Illustrated Human Anatomy: Head and Neck Review

Comprehensive practice flashcards in Question-and-Answer format covering the complete Head and Neck Anatomy lecture notes by M.A. Noor-El-Din, detailing osteology, neuroanatomy, vasculature, musculature, visceral organs, and clinical correlations.

What is the bregma, and what corresponds to its position in the foetal skull?

The bregma is the meeting point of the sagittal and coronal sutures. In the foetal skull, this position is occupied by the rhomboidal anterior fontanelle, which has an anteroposterior extent of about three fingers breadth and normally obliterates in the middle of the second year after birth.

What is the lambda, and when does its foetal counterpart close?

The lambda is the meeting point of the sagittal and lambdoid sutures. In the foetal skull, it is occupied by a small triangular membrane called the posterior fontanelle, which is obliterated in the first three months after birth.

Where is the pterion located anatomically, and what important clinical feature lies on its inner aspect?

The pterion is the junction of the frontal, parietal, squamous temporal, and greater wing of the sphenoid bones, centered $35\,\text{mm}$ behind and $12\,\text{mm}$ above the frontozygomatic suture. Its inner aspect is deeply grooved or tunneled by the anterior (frontal) branch of the middle meningeal artery, making it a frequent site of extradural haemorrhage following head trauma.

Which structures are transmitted through the optic canal?

The optic canal transmits the optic nerve, the ophthalmic artery (lying below the nerve), and their enclosing meningeal sheath derived from the dura, arachnoid, and pia maters.

Which nerves and vessels pass through the superior orbital fissure outside the common tendinous ring?

Arranged from lateral to medial: the lacrimal nerve, frontal nerve, and trochlear nerve, along with the superior and inferior ophthalmic veins, the recurrent meningeal branch of the lacrimal artery, and the orbital branch of the middle meningeal artery.

Which structures pass through the superior orbital fissure inside the common tendinous ring?

The superior division of the oculomotor nerve, nasociliary nerve, inferior division of the oculomotor nerve, and abducent nerve.

What are the five anatomical layers of the scalp?

1. Skin; 2. Superficial fascia (dense fibrous tissue containing vessels and nerves); 3. Occipitofrontalis muscle and epicranial aponeurosis (galea aponeurotica); 4. Layer of loose areolar tissue (the subaponeurotic dangerous area); 5. Pericranium (outer periosteum of the skull vault).

Why do wounds of the scalp bleed profusely?

Because the arteries run within the dense fibrous superficial fascia, where their walls are intimately adherent to fibrous septa, preventing them from contracting or retracting when transected.

What is the 'dangerous area of the face' and what venous pathways cause its clinical significance?

It encompasses the upper lip and lower nose, extending to the median forehead. Retrograde spread of infection can travel via the facial vein into the superior ophthalmic vein or through the deep facial vein into the pterygoid plexus, both of which communicate directly with the cavernous sinus, predisposing to cavernous sinus thrombosis.

What are the embryonic pharyngeal arch origins of the hyoid bone?

The lesser cornua and the upper part of the body are derived from the second pharyngeal arch; the greater cornua and the lower/greater part of the body are derived from the third pharyngeal arch.

What structural role is played by the transverse ligament of the atlas?

It attaches to a tubercle on the medial side of each lateral mass of the atlas, holding the dens (odontoid process) of the axis securely against the anterior arch of the atlas, preventing posterior displacement of the dens into the spinal cord.

Which spinal nerve root rami form the cervical plexus, and where is the plexus situated?

The cervical plexus is formed by the ventral rami of the upper four cervical nerves ($C_1$, $C_2$, $C_3$, and $C_4$). It lies in front of the transverse processes of the upper four cervical vertebrae, scalenus medius, and levator scapulae, deep to the sternocleidomastoid and behind the internal jugular vein.

What are the boundaries of the posterior triangle of the neck?

Anterior: posterior border of the sternocleidomastoid; Posterior: anterior border of the trapezius; Base: intermediate third of the clavicle; Apex: superior nuchal line between the attachments of sternocleidomastoid and trapezius.

Which muscles form the floor of the posterior triangle of the neck from inferior to superior?

Scalenus medius, levator scapulae, splenius capitis, and occasionally the semispinalis capitis.

What are the boundaries and contents of the suboccipital triangle?

Boundaries: Rectus capitis posterior major (superomedially), obliquus capitis superior (superolaterally), and obliquus capitis inferior (inferiorly). Contents: Third part of the vertebral artery, suboccipital plexus of veins, and the dorsal ramus of the first cervical nerve (suboccipital nerve).

Which cranial nerves and vessels pass through the cavernous sinus cavity versus within its lateral wall?

Inside the sinus cavity / floor: Internal carotid artery surrounded by its sympathetic plexus, and the abducent nerve (CN VI). In the lateral wall (from above downwards): Oculomotor nerve (CN III), trochlear nerve (CN IV), ophthalmic nerve ($V_1$), and maxillary nerve ($V_2$).

What are the three compartments of the jugular foramen and what structures traverse each?

Anterior compartment: inferior petrosal sinus; Intermediate compartment: glossopharyngeal (IX), vagus (X), and accessory (XI) nerves; Posterior compartment: sigmoid sinus continuing downwards as the internal jugular vein.

What are the four primary branches of the third (pterygopalatine) part of the maxillary artery?

Posterior superior alveolar artery, infraorbital artery, greater palatine artery, artery of the pterygoid canal, pharyngeal branch, and sphenopalatine artery.

Describe the roots and secretomotor target of the otic ganglion.

Parasympathetic (motor) root: lesser petrosal nerve (originating from inferior salivary nucleus via CN IX); Sympathetic root: plexus around middle meningeal artery. Postganglionic secretomotor fibers join the auriculotemporal nerve to innervate the parotid gland.

Which muscle of mastication acts to depress (open) the mandible?

The lateral pterygoid muscle, acting with its fellow to pull the mandibular head and articular disc forwards onto the articular tubercle, assisted by digastric, geniohyoid, and mylohyoid muscles.

What are the boundaries and contents of the carotid triangle?

Boundaries: Anterior border of sternocleidomastoid, posterior belly of digastric, and superior belly of omohyoid. Contents: Bifurcation of the common carotid artery, external and internal carotid arteries, internal jugular vein, vagus nerve, sympathetic trunk, hypoglossal nerve, ansa cervicalis, and branches of the external carotid artery.

What are the contents of the carotid sheath and their anatomical relationships to each other?

The common or internal carotid artery lies medially, the internal jugular vein lies laterally, and the vagus nerve lies posteriorly in the groove between the artery and vein.

What structures pass between the external and internal carotid arteries?

Styloid process, styloglossus muscle, stylopharyngeus muscle, glossopharyngeal nerve (CN IX), pharyngeal branch of the vagus nerve, and a portion of the parotid gland.

What three main structures traverse the parotid gland from superficial to deep?

1. Facial nerve (CN VII, most superficial); 2. Retromandibular vein (intermediate); 3. External carotid artery (deepest).

Where does the parotid duct open into the oral cavity?

It opens into the vestibule of the mouth on the inner surface of the cheek opposite the crown of the upper second molar tooth.

Describe the dangerous anatomical relationship of the lingual nerve adjacent to the mandible.

The lingual nerve passes on the inner aspect of the mandible above the posterior end of the mylohyoid line, lying directly in contact with the bone medial to the root of the third lower molar tooth, making it vulnerable to injury during tooth extraction.

What structures form the ansa cervicalis, and which muscles does it supply?

It is formed by a superior limb (descendens hypoglossi carrying $C_1$ fibers via CN XII) and an inferior limb (descendens cervicalis from $C_2$ and $C_3$). It supplies the infrahyoid muscles: sternohyoid, sternothyroid, and inferior belly of omohyoid (its superior belly being supplied by the superior limb).

What is the origin, cervical course, and relation of the phrenic nerve?

Arises from ventral rami of $C_3$, $C_4$, and $C_5$ (mainly $C_4$). It forms at the lateral border of scalenus anterior, descends vertically on its anterior surface deep to prevertebral fascia, and passes behind the subclavian vein into the thorax.

What are the three parts of the subclavian artery relative to the scalenus anterior muscle?

First part: medial to scalenus anterior; Second part: behind scalenus anterior; Third part: lateral to scalenus anterior, ending at the outer border of the first rib to become the axillary artery.

What are the three primary branches of the thyrocervical trunk?

1. Inferior thyroid artery; 2. Suprascapular artery; 3. Superficial cervical artery (or transverse cervical artery).

What structures open into the middle meatus of the nasal cavity?

The frontal air sinus (via frontonasal duct into the infundibulum), anterior ethmoidal sinuses (into infundibulum or hiatus semilunaris), middle ethmoidal sinuses (on or above the bulla ethmoidalis), and the maxillary air sinus (into the hiatus semilunaris).

What is Little's area on the nasal septum, and why is it clinically important?

It is an arterial anastomosis on the anteroinferior part of the nasal septum formed by the sphenopalatine, greater palatine, septal branch of superior labial, and anterior ethmoidal arteries; it is the most common site for epistaxis (nosebleeds).

What is the motor and sensory nerve supply of the tongue?

Motor: CN XII (hypoglossal) supplies all intrinsic and extrinsic muscles except palatoglossus (cranial accessory via vagus and pharyngeal plexus). Sensory: Anterior $2/3$ supplied by lingual nerve for general sensation and chorda tympani (CN VII) for taste; Posterior $1/3$ (including vallate papillae) supplied by glossopharyngeal nerve (CN IX) for both general and taste sensation; Most posterior tongue/vallecula by internal laryngeal nerve (CN X).

Which structures pass through the gap between the superior and middle constrictor muscles of the pharynx?

The stylopharyngeus muscle and the glossopharyngeal nerve (CN IX).

What are the single and paired cartilages of the larynx?

Single cartilages: Thyroid, Cricoid, and Epiglottis. Paired cartilages: Arytenoid, Corniculate, and Cuneiform cartilages.

Which intrinsic muscle of the larynx is the sole abductor of the vocal folds?

The posterior crico-arytenoid muscle, which rotates the arytenoid cartilages outwards to abduct the vocal folds and open the rima glottidis.

What is the motor nerve supply to the intrinsic laryngeal muscles?

All intrinsic laryngeal muscles are supplied by the recurrent laryngeal nerve EXCEPT the cricothyroid muscle, which is supplied by the external laryngeal nerve.

What sensory nerves supply the laryngeal mucosa above and below the vocal folds?

Above the vocal folds: internal laryngeal nerve (branch of superior laryngeal nerve from CN X); Below the vocal folds: recurrent laryngeal nerve (CN X).

What is the flow pathway of aqueous humour in the eye?

Secreted by capillaries of ciliary processes into the posterior chamber $\rightarrow$ passes through the pupil into the anterior chamber $\rightarrow$ filtered via the trabecular meshwork at the iridocorneal angle $\rightarrow$ enters sinus venosus sclerae (canal of Schlemm) $\rightarrow$ drains into anterior ciliary veins.

What are the two auditory muscles inside the middle ear and what are their respective nerve supplies?

Tensor tympani muscle (supplied by the mandibular nerve, $V_3$, via nerve to medial pterygoid) and Stapedius muscle (supplied by the facial nerve, CN VII).

What are the main components of the membranous labyrinth?

The utricle, saccule, three semicircular ducts (superior, posterior, and lateral), and the cochlear duct (containing the organ of Corti).

List seven major anatomical events occurring at the level of the sixth cervical vertebra (C6).

1. Termination of the larynx and beginning of the trachea; 2. Termination of the pharynx and beginning of the oesophagus; 3. Vertebral artery enters the foramen transversarium of C6; 4. Prominent carotid tubercle on transverse process of C6; 5. Location of middle cervical sympathetic ganglion; 6. Inferior thyroid artery arches medially behind the carotid sheath; 7. Intermediate tendon of omohyoid crosses the internal jugular vein.

What are the clinical consequences of a cervical rib?

Compression of the subclavian artery leads to ischemic pains and vascular changes in the upper limb; compression of the lower trunk of the brachial plexus ($C_8$, $T_1$) leads to pain/paraesthesia along the medial forearm and hand, as well as weakness and wasting of intrinsic hand muscles.

What is the exception to the rule that all muscles of the palate are innervated by the cranial accessory nerve via the pharyngeal plexus?

The tensor palati (tensor veli palatini), which is innervated by the mandibular nerve ($V_3$) via the nerve to the medial pterygoid.