The stylohyoid muscle is one of the suprahyoid muscles of the neck. Its lower end divides allowing passage of the digastric tendon. Stylohyoid draws the hyoid bone backwards during swallowing.
origin: styloid process of temporal bone
insertion: hyoid bone
action: retracts and eleva...
The styloid apparatus, found within the parapharyngeal space, refers to the structures derived from the 2nd branchial arch along with associated ligaments and muscles:
styloid process of the temporal bone
lesser horn of the hyoid bone
The styloid process (or styloid part of the squamous temporal bone) is a slender pointed part of the temporal bone. It projects anteroinferiorly from the inferior surface of the temporal bone.
It serves as an anchor point for several muscles associated with the tongue and larynx:
The stylomandibular ligament is a cord-like condensation of the deep cervical fascia that extends from the apex of the styloid process of the temporal bone to the angle of the mandible. It is one of the 2 extrinsic ligaments of the mandible. The ligament separates the masseter and parotid gland ...
The stylomandibular tunnel is a space between the mandibular ramus and the styloid process / stylohyoid ligament. It separates the (prestyloid) parapharyngeal space from the carotid space (a.k.a. poststyloid parapharyngeal space).
When there is a mass in the region of the par...
The stylomastoid foramen is a rounded opening on the inferior surface of the petrous temporal bone, between the base of styloid and the mastoid process of the temporal bone. It transmits the facial nerve.
The stylopharyngeus is a muscle of the head and neck, and one of the inner longitudinal muscles of the pharynx.
origin: styloid process of the temporal bone
insertion: thyroid cartilage
innervation: glossopharyngeal nerve (CN IX)
action: elevates the larynx and pharynx; swallowing
The subacromial-subdeltoid bursa (SASD) (also simply known as the subacromial bursa) is a bursa within the shoulder that is simply a potential space in normal individuals.
extends from below the acromion, over the shoulder and the greater tuberosity of the humerus
The subarachnoid cisterns are discrete named spaces within the subarachnoid space where the pia mater and arachnoid membrane are not in close approximation. The subarachnoid tissue is not as abundant here as in the normal subarachnoid space and cerebrospinal fluid (CSF) gathers to form pools or ...
The subarachnoid space is the interval between the arachnoid membrane and the pia mater. It is occupied by delicate connective tissue trabeculae and intercommunicating channels containing cerebrospinal fluid (CSF).
The cavity is small in the normal brain. Over the gyri, the arachnoid membrane a...
The subclavian arteries are asymmetric paired arteries that supply blood to the posterior cerebral circulation, cerebellum, posterior neck, upper limbs and the superior and anterior chest wall.
Right and left subclavian arteries classically have different origins:
Helpful mnemonics to remember the branches of the subclavian artery include:
Very Indignant Tired Individuals Sip Strong Coffee Served Double Daily
VIT C, D (as in vitamins C and D).
Very Indignant Tired Individuals Sip Strong Coffee Served Double Daily
V: vertebral artery
The subclavian nerve, also known as the nerve to subclavius, is an anterior branch from the C5 and C6 roots of the brachial plexus, and supplies the subclavius muscle.
The subclavian nerve is a small branch from the upper trunk of the brachial plexus that arises from the ...
The subclavian vein (SCV) is the major venous channel that drains the upper limb.
Origin and course
The subclavian vein starts at the crossing of the lateral border of the 1st rib. It then arches cephalad, posterior to the medial clavicle before curving caudally and receiving it...
The subclavius muscle is a small triangular muscle that depresses the shoulder. It is a minor member of the anterior group of muscles of the pectoral girdle.
origin: 1st costochondral joint
insertion: subclavian groove on the inferior aspect of the clavicle
innervation: nerve to sub...
Subclavius posticus is an accessory muscle in the root of the neck, lying between the subclavius muscle and the inferior belly of omohyoid. It has an incidence of ~ 7.5% 2,4.
origin: first costal cartilage
insertion: superior margin of scapula
nerve supply: nerve to subclavius or sup...
The subcoracoid bursa is located anterior to subscapularis and beneath the coracoid process and extends caudal to the conjoined tendons of coracobrachialis and short head of biceps brachii. Fluid in the subcoracoid bursa does not normally communicate with the glenohumeral joint but may communica...
The subcostal arteries are bilateral small arteries that arise of the distal descending aorta which courses laterally beneath the 12th rib. They are the last
The subcostal arteries are analogous to the posterior intercostal arteries, instead in the subcostal space rather than an...
The subcostal muscle has variable anatomy and forms part of the intercostal muscle group. It lies on the deep surface of the innermost intercostal muscle in the posterior chest, near the angles of the ribs, usually running over 2-3 intercostal spaces. It is most common in the upper (1-4) and low...
The subcostal nerve can also be considered as the twelfth intercostal nerve. Some authors describe it as the first branch of the lumbar plexus.
The anterior division of the twelfth thoracic nerve, called the subcostal nerve, is larger than the other intercostal nerves. It runs al...
The subcutaneous calcaneal bursa, also referred to as retroachilleal bursa, is located between the calcaneal tendon and the skin.
It is distinct from the retrocalcaneal bursa, which is located between the calcaneal tendon and the posterior angle of the calcaneus.
A useful mnemonic to remember the nine lobules of the cerebellar vermis is:
Like Cats Catching Dogs For The Party Up North
C: central lobule
The subdural space (epiarachnoid space) is a potential space that exists between the meningeal layer of the dura mater and the inner arachnoid mater of the leptomeninges which are adherent to each other 1.
The meningeal layer of dura mater is usually adherent to the underlying ar...
The subglottis is the anatomical region caudal to the true vocal cords and is a subsite of the larynx.
The inferior arcuate line of the vocal cord marks the cranial border whilst the lower margin of the cricoid cartilage marks the caudal border of the subglottis 1. The inferior arcuate line is ...
The subiculum (plural: subicula) is located in the mesial temporal lobe and is a subdivision of the hippocampal formation, along with Ammon’s horn, the entorhinal cortex and the hippocampus proper. It is the predominant output source of the hippocampal formation.
The subiculum occup...
A sublabral foramen or hole is simply separation of the labrum from the underlying glenoid. It is a labral variant of no clinical significance and can be confused with a SLAP lesion.
Sublabral foramen are located anterosuperiorly and can extend down to but not below the 3 o'clock position, whi...
The sublingual glands are salivary glands that lie in the floor of the mouth anterior to the submandibular glands. They secrete predominantly mucous saliva that is drained by a collection of 8-20 excretory ducts collectively termed the duct of Rivinus. The largest of these ducts, the major subli...
The sublingual space is one of the suprahyoid deep spaces of the head and neck.
It is like an inverted V with its apex pointing anteriorly and is located between:
tongue musculature superiorly
and the anterior one-third of the mylohyoid muscle inferolaterally which separates it...
The submandibular duct (also known as Wharton's duct) allows the passage of saliva from the submandibular gland to the sublingual papilla located anteriorly.
The duct extends anteriorly from the submandibular gland superior to the lingual nerve and submandibular ganglion curving over the poster...
The submandibular ganglion is one of four parasympathetic ganglia of the head and neck. It receives parasympathetic fibres from the facial nerve.
small ganglion suspended from the undersurface of the lingual nerve
inferior to submandibular duct sitting on the hyoglossus muscle
The submandibular glands are paired salivary glands located behind and below the ramus of the mandible in the submandibular triangle. They secrete mixed serous and mucous saliva that is excreted into the oral cavity via the submandibular duct that connects the gland to the floor of the mouth.
The submandibular space is a U-shaped compartment of the suprahyoid neck.
The superficial layer of the deep cervical fascia encloses the submandibular space.
medially: anterior belly of digastric muscles (separating it from the submental sp...
The submental space lies in the midline below the chin, medially to the U-shaped submandibular space with which it freely communicates.
superiorly: mylohyoid muscle
inferiorly: superficial layer of the deep cervical fascia
laterally: anterior bellies of the digastr...
The submental triangle is the single midline triangle, part of the anterior triangle of the neck. The triangles of the neck are surgically focussed, first described from early dissection-based anatomical studies which predated cross-sectional anatomical description based on imaging (see deep spa...
The suboccipital muscle group contains four paired muscles, three of which pairs belong to the suboccipital triangle. These muscles all lie below the occipital bone and are responsible for postural support of the head, as well as extension, lateral flexion and rotation. As these muscles are smal...
The subparietal sulcus is a sulcus on the medial surface of the parietal lobe that separates the precuneus from the posterior aspect of the cingulate gyrus. It is considered a posterior continuation of the cingulate sulcus even if these sulci are most commonly discontinuous.
The subscapular artery is the largest branch of the axillary artery.
The subscapular artery originates from the medial surface of the third part of the axillary artery. It passes along the inferior border of the subscapularis muscle and it divides into two branches 1,2:
Subscapularis muscle is one of the four muscles that make up the rotator cuff, the others being: supraspinatus, infraspinatus and teres minor.
origin: subscapular fossa of the scapula
insertion: lesser tuberosity of the humerus
arterial supply: suprascapular, axillary and subscapular...
The subscapularis recess, also known as the superior subscapularis recess or subscapularis bursa, is a normal extension of the glenohumeral joint capsule in between the superior and middle glenohumeral ligaments.
On sagittal oblique sequences and when distended with ...
The substantia innominata, or substantia innominata of Meynert, is an area of mixed grey and white matter located within the anterior perforated substance in the basal forebrain. It contains the acetylcholine rich basal nucleus of Meynert.
The substantia innominata is a thin ban...
The substantia nigra is one of the brainstem nuclei and part of the extrapyramidal system. While other nuclei such as the red nucleus are as small and contained within an axial slice at the superior colliculi (see figure), the substantia nigra is seen in axial slices at both superior and inferio...
The subtalar joint may refer to one or two articulations:
the anatomic subtalar joint, i.e. talocalcaneal joint
the clinical subtalar joint, i.e. talocalcaneal and talonavicular joints
Please see the main articles for further descriptions of the separate joints.
The subthalamic nuclei are small paired structures that are part of the functional basal ganglia. They are located ventral to the thalamus, dorsal to the substantia nigra and medial to the internal capsule.
The subthalamic nucleus receives its main input from the lateral pallidum (external segm...
Subvesical/subvesicular bile ducts are variants of the biliary tree, and knowledge of these are important because they account for a significant portion of post-cholecystectomy bile leaks.
Cholecystohepatic ducts (usually segment V to the gallbladder) are commonly known as bile du...
The Sudeck point (or Sudeck critical point) refers to a specific location in the arterial supply of the rectosigmoid junction, namely the origin of the last sigmoid arterial branch from the inferior mesenteric artery (IMA) 1.
This arterial branch usually forms an anstomosis with a branch of th...
Sulcal arteries are penetrating branches from the anterior spinal artery and extend posteriorly through the anterior median fissure of the spinal cord. The sulcal arteries supply the anterior two-thirds of the spinal cord at any cross-sectional level.
Successive sulcal arteries generally altern...
Superficial bursae are those bursae that are located superficial to the fibrous fascia. They form in the months to years following birth, as a result of direct pressure or friction 1. An example is the olecranon bursa.
In contrast, deep bursae are located deep to the fibrous fascia.
The superficial femoral artery is a continuation of the common femoral artery at the point where the profunda femoris branches. It is the main artery of the lower limb and is, therefore, critical in the supply of oxygenated blood to the leg.
origin: continuation of the common femoral a...
The superficial inguinal nodes are located in the superficial fascia of the upper thigh near the inguinal ligament and great saphenous vein. They number around 10 and drain lymph from the gluteal region, inferior anterior abdominal wall, perineum and superficial lower limbs. They drain into the ...
The superficial middle cerebral vein (SMCV) (also known as the Sylvian vein) is one of the superficial cerebral veins. It usually passes along the Sylvian fissure posteroanteriorly, it collects numerous small tubutaries which drain the opercular areas around the lateral sulcus. It curves anterio...
The superficial palmar branch of the radial artery (also known as the palmar cutaneous branch) is a small branch of the radial artery in the distal forearm. It arises from the radial artery just proximal to the flexor retinaculum, which it passes superficially over before entering the hand to su...
The superficial perineal pouch is an anatomic space below the perineal membrane in the urogenital triangle of the perineum.
The superficial perineal pouch is inferior (superficial) to the perineal membrane in the urogenital triangle, anterior to the transverse line between the is...
The superficial peroneal (fibular) nerve is one of two terminal branches of the common peroneal nerve.
origin: arises as a terminal branch of the common peroneal nerve in the lateral compartment of the leg
course: passes between peroneus longus muscle and the fibula proximally and per...
The superficial posterior compartment of the leg is one of the four compartments in the leg between the knee and foot. Muscles within this compartment primarily produce ankle plantarflexion as all 3 muscles form the Achilles tendon. Of the two posterior compartments, the superficial compartment ...
The superficial radial nerve, also known as the superficial branch of the radial nerve, is a sensory cutaneous nerve that arises from the radial nerve. It supplies the skin on the dorsum of the hand as well as providing articular branches to joints in the hand.
As a branc...
The superficial temporal artery is one of two terminal branches of the external carotid artery. It arises in the parotid gland and runs between the deep and superficial lobes, over the zygomatic process before terminating in three branches - parietal, frontal and transverse facial - to supply pa...
The superficial temporal vein arises in a plexus on the side and vertex of the skull and, in the substance of the parotid gland, joins with the maxillary vein to form the retromandibular vein.
The superficial temporal vein originates from a venous plexus on the side and vertex of...
Superficial veins of the brain predominantly drain the cerebral cortex, and include:
superior cerebral veins (or superficial cerebral veins)
inferior cerebral veins
superficial middle cerebral veins
superior anastomotic vein (of Trolard)
inferior anastomotic vein (of Labbe)
Some also inclu...
The superior accessory fissure is present in around 5% of individuals examined with CT 4.
The superior accessory fissure of the right lower lobe is located in the same plane and posterior to the right minor fissure. It separates the right lower lobe into superior and basal segme...
The superior adrenal (suprarenal) arteries area a group of one of the three adrenal arteries that supply the adrenal gland. There are usually numerous small arteries arising from the inferior phrenic artery.
The superior suprarenal arteries arise from the inferior phrenic...
The superior anastomotic vein (or vein of Trolard) connects the superior sagittal sinus and the superficial middle cerebral vein (of Sylvius).
Its size is dictated by the relative size of the superficial middle cerebral vein and the anastomotic vein of Labbé. The vein of Trolard is smaller than...
The superior aortic recess is one of the pericardial recesses forming a small space within the pericardium, which arises from the superior margin of the transverse pericardial sinus and surrounds the root of the ascending aorta.
Its components are variable and may be further subdivided into:
The superior cerebellar artery (SCA) arises from the distal basilar artery, just below the posterior cerebral artery (PCA) and typically supplies:
whole superior surface of the cerebellar hemispheres down to the great horizontal fissure
most of the cerebellar ...
The superior cerebellar peduncles (SCP) are a paired white matter fibre tracts that connect the cerebellum with the midbrain. The SCP contains vital afferent and efferent fibres including cerebellothalamic, cerebellorubral and ventrospinocerebellar tracts.
The superior ce...
The superior cerebral veins drain the superior portion of the cerebral cortex. They run up and medially before draining into the superior sagittal sinus. In a proportion of patients, a large such vein connects the superficial middle cerebral vein to the sinus, and is known as the superior anasto...
The superior epigastric artery is one of two terminal branches of the internal thoracic artery with the other being the musculophrenic artery.
Origin and course
The superior epigastric artery originates at the level of the sixth or seventh costal cartilage. It descends to the a...
The superior frontal gyrus is the medial most gyrus of the frontal lobe's superolateral surface, running from the the frontal pole anteriorly, all the way to the precentral sulcus and precentral gyrus posteriorly.
Laterally it is bounded by the superior frontal sulcus, which separates it from t...
The superior frontal sulcus is one of the major sulci of the frontal lobe, separating the superior frontal gyrus medially, from the middle frontal gyrus inferolaterally. It runs posteriorly from the frontal pole, parallel to the interhemispheric fissure, back to the precentral sulcus which it in...
The superior gemellus muscle is a small triangular muscle in the gluteal region that together with the inferior gemellus and obturator internus muscles form the tricipital (three headed) triceps coxae which occupies the space between the piriformis muscle (superiorly) and quadratus femoris muscl...
The superior geniculocalcarine tract or superior optic radiation, also known by its eponymous name Baum’s loop, is the posterior/superior fibres of the optic radiation. These superior fibres pass dorsally and posteriorly from the lateral geniculate nucleus through the retrolentiform internal cap...
The superior gluteal artery is the largest branch of the internal iliac artery and supplies structures within the pelvis and gluteal region.
origin: from the posterior division of the internal iliac artery
location: originates from pelvis and enters the gluteal region
The superior gluteal nerve is formed from posterior divisions of L4, L5 and S1 nerve roots of the sacral plexus. The nerve supplies branches to the gluteus minimus and medius muscles and terminates by innervating the tensor fasciae latae muscle.
The superior gluteal nerve...
The superior hypophyseal artery (or arteries) is a branch from the C6 segment of the internal carotid artery. It is usually a single trunk which then divides into many small branches, which go on to supply:
pituitary gland (anterior gland)
It is ofte...
Superior labial artery (old name: superior coronary artery) is one of the facial branches of the facial artery. It is bigger and more serpiginous than the inferior labial artery. It supplies the upper lip, including its labial glands, mucous membranes and muscles.
origin: facial branch...
The superior laryngeal artery accompanies the internal laryngeal branch of the superior laryngeal nerve, beneath the thyrohyoid muscle.
It pierces the thyrohyoid membrane, and supplies the muscles, mucous membrane, and glands of the larynx, anastomosing with the branch from the opposite side.
The superior longitudinal muscle of the tongue is one of the 4 intrinsic muscles of the tongue which alters the shape of the tongue mass, being entirely confined to the tongue without an attachment outside the tongue (like the extrinsic muscles of the tongue).
The muscles fibres ...
The superior lumbar triangle, also known as the triangle of Grynfeltt-Lesshaft, is one of the locations for a lumbar hernia.
medially: the quadratus lumborum muscle
superiorly: twelfth rib
laterally: internal oblique muscle
floor: transversalis fascia and the ap...
The superior meatus is an air passage of the lateral nasal cavity located between the superior nasal concha and lateral nasal wall. The posterior ethmoid air cells and sphenoid sinuses drain into the superior meatus.
Superior mediastinum is an artificially divided wedge-shaped compartment of the mediastinum located between the thoracic plane inferiorly and the thoracic inlet superiorly. The inferior mediastinum, comprising of the anterior, middle and posterior parts, lies inferiorly.
The superior (or anterior) medullary velum is a thin layer of tissue that is suspended between the superior cerebellar peduncles forming the roof of the fourth ventricle along with the inferior medullary velum. It is enclosed by pia mater dorsally and ependyma ventrally. The lingula of the vermi...
The superior mesenteric artery (SMA) is one of the three non-paired major visceral arteries in the abdominal cavity arising from the abdominal aorta and supplying the midgut.
Single vessel arising anteriorly from the abdominal aorta at the level of L1, usually just below ...
The superior mesenteric vein (SMV) accompanies the superior mesenteric artery (SMA) and drains the midgut to the portal venous system.
Origin and course
Mesenteric venous arcades, which accompany the arteries, unite to form the jejunal and ileal veins in the small bowel mesenter...
The superior nasal concha or turbinate is one of the conchae in the nose and is part of the labyrinth of the ethmoid bone, arising as a bony projection from its posterior surface.
The air passage between the superior nasal concha and the lateral nasal wall is known as the superior meatus.
The superior oblique muscle is one of the 6 extra-ocular muscles that control eye movements. It abducts, depresses and internally rotates the eye.
innervation: trochlear nerve (CN IV)
origin: lesser wing of sphenoid bone and is outside of Annulus of Zinn located supero-medially.
The superior occipital sulcus is a sulcus of the occipital lobe that separates the superior from the middle occipital gyri. It is usually seen as a posterior continuation of the intraparietal sulcus.
The superior olivary nuclei (or complex, SOC) are a group of nuclei within the pons contributing to the ascending and descending auditory pathways.
The superior olivary nuclei are located in the pons, while the inferior olivary nuclei are located in the medulla. It is generally s...
The superior ophthalmic vein is a prominent vein of the orbit that is seen on CT and may be enlarged or tortuous in various disease entities.
The vein forms at the confluence of several veins within the superior orbit above the medial palpebral ligament: the angular, supratrochle...
The superior orbital fissure is the communication between the cavernous sinus and the apex of the orbit. It is straddled by the tendinous ring which is the common origin of the four rectus muscles (extraocular muscles).
medial: body of sphenoid
superior: lesser wing ...
Mnemonics for the nerves passing though the superior orbital fissure include:
Live Frankly To See Absolutely No Insult
Live Free To See No Insult At All
Lazy French Tarts Sit Nakedly In Anticipation
The order of the nerves passing through the superior orbital fissure from superio...
The superior pancreaticoduodenal artery is a branch of gastroduodenal artery that supplies the duodenum and pancreas.
Superior pancreaticoduodenal artery arises after branching off from gastroduodenal artery. It divides into anterior and posterior divisions which supply the pylor...
The superior parietal lobule is one of the three subdivisions of the parietal lobe. The other subdivisions include the inferior parietal lobule and postcentral gyrus. It is involved with sensorimotor integration 1.
It is separated from the inferior parietal lobule by t...
The superior petrosal sinus is one of the dural venous sinuses and drains the cavernous sinus, posterolaterally to the transverse sinus. It runs along superior aspect of the petrous temporal bone. It receives:
inferior cerebral veins
labyrinthine vein: draining the inner ear ...
The superior pharyngeal constrictor muscle is one of the pharyngeal constrictor muscles. Its primary action is constriction of the pharynx (in coordination with the middle pharyngeal constrictor and the inferior pharyngeal constrictor muscles) to deliver a bolus of food into the oesophagus.