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Anatomy (gross) > Infratemporal Fossa > Flashcards

Infratemporal Fossa Flashcards

1
Q

Boundaries of infratemporal fossa

A

Roof- infratemporal surface of greater wing of sphenoid.
Medial wall- lateral pterygoid plate of sphenoid
Lateral wall- ramus of mandible
Anterior wall- infratemporal surface of maxilla
Floor- open and extends to the level of the base of mandible
Posterior wall- styloid process of temporal bone

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2
Q

Contents of infratemporal fossa

A
  1. Muscles: lateral pterygoid, medial pterygoid tendon of temporalis
  2. Blood vessels: maxillary artery, maxillary vein, pterygoid venous plexus
  3. Neural structures : Mandibular nerve, chorda tympani nerve, otic ganglion
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3
Q

Muscles of mastication

A

Primary: -masseter
-temporalis
-lateral pterygoid
- medial pterygoid

Secondary: - digastric
-buccinator
-mylohyoid
- geniohyoid

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4
Q

Characteristics of muscles of mastication

A
  1. All are located in or around the infratemporal fossa.
  2. All insert into ramus of mandible.
  3. All are innervated by mandibular division of Trigeminal.
  4. All are concerned with movements of the mandible on the temporomandibular joints.
  5. All develop from mesoderm of first pharyngeal arch
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5
Q

Attachments and actions of temporalis?
- fan shaped and covered by tough temporal fascia

A

Origin: whole floor of temporal fossa except part formed by zygomatic bone
and deep surface of temporal

Insertion: ramus of mandible

Innervation: anterior and posterior deep temporal nerves

Actions: elevates mandible
- posterior fibers retract mandible after it has been protruded

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6
Q

Discuss the masseter muscle
# thick quadrilateral muscle

A

Origin:
superficial layer- arises by thick aponeurosis from maxillary process of zygomatic bone and anterior two third of inferior border of zygomatic arch.
Middle layer- lower border of the posterior one third of zygomatic arch
Deep layer- deep surface of zygomatic arch

Insertion:
superficial fibers-angle and lower posterior half of lateral surface of mandible
Middle fibers- central part of ramus
Deep fibers- upper part of ramus of mandible and its coronoid process

Nerve: masseteric nerve, branch of anterior division of mandibular nerve

Actions: elevates mandible to close mouth

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7
Q

Discuss lateral pterygoid muscle
# short thick conical muscle with apex pointing upwards

A

Origin: 2 heads
-upper small head- infratemporal surface and crest of greater wing sphenoid
-lower large head- lateral surface of lateral pterygoid plate of sphenoid bone

Insertion : converge to form thick tendon
-pterygoid fovea on the front of the neck of mandible
- articular disc and capsule of the temporomandibular joint.

Nerve: branch of anterior division of mandibular nerve

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8
Q

Medial pterygoid muscle
# thick quadrilateral muscle with 2 heads

A

Origin:
-superficial head- maxillary tuberosity and lateral surface of pyramidal process of palatine bone
-large deep head- medial surface of lateral pterygoid plate and grooved surface of the pyramidal process of palatine bone.

Insertion: medial surface and angle of ramus of mandible

Innervation: nerve to medial pterygoid, branch from main trunk of mandibular nerve

Actions:
1. Two of them elevate mandible
2. Acting with lateral pterygoids, protrude mandible
3. Medial and lateral pterygoid of one side acting together, corresponding side is rotated forwards and to opposite side.
4. Lateral and medial pterygoid of two sides when contracted alternately produce,side to side movements which are used to grind food

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9
Q

Discuss maxillary artery(origin, parts and relations)

A

larger terminal branch of external carotid artery

Origin: arises behind neck of mandible, runs horizontally upward up to lower border of head of lateral pterygoid. Turns upwards and forwards crossing lower head of lateral pterygoid superficially. Emerges between two heads of lateral pterygoid.Enters pterygopalatine fossa by passing through pterygomaxillary fissure.

Parts and Relations:
1. First part(mandibular part)- from origin to lower border of lateral pterygoid. Lies between neck of mandible laterally and sphenomandibular ligament medially. Auriculotemporal nerve lies above this part.
2. Second(pterygoid) part- from lower border to the lower border of lower head of lateral pterygoid.
3. Third(pterygopalatine) part- from upper border of the lower head of lateral pterygoid to pterygopalatine fossa. In pterygopalatine fossa it lies in front of pterygopalatine ganglion

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10
Q

Discuss the branches of maxillary artery

A
  1. From the first part:
    1.deep auricular- supplies skin of external acoustic meatus and outer surface of tympanic membrane.
    1. Anterior tympanic- supplies inner surface of tympanic membrane
    2. Middle meningeal- (largest meningeal branch) supplies meninges and skull bone .
    3. Accessory middle meningeal- supplies meninges and structures in infratemporal fossa.
    4. Inferior alveolar/dental- supplies molar, premolar teeth and adjoining gum. It then divides into mental and incisive branches. Incisive branch supplies canine and incisors , mental supplies skin of chin. Before entering mandibular foramen, it gives two branches; lingual branch which accompanies lingual nerve and supply the mucous membrane of cheek. Mylohyoid branch pierces sphenomandibular ligament and runs in mylohyoid groove. Supplies myohyoid muscle.
  2. Second part:
    1. Deep temporal arteries- supply temporalis and lie deep to it
    2. Pterygoid branches- supply medial and lateral pterygoid muscles
    3. Masseteric artery- supplies masseter from its deep surface.
    4. Buccal artery- supplies buccinator
  3. Third part:
    1. Posterior superior alveolar artery- divides into two or three branches and supplies molar and premolar teeth and mucus membrane of maxillary air sinus.
    2. Infraorbital artery- in the orbit; branches to orbital contents, middle superior alveolar artery to premolars, anterior superior alveolar artery which supplies maxillary air sinus, Canine and incisor teeth of upper jaw. In the face; branches to lacrimal sac, medial angle of eye, side of nose and upper lip.
  4. Greater palatine artery- supplies roof of mouth and adjoining gum, gives off lesser palatine arteries in greater palatine canal that emerge through foramina and supply soft palate and tonsil
  5. Pharyngeal artery - supplies mucus membrane of nasopharyngeal, auditory tube and sphenoidal air sinus.
  6. Artery of pterygoid canal- supplies pharynx, auditory tube, tympanic cavity.
  7. Sphenopalatine artery- continuation of maxillary. Divides into posterior lateral nasal branches which supply lateral wall of the nose and sphenoidal and ethmoidal air sinuses and posterior septal branches
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11
Q

largest division of trigeminal, both sensory and motor, nerve of first pharyngeal arch

Course and relations of mandibular nerve

A

Origin: begins in middle cranial fossa from a larger sensory root from the Trigeminal ganglion and smaller motor root from the motor nucleus

Course: passes through foramen ovale and divides into 2 divisions, anterior and posterior

Branches:
-from the trunk; nerve to medial pterygoid (motor) supplies tensor palati and tensor tympani and nervus spinosus(sensory to dura)
-from the anterior division; muscular to muscles of mastication(masseteric nerve supplies massseter, deep temporal nerves supply temporalis and nerve to lateral pterygoid) except medial pterygoid, buccal branch(sensory) to skin and mucus membrane over buccinator,
- from the posterior division ; auriculotemporal, inferior alveolar and lingual nerve

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12
Q

Auriculotemporal nerve

A

Origin: by 2 roots surrounding middle meningeal artery

Distribution: 1. Sensory fibers to scalp, auricle, external auditory meatus, tympanic membrane, parotid gland, temporomandibular joint
2. Parasympathetic fibres to parotid gland from otic ganglion

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13
Q

Inferior alveolar nerve

A

Course: passes through mandibular canal and gives 3 branches

Branches: 1.nerve to mylohyoid(motor) supplies anterior belly of digastric and mylohyoid.
2. Incisive branch which supplies incisors and canines
3. Mental nerve passes through mental foramen to supply chin and lower lip.

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14
Q

Lingual nerve

A

Landmarks: joins the chorda tympani
Runs below last molar

Distribution: lingual nerve carries general sensation from the anterior 2/3 of the tongue.
Chorda tympani fibers- taste sensation from the anterior 2/3 of the tongue.
-Parasympathetic fibers to submandibular and sublingual salivary glands.( synapse in submandibular ganglion)

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15
Q

Trigeminal nerve lesion

A

Paralysis of muscles of mastication of same side
Loss of all sensations on same side of face
Trigeminal neuralgia- pain along distribution of any branch of Trigeminal. It is due to compression of Trigeminal nerve by a tumor or cyst or blood vessel.

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16
Q

Submandibular(digastric) triangle

A

Borders: lower border of mandible and digastric muscle
Floor: mylohyoid and hyoglossus muscles

Contents: submandibular salivary glands
- submandibular lymph nodes
- facial artery and submental branch
- common facial vein
- hypoglossal nerve
- lingual nerve
- nerve to mylohyoid which supplies mylohyoid and anterior belly of
Digastric.

17
Q

Discuss submandibular gland

A

Position: -lies below and deep to mandible in digastric triangle.
-lies over mylohyoid muscles

Extents:
-superior- deep to mandible to mylohyoid line
-inferior- overlap the intermediate tendon of digastric
- anterior- level of mental foramen
-posterior- to angle of mandible

*Capsule: *derived from the investing layer of the deep cervical fascia
- separated from parotid gland by stylomandibular ligament

Parts: divided by mylohyoid muscle
Superficial- superficial to mylohyoid
Deep part-deep to mylohyoid between mylohyoid and hyoglossus

Surfaces:
Medial(deep)- in contact with mylohyoid
Lateral- in contact with mandible
Inferolateral(superficial)- under the skin

Relations:
lateral surface- submandibular fossa, facial artery, medial pterygoid muscle
Infero-lateral- skin and fascia, cervical branch of CN VII, common facial vein,
and submandibular lymph nodes
Deep relations- mylohyoid and digastric, lingual nerve and submandibular ganglion, deep part of submandibular gland and submandibular duct, hypoglossal nerve, stylohyoid muscle

18
Q

(parasympathetic)

Describe the pathway of secretomotor Innervation to submandibular gland

A
  1. Preganglionic parasympathetic fibres arise from superior salivatory nucleus(in the pons)
  2. Facial nerve through **chorda tympani **branch and joins lingual nerve
  3. Fibres synapse at submandibular ganglion(relay station)
  4. Post ganglionic fibres arise from submandibular ganglion to supply submandibular gland
19
Q

Sympathetic and sensory nerve supply to submandibular gland

A

Sympathetic:
1. Preganglionic fibres arise from T1 spinal segment and enter superior cervical sympathetic trunk
2. Superior cervical sympathetic ganglion (relay)
3. Post ganglionic fibres form plexus around facial artery and reach gland.

Sensory: lingual nerve

20
Q

Clinical relevance of submandibular triangle

A
  1. Mandibular nerve injury- results in severe drooling at the corner of the mouth. Injury to anterior cervical branch produces minimal drooling that will disappear in 4-6 months.

2.** Ludwig’s angina**- infection of floor of mouth resulting from dental infections that spread to the submandibular triangle and beyond.

21
Q

Discuss the lingual artery

A

Origin: front of ECA opposite the tip of greater cornu of hyoid bone. Below facial artery and above superior thyroid artery.

Course: divided into 3 by hyoglossus muscle
1. Behind hyoglossus - lies in Carotid triangle. (Forms loop that permits movement of hyoid bone. Loop is crossed superficially by hypoglossal nerve)
2. Deep to hyoglossus
3. Along anterior border of hyoglossus- anastomoses with its fellow of opposite side on the undersurface of tongue.

Branches:
1. First part- suprahyoid artery (anastomoses with fellow Side)
2. Second part- dorsal lingual arteries( to dorsum of tongue and tonsil)
3. Third part- Sublingual artery ( to sublingual gland)

Termination: tongue by forming deep lingual artery

22
Q

Discuss the temporal fossa

A

Boundaries: Bound by temporal lines above and zygomatic arch below
Roof(lateral wall)- temporalis fascia
Floor(medial wall)-pterion
Anterior wall- zygomatic process of frontal bone, zygomatic bone and maxilla

Contents: temporalis muscle which arises from the floor and overlying fascia

Anatomy (gross) (35 decks)

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