Anatomy 2: Skull, Face and Scalp

Question 1

Where is the frontal bone, where are some of it’s features including glabella, zygomatic process, supraorbital notch?

Answer 1

Forms part of forehead, roof of the orbit and nasal.

Glabella: smooth bony prominence between eyebrows
Zygomatic Process: superiolateral edge of orbit
Supraorbital notch: superiomedial edge of orbit.

Question 2

Where are the parietal bones, how do they articulate w/ one another and the occipital bone?

Answer 2

Covers cap of skull.

Articulate w/ one another at coronal suture.
Articulates w/ Occipital bone at Lambdoid suture

Question 3

Temporal bone, location, portions including; zygomatic arch, tympanic part, mastoid process, styloid process, Petrous portion, Squamous portion.

Answer 3

Located on lateral sides of head.

Zygomatic Arch/Process: most lateral portion and anterior
Tympanic Portion: the external acoustic meatus
Mastoid Process - posterior/inferior piece
Styloid Process - also inferior thought more medial than mastoid
Petrous Portion: w/ an apex that forms one of the boarders of the flamen lace rum, the opening of the carotid canal, and the groove for the auditory tube.
Squamous Portion: contains mandibular fossa and prominent articular tubercle.

Question 4

Occipital bone; location, features

Answer 4

Posterior skull.

External Occipital Protuberance (Inion):
Superior and Inferior Nuchal Lines: attachments for nuchal ligament

Basilar part: extends posteriorly to form foramen magnum
Lateral parts: occipital condyles, hypoglossal canal, jugular foramen.
Pharyngeal tubercule

Question 5

Name the 14 facial bones and their approximate locations.

Answer 5

Maxillae (2) - inferior and medial portion of orbit.
Zygomatic (2) - cheekbones, inferior orbit
Nasal bones (2) - Piriform aperture = large opening into nasal cavity
Mandible - anterior body, posterior rams, anterior coronoid process and condylar process
Inferior Conchae (2) - nasal cavity
Lacrimal (2) - orbit
Palatine (2) - inferior
Vomer - inferior

Question 6

3 Sutures of the skull and location.

Answer 6

Coronal - frontal and parietal bones
Sagittal - between two parietal bones
Lambdoid - parietal and occipital bones

Question 7

Orbital group muscles of the face (2)

Answer 7

Orbicularis oculi (encircles eye) - function to close eyelids

Corrugator supercilii - deep to eyebrows, draws eyebrows to midline

Question 8

Nasal group muscles of the face (3)

Answer 8

Procerus - at root of nose, active when frowning
Nasalis - largest, two portions - transverse (compressor naris) and alar (dilator naris)
Depressor septa nasi - assists in widening the nares

Question 9

Oral group muscles of the face (2)

Answer 9

Orbicularis iris (encircles mouth) - active in pursing lips
Buccinator - muscular portion of the cheeks

Question 10

Lower group muscles of the face (3)

Answer 10

Depressor labii inferiors - depressor of the lower lip
Depressor anguli iris - depressor of the angle of the mouth
Mentalis - chin, deepest of the lower oral group, moves lip for drinking or pouting

Question 11

Upper group muscles of the face (5)

Answer 11

Risorius - active in grinning, extends corner of mouth laterally
Zygomaticus major and minor - active in smiling
Levator anguli iris - rises angle of mouth
Levator labii superior - raises upper lip, deepens furrow between nose
Levator labii superiors alaque nasi - lifts upper lip and wing of nose = flaring of nares

Question 12

Other muscles of the face (3):

Platysma

Answer 12

-

Question 13

Composition and Layers of Scalp

Answer 13

S - skin
C - CT (dense)
A - aponeurosis of occipitofrontalis muscles
L - Loose CT
P - periosteum (pericranium)

Clinical correlations - CT keeps veins open, causing profuse bleeding. Scalp veins communicate directly with those of the brain, allowing infections and air emboli to easily go from scalp to brain.

Question 14

External Carotid Artery

Answer 14

S - Superior thyroid
A - Ascending pharyngeal
L - Lingual
F - Facial
O - Occipital
R - greater auRicular
M - Maxillary

Question 15

Venous Drainage

Answer 15

a. Supraorbital and supratrochlear veins drain into orbit and into ophthalmic veins and then into cavernous sinus.
b. Facial vein drains into internal jugular
c. Transverse facial vein accompanies artery. Drains into superficial temporal vein, then forms retromandiublar vein. Unites with posterior auricular vein, forming external jugular
d. Posterior auricular vein - drains scalp behind ear. Empties into retromandibular vein and then external jugular.

Occipital vein - trains posterior scalp and empties into suboccipital plexus, which drains into 2 directions; deep cervical and vertebral venous plexus.

Question 16

Triangle of Danger

Answer 16

i. Veins of the face have no valves. Area between root of the nose and corners of the mouth = triangle of danger. Never squeeze a pimple here because infected material can be pushed via veins into veins that connect with the brain.

Question 17

Sensory Innervation of the Face and Scalp

Answer 17

a. 2 General sources
i. Cranial nerves (Trigeminal nerve - V)
ii. Spinal nerves (branches of cervical plexus)
b. General pattern
i. In front of ear, from top of head to middle of mandible - Trigeminal nerve

Behind hear, from top of head to the posterior neck - Branches of cervical plexus.

Question 18

Trigeminal Nerve

Answer 18

i. OPHTHALMIC DIVISION (v1) - From the level of Eyes and above
1) Supraorbital (skin over forehead and anterior scalp)
2) Supratrochlear (median region of forehead)
3) Infratrochlear (medial side of eyelids, side and bridge of nose)
4) Lacrimal (lateral part of upper eyelid)
5) External nasal (anterior portion of nose)
ii. MAXILLARY DIVISION (v2) - level of eyes to upper lip
1) Infraorbital (medial side of lower eyelid, side of nose, cheek, upper lip)
2) Zygomaticofacial (lateral corner of eyelids)
3) Zygomaticotemporal (anterior part of scalp around temple)
iii. MANDIBULAR DIVISION (v3) - lower lip to middle of mandible.
1) Mental (chin and lower lip angle of mouth)
2) Buccal (cheek)
3) Auriculotemporal (anterior part of ear, meatus, tympanic membrane, most of scalp in the temple area)

Question 19

Trigeminal neuralgia

Answer 19

a. Mostly affects maxillary division, then mandibular division and least likely the ophthalmic division.

Question 20

Innervation of muscles of facial expression

Answer 20

a. ALL FACIAL EXPRESSION MUSCLES INNERVATED BY CNVII
b. Facial nerve leaves through stylomastoid foramen
c. Then enters substance of parotid gland, forming a plexus.
d. Plexus breaks into 5 branches, coursing to 5 regions of the face.
i. Temporal branch - orbicularis oculi
ii. Zygomatic branch - levator labii superioris
iii. Buccal branch - buccinator
iv. Mandibular branch - orbicularis oris
v. Cervical branch - platysma

Question 21

Bell’s Palsy

Answer 21

Damage to facial nerves result in paralysis of muscles on that side of the face.