Mod 4: Lecture 3 - Overview of the Skull and Tempromandibular Joint Flashcards
Divisions of the Cranium
- Neurocranium
- Viscerocranium
Neurocranium
- cranial vault
- bony covering of the brain and the cranial meninges
- contains proximal parts of the cranial nerves and the vasculature of the brain
- calvaria: dome-like roof
- cranial base: floor
Viscerocranium
- facial skeleton
- forms the anterior parts of the cranium
- consists of the bones
- — surrounding the mouth (upper and lower jaws)
- — surrounding the nose/nasal cavity
- — comprising most of the orbits (eye sockets or orbital cavities)
Superior View of the Skull
- somewhat egg-shaped outline
- —- small end is anterior
- four bones visible
- — anteriorly: frontal bone
- — laterally both right and left: parietal bones
- — posteriorly: occipital bone
Sutures of the Top of the Skull
- Coronal: separates frontal bone from parietal bones
- Sagittal/Interparietal: separates the right and left parietal bones
- Lambdoidal: separates the parietal and temporal bones from the occipital bone
- Bregma: the intersection of the sagittal and coronal sutures
- Lambda: the intersection of the lambdoidal and sagittal sutures
Posterior View of the Skull
- Bones visible: occipital, both parietals
- Sutures visible: sagittal, lambdoidal, lambda
- External Occipital Protuberance: a bump in the center about 2/3 down the occipital bone
- Occipital Condyles: on either side of the foramen magnum
- Superior and Inferior Nuchal Lines: areas of attachment for some neck and back muscles
- Mastoid Process: big sticking down thing by the jaw
- Styloid Process: thin sticking down thing anterior to the mastoid process
Frontal View of the Skull
- Bones:
- — right and left maxillae
- — right and left nasal
- — right and left zygomatic
- —- vomer: nasal septum
- —- frontal bone of skull
- — mandible
Apertures in the wall of the orbit
- Superior Orbital Fissure
- — CN III, IV, VI, V1 (1st branch of V)
- Inferior Orbital Fissure
- — CN V2 (2nd branch of V), infraorbital vessels
- Optic Canal
- — CN II, Ophthalmic artery
Lateral View of the Skull
- Temporal Lines
- Pterion
- Temporal Fossa
- External Auditory Meatus
- External Occipital Protuberance or Inion
- Styloid Process
- Mastoid Process
- Temporal Lines
2. Temporal Fossa
- curved ridge in the frontal and parietal bones that serves as the superior limit of the curved origin of the temporalis muscle
- — superior and inferior
- curved ridge in the frontal and parietal bones that serves as the superior limit of the curved origin of the temporalis muscle
- slightly depressed area on the anterolateral aspect of the skull inferior to the temporal lines
- — filled in by the temporalis muscle
- slightly depressed area on the anterolateral aspect of the skull inferior to the temporal lines
- Pterion
- the H shaped (H is on its side) region where the frontal, parietal, temporal, and greater wing of the sphenoid bones intersect
Styloid Process
- sharp slender process that angles inferiorly, medially, and anteriorly
- provides attachment for a number of muscles and two ligaments
- — stylohyoid ligament
- a portion of the tympanic plate wraps itself around the base of the styloid like a scroll
- this is the vaginal process of the temporal bone
- External Auditory Meatus
2. External Occipital Protuberance or Inion
- forms the entrance to the middle ear within the temporal bone
- occupies the central external aspect of the occipital bone
Mastoid Process
- lump of bone immediately posterior and inferior to the external auditory meatus
- serves as part of the insertion of the sternocleidomastoid muscle`
Skull Base
- Anterior Cranial Fossa
- Middle Cranial Fossa
- Posterior Cranial Fossa
Location and Nerves Going Through the Opening:
- Cribiform Plate
- Optic Canal
- Superior Orbital Foramen
- center of anterior fossa
- CN I
- center of anterior fossa
- center border of anterior and middle fossa
- CN II
- center border of anterior and middle fossa
- medial curved border of the anterior and middle fossa, on the side of the middle fossa
- CN III, IV, V1, VI
- medial curved border of the anterior and middle fossa, on the side of the middle fossa
Location and Nerves Going through the Opening:
- Foramen Rotundum
- Foramen Ovale
- Foramen Lacerum and Foramen Spinosum
- little circle directly below the superior orbital fissure
- CN V2
- little circle directly below the superior orbital fissure
- biggish circle below the foramen rotundum
- V3
- biggish circle below the foramen rotundum
- tiny holes right below the foramen ovale
- one on each side of it
- no nerves
- tiny holes right below the foramen ovale
Location and Nerves Going through the Opening:
- IAM: internal auditory meatus
- Jugular Foramen
- Hypoglossal Canal
- in the medial curved border of the middle and posterior fossa on the posterior side
- CN VII, VIII
- in the medial curved border of the middle and posterior fossa on the posterior side
- big hole in the posterior fossa, below the IAM
- CN IX, X, XI
- big hole in the posterior fossa, below the IAM
- in the rim of the foramen magnum
- CN XII
- in the rim of the foramen magnum
Clivus
- the slope of bone going up from the foramen magnum to the center of the middle fossa
Normal Basalis: Anterior Region
- the bottom of the skull, if the lower jaw is removed
- Hard palate: roof of the mouth
- — two bones
- Posterior Nasal Spine: a midline posterior projection from the posterior border of the bony plate
Hard Palate
- roof of the mouth
- Maxillae: palatal processes
- — the anterior 2/3
- — where the teeth fit in
- — incisive foramen: transmits the nasopalatine nerve and vessels
- Palatine Bones: horizontal processes
- —- the posterior 1/3
- — ending as a double crescent shaped posterior free border (no bones in the back of it)
- — greater palatine canal
Greater Palatine Canal opens as the….
- greater palatine foramen onto the horizontal process of the palatine bone
- — in line with the last maxillary molar
- — transmits the greater palatine nerve and vessels
- lesser palatine foramen
- — posterior to the greater palatine foramen
- — transmits the lesser palatine nerve and vessels
Features of the Norma Basalis From Lateral to Medial
- mastoid process of the temporal bone
- stylomastoid foramen: lies between the styloid and the mastoid processes
- — allowing passage of the facial nerve (CN VII) from within the temporal bone
- styloid process
- Foramen Ovale
Intermediate area of the Norma Basalis
- mandibular fossa: which accommodates the condyle of the mandible
- — mandible not seen, just a big dent where it should be
- tympanic plate: forms the anterior wall of the external auditory meatus and the posterior wall of the mandibular fossa
- external auditory meatus: lies behind the mandibular fossa
Middle area of the Norma Basalis
- Jugular Foramen: a large opening through which the internal jugular vein and cranial nerves IX, X, and XI pass
- Carotid Canal: immediately anterior to the jugular foramen and separated from it only by a small wedge of bone
Posterior Section of the Norma Basalis
- Foramen Magnum
- Occipital Condyles: bumps on each side of the foramen magnum
- Hypoglossal canal: in the rim of the foramen magnum
Temporomandibular Joint (TMJ)
- named for the two bones that comprise the joint
- — temporal and mandible
- modified hinge joint
- articular tubercle: a jutting out of the zygomatic process of the temporal bone right next to the mandibular fossa
- — keeps the condyle in the fossa
- mandibular fossa: where the mandible connects to the temporal bone
- condyle of the mandible: the part of the mandible that fits into the fossa
Mandible Features
- condyle: the posterior process, the one that fits into the fossa
- coronoid process: the smaller anterior process
- Ramus: the body
Movements of the Mandible
- elevation/depression: closing/opening the jaw
- protrusion/retrusion: overbite/underbite
- lateral excursion: side to side motion of teeth grinding
Muscles of Mastication
- Temporalis
- Masseter
- Lateral Pterygoid
Temporalis
- Attachments
- Action
- Innervation
- temporal fossa (parietal and temporal bones)
- tip of coronoid process on the mandible
- temporal fossa (parietal and temporal bones)
- gives a lot of force behind bite
Masseter
- Attachments
- Action
- Innervation
- has a deep and superficial part
1. - zygomatic bone and arch - angle and lateral surface/ramus of the mandible
2. close the jaw
Lateral Pterygoid
- Attachments
- Action
- Innervation
- goes laterally over the TMJ
- deep to the masseter
1. - two heads: from sphenoid - both: capsule, disc, condyle
2. - protrusion of the lower jaw
Medial Pterygoid
- Attachments
- Action
- Innervation
- deep to the masseter
- diagonal, below the lateral pterygoid
1. - lateral pterygoid plate - tuberosity of maxilla
- medial ramus of mandible
- — jaw angle, the square corner