Trunk Note Details Flashcards
The neck can be divided into two areas known as the ___ and ___.
Anterior and posterior triangles
The borders of the anterior triangle in the neck are…
Sternocleidomastoid, anterior midline, and the edge of the jaw
The borders of the posterior triangle of the neck are…
Sternocleidomastoid, clavicle, and upper trapezius
What is the u-shaped bone at located at the floor of the neck?
Hyoid bone
The opening in the back of the “U” of the hyoid bone serves as an attachment for the ___.
Pharynx
The hyoid moves ___ when you swallow.
Up and down
The thyroid cartilage is a ___-shaped shield that comes together in the [front/back] and is open in the [front/back]. Deep to it are the ____.
V-shaped shield, comes together in the FRONT, open in BACK. Deep to it are the VOCAL CORDS
The cricoid cartilage is:
(A) V-shaped
(B) U-shaped
(C) Complete ring
(C) complete ring. Below it, tracheal rings begin
The tracheal cartilage is [open/closed] in the back.
Open in the back
___ closes the back of the tracheal cartilage. This acts to _____.
Smooth muscle closes the tracheal cartilage in the back and acts to constrict the airway (or relax to expand it)
The midline of the neck is [vascular/avascular]. Why would this matter?
Midline of neck is AVASCULAR; there isn’t really bleeding if you need to do an emergency tracheotomy
The digastric muscles lie in the ____ . They consist of ___ (#) muscle bellies with a tendon in the middle. This tendon is held down in place by the ___ [bone] and ____.
Floor of the mouth. 2 muscle bellies. Tendon held in place by the hyoid and a little sling.
Name the strap muscles of the neck
Omohyoid, Sternohyoid, Sternothyroid, Thyrohyoid
The ___ and ___ muscles can be overstretched/traumatized in whiplash or extremely forward head position. This can result in _____ due to the changed position of the thyroid cartilage. Why?
Sternothyroid and Thyrohyoid muscles overstretched in whiplash. These muscles help to position the thyroid cartilage, so when they’re overstretched, it can change the “tip” or angle of the thyroid cartilage and cause HOARSENESS in the voice because it rubs on vocal cords
Describe the path of the the Spinal Portion of Accessory Nerve, CN XI
(1) Innervates sternocleidomastoid, (2) Appears at posterior border of SCM at Erb’s Point, (3) Traverses posterior triangle, (4) Runs deep to trapezius and innervates it
All branches of nerves at Erb’s point are ____ [sensory cutaneous/motor] branches.
SENSORY CUTANEOUS BRANCHES
All branches of the cervical plexus emerge at the ___ border of the ___ at ____ point.
All branches of cervical plexus emerge at POSTERIOR border of SCM at ERB’s point
The sensory cutaneous branches of the cervical plexus include __, __, __, and ___. The ___ nerve (C_,,) is also in the vicinity.
Lesser occipital, great auricular, transverse cervical (anterior part of neck), supraclavicular (3 of them!). Phrenic N. (C3,4,5) is nearby.
The ___ is described as a “loop” of cervical nerve.
Ansa Cervicalis
The Ansa Cervicalis consists of ___ [motor/sensory] fibers of the cervical plexus from C_,,. It has __ (#) roots: ____ [name them].
Ansa Cervicalis consists of MOTOR fibers from C1,2,3. It has 2 roots: superior root and inferior root.
The superior root of the ansa cervicalis is AKA ___. It arises from spinal root(s) __. It runs with the ____ nerve for a short distance.
AKA descendens hypoglossi. C1. Runs with hypoglossal n. for short distance.
The inferior root of the Ansa Cervicalis is AKA __. It arises from spinal root(s) __.
AKA Descendens cervicalis. C2,3
The ansa cervicalis appears on either side of the ___ vein. It gives off branches to the ___, ___, and ___, collectively called the ___.
Appears on either side of INTERNAL JUGULAR VEIN. Branches given off to OMOHYOID, STERNOTHYROID, and STERNOHYOID, collectively the STRAP muscles.
The Vagus nerve (CN __ can be found in the ____ sheath. It contains the following branches: ____, __, __, __, and ___.
CN X, Branches include: (1) Pharyngeal branch, (2) Intrinsic laryngeal n., (3) Extrinsic laryngeal n., (4) Recurrent laryngeal n., (5) Branch to Carotid body
The vagus n. runs between the ___ vein and the ___ artery, providing ____ innervation to the ___ and most of the ___.
Vagus n. runs between INTERNAL JUGULAR V. and CAROTID A. Provides parasympathetic innervation to GUT and most of ABDOMEN
The vagus n. gives off branches that innervate the ___, and in the neck, it innervates the ___ and ___.
Innervate larynx, and in neck, it innervates carotid body and sinus.
The hypoglossal nerve (CN ___) exits the skull via the ____. It runs deep to the ___ [ant/post] belly of the ___ muscle. Then, it runs with the ____ into the floor of the mouth, where it innervates the muscles of the ___.
CN XII. Exits skull via hypoglossal canal of the skull. It runs DEEP to the POSTERIOR belly of the DIGASTRIC muscle. It runs with the DESCENDENS HYPOGLOSSI then into the floor of the mouth where it innervates muscles of the TONGUE
The thyroid gland sits at the level of ___ (spinal level). It consists of __ (#) lobes connected by ___. It is [highly vascularized/avascular], and in person, it appears ____ [color & texture]
Lower cervical/T1 level. 2 lobes connected by isthmus. It is HIGHLY VASCULARIZED and appears GRAYISH and SOFT in texture
What are the contents of the carotid sheath? Also, it’s noted to be a ___ sheath.
FACIAL sheath. (1) Common/internal carotid artery, (2) Internal jugular vein, (3) Vagus nerve.
The common carotid artery divides at the _____ [superior/inferior] border of the _____ (C_,_ level) into two things: __ and ___.
Common carotid a. divides at SUPERIOR border of THYROID CARTILAGE (C3, C4 level) into INTERNAL CAROTID and EXTERNAL CAROTID
At the split of the common carotid artery, you can see the ___ and interiorly (though not visible) is the ____.
See the CAROTID SINUS (dilation of the vessel) and interiorly is the CAROTID BODY
The internal carotid artery supplies the _____, and [has/does not have] branches in the neck.
Internal carotid a.: Supplies the ANTERIOR BRAIN, NO branches in neck
The external carotid artery gives off __ (#) branches that supply the ___ and___.
External carotid a.: 8 branches that supply NECK and FACE
The internal jugular vein drains the ____ and ___, including the ___.
Internal jugular v. drains HEAD and NECK including the BRAIN
Superficial veins in the superficial fascia of the neck vary, but the most consistent is the ___ , which is on the ___ [anterior/ posterior/ medial/ lateral] side of the neck. These veins are located in the ___ in the neck.
Most consistent superficial vein is the EXTERNAL JUGULAR VEIN which is on the LATERAL side of the neck. Superifical veins are located in the HYPODERMIS in the neck (similar to cephalic and basilic in arm).
General features of the muscles of facial expressions
(1) Thin and flat, (2) Insert on skin, (3) Some arise from bone or skin or fascia, (4) ALL innervated by CN VII, Facial Nerve, (5) Named by their actions
Muscle responsible for wiggling ears?
Superior, anterior, and posterior auricular muscles
Muscle responsible for closing eyelids?
Orbicularis Oculi
Smiling muscles? What layer are these in?
Zygomaticus major and minor, and Risorius. SUPERFICIAL layer
What runs between the frontalis and occipitalis muscles?
Galea aponeurosis: large sheet of fascia loosely attached to scalp
What nerve innervates all of the muscles of facial expression?
Facial Nerve (CN VII)
The facial nerve exits the skull through the ____ and then courses through the ____. It gives off 5 branches (name them).
Stylomastoid foramen (VERY narrow!), courses through parotid gland, and gives off 5 branches: (1) Temporal, (2) Zygomatic, (3) Buccal, (4) Marginal mandibular, (5) Cervical
Describe Bell’s Palsy (how it happens, clinical appearance)
Facial paralysis due to compression of facial nerve (CN VII) usually in stylomastoid foramen. Inflammation to the nerve compresses nerve because the channel is so small. This blocks action potentials from getting through the nerve. Takes weeks to recover, but most people do recover. NO sensory loss. Affected side difficult movements: smiling, blinking, blowing/pursing lips, frowning, dribbled out of left side of mouth. Looks “droopy” and smooth, unable to completely close eye. Long-term risk is ulcerations of the cornea because you can’t blink and wash tears over eye.
The ____ provides motor innervation of the face, while the ____ provides sensory innervation for the face.
Facial Nerve (CN VII) = motor; Trigeminal Nerve (CN V) provides SENSORY innervation
The trigeminal nerve (CN ) has _ (#) divisions: ____ (V; innervates ____), ____ (V_; innervates ___), and ___ (V_; innervates __)
(1) Ophthalmic (V1), upper nose and eye, and upward
(2) Maxillary (V2), middle of face
(3) Mandibular (V3), lower face
What is special about the mandibular division (V_) of the trigeminal nerve (CN _)?
Mandibular division (V3) of the trigeminal nerve (CN V) provides sensory innervation to the lower face, but it also innervates the muscles of mastication! (SENSORY AND MOTOR)
The parotid gland is a major ___ gland located on the [anterior/posterior/ medial/ lateral] side of the face, in front of ____. The ____ duct empties its secretions into the mouth.
Parotid gland = major salivary gland in the LATERAL face, in FRONT OF EAR to ANGLE OF JAW. The PAROTID duct empties secretion into mouth
What is the blood supply for the muscles of facial expression? What are these arteries branches of? Describe their path.
(1) Facial artery. Branch of EXTERNAL CAROTID a., crosses inferior border of mandible and runs diagonally to the inner corner of the eye. It gives off branches to face
(2) Superficial temporal artery: Terminal branch of external carotid artery, supplies lateral face/head. *This artery can get arteritis which can cut off the blood supply
When are prevertebral muscles subject to injury?
In whiplash-type events
How many prevertebral muscles are there?
2 long (longus capitis, longus colli) to short (rectus capitis anterior, rectus capitis lateralis)
Which is the most superficial of the prevertebral muscles?
Longus capitis
Describe the sympathetic chain in the neck
3 cervical ganglia (not one at every level). Runs from skull to sacrum
Where is the root of the neck?
Area between CLAVICLE, TRAPEZIUS, and behind SCM
What are the muscles in the root of the neck? What do they act to do?
SCALENES: Anterior scalene, Middle Scalene, Posterior Scalene (only one that goes to RIB 2!). Scalenes do lateral flexion (if acting unilaterally), and may be used by people with lung disease to breathe as they try to fill the upper lobes of the lung with air
Where will you see the phrenic n. (C___) passing in the root of the neck?
Pherenic n. = C3,4,5. Passes on the ANTERIOR SURFACE OF THE ANTERIOR SCALENE
The brachial plexus emerges between the ___ and ___ scalene along with the ____ a. You see the ___ rami of C_ - __ here, so the ___ and ___ of the plexus are visible.
Brachial plexus emerges between ANTERIOR and MIDDLE scalenes with the SUBCLAVIAN artery. VENTRAL rami of C5-T1, so the ROOTS and TRUNKS of plexus are visible.
Name its 3 branches of the subclavian artery and their courses.
Subclavian branches into:
(1) Vertebral A.: Enters TRANSVERSE FORAMEN of C6 [i.e. artery runs up cervical vertebrae EXCEPT C7], comes out of root of neck between MIDDLE and ANTERIOR SCALENES, and passes through FORAMEN MAGNUM to enter skull. Then, the 2 vertebral arteries form BASILAR A. on ventral surface of brainstem. *If pt has cervical arthritis, do a cervical artery test to make sure you won’t damage structures as you work with cervical vertabrae!
(2) Thyrocervical Trunk branches: (A) Suprascapular (runs anteriorly to the anterior scalene and phrenic n.), goes to suprascapular fossa
(B) Transverse cervical: runs anterior to anterior scalene, and superior to suprascapular. Its branches supply the trapezius and rhomboids.
(3) Internal thoracic
Describe the subclavian vein (orientation in root of neck and drainage)
Subclavian vein runs ANTERIOR to anterior scalene. The External jugular drains into it
The thoracic duct empties into the __ [right/left] subclavian at the junction with the ____. It drains ___ for ___ [name body parts drained]. The ___ is dumped into the venous system and recirculated.
Thoracic duct empties into LEFT subclavian at junction with LEFT INTERNAL JUGULAR. Drains lymph for lower limbs, pelvis, abdomen, and left UE. Lymph is dumped in venous system and recircultaed
The thoracic cavity is formed by the __ and __. Name its boundaries in each direction.
Formed by rib cage & vertebral column. Bound by: diaphragm (inferiorly), 1st fib (superiorly), rib cage (and associated soft structures),
Name the transverse landmark line in the mediastinum and the divisions of the cavity.
A-P line from T4 to sternal angle
(1) Above line: Superior mediastinum. Arch of aorta is deep to that line, and deep to that, the trachea biforcates
(2) Below line: Inferior mediastinum. Further divided into:
(A) Anterior mediastinum (pleural sacs almost touching thoracic wall)
(B) Middle mediastinum (heart, root of vessels coming in/out of heart)
(C) Posterior mediastinum (esophagus, descending aorta, and things posterior to heart)
The thoracic cavity contains three areas: ___, __, __.
Mediastinum (Superior, anterior, posterior, and middle subdivisions), and two pleural cavities (one per side, contains the lungs)
Describe the superior thoracic aperture and its bounds
Opening between 1st ribs, slopes downward and forward to sternum
- Bounded by 1st rib and manubrium anteriorly, and T1 posteriorly
Describe the inferior thoracic aperture and its bounds
Covered by diaphragm
-Bounded by 12 vertebra, 12th ribs, costal cartilages, and sternum
Ribs 1-_ are considered “___” ribs. They have ___ cartilage and attach directly to the sternum with a ____ joint (these joints then described as ___ joints given their attachments). ___ movement is allowed.
1-7 = TRUE ribs. Have Hyaline cartilage and attach directly to sternum via synchondrosis at these costochondral joints. Little to no movement is allowed.
Ribs - are called “false” ribs. They [do/do not] reach the sternum directly. Ribs - attach to superior ribs via ___. Ribs _ and _ are floating, so they have ___ attachment to the sternum and/or superior ribs.
7-12= FALSE ribs. DO NOT reach sternum directly. Ribs 8-10 attach to superior ribs via HYALINE cartilage. Ribs 11 & 12 are floating and have NO attachment to sternum or superior ribs.
3 bony parts of sternum
Manubrium, body, xiphoid process
The sternal angle is located at the synovial joint of the ___ (#) costal cartilage with the sternum - ie where rib __ (#) attaches.
Sternal angle at level of 2nd costal cartilage attachment - where rib #2 comes in
Describe how the joint between the 1st costal cartilage and sternum (1st rib) differs from the other sternochondral joints.
1st costal cartilage and sternum (1st rib) is a SYNCHONDROSIS, all other sternochondral joints are SYNOVIAL! Also, where costal cartilage meets costal cartilage (e.g. interchondral of false ribs) = SYNOVIAL too!
At the vertebral side, each rib articulates with the vertebra at __(#) levels. Which ones? What are the exceptions? In general, these rib-vertebral joints are called __.
2 levels: vertebra of same level and the one above it (eg. Rib 4 articulates with T4 and T3). Exceptions: Rib 1, 11, 12, and sometimes 10: articulate only with their own vertebra. Called costovertebral joints (SYNOVIAL!)
How many articulations does a typical thoracic vertebra have? Rattle them off!
12 total!
With adjacent vertebrae: Superior facets (2), inferior facets (2), and symphysis joints [intervertebral discs] (2) = 6
With ribs (e.g. T4): 3 per side: attach to own numbered rib (T4 above), Rib below (T5 below), and own rib at transverse process (Rib 4 at transverse process) = 6
Costotransverse joints are __ [fibrous/ cartilaginous/ synovial] and describe the articulations between the ___ of the rib and the ___ of its own vertebra. This is NOT present in ribs ___.
SYNOVIAL joints, articulations between tubercle of rib and the transverse process of its own vertebra. NOT present it ribs 11 and 12.
The external intercostals are angled as if you were ___. These fibers start at the ___ of the rib, and wrap around to the front to hyaline cartilage where they turn into a ____. This means that they’re incomplete ___.
putting hands in pockets. Start at tubercle of rib, wrap around, turn into a membrane. Incomplete anteriorly b/c doesn’t come all the way to the sternum
The internal intercostal muscle runs at a _ angle to the external intercostals. It is incomplete on the __ side.
90 degree angle to external intercostals. Starts at sternum and goes as far back as the angle of the ribs, but incomplete on posterior side.
The innermost intercostals run in the same direction as the __ intercostals. They are incomplete on the ___ side. Run from ___ to ___.
Same direction as internal intercostals. Incomplete BOTH posteriorly and anteriorly. Runs from angle of rib forward to hyaline cartilage.
The thoracic cavity muscles consist of the intercostals as well as the ___ and ___.
Subcostal muscle and Transversus Thoracis
The transversus thoracis muscle helps to hold down what two structures?
Internal thoracic artery and vein
During quiet inspiration, the ribs move ____ (direction) and the diaphragm ____ {rises/drops}
Ribs move up and out with inspiration and diaphragm DROPS
What muscles are involved when you’re breathing with effort?
External intercostals, interchondral part of internal intercostals, sternocleidomastoid and scalenes, even possibly pectoral muscles with reverse action
What is the tripod pose?
Hands on knees after strenuous effort (e.g. running), stabilizes the origin of the pec minor to activate that muscle to aid in effortfull breathing
What muscles are involved with forced expiration? How does this differ from normal expiration?
Forced: internal intercostals, abdominal muscles
Quiet expiration: passive recoil - diaphragm relaxes, ribs move in and down (bucket handle)
Arteries and nerves in the thoracic cavity run in what space?
Intercostal space
The posterior intercostal arteries come from ___.
Thoracic aorta
The internal thoracic artery is clinically referred to as the ____ artery. It is a branch of the ___ artery and gives off the ___ arteries, and then it biforcates into ___ and ___ arteries.
Internal thoracic a. = Internal Mammary a.
- It is a branch of the SUBCLAVIAN a.. THe internal thoracic a. gives off ANTERIOR INTERCOSTAL arteries, before the internal thoracic a. bifurcates into SUPERIOR EPIGASTRIC A. and MUSCULOPHRENIC A.
Th musculophrenic artery and superior epigastric artery are branches of the ___ a. They continue into __ and ___ respectively.
Both branches (terminal via bifurcation) of INTERNAL THORACIC A.. Musculophrenic a. = goes to diaphragm Superior epigastric a. = continues into abdomen
The anterior and posterior intercostal arteries ____, allowing blood flow in either direction. Why is this useful and where do you commonly see this occur?
The arteries ANASTOMOSE. This allows the blood supply to come from either arterial source. Seen a lot around joints because if you’re postured in one position and a set of arteries is compressed, the other side still supplies blood. Also seen in ribs
Describe the drainage path from the anterior intercostal veins.
Anterior intercostal veins drain into internal thoracic vein then to brachiocephalic vein
Intercostal nerves are the ___ rami of spinal nerves. They give off [cutaneous/muscular/both/neither] branches to _____.
Intercostal nerves are VENTRAL rami of spinal nerve. Give off BOTH: CUTANEOUS branches to skin of a single dermatome and MUSCULAR branches to intercostals
What comprises a neurovascular bundle?
Nerve artery and vein
What runs in the costal groove? In what order?
Intercostals neurovascular bundle. Arranged from superior to inferior in the costal groove, we see a Vein, Artery, and Nerve (VAN)
Each intercostal nerve innervates ____. In general, intercostal nerves also innervate what other muscle group? Are there any sensory branches? If so, what patterns of innervation do we see?
Each intercostal nerve innervates intercostal muscles. Intercostal nn. also innervate ABDOMINAL muscles. Some sensory axons continue to skin to give DERMATOMAL pattern in skin
The posterior intercostal veins drain into which veins?
Drain into AZYGOS or HEMIAZYGOS veins then to SUPERIOR VENA CAVA
The anterior intercostal veins drain into which veins?
Drain into INTERNAL THORACIC VV. to BRACIOCEPHALIC VV. on each side
Developmentally, the lung grows into the ___ (space) where it contacts ____ and then becomes inseparable from it.
Pleural cavity; contacts visceral pleura and is inseparable from it
*Lung develops as a bud and “punches” into pleural cavity. As it punches, it picks up a layer (visceral pleura)
What is the outer lining that lies against the body wall? What does it attach to?
Outer layer against body wall is PARIETAL PLEURA. Attaches to ribs via connective tissue called ENDOTHORACIC FASCIA. Parietal pleura attaches to RIBS, DIAPHRAGM, and PERICARDIAL SAC
What is pleura? What is the pleural cavity [i.e. what does it lie between, what does it contain, what does it serve to do]
- Pleura = epithelium that covers lungs
- 2 parts: PARIETAL pleura and VISCERAL pleura
- Pleural cavity = small space between 2 layers of pleura. Pleura secretes small amount of fluid that fills space, reducing friction. Negative pressure in pleural cavity keeps lungs inflated
In the thorax, name the 4 parietal pleuras (named based on attachment)
Costal pleura, Diaphragmatic pleura, Mediastinal pleura, Cupula of pleura
What is the pulmonary ligament? What is its purpose?
Pulmonary ligament = redundant extension of pleura that hangs down at root of lung. Allows for distension and movement during respiration
Spaces or potential spaces where the lungs do not fill the pleural cavity and the parietal pleura opposes itself are called ___.
Pleural Recesses.
What are the two named pleural recesses? Where is the costodiaphragmatic recess located? What are their clinical relevance?
Costodiaphragmatic recess and costomediastinal recess (Sternocostal)
Located between ribs and diaphragm: runs all the way back behind the lung. A chest tube can be inserted in this space and you can aspirate fluid from the lung without actually hitting the lung.
Where is visceral pleura found?
Attached to surface of lungs; dips into fissures of lungs
What is the hilum of the lung? What is found there?
Hilum = depression where structures enter and leave.
Contents: Pulmonary artery, 2 Pulmonary veins, Bronchus
What is unique about the pulmonary arteries and veins?
The artery carries DEOXYGENATED blood from the right ventricle (goes away from heart to lung). The vein contains OXYGENATED blood and is returning to the heart (to left atrium). The oxygenation is opposite that found in typical arteries and veins, but the DIRECTION of flow of oxygenated blood is the same.
What is the root of the lung?
Bundle of structures in the hilum
Describe the lobes on each lung.
Right: upper, MIDDLE, lower
Left: upper, lower
Both lungs have a ___ fissure, and the right lung also has a ___ fissure.
Both have OBLIQUE fissure. Right lung also has HORIZONTAL fissure.
Describe the relationship of the right lung’s middle lobe to the lung’s fissures.
The middle lobe is bounded superiorly by the HORIZONTAL fissure and inferiorly by the OBLIQUE fissure
Which lung is larger? Why?
The right lung is bigger (3 lobes) than the left because the left has to leave room for the heart!
The trachea bifurcates at T__ (aka at level of ____) into a ____ and ____.
Bifurcates at T4 into a right primary bronchus and left primary bronchus
The left bronchus is [smaller/larger] and more [vertical/horizontal], while the right bronchus is ____.
Left = SMALLER, more HORIZONTAL Right = LARGER, more vertical
The main bronchi divide into ___ AKA ____ bronchi. There are __ (#) ____ on the left, and __ (#) ____ on the right. These then divide into ____ AKA ____ bronchi, with ___ (#) on each side that each go to a ___ segment (consisting of bronchus + __).
Main bronchi divide into LOBAR or SECONDARY bronchi. There are 2 lobar bronchi on left, and 3 lobar bronchi on right. Each lobar bronchi divides into TERTIARY or SEGMENTAL bronchi, 10 on each side (some say left has 8). Each tertiary bronchi goes to BRONCHIOPULMONARY segment (artery + bronchus)
Describe the impressions seen on each lung. Are these present in fresh specimen?
Left: Aortic impression (arch of descending aorta; aorta shifted left), Cardiac notch (space for heart), Cardiac impression
Right: Esophageal impression (esophagus shifted right), Azygos vein (above root of lung), Cardiac Impression
Impressions are embalming phenomena - NOT present in living lungs!
The portion of the left upper lobe that hangs below the cardiac notch is called the ___.
Lingula
The osteology of the temporomandibular joint includes the ____ of the temporal bone along with the ____ anterior to it, which articulates with the ____. The ____ is a site for many muscle attachments and is also in the area.
Mandibular fossa of the temporal bone with the Articular tubercle (helps to deepen fossa). Also, condyle of mandible and the lateral pterygoid plate
What is the shape of the condyle of the Mandible?
Football-shaped, long/wide axis from MEDIAL to LATERAL
At the TMJ, you see two synovial cavities separated by ____. This results in a [joint/completely separated] cavity.
2 synovial cavities separated by articular disc, completely separates upper from lower cavity
Describe the borders of the upper and lower cavities of the TMJ
Upper: between disc and skull (temporal bone)
Lower: between disc and condylar process
There is a fibrous capsule at the TMJ. Describe it (mobility, thickness)
Joint is overall rather lax = a LOT of movement. Lateral thickening of capsule =lateral ligament
The articular disc in the TMJ separates the ___ and ___. It consists of ___ and [loose/dense] fibroconnective tissue. It is [strongly/ loosely] attached to the capsule and mandible ____ [ant/post] but ____ [strongly/loosely] attached [ant/post]. The anterior and posterior thirds are [narrower/wider] than the middle third. The disc moves with ___ [bony structure]
Articular disc separates upper and lower synovial cavities. It consists of DENSE fibroconnective tissue and FIBROCARTILAGE. STRONGLY attached to capsule and the mandible ANTERIORLY, but LOOSELY attached posteriorly. Ant. and post. thirds are WIDER than middle third. Disc moves with HEAD OF MANDIBLE
Describe the 2-part movement at the TMJ while opening the jaw.
(1) Initially, ROTATION of condyle against the disc (movement in LOWER joint cavity)
(2) GLIDE of disc & condyle forward (movement in UPPER joint cavity)
Abnormal movement at the TMJ occurs when the rotation and glide do not work in proper sequence, usually result of ____ of soft tissues that ordinarily do ___.
Usually result of LAXITY of soft tissues that ordinarily LIMIT FORWARD MOVEMENT OF DISC. In dysfunction, head may move ANTERIOR to disc
With abduction to the left at the TMJ, the right condyle ____ and the left condyle ___.
Right condyle = slides forward, left condyle = rotates around a vertical axis
Name the muscles of mastication and their innervation
Masseter, Temporalis, Lateral Pterygoid, Medial Pterygoid
Innervated by mandibular division of CN V (V3) [ONLY motor part of trigeminal nerve!]
Which muscle(s) open the jaw?
Lateral pterygoid (also pulls disc forward)
Which muscle(s) close the jaw?
Temporalis, Masseter, Medial pterygoid
Which muscle(s) protract the jaw?
Lateral pterygoid (mostly), masseter
Which muscle(s) retract the jaw?
Posterior fibers of Temporalis (and deep fibers of Masseter)
Which muscle(s) move the jaw from side to side (i.e. abduct)?
Requires protraction on one side and retraction on other
E.g. Lateral pterygoid and some masseter on Right side; Posterior fibers of Temporalis (and deep fibers of Masseter) on Left side
