Head/Neck--Skull And Face Flashcards
Bones of the head (skull)
- composed of 22 bones
- bones are fused by immovable joints
- mandible is the only movable bone
Neurocranium (cranium)
- supports and protects brain
- made of 8 large “flat” bones
Viscerocranium
- facial skeleton
- made up of 14 irregularly shaped bones
- make up face including nasal cavity, oral cavity, and orbits
Be able to identify cranial bones
1) frontal bone
2) parietal bone (2)
3) temporal bone (2)
4) occipital bone
5) sphenoid bone
6) ethmoid bone
Frontal bone
- large bone makes up forehead and roof of the orbit
- forms the supraorbital margin
Parietal bone
- 2 large bones make up the “sides” of the cranium
- articulate with each other in the midline
Temporal bones
Large irregular bones formed from 4 parts
1) squamous (flat part)
2) zygomatic (bridge)
3) tympanic (ear canal)
4) mastoid process
5) petrous (“rock” internal, contains inner ear)
Occipital bone
- Large bone forms the posterior and inferior aspect of the cranium
- contains large opening (foreaman magnum) for the spinal cord
Sphenoid bone
- wedge-shaped bone; butterfly
- the central portion of cavity floor contacts with the frontal, temporal, and parietal bones of the cranium
- **vulnerable to lateral skull fx
Ethmoid bone
- an irregularly-shaped spongy bone that contributes to the anterior cranial fossa
- forms the roof of the nasal cavity
- has Cribriform plate (sieve plate) where olfactory nerves run through
- part of nasal septum and lateral nasal wall
Sutures
- areas on the cranium that mark the joints between the bones of the skulls; immovable joints
- joining of sutures bregma and lambda are used as landmarks (stereotactic atlas) for brain surgery
Sagittal suture
Located between the parietal bones
Coronal suture
Between frontal and parietal bones
Lambdoid suture
Between parietal and occipital bones
Bregma
The junction of Sagittarius and coronal sutures
Lambda
The junction of sagittal and lambdoidal sutures
Fontanelles
- “soft” spots
- feature of the infant skull soft membranous gaps (sutures)between the cranial bones.
- anterior (bregma)
- posterior (lambda)
Cranial vault (floor)
- divided into 3 shelf-like regions
1) anterior cranial fossa: lies over the orbit, shallowest
2) middle cranial fossa: central depression houses pit gland
3) posterior cranial fossa: deepest and most posterior
Associations of cranial fossae with brain regions
1) anterior (frontal lobe of brain)
2) middle (temporal lobe of brain)
3) posterior (cerebellum, pons of brain)
Which bones compose the anterior fossa of cranial vault
- frontal
- sphenoid
- ethmoid
Which bones compose the middle fossa of the cranial vault
- sphenoid
- temporal
- **middle depression (pit gland)
Which bones compose the posterior fossa of the cranial vault
- temporal
- occipital
How do we define the face
- it is the anterior aspect of the head
- it extends from the forehead to the chin and also ear to ear
- it is an important aspect of communication
- individuality of faces is based on anatomical variation
Bones of the face
- composed of 14 bones seen on the anterior view of the skull
1) zygomatic (2)-cheek bones
2) nasal (2)-bridge of the nose
3) maxilla (2)-upper jaw
4) mandible (1)-lower jaw
The skin of the face
1) highly vascular
2) very flexible
3) no deep fascia
4) not connected to underlying bones (except for chin and root of nose)
What is the significance of the skin of the face being highly vascular
Good collateral circulation
What is the significance of the skin of the face having no deep fascia
- No deep fascia to limit/compartmentalize swelling
- skin of face common site of swelling
- ex: blow to the chin, black eyes occur over time
Describe the innervation of the skin of the face
- sensory innervation to the skin of the face is provided by the 3 branches of the trigeminal nerve (largest sensory nerve of face)
1) ophthalmic
2) maxillary
3) mandibular
What are the important face areas of testing the innervation of the face
- ophthalmic nerve (forehead)
- maxillary nerve (cheek)
- mandibular nerve (lower lip)
Trigeminal nerve
- largest sensory nerve to innervate the face
- known as CN V (cranial nerve 5)
- splits into 3 branches (ophthalmic, maxillary, mandibular)
What is the primary blood supply to the face
- facial artery
- it is a branch of the external carotid (branch of the common carotid)
The internal carotid supplies blood where?
- supraorbital
- Supratrochlear
Describe the muscles of facial expression
- primary function is expression of emotions; most important in unspoken communication
- they also maintain the “posture” of the face
- important in the sucking reflex in infants
- help with stabilization of the mandible during infantile swallowing
- minor role in chewing in adults
Characteristics of the muscles of facial experession
1) all supplied by facial nerve CN VII (cranial nerve 7)
2) they are attached to the skin of the face
3) they all lie int eh subcutaneous tissue of the face
4) they surround the openings on the face and act as dilators or sphincters
Label the muscles of the face
1) frontalis (forehead)
2) orbicularis oculi (closing eyes)
3) orbicularis oris (sucking)
4) depressor labii inferioris (lowering bottom lip)
5) levator labii superioris (raising top lip)
6) zygomaticus major (frowning/smiling)
Facial nerve (CN VII)
- motor nerve to the muscles of facial expression
- it penetration other parotid salivary gland as it enters the face
- it has 5 main branches on the face (hand over face)
What are the tests for the integrity of facial nerve CN VII
1) raising eyebrows
2) closing eyelids tightly
3) showing teeth or pursing lips
4) pulling down corners of mouth (frown) or tensing the skin of neck
What is bell’s palsy
- A type of paralysis (weakness) of the muscles of facial expression
- only affects one side of the face at a time
What is the cause of bell’s palsy
- most common cause is inflammation of the facial nerve (CN VII) in middle ear infection
- sudden onset, but most recover over weeks to about 3 months
Why should a person suffering from Bell’s palsy not worry about a stroke
- bell’s only affects the muscles of facial expression
- strokes usually cause muscle weakness in other parts of the body along with facial muscles
What is the deep face
- its an area on the deep side of the mandible
- it includes the muscles of mastication
- it is also the site for the temporomandibular joint (TMJ)
Describe mastication
- it is the process of chewing
- also the first step of digestion (mechanical)
Why do we masticate
- to reduce the size of the particles to facilitate swallowing
- the primary muscles of mastication (4) are all supplied by CN V3
- this is the mandibular branch of the trigeminal nerve
What are the primary muscles of mastication
1) masseter
2) temporalis
3) medial pterygoid
4) lateral pterygoid
What are the secondary muscles involved in masatication
1) Suprahyoid muscles
- diagastric
- mylohyoid
- geniohyoid
What are the actions of the muscles of mastication
1) elevate (close mouth)
2) depress ( open mouth)
3) protrude (stick out chin)
4) retract (pull back chin)
Describe the grinding action of chewing
It is due to the alternation of protrusion (sticking out chin) and retraction (pulling back chin)
Masseter
- a large quadrangular muscle
- the masseter acts to elevate the mandible in closing the mouth
- superficial and deep aspects
Temporalis
- large fan-shaped muscle
- it stretches from the parietal bones to the mandible
- temporalis acts to elevate the mandible and also retracts
Medial pterygoid
- it lies on the deep side of the mandible
- its fibers run in the same direction as the masseter
- the medial pterygoid acts to elevate the mandible
Lateral pterygoid
- lies on the deep side of the mandible
- its fibers run from the posterior maxilla to the mandibular head
- the lateral pterygoid acts to depress the mandible (open mouth)
- it also acts to protrude the mandible (jut it forward)
Suprahyoid muscles
- 4 muscles all attach the inferior margin of the mandible to the hyoid bone
- act to depress the mandible (open mouth)
- **mandible is passively depressed by gravity
Temporomandibular joint (TMJ)
- it is a modified hinge joint (knee/elbow) that permits gliding and rotation
- mandibular head articulates the mandibular fossa of the temporal bone
- an articular cartilage divides the joint space into superior & inferior cavities for (rotation and glide)
