Musculoskeletal System

• Axial skeleton

  Made up of the skull, vertebrae, sternum, ribs, sacrum, and coccyx
• Functions of the skull

  • Protect the brain and brainstem
  • Protect sensory organs
  • Provide attachment sites for muscles
• Skull

  Consists of the cranial bones and facial bones
• Bones in the skull

  • 22 bones, 8 cranial and 14 facial
• Sutures

  Fibrous joints made of dense fibrous connective tissue to allow very small amounts of movement
• Sutures in the skull

  • Coronal suture
  • Sagittal suture
  • Lambdoid suture
  • Squamous suture
• Pterion


  A mark between the parietal, temporal, sphenoid, and frontal bones. There is less protection in this area
• Synostosis


  The fusion of 2 or more bones
• Craniosynostosis


  The premature fusion of cranial sutures
• Types of craniosynostosis

  • Sagittal craniosynostosis
  • Bicoronal craniosynostosis
• Temporomandibular joint (TMJ)

  A synovial condyloid joint which articulates with the mandibular fossa on the temporal bone and the condyle of the mandible. It has an articular disc made of fibrocartilage to improve congruence, allowing for gliding and hinge movement
• Movements of the TMJ

  Depression, elevation, retraction, and protrusion
• Mandible


  • Has a condylar process which articulates with the temporal bone to form the TMJ
  • Has sites for muscle attachments including the coronoid process and ramus
  • Has alveolar processes for teeth
• Temporalis muscle


  Originates at the coronoid process and attaches distally to the temporal lines on the temporal bone. Allows depression/elevation and side to side movement for chewing
• Masseter muscle


  Originates at the zygomatic arch and attaches to the ramus and angle of the mandible. Allows elevation for chewing
• Singular facial bones

  • Mandible
  • Vomer
• Paired facial bones

  • Maxilla
  • Zygomatic
  • Palatine
  • Nasal
  • Lacrimal
  • Inferior nasal conchae
• Singular cranial bones

  • Frontal
  • Ethmoid
  • Sphenoid
  • Occipital
• Paired cranial bones

  • Temporal
  • Parietal
• Frontal bone


  Forms the forehead and contributes to the upper margin of each orbital cavity
• Supraorbital notch/foramen


  Contains the supraorbital artery, nerve, and vein
• Supraorbital ridge/superciliary arch


  Forms the eyebrows
• Trigeminal ganglion


  At the base of the brain, and splits to form the ophthalmic nerve (upper third of face), the maxillary nerve (middle third of the face), and the mandibular nerve (lower third of face)
• Supraorbital nerve


  Supplies the skin and muscles of the forehead
• Orbital cavities

  Margins formed by the frontal, zygomatic, and maxilla bones to house the eyeball, eyeball muscles, and neurovasculature
• Nasal cavity

  Margins formed by the maxilla and nasal bones, while the vomer and ethmoid form the nasal septum
• Temporal bone

  • Has the mandibular fossa, zygomatic process, mastoid process, and external acoustic meatus opening/tympanic part
  • Allows for attachment of neck muscles and an opening for the ear canal
• Occipital bone


  Forms the posterior wall of the skull and has an external occipital protuberance which is important for muscle attachment
• Foramen magnum


  Allows for the passage of the spinal cord
• Occipital condyles


  Articulate with the cervical spine
• Sphenoid bone


  • Looks like a butterfly and has a number of foramen
• Ethmoid bone


  Has perforations for olfactory nerves
• Sphenoid bone


  Has hypophyseal/pituitary fossa
• Foramina in the sphenoid bone

  • Foramen rotundum
  • Foramen ovale
• Regions of the base of the skull

  • Anterior cranial fossa
  • Middle cranial fossa (2)
  • Posterior cranial fossa
  • Pituitary/hypophyseal fossa
• Anterior cranial fossa


  Contains the lower frontal lobes
• Middle cranial fossa


  Contains the temporal lobes
• Posterior cranial fossa


  Contains the cerebellum
• Pituitary/hypophyseal fossa


  Contains the pituitary gland
• Kyphosis


  Posterior curvature of the spine, is superior