10 Questions
What is the function of the lacrimal part of the orbicularis oculi muscle?
Dilates the lacrimal sac and helps in flow of tears
Which nerve supplies the frontal bellies of the occipito-frontalis muscle?
Temporal branch of facial nerve
What is the primary function of the loose areolar tissue layer in the scalp?
To provide a layer of connective tissue that separates the periosteum of the skull from the epicranial aponeurosis
What is the clinical significance of the dense connective tissue layer in the scalp?
It is richly vascularized and innervated, causing profuse bleeding in small wounds
What is the boundary of the scalp superiorly?
The hair margin
What is the function of the occipital bellies of the occipito-frontalis muscle?
Pull the scalp backward
Which layer of the scalp is responsible for the contraction of muscles that causes wounds to gap?
Aponeurosis layer
What is the significance of the septa in the connective tissue layer of the scalp?
They connect the connective tissue layer with the layer above and the layer below
What is the significance of the emissary veins in the 3-loose connective tissue layer?
They can spread infection from the scalp to the cranial cavity
What is the outermost layer of the skull bones?
Pericranium
Study Notes
Scalp Layers and Clinical Significance
- The scalp is formed of 5 layers, which can be remembered using the word "Scalp": S (Skin), C (Connective tissue), A (Aponeurosis), L (Loose areolar tissue), and P (Pericranium)
- The first 3 layers (S, C, and A) are bound together as a single unit and can move along the loose areolar tissue over the pericranium
- Clinical significance of the scalp layers:
- Connective tissue layer: dense, richly vascularized, and innervated, which makes wounds bleed profusely due to the adhesion of artery walls to the connective tissue septa
- Aponeurosis layer: a strong fibrous sheet that can cause wounds to gap due to muscle contraction
- Loose connective tissue layer: continuous with the eyelids, considered the "dangerous layer" as it can spread infection from the scalp to the cranial cavity through emissary veins
Muscles of the Face
- Occipito-frontalis muscle:
- Has 2 frontal and 2 occipital bellies
- Origin: arises from the skin of eyebrows (frontal bellies) and lateral 2/3 of the highest nuchal line (occipital bellies)
- Insertion: epicranial aponeurosis
- Action: pulls the scalp forward and raises the eyebrows (frontal bellies), pulls the scalp backwards (occipital bellies)
- Nerve supply: temporal branch of facial nerve (frontal bellies) and posterior auricular branch of facial nerve (occipital bellies)
Face and Facial Muscles
- Boundaries of the face: superiorly (hair margin), inferiorly (lower border of mandible), and sideways (from one auricle to the other)
- The face has no deep fascia except over the parotid and buccinator muscle
- Orbicularis oculi muscle:
- Has 3 parts: orbital, palpebral, and lacrimal
- Actions: closes eye lids tightly for protection (orbital part), closes eye lids gently as in blinking and helps in spread of tears (palpebral part), and dilates the lacrimal sac and helps in flow of tears (lacrimal part)
- Supplied by temporal and zygomatic branches of facial nerve (7th cranial nerve)
Trigeminal Nerve
- Not mentioned in the provided text, but the trigeminal nerve is a cranial nerve that plays a key role in facial sensations and motor functions.
This quiz covers the characteristics and functions of the loose connective tissue layer, including its continuity with the eyelids and its role in spreading infections. It also discusses the emissary veins and their connection to the cranial cavity.
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