Anatomy - Week 10 PP Flashcards
Osteology
-The study of bones
-Bones cover and protect the internal structures
-Bones serve as landmarks for us
Skeletal Terminoloy
Articulation - is an area of the skeleton where the bones are joined to eachother. They can be either movable or immovable (joined together)
Sutures - appear on the skulls as “cracks”. Firm joining of two or more bones (where two bones are coming together - wiggly look)
Joint - is the moveable junction of two or more bones (TMJ is an example, knee, elbow)
Process - is an extension of a bone
Fossa - is a depression in a bony surface, a place for a joint or muscle attachment to be located
Bony Openings
- The cranium has a number of holes called foramina (singular, foramen).
◦ Major blood vessels supply the brain with blood through foramina into the cranium - Meatus: canal-like opening into a bone from outside of the body [external] as in the opening to the ear
Foramina
- Mental Foramen
-Foramen Magnum - largest hole in skull
-Supraorbital
-Infraorbital Foramen
Cranium has a total of 8 bones..
◦ Frontal: Single
◦ Parietal: Paired
◦ Occipital: Single
◦ Temporal: Paired
◦ Sphenoid: Single
◦ Ethmoid: Single
How many facial bones?
14 facial bones
How many bones in the skull total? (excluding ossicles in the inner ear)
22 bones in total
Frontal Bone - Single
- Forms the forehead, part of the floor of the cranium and most of the roof of the orbits
- Contains the two frontal sinuses
- The frontal bone protects the frontal lobe of the brain, which is largely involved with motor and control functions of the body
Parietal Bones
- Paired
-Forms most of the roof and the upper sides of the cranium
-Joined by the sagittal suture at the midline of the skull
-The suture between the frontal bone and the parietal bones, is the coronal sture
Occipital Bone - Single
-Forms the back and base of the cranium
-Joins the parietal bones at the lambdoidal suture
-The spinal cord passes through the foramen magnum of this bone, to join with the brain
Temporal Bones - Paired
Paired (2)
-Form the sides and base of cranium
-Enclose the ear and contain the external auditory meatus (bony passage of the outer ear)
* Extend toward the zygomatic bone (check bones)
* Have a depression, called the glenoid fossa into which the lower jaw articulates
Sphenoid Bone
-Forms the anterior portion of the base of the skull
-It articulates with the temporal bones and the frontal bone to form the back of the eye orbit
Greater Wing - larger outer wings
Lesser wings - smaller & higher
Ethmoid Bone
-Forms part of the floor of the cranium, the orbit, and the nasal cavity
Facial Bones - 14 in total
- Maxilla (paired)
- Zygomatic (paired)
- Palatine (paired)
- Nasal (paired)
- Lacrimal (paired)
- Inferior nasal conchae (paired)
- Vomer (single)
- Mandible (single)
Maxilla
-Forms the upper jaw and part of the hard palate
-The two bones are joined together by the maxillary suture at the midline
-Contain the maxillary sinuses
-Contains the maxillary tuberosity where the blood vessels and nerves enter This is also where much of the growth of the maxilla takes place
Zygomatic Bones
- Also called the Malar bones
- Forms the prominence of the cheek, distal walls and floor of the orbit * Rest on the maxillary bones
- There is a temporal process of the Zygomatic bone (that projects backwards) articulates with the Zygomatic process of the temporal bone – This forms the Zygomatic arch
Palatine Bones
Made up of a horizontal plate (hard palate) and a vertical plate
* Horizontal plate – posterior portion
* Vertical plate – lateral walls of the nasal cavity
* It is joined midsagittally at the median palatine suture. This is covered by the tissue of the palatine raphae
The Nasal Bones
-Two bones that are joined
-Articulate with the Frontal Bone to make up a small portion of the nasal septum
Lacrimal Bones
- Paired bones found at the inner angle of the eye
-resemble a fingernail
-smallest bones of the face
-located posterior and laterla to the naasal bone
-Contain the lacrimal duct, where tears pass into the nasal cavity and out to the surface
Nasal Conchae
3 TYPES
-They are formed from the Ethmoid Bone
-The superior and middle nasal concae are extensions of the ethmoid
-The inferior is a separate bone
-extend ineward from the maxilla
-allow for circulation and filtration of air before it goes to the lungs
Vomer
-Single Bone
-Triangular shaped, it forms the inferior and posterior part of the nasal septum
Hyoid Bone
-Does not articulate with any other bones
-It is suspended in the neck and is an attachment point for neck and tongue muscles
-it is horshoe shaped
Auditory Ossicles
-Composed of six main bones
-They are tiny, highly specialized bones of the inner ear
-There are three types per side:
- Stapes - stirrup
- Incus - anvil
- Malleus - hammer
The Hard Palate
-is composed of the palatine process of the maxilla and the palatine bones
-The right and left sides are joined by the median palatine suture
-Incisive foramen is located at the mid-line, just behind the upper central insisors
-Greater Palatine foramen is located in the palatine bone
Mandible
-Single bone
-Forms the lower jaw
-is the movable bone of the skull
-The alveolar process of the mandible supports the teeth in the mandiblar arch
- it is composed of three parts:
1. Body
2. Alveolar Process
3. Ramus
Parasnasal Sinuses
- The maxillary sinuses are the largest of the paranasal sinuses
-The frontal sinuses are located within the forehead, just above both eyes
-the ethmoid sinuses are irregulary shaped air cells seprated from the orbital cavity by a very thin layer of bone
-the sphenoid sinuses are located close to the optic nerves, where an infection may damage vision
Functions of th sinuses
- Lighten the skull bones
- Act as sound resonators
- Provide mucus for the nasal cavity
Temporomandibular Joint (TMJ)
- Is a joint on each side of the head that allows for movement of the mandible for speech and mastication
3 bony parts
-Glenoid fossa of the temporal bone
-Articular eminence of the temporal bone
-Condyloid process of the mandible
Capsular Ligament
-a fibrous joint capsule completely encloses the TJ
-The capsule wraps around the margin of the temporal bone’s articular eminence and articular fossa superiorly
-Inferiorly, the capsule wraps around the circumference of the mandibular clondyle’s neck
Articular Space
-The area between the capsular ligament and the surfaces of the glenoid fossa and condyle
-Articular disc (meniscus) is a cushion of dense, specialized connective tissue that divies the articular spce into upper and lower compartments
-These compartments are filled with synovial fluid, which helps lubricate the joint and fills the synovial cavities
Jaw Movement of the TMJ
-Hing Action
*The first phase of the mouth opening
*Only the lower comartment of the joint is used
-Gliding movement
*Allows the lower jaw to move forward or backward
*it involves both the lower and upper compartments of the joint
*The condyle articular disc “glide” forwrad and downward along the articular eminence
Gliding Movement
Protrusion is the forward movement of the mandible
* The reversal of this movement is the backward movement of the mandible, called retrusion
* Lateral movement of the mandible occurs when the internal and external pterygoid muscles on the same side of the face contract together
Rest Position of the TMJ
- Elimination of muscle tension and rest of the TMJ is essential throughout the day
- Clenching and grinding [bruxism] contribute to the tension and eventually lead to TMJ and muscle discomfort
- The ‘rest’ position of the TMJ is achieved with lips together, but teeth slightly apart – carrying the TMJ like this whenever possible will reduce tension and discomfort
Temporomandibular Disorder (TMD)
Etiology
*Trauma
*Genetic Factors
*Developmental Disorders
*Behavioural Stresses
*Para-Functional habits
*Malocclusion
*Arthritis
Signs and Symptoms of TMD
-Pain
-Stiffness
-TMJ sounds (clicking/popping)
-Internal Disc derangment
-Subluxation (locking open)
-Limitation of movement (trismus)
Malocclusion (Shift in the way the teeth align)
*No solution to TMJ disorders - but can provide “help”
-Patient education
-CBT
-Physical therapy
-Medication - antidepressant, muscle relaxants
-Muscular Therapy
Muscles of the Head And Neck - why is it imortant to know?
- To perform a thorough patient examination, it is necessary to know the location and action of many muscles of the head and neck
- Malfunctions of muscles may be involved in malocclusions (improper bite), TMJ disorder, and even the spread of dental infections
Mastication definition
act of chewing/grinding
Elevation definition
raising of the mandible (closing the mouth)
Protrusion defintion
the forward movement of the mandible
Retrusion definition
the process of moving the mandible backwards
Depression definition
the lowering of the mandible
Lateral excursion definition
the sideways movement
Origin definition
A site from which something arises, the beginning
Insertion definition
A site in which something inserts, the end
Muscles of Mastication
Accomplish the movements of the jaw, opening of the mouth and depression of the mandible
-Masseter
-Temporal
-Lateral (external) pterygoid
-Medial (internal) pterygoid
Muscles of Mastication - Masseter
Raises the mandible and closes the jaw
Muscles of Mastication - Temporal
Raises the mandible and closes the jaw
Muscles of Mastication - Medial (internal) pterygoid
Closes the jaw, pulls the mandible to one side
Muscles of Mastication - Lateral (external) pterygoid
Depresses the mandible to open the jaw
Muscles of Mastication: Temporal Muscle Origin & Insertion
Origin -Temporal fossa of temporal bone
Insertion - Coronoid process and anterior border of mandibular ramus
Muscles of Mastication: Masseter Muscle Orgin & Insertion
Origin - Superficial part: lower border of zygomatic arch
Deep part: posterior and medial side of zygomatic arch
Insetion - Superficial part: angle and lower lateral side of mandibular ramus Deep part: upper lateral ramus and mandibular coronoid process
Muscles of Mastication: Internal (medial) pterygoid Origin & Insertion
Origin - Medial surface of lateral pterygoid plate of sphenoid bone, palatine bone, and tuberosity of maxillary bone
Insertion - Into inner (medial) surface of ramus and angle of mandible
Muscles of Mastication: External (lateral) pterygoid Origin & Insertion
Origin - Originates from two headsl upper head originates from greater wing of sphenoid bone
Insertion - Into neck of condyle of mandible and into articular disc and capsular ligament of TMJ
Hyoid Muscles - Floor of the Mouth
-Are the muscles that accomplish the opening of the mouth
- THey are associated with the hyoid bone found beneath the mandible
-Divided into two groups:
1. Suprahyoid (above)
2. Infrahyoid (below)
Muscles of the Floor of the Mouth
- Digastric
- Mylohyoid
- Stylohyoid
- Geniohyoid
Suprahyoid Muscles - Digastric
Elevation of the hyoid bone, as well as
depression of the mandible
◦ Anterior Digastric
-Posterior Digastric
Suprahyoid Muscles - Stylohyoid
Assists in swalling by raising the hyoid bone
Suprahyoid Muscles - Mylohyoid
Forms the floor of the mouth (raises the tongue and dpresses the lower jaw)
Suprahyoid Muscles - Geniohyoid
pulls the tounge and hyoid bone forward
Infrahyoid Muscles
- Omohyoid Muscle*
- Sternohyoid Muscle*
- Thyrohyoid Muscle - depress the hyoid bone
- Sternothyroid Muscle - depresses the thyroid cartilage.
Muscles of Facial Expressions
-Usually symmetrical -
-Originate in Bone and insert on skin
-Loss of symmetry is an early sign of injury to the facial nerve on one side
-Some are superficial and some are deep
-Usually function as a group
Muscles of Facial Expression: Orbicularis Oris
Closes and puckers lips -
Muscles of Facial Expressions: Buccinator
-Compresses the cheeks against the teeth and retracts the angle of the mouth
Muscles of Facial Expressions: Mentalis
Raisies and wrinkles the skin of the chin and pushes the lower lip up - POUTY FACE
Muscles of Facial Expressions: Zygomatic Major
Draws the angles of the mouth upward and backward, as in laughing - or smiling
Muscles of Facial Expressions: Orbicularis Oris Origin & Insertion
Origin - From muscle fibers around mouth; no skeletal attachment
Insertion - Into itself and surrounding skin
Muscles of Facial Expressions: Buccinator Origin & Insertion
Origin - Posterior portion of alveolar process of maxillary bone and mandible
Insertion - Fibers of orbicularis oris at angle of mouth
Muscles of Facial Expressions: Mentalis Origin & Insertion
Origin - Inscisive Fossa of mandible
Insertion - Skin of chin
Muscles of Facial Expressions: Zygomatic Major Origin & Insertion
Origin - Zygomatic bone
Insertion - Into fibers of orbicularis oris
Muscles of the Neck
- These are the muscles found from the neck to the
lower aspect of the mandible. * These muscles can become affected by improper
posture while assisting the dentist or performing
independent duties (Bird & Robinson, 2021) * There are three: Platysma
Trapezius Sternocleidomastoid
3 Muscles of the Neck
Platysma
Trapezius
Sternocleidomastoid
Neck Muscle - Platysma Muscle
- Function
◦ Grimacing
◦ Raises the skin of the neck and pulls the corners of the mouth down
Neck Muscle - Trapzius
Is a large, flat triangular muscle that covers the
back of the neck, the clavicle and shoulder * Function
◦ Lifts the clavicle and shoulder blade – as when
the shoulders are shrugged
Neck Muscle - Sternocleidomastoid Muscle
- Function
◦ If one SCM is contracted the head turns to that
side. ◦ If both are contracted the head will flex at the
neck and move forward and down ◦ Serves as a landmark of neck during an
extraoral examination
Neck Muscle: Sternocleidomastoid Origin & Insertion
Origin - Clavicle (collarbone) and lateral surfaces of sternum
Insertion - Posterior and inferior to external acoustic meatus
Trapezius Origin & Insertion
Origin: External surface of occipital bone
Insertion: Lateral third of clavivle and parts of the scapula
Muscles of the Tongue - 2 types
Intrinsic (within the toung) - ◦ Responsible for shaping the tongue during speech,
chewing, and swallowing
Extrinsic - assist in the movement and function of the tongue
Extrnisic Muscles of the Tongue
- Genioglossus - Depresses and protrudes the tongue
- Hyoglossus - Retracts and pulls down the side of the tongue
- Styloglossus - Retracts the tongue
Major Muscles of the Soft Palate
- Palatoglossus - Elevates base of tongue, arching tongue against soft
palate; depresses soft palate toward tongue - Palatopharyngeus - Forms posterior pillar of fauces; serves to narrow fauces and helps shut off nasopharynx
Muscles of the Floor of the Mouth: Digastric Origin & Insertion
Origin - Anterior belly: lower border of mandible
Posterior belly: mastoid process of temporal bone
Insertion - Body and great horn of hyoid bone
Muscles of the Floor of the Mouth: Stylohyoid Origin & Insertion
Origin - Styloid process of temporal bone
Insertion - Body of hyoid bone
Muscles of the Floor of the Mouth: Mylohyoid Origin & Insertion
Origin - Left and right portions are joined at the midline; each portion originates on mylohyoid line of mandible
Insertion - Body of Hyoid bone
Muscles of the Floor of the Mouth: Geniohyoid Origin & Insertion
Origin - Medial (inner) surface of mandible, near symphysis
Insertion - Body of hyoid bone
Extrinsic Muscles of the Tongue: Genioglossus Origin & Insertion
Origin - Medial (inner) surface of mandible, near symphysis
Insertion - Hyoid bone and inferior (lower) surface of the tongue
Extrinsic Muscles of the Tongue: Hyoglossus Origin & Insertion
Origin - Body of the hyoid bone
Insertion - Side of the tongue
Extrinsic Muscles of the Tongue: Syloglossus Origin & Insertion
Origin - Syloid process of temporal bone
Insertion - Side and undersurface of tongue
Muscles of the Soft Palate: Palatoglossus Origin & Insertion
Origin - Anterior arch on each side of throat; arises from soft palate
Insertion - Along posterior side of tongue
Muscles of the Soft Palate: Palatopharyngeal Origin & Insertion
Origin - Posterior border of thyroid cartilage and connective tissue of pharynx
Insertion - Thyroid cartilage and wall of pharynx
