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Head and Neck

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1 Topographic Surface Anatomy

STUDYAIMS

At the end of your study, you should be able to:

Identifythe keylandmarks in the midline of the neck and their significance

State the structures that are situated at the level of C6

Outline the boundaries of the triangles of the neck

Describe the landmarks for palpation of the main arteries, which can be palpated in the face and neck

Identifyprominent features of the face

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GUIDE

Head and Neck: Topographic Anatomy

[Plate 1, Head and Neck]

Key Landmarks Midline of Neck

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There are a number of landmarks visible on the body's surface that correspond to deeper structures.

Hyoid bone

Lies at level of C3 vertebra

U-shaped bone

Does not articulate with anyother bone

Is suspended bymuscles from

Mandible

Styloid processes of temporal bones

Thyroid cartilage

Manubrium of sternum

Scapulae

Thyroid cartilage

Formed from anterior, midline fusion of two laminar plates = laryngeal prominence (Adam's apple)

Laminae diverge superiorly

Form V-shaped thyroid notch

Lie at the level of C4 vertebra

C4 vertebral level

Bifurcation of common carotid arteryinto external and internal carotid arteries

Site of carotid sinus (baroreceptor) and carotid body(chemoreceptor)

Carotid pulse can be palpated at anterior border sternocleidomastoid (level of C5 vertebra)

Cricoid cartilage

Onlycomplete ring cartilage in respiratorytract

Shaped like signet ring with band anteriorly

Lower border corresponds to level of C6 vertebra

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C6 vertebral level

Junction of larynxand trachea

Junction of pharynxand esophagus

Level at which inferior and middle thyroid arteries enter the thyroid gland

Vertebral artery(first branch subclavian artery) enters foramen transversarium of C6 transverse process to ascend to brain through successivelyhigher foramina

Superior bellyof omohyoid muscle crosses carotid sheath

Level of middle cervical sympathetic ganglion

Carotid arterycan be compressed and palpated against transverse process C6 Isthmus of thyroid gland overlies second and third tracheal cartilages

Jugular (suprasternal) notch

Concave center of superior border of manubrium Between medial ends of clavicles

Other Landmarks in the Neck

Platysma

Thin, broad sheet of muscle within superficial fascia of the neck

Amuscle of facial expression, tensing the skin

Draws corners of mouth down, as in a grimace, and depresses mandible External jugular vein

Deep to platysma, descends from angle to mandible to midpoint of clavicle

Useful for assessment of venous filling with patient sitting at 45 degrees Sternocleidomastoid (SCM)

Keylandmark of neck

Divides neck into anterior and posterior triangles (Section 1-4: Head and Neck - Neck)

Sternal head attaches to manubrium of sternum

Clavicular head attaches to superior middle third of clavicle

Can be seen and palpated when acting unilaterallyto flexand rotate head and neck to one side, so that ear approaches shoulder and chin turns in the opposite direction

Landmarks of the Face

Glabella

Smooth midline prominence on the frontal bone

Located above the root of the nose, between supraorbital margins Zygomatic arch

Forms prominence of cheek

Can palpate superficial temporal arteryat lateral end

Prone to fractures in facial trauma Mastoid process

Bonyprominence behind external acoustic meatus

Site of proximal attachment sternocleidomastoid muscle Inion-prominent point of external occipital protuberance at back of head Auricle-part of external ear

Skin-covered cartilage, except for lobule

Features include: pinna; tragus; antitragus and helix External nose

Skeleton mainlycartilaginous

Dorsum extends from root to apex

Inferior surface has two openings or nares (nostrils)

Bounded laterallybyalae of nose

Separated byskin over nasal septum Philtrum-midline infranasal depression of upper lip Masseter muscle

Felt over ramus of mandible when teeth are clenched

Parotid duct can be palpated at medial border (duct opens over second molar inside cheek) Temporalis muscle can be felt above zygomatic arch when teeth clenched

Facial arterycan be palpated over lower margin bodyof mandible in line with a point one fingerbreadth lateral to the angle of the mouth

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FACTS & HINTS

High-Yield Facts

Clinical Points

Tracheostomy

Transverse incision through skin of neck and anterior wall of trachea

Method for achieving a definitive airway

Transverse incision made through skin, at midpoint between suprasternal notch and thyroid cartilage

Platysma and pretracheal fascia divided

Strap muscles retracted

Thyroid isthmus divided or retracted

Opening made between first and second tracheal rings or through second through fourth tracheal rings

Tracheostomytube inserted

Clinical Points

Needle Cricothyrotomy

Done in extreme emergency

Performed if proximal airwayis obstructed, to temporarilyoxygenate the patient

Large-bore needle inserted into the cricothyroid membrane and connected to an oxygen supply

Clinical Points

Central venous line

Large veins such as the subclavian have relativelyconstant relationships to easilyidentifiable anatomic landmarks Placement of large-bore venous catheter in an emergent situation to deliver high flow of fluid or blood products Used for administration of chemotherapeutic agents, hyperalimentation fluids, and so on

Used for assessing right heart (venous) pressures

Vein located in an area bounded bythe sternal and clavicular attachments of sternocleidomastoid and the clavicle-just deep to middle third of clavicle

Subclavian vein is inferior and anterior to subclavian arteryand separated from it byanterior scalene muscle

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2 Bones and Ligaments

STUDYAIMS

At the end of your study, you should be able to:

Describe the anatomic division of the head into a neuroand viscerocranium Describe the function of the neuroand viscerocranium

Outline the bones that form the neurocranium Know the major sutures of the skull

Describe the division of the base of skull into anterior, middle, and posterior cranial fossae and the contents of each List the foramina and keystructures that pass through them

Identifythe prominent features of the mandible

Describe the structure of the temporomandibular joint and the ligaments that stabilize it

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