Muscles of the head and neck

TMJ

Mandibular fossa of temporal bone with condyle of mandible

Incongruent surfaces Two joint cavities with articular disc

interposed Lower cavity = hinge joint Upper joint = gliding

TMJ

TMJ

Mandible

Mandible

TMJ

Capsule– Surrounds the joint– Encloses the disc– Attaches above the margins of the mandibular

fossa– To the neck of the mandible– Inner aspect of capsule attaches to disc– Above disc – capsule loose– Below disc - taut

TMJ Capsule

TMJ Capsule

TMJ Ligaments Lateral ligament - AKA TMJ ligament

– From zygomatic bone to run inferiorly and posteriorly to blend with the joint capsule to attach to lateral and posterior parts of the neck of the mandible

Sphenomandibular – Strong thin flat band lying on medial aspect of the joint– Passes inferiorly and forwards from the spine of the sphenoid

to the lingula Stylomandibular

– Extends from the apex of the styloid process to the lower part of the posterior border of the ramus of the mandible, near the angle

TMJ Capsule

TMJ Innervated by CN V, Mandibular branch Movements

– Elevation, depression, retraction, protraction, side to side Elevation and depression involves the hinge like

rotation of the condyle against the disc in the lower compartment

Protraction and retraction – actions whereby the condyle and disc move as one unit against the mandibular fossa. In protraction the condyle and disc glide forwards so that the condyle rides on the articular eminence – retraction = opposite

CN V Trigeminal

TMJ Motions

TMJ Motions

TMJ

Side to side – grinding movements– Mandible is alternately protracted and retracted

with the two sides moving in opposite directions so that one side is protracted while the other is retracted

– Actions combined with elevation and depression, rhythmically and alternately

Muscles of Mastication

Masseter Temporalis Lateral pterygoid Medial pterygoid All innervated by CNV Opening of jaw (depression) primarily

passive or gravity assist

Masseter

Temporalis

Pterygoids

Pterygoids

Pterygoids

Nerve Supply to Face

Sensory by three divisions of CN V – opthalmic, maxillary, mandibular

Innervation of muscles of facial carried out by CN VII – the Facial Nerve

Origin, branches, motor functions, sensory functions, parasympatheric functions

CN V

CN V

Sensory to Face

Sensory

Scalp

Three Layers– Outer = skin

– Beneath that – subcutaneous layer with many nerves and vessels running through here, binds skin to inner layer

– Galea Aponeurotica – AKA epicranial aponeurosis

– Galea attaches to pericranium via loose CT

This allows scalp to move over the skull Most muscles of face attach to skin, this

arrangement allows them to be more mobile.

Scalp

Scalp

CN VII – The Facial Nerve

Motor nerve to muscles of facial expression with one notable exception

Origin = lower pons Branches – common nerve enters face

– Temporal– Zygomatic– Buccal – Mandibular– Cervical

Motor to Face CNVII

CN VII

Motor Functions– Muscles of facial expression– External ear

Sensory functions– Ant. 2/3 of tongue– Soft palate– Pharynx

Parasympathetic– Gland stimulation

CN VII

Muscles of Facial Expression

Primary action is to act as either a sphincter or dilator of the orifices of the face

Facial expression is a by-product Orifices

– Lips = labia– Nose = nares; Nostrils, Septum, Ala, Apex,

Root– Eyelids = palpebrae

External Ear = auricle, lobule = soft portion

Selected Muscles of Facial Expression * = learn Orbicularis Oculi Levator Palpebrae Superioris*

– O: Root of Orbital Cavity– I: Skin of upper eyelid– A: Raises upper eyelid– N: Note Well, Nerve = CN III

Ptosis is a condition of denervation to this muscle causing drooping of the eyelid, a clinical symptom indicating more loss

Facial MM

Facial MM

Facial MM

Facial MM

Muscles Continued

Occipitofrontalis Corrugator Auricular muscles of the ear – ant., post.,

sup. Nose

– Nasalis– Procerus– Depressor Septi

Facial MM

Facial MM

Ear MM

Nose MM

Nose MM

Muscles Mouth

– Depressor anguli oris– Depressor labii inferior– Mentalis– Risorius– Orbicularis oris– Buccinator*– Zygomaticus major– Zygomaticus minor– Levator labii superioris– Platysma

Platysma

Mouth

Facial MM

Extra Occular Muscles of the Eye

Muscles that move the eyeball Innervated by: CN III (most), CN IV

(1),CN VI (1) Many have an origin from the annulus

tendinous, a common tendon ring attached around the optic canal

Most attach to the sclera of the eyeball

Eye MM

Muscles *

Superior Rectus – rotates eyeball upward and medially –CN III

Medial Rectus – rotates medially (ADD) – CN III

Lateral Rectus – rotates eyeball laterally (ABD) – CN VI

Inferior Rectus – rotates eyeball downward and medially – CN III

Eye MM

Eye MM

Eye MM

Eye MM

Muscles * Superior Oblique – rotates eyeball downward and

lateral – CN IV Inferior Oblique – rotates eyeball upward and lateral –

CN III Combined motions

– Up and medial = sup.rectus– Up and lateral = inferior oblique– Straight up = sup. rectus and inf. oblique– Straight down = inf. rectus and sup. oblique– Down and medial = inferior rectus– Down and lateral = superior oblique– Lateral Gaze = ABD of one eye with ADD of the other

Eye Movements

Eye Movments

Eye Movements