Skull Vertebral column 66

Human Skeleton Overview

General Structure

The human skeleton consists of:

  • Cranium: Protects the brain

  • Facial bones: Provides structure to the face

  • Clavicle: Connects the arm to the body

  • Thoracic cage: Protects vital organs (ribs and sternum)

  • Vertebral column: Supports the body and protects the spinal cord

  • Limbs (Humerus, Radius, Ulna, etc.): Allows for movement

Functions of the Skeleton

  • Support: Provides structure to the body.

  • Movement: Facilitates movement by serving as levers for muscle action.

  • Protection: Shields vital organs (e.g., cranium protects the brain).

Skull Composition

Bone Structure

22 bones categorized into two groups:

  • Cranial Bones (8):

    • Enclose the brain in the cranial cavity

    • Provide attachment points for muscles

    • Offer structural support

  • Facial Bones (14):

    • Framework of the face

    • Create cavities for senses of sight, taste, and smell

    • Include openings for air and food passage

    • Serve as attachment points for teeth and facial muscles

Cranial and Facial Bones

  • Cranial Bones:

    • Frontal, Parietal (2), Occipital, Temporal (2), Sphenoid, Ethmoid

  • Facial Bones:

    • Mandible, Maxillary bones (maxillae) (2), Zygomatic bones (2), Nasal bones (2), Lacrimal bones (2), Palatine bones (2), Vomer, Inferior nasal conchae (2)

Skull Sutures and Fontanelles

Major Sutures

  • Lambdoid suture: between occipital and parietal bones

  • Parietal suture: connects left and right parietal bones

  • Sagittal suture: divides the left and right sides

  • Coronal suture: between frontal and parietal bones

Fontanelles

Soft regions of connective tissue in infants: permit brain growth and entry into the birth canal.

  • Anterior fontanelle: replaced by bone approx. 1.5 years old.

  • Posterior fontanelle: replaced by bone approx. 1 year old.

Openings in the Skull

Allow passage for blood vessels and nerves. Approximately 85 named openings: foramina, canals, fissures.

  • Largest opening: Foramen magnum.

Sinuses

Paranasal Sinuses

Lighten the skull and serve as resonation chambers for voice. Include:

  • Frontal sinus

  • Sphenoidal sinus

  • Maxillary sinus

  • Ethmoid air cells

Sinusitis

Inflammation of sinuses, can cause discomfort and complications.

Vertebral Column

Structure and Function

Comprised of 26 vertebrae and intervertebral discs. Functions:

  • Protection of the spinal cord

  • Support for the body

  • Movement flexibility

Vertebral Types

  • Cervical (C1-C7): 7 vertebrae, including Atlas (C1) and Axis (C2).

  • Thoracic (T1-T12): 12 vertebrae.

  • Lumbar (L1-L5): 5 vertebrae.

  • Sacrum: 5 fused vertebrae.

  • Coccyx: 4 fused vertebrae.

Vertebral Column Curvatures

Curvatures increase resilience and flexibility:

  • Posteriorly concave: Cervical and lumbar

  • Posteriorly convex: Thoracic and sacral

Abnormal Curvatures

  • Scoliosis: Abnormal lateral curve.

  • Kyphosis: Hunchback.

  • Lordosis: Swayback.

Important Anatomical Structures

Vertebrae Anatomy

Key components: Lamina, Vertebral body, Spinous process, Transverse processes, and various ligaments. Intervertebral discs: Absorb shock between vertebrae.

Vascularization

Important blood vessels associated with the vertebrae:

  • Vertebral artery: Supplies blood to the brain.

  • Branches include anterior and posterior meningeal branches.