Atlas of Human Anatomy by Netter

FACTS & HINTS

High-Yield Facts

Clinical Points

Scalp lacerations

Scalp has rich blood supply

Bleeding from scalp lacerations often profuse, because blood enters periphery of scalp and vessels anastomose

Because of dense connective tissue in second layer of scalp, bleeding vessels do not retract into wound but stay open

Patient can exsanguinate if bleeding is not controlled

Bleeding controlled initially by direct pressure initially followed by suturing in layers rather than tying individual vessels

Clinical Points

Blood or infections in the scalp

Blood or pus from an infection collects in loose connective tissue

Can spread easily

Prevented from passing into the neck or subtemporal regions, because of attachments of the epicranial aponeurosis

Fluid can descend into orbits because orbitalis muscle attaches to skin in this region

Orbital hematomas commonly occur following injury to the scalp

Clinical Points

Facial palsy (Bell's palsy)

Facial nerve palsy without a known cause

Can follow exposure to cold, dental work, Lyme disease, or otitis media

Results in inflammation, compression, or edema of the nerve

Facial nerve supplies muscles of facial expression

Thus result is loss of facial muscle tone on the affected side

Symptoms generally seen:

Paralysis orbicularis oris causes drooping of mouth on affected side and dribbling of saliva

Paralysis of orbicularis oculi causes eyelid to droop and evert, leaving cornea inadequately lubricated and eye constantly tearing

Paralysis of buccinator together with orbicularis oris leads to accumulation of food between cheek and teeth when chewing

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Clinical Points

Table I00-2. Sites of lesions of the facial nerve and resulting symptoms

Site of Lesion Symptoms

Below stylomastoid

foramen (parotid gland

tumor, trauma

1) Facial paralysis (mouth draws to opposite side; on affected side, patient unable to close eye or

wrinkle forehead; food collects between teeth and cheek as a result of paralysis of buccinator muscle.

Facial canal 2) All symptoms of (1), plus loss of taste in anterior tongue and decreased salivation on affected side

as a result of chorda tympani involvement. Hyperacusis as a result of effect on nerve branch to

stapedius muscle.

Geniculate ganglion 3) All symptoms of (1) and (2), plus pain behind ear. Herpes of tympanum and of external auditory

meatus may occur

Intracranial and/or internal

auditory meatus

4) All symptoms of (1-3), plus deafness as a result of involvement of eighth cranial nerve

Mnemonics

Memory Aids

Layers of scalp: SCALP

Skin

Connective Tissue

Aponeurosis

Loose connective tissue

Periosteum of skull

Memory Aids

Branches Facial Nerve: "To Zanzibar By Motor Car"

Temporal

Zygomatic

Buccal

Mandibular

Cervical

Memory Aids