ANHB3324 Lecture Notes - Lecture 2: Pterygoid Processes Of The Sphenoid, Stretch Reflex, Lateral Pterygoid Muscle
3 Jun 2018
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LECTURE TWO: First Arch Structures and Mastication
Pharyngeal Arches:
• Appear at mid week 4
• Form face, jaws, pharynx
• Each arch is a package → cells that produce bone, muscular tissue, nerve
tissue, artery/venous tissue
• Grow rapidly, migrate and produce things
• Arches can be overlaid by other arches → buried in the growing embryos
Skeletal Component of Arch 1:
• Incus and malleus → ear bones
• Ligaments → sphenomandibular
• Cartilaginous precursor → Meckles cartilage
• Drives the development of the mandible and maxilla but does not become
bones → releases growth factors and drives surrounding CT into
development of bones
TMJ:
• Tempero-mandibular joint
• Largest envelope of movement
• Joint is passive
• Faces enormous loads
• Movements generated by complex bilateral muscles (muscles of
mastication)
• Guided by occlusion (teeth) → very complex
• High sensitivity to manage loads on joint
• Articular disc → lateral pterygoid muscle and the disc
• Divides joint into 2 → allows for expanded envelope of movement and
optimum load distribution into skull
Muscles of Mastication:
• All derived from first pharyngeal arch
• Supplied by a single nerve (5th cranial nerve)
• Most are large chewing muscles
• Commonly accepted muscles
o Masseter
o Temporalis
o Medial pterygoid
o Lateral pterygoid
• Additional muscles
o Mylohyoid → swallowing
o Anterior belly of digastric → swallowing
o Tensor tympani → not masticatory, embryologically derived from
1st pharyngeal arch
o Tensor palate → not masticatory
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Document Summary
Tmj: tempero-mandibular joint, largest envelope of movement, faces enormous loads, movements generated by complex bilateral muscles (muscles of. 1st pharyngeal arch: tensor palate not masticatory. Masseter: origin tough dendinous attachment, parts tailor envelope of movement. Insertion broad (cid:494)fleshy(cid:495) attachment: deep vertical fibres, superficial the greater mass with oblique fibres, action elevation of mandible with force. Medial pterygoid: origins, posterior of tuberosity, media surface of lateral pterygoid plate, pterygoid fossa. Insertion: medial lower surface of ramus, tendinous and fleshy head, key relationships in the infratemporal fossa. Lateral pterygoid: origins, roof of itf, lateral surface of lateral pterygoid plate. Insertion: upper head attachment into disc (10%, lower attachment into mandible, manages movement of disc, action protrusion of mandible. Control of mandibular movements: myotatic reflex, single synapse fastest reflex, stop overload of muscles in wrong location. Muscles of the face: embryologically derived from pharyngeal arch 2, thin, relatively small muscles, make up all muscles underneath skin, more expansive, supplied by cn7.
