Session 1.2b - CTF-led Tutorial Flashcards
Workbook/Slides
Why is it important to understand the actions of the muscles of the head and neck?
In clinical practice, you will ask patients to demonstrate actions of these muscles so that the integrity of the cranial nerves supplying them can be determined. It is important, therefore, to understand the action of these muscles and the functional consequences that arise as a result of injury to the nerves supplying them e.g. inability to close the eyelid.
- It is not expected that you learn the origins/insertions of these muscles in detail!*
- However, it is important that you understand where these muscles are found and what their action is; this in itself necessitates a general understanding of muscle origin and insertion!
Pathway of the facial nerve - what are the five terminal branches?
Temporal Zygomatic Buccal Mandibular Cervical
To Zanzibar By Motor Car
Slide 3
a) Label the structures
b) Draw the segmentation of the five terminal branches of the facial nerve
See image
What is the action of the platysma muscle?
- Depresses lower jaw
- Small function in drawing down lower lip
- Tenses skin (e.g. shaving)
What is the innervation of the platysma muscle?
Cervical branch of facial
How is the function of the platysma muscle examined?
Not usually examined
An example of the level of detail expected is demonstrated for the platysma muscle:
- Function/action
- Rough origin/insertion
- Relation to other structures (deep/superficial)
Depresses angles of mouth; also used to tense skin of neck e.g. during shaving; arises from skin/fascia of lower face and mandible, inserts into fascia covering anterior chest wall; runs superficial to SCM and over clavicles
What is the rough origin/insertion of the platysma muscle?
Skin/fascia of lower face and mandible, to the fascia covering the anterior chest wall (See image page 4/workbook page 25)
What is the 3D anatomical relationship of the platysma to other structures?
It runs deep to the skin but superficial to the SCM and clavicles. (See image page 4/workbook page 25)
What is the action of orbicularis oculi?
Closes the eye (although separate parts have separate actions)
What is the innervation of orbicularis oculi?
Temporal and zygomatic branches of facial nerve
How is the function of orbicularis oculi examined?
Close eyes and resist opening
What is the rough origin/insertion of orbicularis oculi and its 3D relationship?
A sphincter muscle around the eye (see image page 5), lying superficially over the skull and deep to the skin.
What are the two parts of orbicularis oculi?
The orbital and palpebral part (there is also a lacrimal section; lacrimal obicularis)
Where is the orbital part of orbicularis oculi found?
Orbital ocularis surrounds the orbital margin.
What is the function of the orbital part of orbicularis oculi (orbital ocularis)?
It is a thick muscle used to consciously close the eye - used for forceful closure.
Where is the palpebral part of orbicularis oculi found?
Palpebral orbicularis is found in the eyelid.
What is the function of the palpebral part of orbicularis oculi (palpebral ocularis)?
Used for unconscious ‘light’ closure of the eye in blinking/sleep.
The platysma muscle is a muscle of ___?
Facial expression
Orbicularis oculi is a muscle of ___?
Facial expression
What is the function of levator palpebrae superioris?
Elevates upper eyelid
What is the innervation of levator palpebrae superioris?
Oculomotor nerve
take note of its nerve supply
How is the function of levator palpebrae superioris examined?
Inspection of eyes for ptosis (drooping of upper eyelid)
What is the rough origin/insertion of levator palpebrae superioris and its 3D relationship to other structures?
It arises from the sphenoid bone and inserts into the upper eyelid; it is the most superior of the eyelid muscles (see image page 7).
Is levator palpebrae superioris a muscle of facial expression or mastication?
It is neither! (Hence nerve supply is not facial nerve)
This muscle we be revisited in Session 9: The Eye, Ocular Muscles and the Orbit
What is the function of occipitofrontalis?
Elevates eyebrows
What is the innervation of occipitofrontalis?
Frontal belly - temporal branch of facial nerve
dual innervation
Occipital belly - posterior auricular branch of facial nerve
How is the function of occipitofrontalis examined?
Elevate eyebrows against resistance
What are the two parts of occipitofrontalis?
Frontalis (anterior)
Occipitofrontalis (posterior)
What is the rough origin/insertion of occipitofrontalis and its 3D relationship to other structures?
From orbicularis oculi (frontal belly) to the superior nuchal line of the occipital bone and mastoid process (occipital belly) - connected via the galea aponeurotica. It is a superficial scalp muscle.
Occipitofrontalis is a muscle of ___?
Facial expression
Occipitofrontalis, namely its ___________, forms ___ of the layers of the _____.
Occipitofrontalis, namely its aponeurosis, forms one of the layers of the scalp.
Epicranial aponeurosis can otherwise be known as ___?
Galea aponeurotica
Galea aponeurotica can otherwise be known as ___?
Epicranial aponeurosis
What are the layers of the scalp?
S: Skin C: dense Connective tissue A: Aponeurosis of occipito-frontalis L: Loose connective tissue P: Pericranium
(see image page 9)
Which layers of the scalp form a single functional layer?
The first 3 layers: skin, dense CT, aponeurosis (S.C.A.)
What is the action of orbicularis oris?
Closes mouth
What is the innervation of orbicularis oris?
Buccal branch of facial nerve
How is the function of orbicularis oris examined?
Face inspection - drooping angle of the mouth in CNVII palsy (facial nervy palsy)
Where is the rough origin/insertion of orbicularis oris and its 3D relationship to other structures?
It forms a sphincter around the lips, attaching to the maxilla and mandible. It lies superficially underneath the skin.