Session 1.2a - Group Work Flashcards
Workbook
1.1a) On the cross sectional image opposite, label and highlight the superficial and the four deep cervical fascial layers (highlight with different colours).
See workbook answers
- 1b) Label the following structures:
- Internal jugular vein
- Common carotid artery
- Vagus nerve
- Sternocleidomastoid
- Spinous process of cervical vertebrae
- Ligamentum nuchae
- Trachea
- Infrahyoid muscles
- Thyroid gland
- Oesophagus
- Platysma
See workbook answers
1.1c) Indicate with an ‘X’ (on the cross-sectional image) where the retropharyngeal space is found (clue- retro means ‘behind’).
See workbook answers
1.1d) Which anatomical area does the retropharyngeal space communicate with inferiorly?
The thorax and mediastinum
1.2) Can you determine the vertebral level at which the cross-sectional image is taken? Explain how you worked out the answer you have given.
(Clue … once you have determined the structures you can see in this image, consider whether they are structures seen consistently throughout the length of the neck or only at certain cervical levels …)
Around C7 vertebral level - it must be fairly low down the neck because the thyroid gland is visible. We can tell it is roughly about C7 because the two lateral loves AND central isthmus is visible; the central isthmus is approximately at the level of the C7 cervical vertebra.
(Accept C6)
1.3) In a patient with a retropharyngeal abscess, why is swallowing and movement of the neck typically difficult and painful (clue: look at the anatomical relations to the retropharyngeal space)?
The retropharyngeal space is located directly behind the oesophagus. An infection here would cause this space to distend, hence impinging on the oesophagus, and making swallowing hard (substances pass from the mouth, pharynx to the oesophagus; while shutting the epiglottis).
Normally, the fascia also allows for ease of movement between structures, e.g. when swallowing - due to infection the fascia would be inflamed causing friction as the planes rub over each other, making movement difficult and painful.
Similarly, movement of the neck is difficult because posteriorly, the retropharyngeal space when distended would impinge on the muscles associated with the vertebral column; making it hard to move the neck.
- 4) Use an online resource or image in an anatomy textbook, to identify and label the muscles on the images opposite.
- Highlight which are muscles of facial expression, which are muscles of mastication and which muscles do not fall into either of these two groups.
(Left top to bottom; Right top to bottom)
- Frontal belly of Occipitofrontalis (Frontalis) [FE]
- Occipital belly of Occipitofrontalis (Occipitalis) [FE]
- Masseter [M]
- Splenius (Capitis/Cervicis)
- Sternocleidomastoid
- Trapezius
- Epicranial aponeurosis/Galea aponeurotica
- Temporalis [M]
- Orbicularis Oculi [FE]
- Zygomaticus major/minor [FE]
- Buccinator [FE]
- Orbicularis Oris [FE]
- Platysma [FE]
- Lateral Pterygoid [M]
- Medial Pterygoid [M}
Muscles of Facial Expression [FE] (facial nerve):
Occipitofrontalis; Orbicularis oculi; Orbicularis oris; Zygomaticus major/minor; Buccinator; Platysma
https://en.wikipedia.org/wiki/Facial_muscles
Muscles of Mastication [M]:
Masseter; Temporalis; Lateral Pterygoid; Medial Pterygoid
- 5) On the basis of just looking at the images opposite and noting how the muscles are arranged, write down which muscles you think are involved with the following actions (do this without searching for the answer on an online resource).
- squeezing eye shut
- closing/pursing the lips
- smiling
- raising eyebrows
- moving the mandible (jaw): opening [depression] and closing [elevation]
- Squeezing eye shut:
Orbicularis oculi - Closing/pursing the lips:
Orbicularis oris; (Buccinator - blowing) - Smiling:
Zygomaticus major/minor; (Orbicularis oculi - causes the eye crinkle) - Raising eyebrows:
Occipitofrontalis (frontal belly) - Opening [depression] the mandible (jaw):
Lateral pterygoid - Closing [elevation] the mandible:
Masseter; Temporalis; Medial pterygoid
1.6a) A patient presents to her GP reporting her face feels weak on one side and she has struggled to keep food and drink inside her mouth. The GP asks her to smile while inspecting her face (image below). She has no weakness in opening or closing her jaw.
Which side is affected (patient’s right or left side)?
Patient’s LEFT side (the patient is able to smile on her right side so weakness is reported on her left side - note: this appears on the right side of the image)
1.6b) A patient presents to her GP reporting her face feels weak on one side and she has struggled to keep food and drink inside her mouth. The GP asks her to smile while inspecting her face (image below). She has no weakness in opening or closing her jaw.
What is she unable to do, which is causing the asymmetry of the face?
She is unable to use the muscles of facial expression on her left side (but is able to use them on her right side), causing asymmetry of the face
Signs and symptoms - cannot smile [zygomaticus major/minor], cannot keep food and drink insider her mouth [buccinator], no eye crinkles when smiling [orbicularis oculi]
The muscles of mastication appear to be okay because she has no weakness in opening or closing her jaw.
1.6c) A patient presents to her GP reporting her face feels weak on one side and she has struggled to keep food and drink inside her mouth. The GP asks her to smile while inspecting her face (image below). She has no weakness in opening or closing her jaw.
Which nerve do you think has been affected?
The facial nerve
All the muscles of facial expression are innervated by the facial nerve
1.7) A patient presents to her GP reporting her face feels weak on one side and she has struggled to keep food and drink inside her mouth. The GP asks her to smile while inspecting her face (image below). She has no weakness in opening or closing her jaw.
The GP checks whether she is able to raise her eyebrows on the affected side.
Why is this especially important to check in patients presenting with facial weakness?
Differential diagnosis between Bell’s Palsy + Stroke
Bell’s palsy = unable to raise eyebrows on affected side
- due to a LOWER motor lesion, which affects ALL the muscles on the IPSILATERAL side
Stroke = Can raise eyebrows symmetrically
- due to an UPPER motor lesion, which spares the upper facial muscles and affects the LOWER muscles on the CONTRALATERAL side
RATIONALE:
The fibres controlling the face travel from the cortex to the brainstem. For the lower face, these fibres cross over in the brainstem to the contralateral (opposite) facial nerve. For the upper face, half the fibres cross over in the brainstem to the contralateral facial nerve; however, the other half remains on the same side and contributes to the ipsilateral facial nerve.
Therefore, the eyes and forehead receive innervation from both hemispheres, while the lower face only receives innervation from the contralateral hemisphere.
This means that lesions which damage the motor cortex (upper motor lesions), such as in stroke, will result in contralateral facial weakness of the lower face only. The muscles of the upper face are preserved, as there is still innervation from the ipsilateral nerve, which is unaffected.
Lesions that damage the facial nerve in or after exiting the brainstem (lower motor lesions), such as in Bell’s palsy, result in ipsilateral facial weakness involving both the upper and lower face. This is because both the ipsilateral upper face nerve AND contralateral lower face nerve have been affected, resulting in no (reduced?) innervation to the ipsilateral full face.
1.8) On the image below, label the terminal extracranial branches of the facial nerve. Without referring back to your lecture notes, see if you can recall the branches from memory first!
A mnemonic to help you recall … “To Zanzibar By Motor Car” (other mnemonics are available …)
Temporal Zygomatic Buccal Mandibular Cervical
1.9) On the image below name the branches circled as 1-3
Indicate which of these three main branches innervates the muscles of mastication.
(Push yourself to recall these branches before checking your answers against your lecture notes or online resources. The bony anatomical structures with which these branches are either geographically associated with or heading towards give a big clue to their name!)
Opthalmic
Maxillary
Mandibular
Only the mandibular division/branch (Vc) innervates the muscles of mastication.
