recursal/Fanatic-Fandom huggingface dataset:
Joint:Joints of the shoulder girdle:Acromioclavicular joint

The **acromioclavicular (AC) joint**is a plane synovial joint of the pectoral girdle.

The AC joint is between the small facets of the convex oval distal clavicle and flat medial acromion. The articular surfaces are lined with hyaline cartilage. A wedge-shaped articular disc made from fibrocartilage separates the two articular surfaces.

Capsule

A weak, synovium-lined joint capsule is attached to the articular margins and is reinforced superiorly by blended fibres of the trapezius muscle

Ligaments

Static stabilisation is provided by:

* coracoclavicular ligament: separate from the acromioclavicular joint but is the main stabilizer. It is formed by two ligaments: trapezoid and coniod ligaments (from conoid tubercle).
	+ The trapezoid ligament is anterolateral, broad and thin. It ascends from the coracoid surface to the trapezoid line of the clavicle.
	+ The conoid ligament is posteromedial and is a dense vertical triangular band. It is attached to the conoid tubercle of the clavicle and the root of the cornoid process.
* superior and inferior acromioclavicular ligaments: quadralateral in shape and joins the lateral end of the clavicle with the acromion. This interlaces with ligaments of the trapezius and deltoid.

Dynamic stabilisation is also provided by the deltoid and trapezius muscles, with the superior AC ligament blending with these muscles' aponeuroses.

Blood supply

* arteries: suprascapular and thoraco-acromial arteries

Nerve supply

* axillary, suprascapular and lateral pectoral nerves

Variant anatomy

* AC joint configuration
	+ horizontal: normal
	+ low lying: associated with shoulder impingement
	+ inferolateral: associated with shoulder impingement
* os acromiale
Muscle/Group:Forearm:Extensor compartment deep layer:Extensor pollicis brevis

**Extensor pollicis brevis**

* Origin: Posterior surface of radius and interosseous membrane
* Insertion: Posterior surface of base of 1st proximal phalanx
* Innervation: Posterior interosseous nerve
* Action: Extends thumb at carpometacarpal and metacarpophalangeal joints
* Distal tendon forms anterior (volar) aspect of anatomic snuff box of wrist
Muscles:Foot:Adductor hallucis

One of the three muscles of the third layer of the ventral foot.

Origin: 1) oblique head - long plantar ligament and the base of 2nd, third and fourth metatarsal bones. 2)transverse head - deep transverse ligament

Insertion: both heads unite and insert into the lateral plantar surface of the base of the proximal phalanx of big toe

Nerve: lateral plantar nerve

Action: adduction of big toe
Cerebral cortex

Two hemispheres, typically of nearly equal size, linked by commissural fibers

* Separated by a deep median cleft, the great longitudinal (interhemispheric) fissure
* Falx cerebri lies within interhemispheric fissure

* External highly convoluted mantle of cortical gray matter overlies white matter
* Deep gray nuclei (basal ganglia, thalami), ventricles centrally

* Limbic system
	+ Subcallosal, cingulate, parahippocampal gyri
	+ Cingulate gyrus extends around corpus callosum; tapers rostrally (anteriorly) into paraterminal gyrus, subcallosal area
	+ Hippocampus including dentate gyrus, Ammon horn (cornu ammonis)
* Base of brain
	+ Orbital gyri cover base of frontal lobe: Gyrus rectus medially
	+ Olfactory bulb/tract lie within olfactory sulcus
* White matter tracts: Three major types of fibers
	+ Association fibers: Interconnect different cortical regions in same hemisphere
		- Cingulum is a long association fiber which lies beneath cingulate gyrus
	+ Commissural fibers: Interconnect similar cortical regions of opposite hemispheres
		- Corpus callosum is largest commissural fiber, links cerebral hemispheres
	+ Projection fibers: Connect cerebral cortex with deep nuclei, brainstem, cerebellum, spinal cord
		- Internal capsule is a major projection fiber
* Deep gray nuclei:
	+ Basal ganglia: paired deep gray nuclei made up of caudate nucleus, putamen, globus pallidus
	+ Thalamus: Paired nuclear complexes, serve as relay station for most sensory pathways
Muscles:Deep fascia:Flexor Retinaculum

Thickening of the deep fascia of the medial lower leg which bridges the deep flexor tendons and neurovascular bundle.

Extend from tip of medial malleolus to the medial process of the calcaneus.

Tom Dick And Very Naughty Harry run through here, from medial to lateral.

**T**ibialis posterior, flexor **D**igitorum longus, posterior tibial **A**rtery, tibial **N**erve and flexor **H**allucis longus.
Muscle/Group:Shoulder (Pectoral):Biceps (brachii)

**Biceps muscle, short head**

* Origin: Coracoid process tip, in common with and lateral to coracobrachialis tendon
* Insertion: Radial tuberosity after joining long head
* Nerve supply: Musculocutaneous nerve
* Blood supply: Brachial artery, muscular branches
* Action: Flexes elbow & shoulder, supinates forearm

**Biceps muscle, long head**

* Origin: Predominantly supraglenoid tubercle; also superior glenoid labrum and coracoid base
* Insertion: Radial tuberosity after joining with short head
* Nerve supply: Musculocutaneous nerve
* Blood supply: Brachial artery, muscular branches
* Action: Flexes elbow & shoulder, supinates forearm
* Lacertus fibrosus (distal bicipital fascia/aponeurosis) provides traction on deep fascia of forearm
* Variants, biceps muscle: Third head in 10% arising at upper medial aspect of brachialis muscle, fourth head can arise from lateral humerus, bicipital groove or greater tuberosity
Fourth ventricle

The **fourth ventricle** is the final chamber of the ventricular system and extends from the cerebral aqueduct (of Sylvius) to the obex (tip of the 4th ventricle), lying behind the pons and the upper medulla. It is characterized by a diamond shaped cross section.

CSF enters the ventricle via the cerebral aqueduct and leaves via one of three routes:

* via the median aperture (of Magendie) into the cisterna magna
* via ones of the two lateral apertures (of Luschka) into the cerebellopotine angle
* with central canal of cord via obex

The choroid plexus of the fourth ventricle is small which indents the medulla part of the roof

Recesses

* Paired posterior superior: Thin, flat pouch capping tonsils
* Paired lateral: Curve anteriorly under brachium pontis, contain choroid plexus, communicate with SAS via foramina of Luschka
* Fastigium: Blind-ending, dorsally pointed midline outpouching from body of fourth ventricle

Relations:

* Roof (posterior wall): cerebellum, specifically,
* Floor (anterior wall): rhomboid fossa, median sulcus (midline groove dividing the brainstem into right and left halves, forming "medial eminence" on each side). It extends from cerebral aqueduct of the midbrain to central canal of the spinal cord).
* Laterally: gracile and cuneate tubercles and inferior cerebellar peduncle inferiorly, superior cerebellar peduncle superiorly (these border the rhomboid fossa).

Brainstem structures relating to the floor of the fourth ventricle:

1. **facial colliculus**: formed by the internal part of the facial nerve as it loops around the abducens nucleus in the lower pons;
2. **sulcus limitans**: which represents the border between the alar plate and the basal plate of the developing neural tube, Bounds the sulcus limitans.
3. "stria medullaris" - fibers derived from arcuate nuclei, which emerge from the median sulcus and run transversely across the floor to enter into the inferior cerebellar penducles.
4. "vestibular area" - lateral to sulcus limitans vestibular nuclei is overlied by this.
5. Other features are the hypoglossal trigone (overlying 12th nerve) and the vagal trigone (overlying 10th nerve)
Arterial supply to brain:Vertebral & basilar artery

The **basilar artery** is part of the posterior cerebral circulation. Its artery arises from the confluence of the left and right vertebral arteries at the base of the pons as they rise towards the base of the brain.

Course

The basilar artery runs cranially in the central groove of the pons towards the midbrain within the pontine cistern. It travels within this groove from the lower pontine border adjacent to the exit of the abducens nerve to the upper pontine border and the appearance of the occulomotor nerve. It bifurcates at the upper pontine border.

Branches

Before terminating at the upper pontine border where it divides into the two posterior cerebral arteries, it provides several paired branches:

* Anterior inferior cerebellar artery (AICA): lies anteromedial to CN7-8 and loops into IAC. Supply the anterior and lateral aspect of the inferior surface of cerebellum.
* Labyrinthine artery (variable origin; more commonly a branch of AICA vs basilar): accompanies the vestibulocochlear nerve through the internal acoustic meatus, and is distributed to the internal ear
* Pontine arteries: supply the pons
* Superior cerebellar artery (SCA): supplies the superior half of the cerebellum. Course posterolaterally around midbrain below CN3.
* Posterior cerebral arteries as the terminal branch

Vascular Territory

* Pontine perforating branches: Central medulla, pons, midbrain
* AICA: internal acoustic canal, CN7 and 8, anterolateral cerebellum
* SCA: Superior vermis, superior cerebellar peduncle, dentate nucleus, brachium pontis, superomedial surface of cerebellum, upper vermis

Variant anatomy

* basilar artery fenestration
* persistent carotid-basilar artery anastomosis: these include persistent trigeminal artery (, hypoglossal artery (from ICA to hypoglossal canal to vertebral),
Intracranial cavity (extra axial): Posterior cranial fossa:Hypoglossal canal & CN XII

The hypoglossal canal is located between the occipital condyle and jugular tubercle and runs obliquely forwards (posteromedial to anterolateral) allowing the hypoglossal nerve (12th cranial nerve) to exit the posterior cranial fossa.

Its proximal portion is often divided by a fibrous (sometimes ossified) septum, which separates the two roots of the hypoglossal nerve (these have formed by the convergence of numerous rootlets). These roots merge within the canal and a single nerve emerges.
Meninges:Tentorium cerebelli

The **tentorium cerebelli** is the second largest dural fold after the falx cerebri. It lies in the axial plane attached perpendicularly to the falx cerebri and divides the cranial cavity into supratentorial and infratentorial compartments. It contains free and attached margins.

The tentorium cerebelli is attached to the falx cerebri at its midline, and this attachment contains the straight sinus. This attachment is more superior than its anterolateral and posterolateral attachments giving it a "tented" appearance.

The anterior portion contains the deep tentorial notch (or tentorial incisure) which is a U-shaped (concave) free edge and extends anteriorly to attach to the anterior clinoid processesand forms the lateral part of the cavernous sinus. The deep tentorial notch allows communication between the supratentorial and infratentorial compartments.

The anterolateral margin attaches to the superior border of the petrous part of thetemporal bone. This margin lies inferior to the tentorial notch and extends anteriorly to attach to the posterior clinoid process and contains the superior petrosal sinus.

The posterolateral margin separates into the two layers of dura and attaches to the edges of the transverse sulci of the occipital bone. As it extends anteriorly it attaches to the posteroinferior angles of the parietal bone. At its most posterior aspect it is attached to the internal occipital protuberance and posterolaterally contains thetransverse sinus.

Relations

* superiorly: occipital lobe
* inferiorly: cerebellum
* anteriorly: midbrain, cerebral aqueduct
* medially:  extends over the anterior surface of the petrous part of the temporal bone forming Meckel's cave
Joint:Shoulder joint:Articular surfaces

The glenohumeral joint is a synovial ball and socket joint between head of the humerus and glenoid cavity.
It is multiaxial and provides wide range of stability due to the lack of bony constraint. It is the most mobile joint in the body and most likely dislocated.
The glenoid cavity is deepened by the glenoid labrum. This is continuous with the long tendon of the biceps brachii superiorly.

The surfaces are reciprocally curved and the area of the humeral convexity exceeds the glenoid concavity. Only a small portion of the humeral head opposes the glenoid at any position. The remaining surface is in contact with the capsule

The glenoid fossa is deepened by the glenoid labrum. This is a fibrocartilaginous rim around the fossa and triangular in section. Above it blends with the long tendon of the biceps. It may be deficient anterosuperiorly where the synovial membrane protrudes through the gaps.

Both surfaces are covered by hyaline cartilage, which is thickest centrally over the humerus and reverse in the glenoid cavity.
Abdomen:Visceral arteries:Common hepatic

The **common hepatic artery** (CHA) is a terminal branch of the coeliac artery.

Origin & course

The CHA is a terminal branch of the coeliac artery, it passes to the right in the lesser sac, and enters the lesser omentum to pass slightly upwards towards the porta hepatis. It gives off the **right gastric artery** that runs along the lesser curvature of the stomach to anastomose with the left gastric artery.  The common hepatic artery then bifurcates into the **gastroduodenal artery** and **proper hepatic artery**.

Branches

* right gastric artery
* proper hepatic artery
* gastroduodenal artery

Variant anatomy

Variation in hepatic arterial anatomy is seen in 40-45% of people.  Classic branching of the common hepatic artery from the coeliac artery, and the proper hepatic artery into right and left hepatic arteries to supply the entire liver, is seen in only 55-60%.

In general, the common hepatic artery may arise from the abdominal aorta or superior mesenteric artery (SMA) and all or part of the right and left hepatic arteries may arise from (be replaced to) other vessels.

The two most common variants are:

* right hepatic artery replaced to the SMA
* left hepatic artery replaced to the left gastric artery

Another common finding, though not considered a variant by many authors, is trifurcation of the common hepatic artery into right hepatic artery, left hepatic artery and gastroduodenal artery (GDA). With this branching pattern there is no proper hepatic artery.

Common hepatic artery

* from aorta: 2%
* from SMA: 2%
* trifurcation into RHA, LHA and GDA: ~6% (range 4-8%)

Right hepatic artery (RHA)

* from coeliac artery: ~2.5% (range 1-4%)
* from SMA: ~12.5% (range 9-15%)
* accessory RHA from SMA: ~4% (range 1-7%)

Left hepatic artery (LHA)

* from left gastric artery (LGA): ~7.5% (range 4-11%)
* accessory LHA from LGA: ~7.5% (range 4-11%)

Right and left hepatic arteries

* RHA from SMA and LHA from LGA: ~1% (range 0.5-2%)
* accessory RHA and LHA: 1%

**Classification**

Another classification method is the one described by **Michel** et al in 1955 6

* **I:** standard anatomy ~60% (range 55-61%)
* **II:** replaced LHA ~7.5% (range 3-10%)
* **III:** replaced RHA ~10% (range 8-11 %)
* **IV:** replaced RHA and LHA  ~1%
* **V:** accessory LHA from LGA ~10% (range 8-11%)
* **VI:** accessory RHA from SMA ~5% (range 1.5-7%)
* **VII:** accessory RHA and LHA ~1%
* **VIII:** accessory RHA and LHA and replaced LHA or RHA ~2.5%
* **IX:** CHA replaced to SMA ~3% (range 2-4.5%)
* **X:** CHA replaced to LGA ~0.5%
* unclassified:
	+ CHA separate origin from aorta ~2%
	+ double hepatic artery ~4%
	+ PHA replaced to SMA; GDA origin from aorta <0.5%
Joint:Pelvis:Pubic symphysis

The **pubic symphysis** (or **symphysis pubis**) is a midline secondary amphiarthrodial, fibrocartilaginous joint of the bony pelvis, uniting both pubic bodies.

Articulations

The pubic symphysis is a secondary cartilaginous joint, with a wedge-shaped fibrocartilaginous **interpubic disc** situated between two layers of hyaline cartilage, which line the oval-shaped medial articular surfaces of the pubic bones.

The width of the joint space differs at different ages:

* ~10 mm at 3 years
* ~6 mm at 20 years
* ~3 mm at 50 years

Attachments

**Ligaments**

The pubic symphysis is reinforced by four strong ligaments:

* superior pubic ligament - runs from pubic crest to pubic crest
* arcuate pubic ligament - runs from inferior pubic ramus to inferior pubic ramus
* anterior pubic ligament - blends with periosteum laterally as well as the interpubic disc
* posterior pubic ligament - blends with periosteum of both pubic bodies posteriorly

**Musculotendinous**

* adductor longus, adductor brevis and rectus abdominis muscles attach to the anterior pubic ligament and interpubic disc
* external oblique aponeurosis also reinforces the pubic symphysis anteriorly

Relations

* anteriorly
	+ proximal ends of the penile/clitoral shafts
* inferiorly
	+ urethra
	+ deep dorsal vein of penis/clitoris
* posteriorly
	+ bladder (separated from pubic symphysis by the retropubic fat pad)
	+ prostate and prostatic venous plexus

Movement

Normally very little movement - up to 2mm shift and 1 degree rotation

Blood supply

* mainly supplied by branches of obturator and inferior epigastric arteries

Nerve supply

* supplied by branches of the pudendal and/or genitofemoral and/or iliohypogastric/ilioinguinal nerves

Variant anatomy

* congenital widening of the pubic symphysis (rare)
Intraperitoneal Spaces & Cavities

Divisions

* Greater sac of peritoneal cavity
* Lesser sac (omental bursa)

Peritoneum

* Thin serous membrane consisting of a single layer of squamous epithelium(mesothelium)
	+ Parietal peritoneum lines abdominal wall; contains nerves to adjacent abdominal wall and is pain sensitive (with sharp localization)
	+ Visceral peritoneum (serosa) lines abdominal organs; sensitive to pain due to stretching of bowel or mesentery (with poor localization)

Mesentery

* Double layer of peritoneum that encloses an organ and connects it to abdominal wall
* Covered on both sides by mesothelium and has a core of loose connective tissue containing fat, lymph nodes, blood vessels and nerves passing to and from viscera
* Most mobile parts of intestine have mesentery, while ascending and descending colon are considered retroperitoneal (covered only by peritoneum on their anterior surface)
* Root of mesentery is its attached border with posterior abdominal wall
* Root of small bowel mesentery is ≈ 15 cm in length and passes from left side of L2 vertebra downward and to the right; contains superior mesenteric vessels, nerves and lymphatics
* Transverse mesocolon crosses almost horizontally in front of pancreas, duodenum and right kidney

Omentum

* Multi-layered fold of peritoneum that extends from stomach to adjacent organs
* Lesser omentum joins lesser curve of stomach and proximal duodenum to liver
	+ Hepatogastric and hepatoduodenalligament components contain common bile duct, hepatic and gastric vessels and portal vein
* Greater omentum
	+ 4 layered fold of peritoneum hanging from greater curve of the stomach like an apron, covering transverse colon and much of the small intestine
		- Contains variable amounts of fat and abundant lymph nodes
		- Mobile and can fill gaps between viscera
		- Acts as barrier to generalized spread of intraperitoneal infection or tumor

Ligaments

* All double layered folds of peritoneum other than mesentery and omentum are peritoneal ligaments
* Connect one viscus to another (e.g., splenorenal ligament) or a viscus to abdominal wall (e.g., falciform ligament)
* Contain blood vessels or remnants of fetal vessels

Folds

* Reflections of peritoneum with defined borders, often lifting peritoneum off abdominal wall (e.g., median umbilical fold covers urachus and extends from dome of urinary bladder to umbilicus)

Peritoneal Recesses

* Dependent pouches formed by reflections of peritoneum
* Because of clinical relevance, often have eponyms [e.g., Morison pouch forposterior subhepatic (hepatorenal) recess; pouch of Douglas forrectouterine recess]
Arterial:Femoral:Profunda femoris artery

The **profunda femoris** (also known as the **deep femoral artery** or **deep artery of thigh**) is a branch of the common femoral artery and is responsible for providing oxygenated blood to the deep structures of the thigh, including the femur.

Course:

* Arises laterally in femoral triangle
* Dives between pectineus & adductor longus ms.
* Medial to femur, deep to adductor longus m.

Branches:

* In femoral triangle: Medial circumflex femoral (main supply femoral head & neck), lateral circumflex femoral, muscular branches
* Branches in adductor canal: 3 perforating branches, descending genicular
* Terminal branch: 4th perforating artery
Abdomen:Venous:IVC and tributaries

The **inferior vena cava** **(IVC)** drains venous blood from the lower trunk, abdomen,pelvis and lower limbs to the right atrium of the heart.

Course: The IVC has a retroperitoneal course within the abdominal cavity

* The IVC is formed by the confluence of the two common iliac veins at the L5 vertebral level.
* It runs along the right side of the vertebral column with the aorta lying on the left.
* In the infracolic compartment, it is crossed by the root of the mesentery, right gonadal artery and D3.
* In supracolic compartment, it lies behind portal vein, head of pancreas and grooves the bare area of the liver
* It passes through the diaphragmatic caval hiatus at the T8 level.
* It has a short intra-thoracic course before draining into the right atrium.

Tributaries

* T8: paired inferior phrenic veins - accompany the arteries on lower surface of the diaphragm, and join vena cava below the liver.
* T8: hepatic veins - right, central and left and other accessory hepatic veins enter to vena cave as it groove the back of the liver.
* L1: right suprarenal vein - short course that pass to the IVC behind the bare area of the liver.
* L1: renal veins - lie anterior to renal arteries and behind pancreas. Each emerges from hilum of the kidney as five-six tributaries. The left renal vein crosses the aorta and receives left suprarenal vein.
* L2: right gonadal vein - accompany the arteries, runs up the psoas and drain into the renal veins (or IVC for the right vein)
* L1-L5: lumbar veins - accompany the lumbar arteries and drain the lateral and posterior abdominal walls. 3rd and 4th empty into vena cava while 1st and 2nd drain into ascending lumbar and joints the subcostal vein to form azygos veins/hemiazygos.
* L5: common iliac veins - formed by external and internal iliac in front of SI joint, behind right common iliac artery.

Since the IVC is not a midline structure, there is a degree of asymmetry of drainage, e.g. the gonadal and suprarenal veins drain into the IVC on the right side, but into the left renal vein on the left.

Variant anatomy

Inferior caval abnormalities are typically the result of persistent embryological veins:

* IVC duplication
* azygos continuation of the IVC
* left sided IVC
* circumcaval ureter
* circumaortic venous collar

Rarely an Eustachian valve at the IVA/RA junction may be present.

Alternative pathway from IVC to SVC

* Azygous
* Epidural plexus
* Epigastric vein
Abdomen:Venous:Portosystemic anastomoses

In portal hypertension shunting of blood away from the liver into the systemic venous system provides a mechanism of reducing portal venous pressure.

Spontaneous **portal-systemic collateral pathways** (also called **varices**) develop via enlargement of pre-existing anastomoses between the portal and systemic venous system. However these are not sufficient to normalise portal venous pressure.

The main sites of collateral pathways are :

* **distal oesophagus**: left gastric (coronary) vein & short gastric veins to distal oesophageal veins (azygos system)
* **bare area of the liver:** through the diaphragm
* **retroperitoneum**: superior mesenteric veins/splenic vein to retroperitoneal/lumbar veins to the left renal vein (inferior vena cava)
* **anterior abdominal wall**: paraumbilical vein to subcutaneous periumbilical veins (caput Medusae) and the epigastric veins (superior and inferior epigastric)
* upper **anal canal**: superior rectal vein (from inferior mesenteric vein) to mid rectal and inferior rectal veins (from internal iliac). These form haemorrhoids.
Key gyri:Cingulate

The **cingulate gyrus**lies on the medial aspect of the cerebral hemisphere. It forms a major part of the limbic system which has functions in emotion and behaviour. The frontal portion is termed the anterior cingulate gyrus (or cortex).

Relations:

* Anterior: inferior of superior frontal gyrus, rostrum of corpus of callosum, subcallosal gyrus in the frontal lobe
* Middle: middle and most horizontal portion lies inferior to the paracentral lobule separated from it by the cingulate sulcus
* Posterior: posterior portion (posterior cingulate gyrus) lies inferior to the precuneus separated from it by the subparietal sulcus, anterior to the occpital lobe separated by the parieto-occipital sulcus.
* It follows the superior convexity of the corpus callosum separated from it by the callosal sulcus
Abdomen:Hollow viscus:Oesophagus (abdo)

Abdominal oesophagus lies below the diaphragm for 1 -2 cm, and enters the cardiac orifice of the stomach. The right margin is continuous with the lesser curvature and the left margin is met acutely by the stomach fundus.

Relationship:

- anteriorly, grooves the the posterior aspect of the liver

- posteriorly, the left inferior phrenic artery

- covered by peritoneum that extend to the right as the lesser omentum.

- the right crus of the diaphragm forms a sling around lumen
Carpal tunnel

The **carpal tunnel** is a fibro-osseous canal that acts as a passageway from the forearm to the anterior hand. It is found in the anterior wrist.

Boundaries

* superficial border (roof): flexor retinaculum
* deep border (floor): carpal bones, scaphoid and trapezium tubercles laterally and hook of hamate and pisiform medially.

Contents

The carpal tunnel contains nine structures, from superficial to deep:

* flexor digitorum superficialis tendons (four)
* median nerve (laterally)
* flexor pollicis longus tendon (laterally)
* flexor digitorum profundus tendons (four)

Note, the flexor carpi radialis is often wrongly stated to be within the carpal tunnel, its course is in fact between the superficial and deep layers of the flexor retinaculum itself.

The tendons within the carpal tunnel are surrounded by synovial sheaths. One which envelopes the flexor digitorum superficialis and profundus together, and a separate sheath for the flexor pollicis longus.

Variant anatomy

Variant anatomical structures within the carpal tunnel

* persistent median artery of the forearm
* bifid median nerve
* presence of the motor branch of the median nerve within the carpal tunnel
* presence of palmaris longus tendon within the carpal tunnel
* reversed palmaris longus, palmaris profundus, accessory FDS, aberrant thenar or lumbrical origins
Abdomen:Nerves:Autonomic plexuses and ganglia

* **Sympathetic innervation**, from **lower thoracic** and **abdominopelvic splanchnic nerves** from spinal cord levels T5-L3; via para-aortic prevertebral ganglia (innervates blood vessels of abdominal viscera; inhibitory to parasympathetic innervation)
* **Parasympathetic**, from **vagus nerve** (esophagus through transverse colon) and **pelvic splanchnic nerve S2-S4** (descending colon to rectum)
* **Intrinsic parasympathetic ganglia** within muscular wall of stomach and gut, called **myenteric plexus** (**of Auerbach**); promotes peristalsis and secretion (though secretion is largely controlled hormonally)

* **Sensory innervation of viscera**, pain sensation carried by fibers accompanying sympathetic nerves; reflex afferent innervation accompanies **vagus** (parasympathetic) nerves
Common variants:Upper limb:Nervous

**High bifurcation of the median nerve:**

* bifurcation of the median nerve proximal to the transverse carpal ligament

**Variations of the motor branch of the median nerve**

* extra-ligamentous takeoff: recurrent motor branch arises from the median nerve distal to the transverse carpal ligament on the radial side
* sub-ligamentous takeoff: motor branch arises within the carpal tunnel
* trans-ligamentous takeoff: motor branch pierces the transverse carpal ligament on its course toward the thenar musculature (Figure 3C).
* the motor branch may have a course superficial to the transverse carpal ligament

**Variations of the palmar cutaneous branch of the median nerve**

* pierce the transverse carpal ligament.
* course within the tunnel

**Variations of the ulnar nerve**

* ulnar nerve within carpal tunnel
Basal CSF cisterns:Cisterna magna

The **cisterna magna** (also known as the **cerebellomedullary cistern**) is the largest of the subarachnoid cisterns.

The cisterna magna is located between the cerebellum and the dorsal surface of the medulla oblongata. CSF produced in the ventricular system drains into the cisterna magna from the fourth ventricle via the median aperture (of Magendie) and the lateral apertures (of Luschka).

Content:

- lateral part the vertebral artery and the posterior inferior cerebellar branch
Cerebellum:Dentate nuclei

**Dentate nucleus** is a cluster of neurons located within the deep white matter of each cerebellar hemisphere. It is the largest and most lateral of the four pairs of deep cerebellar nuclei.

The dentate nucleus is responsible for the planning, initiation and control of voluntary movements.

It forms a crenated crescent, open toward the superior peduncle. The main connections are:

- afferent cerebropontocerebellar fibres

- efferent fibres leave the hilum and pass to the contralateral red nucleus, thalamus and cerebral cortex.
Hyoid bone and related muscles and ligaments

The **hyoid**is a "horseshoe"-shaped bone that serves as a structural anchor in the mid-neck. It is a place of convergence of multiple small neck muscles that permit the pharyngeal phase of swallowing. Structures in the neck are often located in relation to the hyoid (i.e. suprahyoid neck; infrahyoid neck).

The hyoid bone is located above the thyroid cartilage, anterior to the trachea at the C2/C3 level. The hyoid consists of three parts:

* a body
* two superior genu
* two inferior genu

Attachments

Multiple small neck muscles insert in the three parts:

* body
	+ mylohyoid muscle
	+ sternohyoid muscle
	+ thyrohyoid muscle
	+ geniohyoid muscle
	+ omohyoid muscle
	+ stylohyoid muscle
	+ digastric muscles
* superior genu
	+ hyoglossus muscle
	+ middle pharyngeal constrictor muscle
* inferior genu
	+ stylohyoid ligament (i.e. no muscular attachment)

Relations

The position of the hyoid defines a few lymph node levels of the neck.  Anteriorly, the hyoid separates levels Ia (above) from VI (below). Laterally, the level of the hyoid separates level II from level III.

Blood supply

Branches of the external carotid artery, predominantly the infrahyoid artery (from superior thyroid artery) and lingual artery.
Bone:Metacarpals & phalanges:Bony features

METACARPAL

There are five metacarpal bones which have a distal head, shaft and expanded base.

* The rounded head articulates with the proximal phalanges and the articular surfaces are convex.
* The bases are trapezoid and articulate with the distal carpal row.
* The shafts is roughly triangular in cross-section with concave palmar surfaces which forms hollows for the palmar muscles.

The first metacarpal is more anterior and medially rotated than the others to allow opposition. Thumb metacarpal is shorter and thicker than the others. The base has a saddle shape for the trapezium. The convex shape for the head is not as rounded. The flexor margin is grooved for the sesamoid bones.

First metacarpal: Short and thick. Opponens pollicis is attached to the radial border and palmar surface. the first dorsal interosseous muscle is attached to the ulnar border. Abductor pollicis longus is attached to the palmer side and the first palmar interosseous muscle to its ulnar side. The base articulates with the trapezium. Sesamoid bones are present on the palmar aspect.

Second metacarpal: Longest shaft and largest base. Articulates with the trapezoid and capitate.

Third metacarpal: Has a short styloid process and articulates with the capitate.

Fourth metacarpal: Shorter and thinner. Articulate with the hamate.

Fifth metacarpal: Medial basal surface is non articular and has a tubercle for the extensor carpi ulnaris, while lateral surface articulate with hamate.

PHALANGES

There are 14 phalanges (3 in each finger and two in the thumb). Also comprised of base, shaft and head.

* Heads are bicondylar volarly with condyles separated by shallow groove
* There is a concave facet for the base for the trochlea shaped heads.

A corresponding tendon for the flexor digitorum profundus and extensor digitorum is attached to the base of each distal phalanx. Tendon for flexor digitorum superficialis are attached to the sides of the middle phalanx. Extensor digitorium is attached to the base.
Abu Bakr al-Baghdadi

Abu Bakr al-Baghdadi es un personaje Menor de la serie Harvey Beaks.

## Personalidad

es el líder terrorista se autoproclamó nuevo califa de todos los musulmanes, exigiendo obediencia a los musulmanes de todo el mundo. Eligió el nombre de guerra Abu Bakr al-Siddiq, el primer califa del Islam, suegro de Mahoma, y a su vez el iniciador de la serie llamada de los califas ortodoxos.

## Relaciones

### Fee

El Descarga la ira contra Fee junto a Foo hasta los quiere matar y subirlos a diversos instrumentos de tortura.

### Foo

El Descarga la ira contra Fee junto a Foo hasta los quiere matar y subirlos a diversos instrumentos de tortura.

### Harvey Beaks

El quiere matar a su familia pero Harvey no le hace caso y Harvey, Fee y Foo se escapan del Bosque que ellos viven.

## Trivia

* Abu Bakr al-Baghdadi es el Primer personaje existente que aparece en Harvey Beaks.
Arterial structures:Pelvis:Median sacral artery

The **median sacral artery** (or **middle sacral artery**) is a small vessel that arises posterior to the abdominal aorta and superior to its bifurcation.

It descends in the middle line in front of the fourth and fifth lumbar vertebrae, the sacrum and coccyx, ending in the glomus coccygeum (coccygeal gland).

On the last lumbar vertebra it anastomoses with the lumbar branch of the iliolumbar artery; in front of the sacrum it anastomoses with the lateral sacral arteries, sending offshoots into the anterior sacral foramina.

It is crossed by the left common iliac vein and accompanied by a pair of venae comitantes; these unite to form a single vessel that opens into the left common iliac vein.
Bone:Radius and ulna:Bony features

RADIUS

The radius is the lateral bone of the forearm. It has expanded proximal and distal ends. The shaft widens to its distal end.

* Proximal end: Consists of a head, neck and tuberosity. The radial head is cylindrical and articulates with the capitulum. The articular periphery is deepest medially where it articulates with the ulnar radial notch. The radial tuberosity is distal to the medial part of the neck.
* Shaft: The shaft of the radius is triangular in section. The interosseous membrane is attached to the distal three-fourth on the medial aspect.
* Distal end: The distal end is broad and has four surfaced. The lateral surface projects as the styloid process. The base is an articular surface with the scaphoid and lunate. The medial surface is the ulnar notch. The posterior surface has a palpable dorsal tubercle.

ULNA

The ulna is medial to the radius and consists of a large proximal end and a smaller distal end. The lateral border of the shaft forms a sharp interosseous crest.

Proximal end:

* Projections that grip the trochlea surface of the humerus: olecranon and coronoid processes, and trochlear and radial notches.
* The **olecranon** is posteriorly situated, proximal extension of the shaft, subcutaneous and palpable. In extension, it is lodged in the olecranon fossa. On the posterior surface, the triceps inserts on the upper surface. The olecranon bursa lies on top of the posterior surface of the olecranon. The anconeus is attached to the lateral surface. Anteriorly, the flexor digitorum profundus attaches on the medial side.
* The **coronoid process** projects forwards anteriorly distal to the olecranon. The **ulnar tuberosity** is the anterior inferior aspect of the olecranon.
* The coronoid and olecranon process form the distal and proximal part of the **trochlear notch** (articulate with ulnar head). On the lateral surface, distal to the trochlear notch, there is a shallow, smooth oval surface called the **radial notch** (articulates with the radial head). Medially, the lip has a prominent tubercle and the flexor digitorum superficialis attaches here. The pronator teres is attached to the medial border. The anterior surface receives the brachialis.

Shaft:

Triangular in cross-section proximally and cylindrical distally. The interosseous border is a lateral crest in the middle of the shaft. The supinator fossa, is on the lateral side below radial notch and gives origin to the ulnar head of the supinator. Posterior to this is the ulnar head origin of supinator muscles and lateral ulnar collateral ligament.

* Laterally attachment site of interosseous membrane
* Posteriorly rounded edge, dividing between extensors and flexors
* Anteriorly covered by flexor digitorum profundus

Distal end:

Consists of a head and styloid. The lateral convex articular surface of the head fits into the radial ulnar notch. The distal surface is seperated from the carpal bones by an articular disc. The styloid process is a short, round posterolateral projection of the ulna.
Cranial nerve systems:Trochlear nucleus & n.

CN4 is a pure motor nerve arising from the midbrain that supply the superior oblique.

Origin:

**Trochlear nuclei**

* Paired nuclei located in paramedian midbrain
	+ Anterior to cerebral aqueduct
	+ Dorsal to medial longitudinal fasciculus
	+ Caudal to oculomotor nuclear complex at level of inferior colliculus

Intra-Axial Segment

* Trochlear nerve fascicles course posteriorly & inferiorly around cerebral aqueduct, behind the inferior colliculus.
	+ Fibers then decussate within superior medullary velum
	+ Each superior oblique muscle is innervated by contralateral trochlear nucleus
	+ Key concept: CN4 is the only cranial nerve to exit dorsal brainstem

Cisternal Segment

* CN4 courses anterolaterally in ambient cistern
	+ Runs underneath the margin of the tentorium
	+ Passes between free edge of tentorium cerebelli and midbrain just superolateral to pons
* Passes between posterior cerebral artery above and superior cerebellar artery inferolateral to the occulomotor nerve.
* Penetrates dura to enter lateral wall of cavernous sinus just inferior to oculomotor nerve

Cavernous Segment

* Courses anteriorly through lateral dural wall of cavernous sinus
* Intracavernous relationships of CN4
	+ Remains inferior to CN3
	+ Superior to ophthalmic division of trigeminal nerve (CNV1)
	+ Lateral to cavernous internal carotid artery

Extracranial Segment

* CN4 enters orbit through superior orbital fissure together with CN3 and CN6
* Crosses over CN3 and courses medially
* Passes above annulus of Zinn (CN3 and CN6 go through annulus)
* Supplies motor innervation to superior oblique muscle
Ligaments:Ankle Joint:Collateral ligaments (medial & lateral)

**Deltoid:** Medial collateral ligament, from the medial malleolus to talus. Made up of two layers:

* Deep part: a narrow band (anterior and posterior tibiotalar band extending from the tibial malleolus to the medial aspect of the talus).
* Superficial part: triangular ligament, and fans from the tibial malleolus to the medial tubercle of the talus along the edge of the sustentaculum tali and spring ligament to the tuberosity of the navicular.

**Lateral Ligament:** Has three components that radiate from the lateral malleolus.

* Anterior talofibular ligament
	+ Originates 1 cm proximal to lateral malleolar, inserts on talar neck
	+ Stabilizes talus against anterior displacement, internal rotation & inversion
	+ Weakest, first to tear
* Calcaneofibular ligament
	+ Originates from lateral malleolar, inserts on calcaneal trochlear eminence
	+ Deep to peroneal tendons
	+ Lateral restraint of subtalar joint, often tears with anterior talofibular ligament
* Posterior talofibular ligament
	+ Extends from lateral malleolar fossa to lateral talar tubercle
	+ Strongest, rarely tears

These ligaments are supplied by the anterior and posterior tibial arteries and innervated by the deep peroneal and tibial nerves.
Arterial supply to brain:Posterior communicating artery (PComA)

The **posterior communicating artery (PCOM)**makes up the posterior linkage in the circle of Willis.

Course

The PCOM originates from the posterior aspect of the C7 (communicating) segment of the internal carotid artery and extends posteriormedially to anastomose with posterior communicating artery and form part of the circle of Willis.

Branches

The PCOM gives off many fine, scarcely visible, perforating branches. The largest perforating branch is called the premamillary (or anterior thalamoperforating) artery.

Supply:

* posterior part of the optic chiasm and optic tract
* posterior part of the hypothalamus and mamillary body
* part of the thalamus

Variant anatomy

* PCOM duplication: rare
* PCOM fenestration: extremely rare
* foetal origin of posterior cerebral artery: common
* PCOM hyoplasia: incidence ~35%
* PCOM infundibulum
* anterior choroidal artery origin from PCOM
Intracranial cavity (extra axial): Middle cranial fossa:Foramen lacerum

The **foramen lacerum** is a triangular opening located in the middle cranial fossa anterior to the petrous apex, which forms its posterior border. Its anterior border is formed by the body of the sphenoid bone at the junction of greater wing and pterygoid process and medial border is formed by the basilar part of the occipital bone. It measures approximately 9 mm in length and 7 mm in breadth.

The foramen lacerum is filled with connective tissue and transmits the small meningeal branches of the ascending pharyngeal artery and emissary veins from the cavernous sinus. The internal carotid artery passes along its superior surface but does not traverse it.
Anatomy of the Head & Face (Excluding CNS)

Anatomy

Frontal bone & sinus
Sphenoid: Lesser wing
Olfactory bulb and tract | Meningeal coverings
Temporal bone & apex
Middle meningeal artery
Foramina of middle cranial fossa & contents
Optic canal
Superior orbital fissure
Foramen rotundum
Foramen ovale
Carotid canal | Meningeal coverings
Vidian canal
Foramen spinosum
Occipital bone
Foramina of posterior cranial fossa & contents
Internal auditory meatus with CN VII & VIII
Jugular foramen & contents
Hypoglossal canal & CN XII
Foramen magnum | Meningeal coverings
**Bones including prominences, foramina and key vascular markings**
Frontal
Parietal
Sphenoid
Temporal
Occipital | Dural coverings
Arachnoid granulations
Blood supply to scalp | Frontalis muscle
Foramina & contents
Optic canal
Superior orbital fissure
Inferior orbital fissure | Lacrimal fossa/crest
Periorbita
Medial & lateral tubercles
Blood supply & venous drainage
Levator palpebrae superioris &
Nerve supply
Conjunctival sac boundaries
Choroid & retina
Iris & lens |  | Canal of Schlemm
Macula position
Short ciliary arteries
Nerve supply
Short and long ciliary nerves
Optic nerve
Central artery of retina
Central retinal vein
Infraorbital artery
Central artery of retina | Supraorbital
Supratrochlear
Lacrimal
Dorsal nasal
Anterior & posterior ethmoidal | Anterior ciliary
Posterior ciliary
Zygomaticotemporal
 Ciliary ganglion
 Ophthalmic nerve
Maxillary nerve
 Infraorbital nerve |  Branches of ophthalmic nerve
Ethmoid bone
Palatine bone
Maxilla
Conchae & meati
Ostiomeatal complex & its components
Sphenoid sinus
Sphenoethmoidal recess | **Other bones**
Premaxilla
Pterygoid plates of sphenoid
Nasal bone
Lacrimal bone
Nasal septum & vomer
Ethmodial cell variants
Haller cell
Agger nasii cell
**Foramina**
Sphenopalatine foramen
Palatine canals
Incisive foramen
 Anterior and posterior ethmoidal arteries
Nasopalatine
Sphenoid
Palatine
Ethmoid
Nasal
Vomer
Zygoma
Maxilla
Tympanic membrane
Mastoid air cells |  | Auricle & its innervation
**Ossicular Chain**
Malleus
Incus
Stapes
**Nerves**
Facial nerve
Chorda tympani | Ossicular chain joints & ligaments
**Muscles**
Tensor tympani
Stapedius
Bony & membranous labyrinth
Facial nerve canal
Stylomastoid foramen | Dorello’s canal
Cochlear aqueduct
Articular disc & components
Condyle & articular cartilage
Fully open & closed positional anatomy | Joint capsule
Muscle attachments
Inferior alveolar artery & nerve
**Canals & foramina**
Mandibular canal
Lingula
Inferior alveolar foramen
Mental foramen | Mental nerve
Dental nerves
Nerve to mylohyoid
Parts of tooth
Facial venous anastomoses | Supratrochlear
Muscle/Group:Forearm:Flexor compartment intermediate layer:Flexor digitorum superficialis

**Flexor digitorum superficialis**

* Has two heads
* Origin of humero-ulnar head: Common flexor tendon, ulnar collateral ligament, coronoid process
* Origin of radial head: Anterior aspect of proximal radius
* Insertion: Volar aspect of middle phalanges of 2nd-5th fingers
* Innervation: Median nerve
* Action: Flexes the proximal interphalangeal joints, weak flexor of metacarpophalangeal and wrist joints
Abdomen:Solid viscus:Couinaud segments

The **Couinaud classification** is used to describe functional liver anatomy. It divides the liver into eight independent functional units based on independent vascular inflow, outflow and biliary as well as lymphatic drainage. In the centre of each segment there is a branch of the portal vein, hepatic artery and bile duct; in the periphery of each segment there is vascular outflow through the hepatic veins.

* right hepatic vein located in the right intersegmental fissure, divides the right lobe (cephalic aspect) into anterior and posterior segments
* middle hepatic vein lies in the main lobar fissure, divides the liver into right and left lobes (or right and left hemiliver): this plane runs from the inferior vena cava to the gallbladder fossa also known as Cantlie's line
* left hepatic vein located in the left intersegmental fissure, divides the left lobe (cephalic aspect) into a medial and lateral part
* portal vein divides the liver into upper and lower segments: the left and right portal veins branch superiorly and inferiorly to project into the centre of each segment

The division of the liver into self-contained units means that each segment can be resected without damaging those remaining. For the liver to remain viable, resections must proceed along the vessels that define the peripheries of these segments. This means, that resection-lines parallel the hepatic veins and there is preservation of the centrally located portal veins, bile ducts, and hepatic arteries.

* **unit I** is the caudate lobe and is situated posteriorly and it may receive its supply from both the right and the left branches of portal vein. It contains one or more hepatic veins which drain directly into the IVC

The remainder of the units (II to VIII) are numbered in a clockwise fashion:

* **units II and III**lie lateral to the falciform ligament with II superior to the portal venous supply and III inferior
* **unit IV** lies medial to the falciform ligament and is subdivided into **IVa** (superior) and **IVb** (inferior)

Units V to VIII make up the right hemiliver:

* **unit V** is the most medial and inferior
* **unit VI**is located more posteriorly, with
* **unit VII** above it
* **unit VIII** sits above unit V in the superio-medial position
Muscle/Group:Shoulder (Pectoral):Teres major

**Teres major** is one of the seven scapulohumeral muscles that act around the glenohumeral joint to facilitate shoulder movement:

* **origin**: caudal two thirds of lateral border and inferior angle of scapula
* **insertion**: medial border of the intertubercular goove, which is the crest of lesser tubercle of humerus
* **innervation**: lower subscapular nerve (C5/C6)
* **action**: medial shoulder rotation and shoulder adduction