Scalp, Facial Muscles of Expression and Mastication Flashcards
What is the scalp?
- the part of the head that extends from the superciliary arches anteriorly to the external occipital protuberance and superior nuchal lines posteriorly
- laterally it continues inferiorly to the zygomatic arch
What are the 5 layers of the scalp?
- skin
- dense subcutaneous tissue
- epicranial aponeurosis
- loose areolar connective tissue
- periosteum
What are the boundaries of the scalp?
- anteriorly - eyebrows
- laterally - ears/zygomatic arches
- posteriorly - superior nuchal line
Describe the skin of the scalp?
- thick
- hair bearing
- contains numerous sebaceous glands
Describe the connective tissue of the scalp?
- is fibrofatty
- the fibrous septa uniting the skin to the underlying aponeurosis of the occipitofrontalis muscle
- has numerous arteries and veins
> the arteries are branches of the external and internal carotid arteries and a free anastomosis takes place between them
Describe the epicranial aponeurosis of the scalp?
- thin + tendinous sheet
- unites the occipital and frontal bellies of the occipitofrontalis muscle
- the lateral margins of the aponeurosis are attached to the temporal fascia
Describe the loose areolar tissue of the scalp?
- occupies the subaponeurotic space
- loosely connects the epicranial aponeurosis to the periosteum of the skull (pericranium)
- contains a few small arteries
- contains emissary veins
> valveless veins that connect the superficial veins of the scalp and the diploic veins of the skull bones and with the intracranial venous sinuses
Describe the clinical correlates of the loose areolar tissue of the scalp?
- known as dangerous layer of the scalp
- emissary veins open here and carry any infections inside the brain (venous sinus)
- bleeding lead to black eye
Describe the pericranium of the scalp?
the periosteum covering the outer surface of the skull bones
Describe the muscle of the scalp?
occipitofrontalis muscle
- anteriorly = frontal belly
- posteriorly = occipital belly
- aponeurotic tendon (epicranial aponeurosis) connecting the two
Describe the occipital belly of the occipitofrontalis muscle of the scalp?
origin - highest nuchal line of occipital bone
insertion - epicranial aponeurosis
nerve supply - facial nerve
action - moves scalp on skull and raises eyebrows
Describe the frontal belly of the occipitofrontalis muscle of the scalp?
origin - skin + superficial fascia of eyebrow
insertion - epicranial aponeurosis
nerve supply - facial nerve
action - moves scalp on skull and raises eyebrows
What are the 3 layers of the skull cap?
- outer table
- diploe
- inner table
What is the function of emissary veins?
drain blood from the external surface of the skull into the dural sinuses
Describe the course and function of the diploic veins?
- course in diploe
- connect both cranial cavity and surface of skull
- drain blood from the space within the bone of the skull (diploic space) into the dural sinuses
- can transmit infection from scalp to brain via emissary veins
What is the dangerous area of the scalp?
the 4th layer of the scalp - loose areolar tissue
- infection in the subaponeurotic space with pus collection readily spread to intracranial sinuses through emissary veins (valveless)
What is the clinical relevance of the scalp?
- infection spreading from loose areolar connective tissue, via emissary veins, to meninges-meningitis
- hematoma