dr robert h. mannell department of linguistics...

Speech Physiology

Articulation and ResonanceLecture 3

Dr Robert H. MannellDepartment of Linguistics

Macquarie University

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Overview

• In this lecture we will start by examining the anatomy and physiology of the lips and the velum.

• We will then examine the first workshop topic:-Electromyography (EMG)

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The Velum (1)

• The velum, or soft palate, consists of mucous membrane covering muscle, loose connective tissue and adipose tissue.

• The velum attaches anteriorly to the hard palate and laterally it is continuous with the soft tissue of the oral and nasal cavities and is connected to the sides of these cavities by muscle, loose connective tissue and mucous membrane.

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The Velum (2)

• The velum has a single intrinsic muscle, the uvulae muscle, which tightens and raises the uvula to provide a firmer contact with the back wall of the naso-pharynx.

• The paired palatal tensor muscle pulls sideways on the velum and tightens the velum. This prevents the velum from sagging down and thus helps to raise the velum.

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The Velum (3)

• Working together (in synergy) with the palatal tensor muscle is the paired palatal levator muscle which has a main effect of raising the velum and a secondary effect of tensing the velum.

• The next slide displays a very stylised illustration of the synergistic actions (working together) of these two muscles.

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The Velum (4)

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The Velum (5)

• In the next slide we can see a stylised representation of the elevator and depressor muscles.

• The palatoglossus and palatopharyngeus muscles (both paired) can act to lower the velum. They are velum depressor muscles. When they act together (in synergy) they provide an even stronger downward force on the velum.

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The Velum (7)

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The Velum (8)

• When two muscles work against each other they are said to be antagonistic with each other.

• The more directly a muscle pulls in a certain direction (say straight up for velum levators) the greater the force it can apply to movement in that direction. The palatal levator pulls more directly upwards than the palatal tensor so more of its energy pulls in an upward direction.

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The Velum (9)

• In order to determine the extent to which a muscle pulls in a certain direction we apply a simple vector analysis to determine the proportion of its force that pulls in that direction.

• For the velum muscles we can talk about the “upward component” of each levator’s action and the “downward component” of each depressor’s action.

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The Velum (10)

• The velum conveniently provides a simple illustration of the principles of synergy and antagonism in muscle activity.

• The two levator muscles work in synergy with each other to raise the velum or to resist the lowering of the velum.

• The two depressor muscles work in synergy with each other to lower the velum and they are assisted in this by gravity.

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The Velum (11)

• The depressor muscles (plus gravity) work in antagonism with the levator muscles. The two sets of muscles are effectively involved in what is similar to a game of “tug-of-war”. The winner is the team that pulls the hardest.

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The Velum (12)

• To determine whether the velum will be raised or lowered, determine:-(A) the sum of force of the upward component of the two levators (B) the sum of the downward component of the two depressors PLUS the effect of gravity.

• If A > B then the velum is raised• If B > A then the velum is lowered• If B = A then the velum doesn’t move

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The Velum (13)

• The palatoglossus muscle is also an extrinsic muscle of the tongue. It can assist in the raising of the tongue IF the palate is braced by its levator muscles.

• We will examine these issues in further detail when we look at the oral-nasal airflow workshop in the next lecture.

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The Lips (1)

• The muscles of the lips have their origins in the maxilla (upper jaw), the mandible (lower jaw) and the zygomatic bone.

• The mandible is a single bone which results from the fusion of the embryonic mandibular arch.

• The maxilla is a single bone which results from the fusion of the embryonic maxillary process.

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The Lips (2)

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The Lips (3)

• An additional relevant embryonic feature is the nasomedial process which gives rise to the nose.

• When the embryonic nasomedial and maxilliary processes meet the palate and philtrum form.

• These embryonic structures give rise to bony and cartilaginous structures, as well as soft structures including the upper and lower lips.

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In this diagram we can see the philtrum which forms during embryonic development when the nasomedial and maxilliaryprocesses meet. The columella nasi is the skin covered soft tissue externally visible between the nostrils and it also extends down towards the upper lip on either side of the philtrum.

The fleshy, reddish parts of the lips are covered by mucous membrane rather than skin.

The Lips (4)

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The Lips (5)

• In the next slide we can see that there is a central sphincter muscle, the orbicularis oris (“oo”), which surrounds the lip orifice and which constitutes the bulk of the lip mass. The oo is the sole intrinsic lip muscle.

• The arrows show the direction that the extrinsic lip muscles pull the oo when they contract (and the effect of these movements is described on the following slide).

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The Lips (6)

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The Lips (7)

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• The next two slides provide a more realistic view of the muscles of the lips (and some surrounding muscles) from a side and frontal perspective.

• Its helpful to examine these slides along with the Hardcastle vectorial diagram. The Hardcastle diagram shows the direction of the forces applied whilst the Zemlin diagrams show the spread of those effects.

The Lips (8)

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The Lips (9)

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The Lips (10)

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The Lips (11)

• One final, and very important, influence on the opening of the lips is the position of the jaw. All else being equal, opening the jaw opens the lips.

• The more open the jaw is the more difficult it is to maintain lip closure. For a very open jaw, lip closure isn’t possible.

• We will return to the lips when we examine the electromyography workshop in the next lecture.

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Further Reading

• Clark, J., Yallop, C. & Fletcher, J. (2007), An introduction to phonetics and phonology, 3rd. edition, Blackwell, Oxford (pages 84-90 and Section 7.17)

• J.A. Seikel, D.W. King and D.G. Drumright, (1997), Anatomy and Physiology for Speech, Language, and Hearing, Singular, San Diego (or a more recent edition of the same text)

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References

The following books were used as sources for materials used in this lecture:-

• W.J Hardcastle, 1976, Physiology of Speech Production, Academic Press, London

• J.A. Seikel, D.W. King and D.G. Drumright, 1997, Anatomy and Physiology for Speech, Language, and Hearing, Singular, San Diego

• Zemlin, W. R. (1998) Speech and Hearing Science. 4th edn. Allyn and Bacon, Boston.