BIO210Y5 Lecture Notes - Lecture 5: Occipital Condyle, Sagittal Plane, Hinge Joint

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18 Feb 2016
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Lecture 5A Notes – Axial Movement: Muscles
Temporomandibular Joint (TMJ)
Gliding hinge joint
The triangle is showing the centre of rotation (the joint)
The two elements that are moving around it are the skull and the mandible
There could be several degrees of freedom (what kind of planes they are moving in)
We can open/close, rotate (like cows), and glide it
This is a multiaxial joint
Atlantoocciptal Joint (AOJ)
“world on shoulders”
Condyle is an articulation surface – occipital condyle (convex surface)
The articular facets on the vertebrae are concave
There is rotation, angular motion (flexion/extension)
Motions around Axial Joints
Flexion/extension is around transverse plane but on sagittal plane – always decreasing the angle
Depression of Mandible
Platysma is a flat, thin muscle
Responsible for depressing the mandible (pulling the mandible down) – opening your jaw
There is an anchoring point that is shortening the distance between two items (origin and insertion)
Insertion is the inferior border of the mandible and the origin is the muscles in the superior thoracic area
Force is applied to move that element
Insertion is fixed point and the origin is what you are trying to move
Origin is pulling the insertion towards it
Elevation of Mandible
Temporalis originates in the temporal bone and inserts into the coronoid process (ELEVATES mandible)
Masseter originates in the zygomatic arch and insets into the mandibular ramus (elevates mandible)
Protrusion of Mandible
Pterygoid (shown mostly medial pterygoid) – protrudes the mandible and slides the jaw
Originates in the pterygoid plate (base of the skull in the middle) and inserts in the mandibular ramus
Pulls away from the skull and does side to side actions
Flexion of Neck
Flexion of the neck is done by the sternocleidomastoid originates in the manubrium (or clavicle,
sternal end) and inserts into the mastoid region of the skull & superior nuchal line
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