Levator palpebrae superioris muscle
The levator palpebrae superioris is the muscle in the orbit that elevates the superior eyelid. The levator palpebrae superioris originates on the lesser wing of the sphenoid bone, just above the optic foramen, it decreases in thickness and becomes the levator aponeurosis. This portion inserts on the skin of the upper eyelid, as well as the superior tarsal plate, it is a skeletal muscle. The superior tarsal muscle, a smooth muscle, is attached to the levator palpebrae superioris, inserts on the superior tarsal plate as well; as with most of the muscles of the orbit, the levator palpebrae receives somatic motor input from the ipsilateral superior division of the oculomotor nerve. An adjoining smooth muscle, the superior tarsal muscle, confused to be a portion of the levator palpebrae superioris, is only attached, it is separately innervated by sympathetic fibers that originate in the cervical spinal cord; the levator palpebrae superioris muscle retracts the upper eyelid. Damage to this muscle or its innervation can cause ptosis, drooping of the eyelid.
Lesions in CN III can cause ptosis, because without stimulation from the oculomotor nerve the levator palpebrae cannot oppose the force of gravity, the eyelid droops. Ptosis can result from damage to the adjoining superior tarsal muscle or its sympathetic innervation; such damage to the sympathetic supply presents as a partial ptosis. It is important to distinguish between these two different causes of ptosis; this can be done clinically without issue, as each type of ptosis is accompanied by other distinct clinical findings. Blepharospasm Ptosis Superior tarsal muscle Anatomy figure: 29:01-01 at Human Anatomy Online, SUNY Downstate Medical Center lesson3 at The Anatomy Lesson by Wesley Norman
Superior rectus muscle
The superior rectus muscle is a muscle in the orbit. It is one of the extraocular muscles, it is innervated by the superior division of the oculomotor nerve. In the primary position, the superior rectus muscle's primary function is elevation, although it contributes to intorsion and adduction, it elevates and helps intort the eye. The superior rectus muscle is the only muscle, capable of elevating the eye when it is in a abducted position. Anatomy figure: 29:01-02 at Human Anatomy Online, SUNY Downstate Medical Center "Diagram". Archived from the original on March 25, 2010
Deep temporal nerves
The deep temporal nerves, branches of the mandibular division of the trigeminal nerve, are two in number and posterior. They pass above the upper border of the pterygoideus externus and enter the deep surface of the temporalis; the posterior branch, of small size, is placed at the back of the temporal fossa, sometimes arises in common with the masseteric nerve. The anterior branch is given off from the buccinator nerve, turns upward over the upper head of the pterygoideus externus. A third or intermediate branch is present. Deep temporal arteries This article incorporates text in the public domain from page 895 of the 20th edition of Gray's Anatomy lesson4 at The Anatomy Lesson by Wesley Norman
Platysma muscle
The platysma is a superficial muscle that overlaps the sternocleidomastoid. It is a broad sheet arising from the fascia covering the upper parts of the pectoralis major and deltoid. Fibres at the front of the muscle from the left and right sides intermingle together below and behind the symphysis menti, it is not a true symphysis. Fibres at the back of the muscle cross the mandible, some being inserted into the bone below the oblique line, others into the skin and subcutaneous tissue of the lower part of the face. Many of these fibers blend with lower part of the mouth. Sometimes fibers can be traced to the margin of the orbicularis oris. Beneath the platysma, the external jugular vein descends from the angle of the mandible to the clavicle. Variations occur over the clavicle and shoulder. A more or less independent fasciculus, the occipitalis minor, may extend from the fascia over the trapezius to fascia over the insertion of the sternocleidomastoideus; the platysma is supplied by cervical branch of the facial nerve.
When the entire platysma is in action it produces a slight wrinkling of the surface of the skin of the neck in an oblique direction. Its anterior portion, the thickest part of the muscle, depresses the lower jaw. However, the platysma plays only a minor role in depressing the lip, performed by the depressor anguli oris and the depressor labii inferioris. In a similar fashion to other muscles, the platysma is vulnerable to tears and muscle atrophy among many other possible conditions; the platysma is vulnerable to neck injuries. A type of medical imagining called CTA, used to visualise arterial and venous vessels, is useful to minimise the number of neck explorations, thus improving the handling of the condition. Another area of importance of the platysma lies in plastic surgery. Neck bands in the area become most noticeable with age, aggravated by facelift. If it doesn't heal with time, there are many options to correct this: Botox/Dysport/Xeomin and platysmaplasty. Platysmaplasty is a surgery in this area, that can be open or closed, in the latter a specialised instrument called plastymotome that allow the surgery to be done without incisions.
It takes 2 weeks for the symptoms to be reduced. This article incorporates text in the public domain from page 387 of the 20th edition of Gray's Anatomy BooksSusan Standring. Gray's anatomy: the anatomical basis of clinical practice. London: Churchill Livingstone. ISBN 978-0-8089-2371-8
Mandible
The mandible, lower jaw or jawbone is the largest and lowest bone in the human face. It holds the lower teeth in place; the mandible sits beneath the maxilla. It is the only movable bone of the skull; the bone is formed in the fetus from a fusion of the left and right mandibular prominences, the point where these sides join, the mandibular symphysis, is still visible as a faint ridge in the midline. Like other symphyses in the body, this is a midline articulation where the bones are joined by fibrocartilage, but this articulation fuses together in early childhood; the word "mandible" derives from the Latin word mandibula, "jawbone", from mandere "to chew" and -bula. The mandible consists of: The body, found at the front A ramus on the left and the right, the rami rise up from the body of the mandible and meet with the body at the angle of the mandible or the gonial angle; the body of the mandible is curved, the front part gives structure to the chin. It has two borders. From the outside, the mandible is marked in the midline by a faint ridge, indicating the mandibular symphysis, the line of junction of the two pieces of which the bone is composed at an early period of life.
This ridge divides below and encloses a triangular eminence, the mental protuberance, the base of, depressed in the center but raised on either side to form the mental tubercle. On either side of the symphysis, just below the incisor teeth, is a depression, the incisive fossa, which gives origin to the mentalis and a small portion of the orbicularis oris. Below the second premolar tooth, on either side, midway between the upper and lower borders of the body, is the mental foramen, for the passage of the mental vessels and nerve. Running backward and upward from each mental tubercle is a faint ridge, the oblique line, continuous with the anterior border of the ramus. From the inside, the mandible appears concave. Near the lower part of the symphysis is a pair of laterally placed spines, termed the mental spines, which give origin to the genioglossus. Below these is a second pair of spines, or more a median ridge or impression, for the origin of the geniohyoid. In some cases, the mental spines are fused to form a single eminence, in others they are absent and their position is indicated by an irregularity of the surface.
Above the mental spines, a median foramen and furrow are sometimes seen. Below the mental spines, on either side of the middle line, is an oval depression for the attachment of the anterior belly of the digastric. Extending upward and backward on either side from the lower part of the symphysis is the mylohyoid line, which gives origin to the mylohyoid muscle. Above the anterior part of this line is a smooth triangular area against which the sublingual gland rests, below the hinder part, an oval fossa for the submandibular gland. Borders The superior or alveolar border, wider behind than in front, is hollowed into cavities, for the reception of the teeth. To the outer lip of the superior border, on either side, the buccinator is attached as far forward as the first molar tooth; the inferior border is rounded, longer than the superior, thicker in front than behind. The ramus of the human mandible has four sides, two surfaces, four borders, two processes. On the outside, the ramus marked by oblique ridges at its lower part.
On the inside at the center there is an oblique mandibular foramen, for the entrance of the inferior alveolar vessels and nerve. The margin of this opening is irregular. Behind this groove is a rough surface, for the insertion of the medial pterygoid muscle; the mandibular canal runs obliquely downward and forward in the ramus, horizontally forward in the body, where it is placed under the alveoli and communicates with them by small openings. On arriving at the incisor teeth, it turns back to communicate with the mental foramen, giving off two small canals which run to the cavities containing the incisor teeth. In the posterior two-thirds of the bone the canal is situated nearer the internal surface of the mandible, it contains the inferior alveolar vessels and nerve, from which branches are distributed to the teeth. Borders The lower border of the ramus is thick and continuous with the inferior border of the body of the bone. At its junction with the posterior border is the angle of the mandible, which may be either inverted or everted and is marked by rough, oblique ridges on each side, for the attachment of the masseter laterally, the medial pterygoid muscle medially.
The anterior border is thin above, thicker below, continuous with the oblique l
Inferior rectus muscle
The inferior rectus muscle is a muscle in the orbit. As with most of the muscles of the orbit, it is innervated by the inferior division of oculomotor nerve, it depresses and helps extort the eye. The inferior rectus muscle is the only muscle, capable of depressing the pupil when it is in a abducted position. Anatomy figure: 29:01-07 at Human Anatomy Online, SUNY Downstate Medical Center lesson3 at The Anatomy Lesson by Wesley Norman Diagram at mun.ca
Superior tarsal muscle
The superior tarsal muscle is a smooth muscle adjoining the levator palpebrae superioris muscle that helps to raise the upper eyelid. The superior tarsal muscle originates on the underside of levator palpebrae superioris and inserts on the superior tarsal plate of the eyelid; the superior tarsal muscle receives its innervation from the sympathetic nervous system. Postganglionic sympathetic fibers originate in the superior cervical ganglion, travel via the internal carotid plexus, where small branches communicate with the oculomotor nerve as it passes through the cavernous sinus; the sympathetic fibres continue to the superior division of the oculomotor nerve, where they enter the superior tarsal muscle on its inferior aspect. The superior tarsal muscle works to keep the upper eyelid raised after the levator palpebrae superioris has raised the upper eyelid. Damage to some elements of the sympathetic nervous system can inhibit this muscle, causing a drooping eyelid; this is seen in Horner's syndrome.
The ptosis seen in Horner's syndrome is of a lesser degree than is seen with an oculomotor nerve palsy. The muscle derives its name from Greek ταρσός, meaning'flat surface' used for drying; the term Müller's muscle is sometimes used as a synonym. However, the same term is used for the circular fibres of the ciliary muscle, for the orbitalis muscle that covers the inferior orbital fissure. Given the possible confusion, the use of the term Müller's muscle should be discouraged unless the context removes any ambiguity. Heinrich Müller
