Head Flashcards
what are the 5 layers of the scalp from superficial to deep
1) skin
2) dense CT
3) aponeurosis
4) loose CT
5) pericranium (periosteum)
skin
contains all epidermal appendages including hair follicles and sebaceous glands
dense connective tissue
- highly vascularized and innervated layer, also contains hair follicles
- scalp lacerations that penetrate this layer bleed profusely due to rich blood supply
aponeurosis
thin, broad, tendon-like sheet that covers the dome of the skull and serves as an intermediate tendon between the occipitalis muscle posteriorly and frontalis muscle anteriorly
loose connective tissue
- referred to as “danger area of scalp” because infections can spread within it and enter the cranial cavity
- provides an easy plan of separation between the upper 3 layers and pericranium (the external periosteum of the skull)
pericranium (periosteum)
- very thin layer of connective tissue that covers the bones of the skull
- protects skull and provides nutrients to the bone
salivary glands
- parotid gland
- sublingual gland
- submandibular gland
parotid gland
- secretions exit through Stensen’s duct (parotid duct)
- Stensen’s duct passes superficial to masseter muscle, then pierces the buccinator to open into the oral cavity opposite the 2nd upper molar tooth
submandibular gland
- 2nd largest salivary gland
- can be palpated in neck medial to lower border of mandible
muscles of facial expression
- specialized group of voluntary muscles that protect orifices of face by acting as sphincter and dilators
- attach to skin therefore can change facial expression
buccinator
contraction pulls cheeks tightly against teeth, preventing food from collecting between teeth and gums during mastication and working in concert with tongue to keep food between molars
what are the branches of the facial nerve
- CN VII
- supplies both sensory and motor innervation
- temporal
- zygomatic
- marginal mandibular
- cervical
- buccal
trigeminal nerve
- CN V
- carries sensory and motor info to face
- each branch supplies sensory info to specific areas of the face
what are the 3 branches of the trigeminal nerve
- mandibular (V3)
- maxillary (V2)
- ophthalmic (V1)
Mandibular branch (V3) of the trigeminal nerve
supplies skin of lower lip, lower face, temporal region and upper part of external ear
- only division that carries motor innervation to the muscles of mastication
maxillary branch (V2) of the trigeminal nerve
- innervates skin of lateral sides of nose, lower eyelid, cheek, temporal region and upper lip
ophthalmic branch (V1) of trigeminal nerve
carries sensory info from skin of forehead, upper eyelid and midline of nose
how many extraocular muscles control the movements of the eyeball and eyelid
7
movement of eyeball about horizontal axis
- elevation of eyeball with pupil in midline by the superior rectus and inferior oblique muscles
- depression facilitated by inferior rectus and superior oblique muscles
movement of eyeball about vertical axis
- abduction of eyeball facilitated by lateral rectus muscle
- adduction performed by medial rectus muscle
arterial supply of orbit
- ophthalmic artery = branch of internal carotid artery
- enters orbit with optic nerve (CN II) through the optic canal
- branches of ophthalmic artery supply contents of orbit and eyelids (ex. central retinal artery supplies retina)
venous drainage of orbit
- superior ophthalmic vein formed by smaller veins that drain orbit
- passes through superior orbital fissure to drain into cavernous sinus
- small inferior ophthalmic vein usually joins superior ophthalmic vein before draining into cavernous sinus
ear
- contains organs of hearing and balance
- divided into 3 parts: external, middle and inner ear
lateral border of middle ear
tympanic membrane
medial border of middle ear
medial (labyrinthine) wall separates middle and inner ear
posterior border of middle ear
thin bone separating tympanic cavity from mastoid air cells in the temporal bone
roof of middle ear
tegmen tympani, thin plate of bone which separates the middle ear from the middle cranial fossa
floor of middle ear
jugular wall, thin bone which separates middle ear from internal jugular vein
anterior border of middle ear
lower anterior wall is thin bone that separates tympanic cavity from internal carotid artery (upper anterior wall incomplete because of opening of eustachian tube)
eustachian tube
- channel between middle ear and nasopharynx
- helps equalize pressure on either side of tympanic membrane allowing it to vibrate properly for transmission of sound to inner ear