Lecture 6: Skeletal Muscles Muscles of the Head and Neck 10/24/2013

Transcription

1 Lecture 6: Skeletal Muscles Muscles of the Head and Neck 10/24/2013 Muscle Architecture Muscles in the same compartments typically have same function (originate from same cell) Sartorius crosses the thigh (due to tailors) Pectoralis major = major is describing the largest muscle of that region Pectoralis minor is underneath pectoralis major and is smaller Rectus Femoris = straight muscle of the femoral region Rectus = straight Muscle Function Only one nerve innervates facial expressions = facial nerve (CRANIAL VII) Muscles of facial expression Muscles of chewing Muscles of the tongue, eye and throat Anterior and posterior neck muscles Facial Expressions Tend not to organize by attachments some with fascia, sometimes bone Occipitofrontalis muscle:

2 Two bellies and one central tendon Different function depending on which belly is contracted Frontalis(close to frontal bone) causes you to raise eyebrows Occipitalis (close to occipital bone) draws the scalp backwards Orbicularis Oculi Goes around the eye Soft tissue, eyelid is a big attachment for this muscle, functionally know as the winking muscle Zygomatic Major & Minor originates from zygomatic process and to corners of the mouth and soft tissue around the lips Allows you to smile smiling muscle Orbicularis Oris Kissing muscle Around the mouth Draws lips to closed postion Depressor Anguli Oris Origin: Center of the mandibular angle and attaches on the corner of the mouth Known as the frowning muscle Platysma Originates from pectoralis major: Reaches superiorly to the mandible Large muscles

3 Called the shaving muscle Buccinator Doesn t fit in a compartment no common function Under zygomatic major Look at as a muscle involved in chewing Whistling muscle draws corner of lips inwards One on each side not usually contracted at the same time usually contracted in a pattern (one side then other side) Common innervation to all: facial nerve cranial VII Facial nerve There is 2 parotid glands: one on left side one on right Parotid gland Salivary gland Secretes juices into the oral cavity helps moisten the food as we mechanically break it down Sometimes this gland can become infected it swells The swelling of this gland puts a lot of pressure on the facial nerve More often than not it is just one of the glands that is affected Leaves droopiness on one side of the face Interacoustic metus Not a true foramen but somewhat Leads into a temporal bone

4 Specific in that it carries the facial nerve exits out of the skull through the styloid masto foramen Temporal: running up towards temporal bone Zygomatic: running from zygomatic process to zygomatic bone Buccal: cheek Mandibular jaw Cervical: neck/throat Permanent damage = won t be able to perform certain facial movements associated with that nerve Muscles of Mastication aka chewing Masseter superficial originates from the zygomatic process on the temporal bone and attaches down to the angle of the mandible Contraction of this muscle closes the jaw Agonist is the temporalis muscle Isn t positioned in the best position to close the jaw We sacrifice some of the position of masseter, but it over compensates with strength that provides maximal power for closing the jaw Temporalis

5 Originates off of the temporal bone Moves underneath the zygomatic process Inserts onto the coronoid process of the mandible Has maximal pull on the jaw Buccinator Largely responsible for moving our cheeks inwards Moving the jaw from side to side Allows us to put food between our molars so we can mechanically break it down (chewing) Impediment in this muscle will strongly affect chewing ability ^ these two are primary movers of the jaw very strong * Aside from the buccinators all of the muscles that are involved in chewing innervated by the third branch of the trigeminal nerve Trigeminal Nerve: 3 rd branch = mandibular nerve Mandibular nerve innervates temporalis and masseter has sensory nerves and picks up sensory info from mandibular region 2 nd branch of trigeminal nerve = maxillary nerve

6 above jaw can be picked up 1 st branch of trigeminal nerve = Insertion: point of attachment that is being pulled Origin: where its being pulled from Deeper layers Pterygoid process (or plate) Both pterygoid medial and lateral both arise from each pterygoid process (medial lateral from each side) Lateral Pterygoid: Moves laterally from sphenoid temporal mandibular joints and attaches When it contracts it pulls the joint forward in effect causes you to bring your jaw forward (protraction) Delicate movements Medial Pterygoid: Moves downwards towards the angle of the mandible (on the inside of the jaw) Moves jaw to side to side assist in keeping food between molars

7 More to do with speech Delicate movements Innervation of these muscles is via the mandibular nerve Muscles of the Tongue or Glossus Not prime movers of the jaw Use it in speech x sounds Styloglossus Moves from the styloid process down to the glossus (attachment is underneath the tongue) Contraction will move tongue towards the styloid processes (brings the tongue backwards or retracts the tongue and ELEVATES the tongue slightly Hyloglossus Runs form the hyoid bone to the underside of the glossus Contraction will draw the muscle downwards (draws sides of tongue downwards) Genioglossus Inner side of the mandible (chin region) to the underside of the tongue When contracts bring the tongue forwards

8 Palatoglossus Runs from the soft pallet down to the underside of the tongue Pushes the tongue up against the soft pallet Innervated by the vagus nerve Is involved in swallowing and speech and less to do with chewing Gag reflex! helps in throwing up food (CONTROLLED BY VAGUS NERVE) A way to elicit the gag reflex is to put pressure on the soft pallet thus eliciting the gag reflex which is controlled by the vagus nerve BLUE muscles are innervated by the hypoglossus nerve Extrinsic Muscles of the Eye Innervated by oculomotor nerve (CN III) Oculomotor muscles = move the eye Optic Nerve Exists the skull through the optic foramen (optic canal) Around the optic nerve we have the common tenuous ring Medial rectus Contraction = eye to move towards the nose (adduction)

9 Lateral Rectus abducens nerve (CN VI) Movement of eye away from the nose (Abduction) Superior Rectus: Contraction = elevation of the eye (raising the eye) Inferior Rectus Depression of the eye *all rolling of the eye Oblique eye muscles come at them at an oblique angle and cause twisting Superior oblique trochlear nerve (CN IV) First moves through a trochlea (pulling device situated on the medial side, inside the eye orbit) and then abruptly turns to the superior attachment of the eye Contraction = medial rotation of the eye Inferior Oblique Originates off of bone in the interior eye orbit and inserts itself on the eye inferiorly coming across the eye at an oblique angle Contraction = lateral rotation of the eye

10 Abducens nerve (CN VI) Lateral rectus Trochlear nerve (CN IV) Superior oblique Oculomotor nerve (CN III) All others *These nerves exit through the phisher EXCEPT optic nerve which runs through optic foramen or optic canal Muscles of the pharynx (aka Throat) Pharyngeal constrictors Group of muscles Constrict throat/pharynx to push food down into esophagus innervated by VAGUS nerve (CN X) Stylopharyngeus innervated by glossopharyngeal nerve!! stretches between styloid process and pharynx

11 elevates pharynx Palatopharyngeus Either longitudinal (straight like) or a circle around the pharynx work to push food down into esophagus. Elevates pharynx to help with swallowing Vagus nerve is heavily involved in digestion (part of autonomic NS parasympathetic nervous system rest and digest) When you constrict these muscles it opens the entrance into the nasal pharynx When you swallow you here a popping sound and are constricting muscles you close the entrance Eustachian tube: running from middle ear to nasal pharynx which opens **Attachments to cartilage, bone and ligaments Anterior Neck Muscles Hyoid bone: Attached to thyroid cartilage through band like ligament (thyroid membrane) When you move hyoid you move larynx (voice box) Sternocleidomastoid

12 Multiple attachments: Sternum x clavicle to mastoid process Two heads (sternal and clavicular) Superiorly attaches to mastoid process One on each side If you contract both you will have flexion of the neck If you contract just one your head will move to the opposite side Stylohyoid Slender muscles, lying anterior and superior to the posterior belly of the digastric muscle Draws hyoid bone backwards and elevates the tongue Mylohyoid Actually one of the more superficial ones appearance of a mill Paired muscle running from mandible to hyoid bone Digastric muscle (ANTERIOR AND POSTERIOR BELLY): Utilizes a trochlea located on the hyoid (or stirrup) Doesn t attach to the hyoid!! Means 2 belly s and in the center is where it attaches (anterior bigger than posterior) First attachment is on inner side of the mandible (anterior belly)

13 From the inner side of the mandible through the stirrup and its lateral attachment is to the mastoid process (posterior belly) 2 bellys for multiple functions increase in the strength of the muscle as a result of the 2 bellys! Suprahyoid: (mylohyoid, stylohyoid, digastric, geniohyoid) ^ 1. push larynx up (elevate) 2. depress mandible (lowering the jaw) 3. most attached to the hyoid (all except digastric) 4. OPEN MOUTH infrahyoid: (thyrohyoid, sternothyroid, sternohyoid, omohyoid) muscles that attach to the hyoid collectively these work to lower (depress) the larynx and hyoid bone during speaking and swallowing(after its raised its brought back down using these infrahyoid muscles to basal/no swallowing position) omohyoid: 2 bellys separated by trochlea/stirrup that s attached to the clavicle scapula attachment if we contract both at same time what we get is the origin and the suprahyoid muscles contract and they pull down the jaw (RELAX TEMPORALIS MASSETER AND TERI..)

14 Supra and infra participate in opening of the mouth Suprahyoid muscle attached to the jaw, and lower the jaw Hyoid doesn t move, so with contraction of this muscle the jaw has to go down raising of the larynx Sternocleidomastoid and lateral musculature Anterior Bordering muscle for anterior and posterior component is the sternocleidomastoid (indicating its attachment on the mastoid process on the temporal bone) o Borders anterior compartment from posterior o when BOTH(sides) are contracting = flexion of the neck o if just one contracts = rotation of the head to the opposite side o innervated by accessory nerve (cranial nerve 11) and cervical roots scalene muscles (group of muscles that.. o their superior attachment is the transverse processes of the cervical vertebrae o attach posteriorly to ribs 1 and 2 cervical roots o root fibers coming off the spinal chord Posterior Extension of the head and neck Splenius Capitis = rounded head Splenius Cervicis = attaches to cervical vertebrae (moves behind capitus) Super spinous ligament = keeps spines of vertebrae close together so there is no fish tailing This thickening of super spinous ligament serves a prominent attachment for muscles of the back Innervation by cervical roots

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