Participate in quizzes or practical activities to solidify the knowledge on bones and anatomy.