Head and Neck Flashcards
(23 cards)
What are the borders and components of Scalene Triangle of the Neck
Borders: 1st rib, anterior and medial scenic muscles
Components: Brachial plexus and subclavian a.
What is Thoracic outlet syndrome? What are the causes and symptoms?
Compression of the trunks of the
brachial plexus and the subclavian artery within the scalene triangle.
Causes:
- Pancoast tumor
- Cervical rib
- Hypertrophy of the scalene muscles
Symptoms:
• Numbness and pain on medial aspect of the forearm and hand
• Weakness of the muscles supplied by ulnar nerve in the hand (claw
hand)
• Decreased blood flow into upper limb, indicated by weakened radial
pulse
What is the most significant artery of the
external carotid system?
Middle meningeal artery. It arises from the maxillary artery in the infratemporal fossa and enters the skull through the foramen spinosum to supply skull and dura. Lacerations of this vessel result in an epidural hematoma.
What are the components of Pharyngeal Apparatus of Embryo?
- Pharyngeal arches (1, 2, 3, 4, and 6) composed of mesoderm and neural crest
- Pharyngeal pouches (1, 2, 3, 4) lined with endoderm
- Pharyngeal grooves or clefts (1, 2, 3, and 4) lined with ectoderm
What are the components of the pharyngeal arches?
1st arch: Trigeminal: mandibular nerve Four muscles of mastication: Plus: • Digastric (anterior belly) • Mylohyoid • Tensor tympani • Tensor veli palatini Maxilla Mandible Incus Malleus
2nd arch: VII nerve Muscles of facial expression: Plus: • Digastric (posterior belly) • Stylohyoid • Stapedius Stapes Styloid process Lesser horn and upper body of hyoid bone
3d arch: IX nerve Right and left common carotid arteries Right and left internal carotid arteries Stylopharyngeus muscle Greater horn and lower body of hyoid bone
4th arch: X nerve: – Superior laryngeal nerve – Pharyngeal branches Right subclavian artery (right arch) Arch of aorta (left arch) Cricothyroid muscle Soft palate Pharynx (5 muscles) Thyroid cartilage
6th arch: X nerve Recurrent laryngeal nerve Right and left pulmonary arteries Ductus arteriosus (left arch) Intrinsic muscles of larynx (except cricothyroid muscle) All other laryngeal cartilages
What are the Adult Structures Derived From the Fetal Pharyngeal Pouches?
1st pouch: Epithelial lining of auditory tube and middle ear cavity
2nd pouch: Epithelial lining of crypts of palatine tonsil
3d pouch: Inferior parathyroid (IP) gland, Thymus (T)
4th pouch: Superior parathyroid (SP) gland, C-cells of thyroid
How does thyroid gland develop?
It develops from the thyroid diverticulum, which forms from the midline endoderm in the floor of the pharynx.
• The thyroid diverticulum migrates caudally to its adult anatomic position in the neck but remains connected to the foregut via the thyroglossal duct, which is later obliterated.
• The former site of the thyroglossal duct is indicated in the adult by the foramen cecum.
How is tongue innervated?
Sensory:
Post. 1/3: general sensation - IX, taste - IX
Ant. 1/3: general sensation - V (mandibular), taste - VII (chorda tympani)
Motor: XII
When does cleft lip and cleft palatine occur?
Cleft lip: the maxillary prominence fails to fuse with the medial nasal prominence
Cleft palatine: the palatine shelves fail to fuse with each other or the primary palate
What is First arch syndrome?
Abnormal formation of pharyngeal arch 1 because
of faulty migration of neural crest cells, causing facial anomalies. Two well-described syndromes are Treacher Collins syndrome and Pierre Robin sequence. Both defects involve neural crest cells
What is Treacher Collins syndrome?
Mandibular hypoplasia, zygomatic hypoplasia, down-slanted palpebral fissures, colobomas, and malformed ears
What is Pierre Robin sequence?
Triad of poor mandibular growth, cleft palate, and a posteriorly placed tongue
When does pharyngeal fistula occur?
When pouch 2 and groove 2 persist, thereby forming a fistula generally found along the anterior border of the muscle
When does pharyngeal cyst occur?
When pharyngeal grooves that are normally obliterated persist, forming a cyst usually located at the angle of the mandible
When does ectopic thyroid, parathyroid, or thymus occur?
Results from abnormal migration of these glands from their embryonic position to their adult anatomic position. Ectopic thyroid tissue is found along the midline of the neck. Ectopic parathyroid or thymus tissue is generally found along the lateral aspect of the neck. May be an important issue during neck surgery
Whe does thyroglossal duct cyst or fistula occur?
Occurs when parts of the thyroglossal duct persist, generally in the midline near the hyoid bone. The cyst may also be found at the base of the tongue (lingual cyst).
When does jugular foramen syndrome occur? What are the symptoms and which CN are altered?
May be caused by a tumor pressing on CN IX, X, and XI. Patients present with hoarseness, dysphagia (CN IX and X), loss of sensation over the oropharynx and posterior third of the tongue (CN IX), and trapezius and sternocleidomastoid weakness (CN XI). The nearby CN XII may be involved, producing tongue deviation to the lesioned side.
What are the Cranial Meninges?
- pia mater ( cannot be dissected)
- arachnoid (lines the inner surface of dura mater)
- dura mater
v periostal layer (can be easily pealed away)
v meningeal layer (fused with periostal layer, they form the dural venous sinuses and connective tissue foldings:)
1) fall cerebri
2) diaphragma sellae
3) tentorium cerebelli
What are the potential cranial spaces?
- epidural: between periostal layer and bone
- subdural: between meningeal layer and arachnoid
- subarachnoid: between arachnoid and pia mater
Which important structures pass through cavernous sinus and could be damaged if there is sinus thrombosis? Which CN is affected the first?
- III CN
- IV CN
- VI CN (is affected the first)
- V CN (Ophtalmic and maxillary)
Which vessels are altered if there is Epidural Hematoma? What is the radiological sign of it?
- middle meningeal a. (branch of maxillary a. of I. carotid a.)
- lens-shaped on X-Ray
Which vessels are altered if there is Subdural Hematoma? What is the radiological sign of it?
- bridging veins
- crescent-shaped on X-Ray
Which vessels are altered if there is Subarachnoid Hemorrhage?
Aneurism of Willi’s circle (usually anterior part)
