recursal/Fanatic-Fandom huggingface dataset:
Abdomen:Solid viscus:Spleen

The **spleen**is an organ of the haematological system and has a role in immune response, storage of red blood cells and hematopoiesis. The spleen is a wedge-shaped organ lying mainly in the left upper quadrant (left hypochondrium and partly in the epigastrium) and is protected by the left 9th to 11th ribs. It is soft, highly vascular and dark purple in colour.

Size and weight vary from person-to-person but on average is around 2.5 cm thick, 7.5 cm broad and 12.5 cm in length.

The spleen has two poles (superior and inferior), three borders and two surfaces (diaphragmatic and visceral). It is enclosed by a thin capsule, which is easily ruptured.

The spleen is completely covered by peritoneum, except at the hilum, and forms a number of ligaments:

* gastrosplenic ligament
	+ attaches the spleen to the greater curvature of the stomach
	+ contains short gastric and left gastroepiploic arteries
* splenorenal ligament
	+ attaches the spleen to the left kidney
	+ contains splenic artery and vein and the pancreatic tail

Relations

* medially: splenic vessels, stomach, splenic flexure, pancreatic tail
* anteriorly and superiorly: dome of the left hemidiaphragm
* inferior: phrenico-colic ligament
* posterior and inferiorly: left kidney, left adrenal gland

Blood supply

* arterial supply - splenic artery. Passes between the layers of splenorenal ligament and divide into 5 branches to supply the spleen
* venous drainage - splenic vein

Lymph drainage

* drain into nodes at the hilum and pass to the pancreaticosplenic nodes and then to coeliac nodes

Nerve supply

Coeliac plexus with sympathetic fibres only

Variant anatomy

* ~10% of patients are noted to have an accessory spleen (splenunculus), most commonly in the splenic hilum with a mean size of 10mm
* wandering spleen
* polysplenia
* asplenia
* splenogonadal fusion
* retrorenal spleen
Abdomen:Arterial:Inferior phrenic

The **inferior phrenic arteries** (**IPA**) are the first branches of the abdominal aorta. These are paired branches of the abdominal aorta/coeliac trunk supplying the diaphragm. Its importance lies in that the right IPA is the most common extrahepatic arterial supply of hepatocellular carcinoma.

* **origin:** abdominal aorta or coeliac trunk at the level of T12-L2
* **course:** superiorly in retroperitoneal fat in close relation to the diaphragmatic crura. The left artery pass behind the oesophagus and the right behind the IVC.
* **branches:** anterior, posterior, superior, and middle suprarenal branches
* **supply:** diaphragm, inferior vena cava, oesophagus, liver (segments II, III, VII - bare area)

#### Variant anatomy

* may arise from renal arteries, left gastric artery, hepatic artery, superior mesenteric artery or spermatic artery.

**Superior epigastric artery** is the direct continuation of the internal thoracic artery.

* enters the rectus sheath superiorly through it posterior layer
* continues inferiorly - anastomoses with inferior epigastric artery at the level of the umbilicus
* supplies superior part of rectus abdominis

**Inferior epigastric artery** arises from the external iliac artery just superior to the inguinal ligament

* runs superiorly to the transversalis fascia to enter the rectus sheath below the arcuate line
* runs deep to the rectus abdominis
* anastomoses with the superior epigastric artery superiorly
* important to avoid during interventional procedures such as ascitic taps or drains.
Abdomen:Hollow viscus:Jejunum

The **jejunum** is defined as the proximal two-fifths of the small intestine and is, on average, ~300cm in length.

It is wider bored and thicker walled than the ileum (has a shirt sleeve through coat sleeve) texture. It also has more valvulae conniventes and fewer folds per unit length.

Like the ileum, normal jejunal wall thickness is less than 3mm. The jejunum has a smaller diameter (average 2.5cm) compared to the ileum (3.0cm).

Blood supply:

* Jejunal branches from the left side of the SMA. These join each other in a series of anastomosing loops called arterial arcades. From the arcades straight arteries pass to the mesenteric border of the gut. The spaces between are close forming high narrow "window" appearance.
* Veins corresponding to the artery drain into the SMV

Nerve supply:

* The parasympathetic (posterior vagal) supply peristaltic activity and intestinal secretions. Follow arterial branches.
* Sympathetic supply is vasoconstrictor and normally inhibits peristalsis (lateral horn cells of T9-T10) via splanchnic nerves. Afferent pain pathway, pass through with sympathetic fibres. Follows SMA and branches..
Abdomen:Muscles:Psoas

The **psoas major muscle**(normally referred to as **psoas muscle**) is one of the muscles of the posterior abdominal wall. Its action is the lateral flexion of the trunk, and stabilization of the flexor of the hip. The muscle comes to lie medial to and fuses with the iliacus muscle at level L5-S2, such that inferiorly the two are often referred to together as iliopsoas muscle. It passes inferiorly beneath the inguinal ligament to the femur.

It is situated in the gutter between the bodies and the transverse processes of lumbar vertebrae. The psoas muscle is enclosed by the **psoas fascia** and retention of pus leads to a psoas abscess. At L1, the thickening of the psoas fascia form the medial arcuate ligament from which fires of the diaphragm arise in continuity alongside the crus. The lumbar plexus is embedded within the muscle.

Origin: vertebral bodies, intervertebral discs and transverse processes of T12 to L5

Insertion:the lesser trochanter of the femur.

The lumbar plexus is embedded within the muscle and its branch emerge from it.

* anterior aspect - genitofemoral nerve
* lateral border - iliohypogastric, ilioinguinal, lateral femoral cutaneous and femoral nerves
* medial border - obturator nerve and lumbosacral trunk
* posterior aspect - lumbar arteries and veins

Nerve supply

 Lumbar plexus via branches from L1-L3 (mainly L2)

Variant anatomy

* asymmetry of the psoas major muscle, which is usually no clinical significance
Intracranial cavity (extra axial): Posterior cranial fossa:Jugular foramen & contents

The jugular foramen courses anteriorly, laterally, and inferiorly as it insinuates itself between the petrous temporal bone and the occipital bone.

The jugular foramen is divided by a fibrous or bony septum, the jugular spine,  into:

* the pars nervosa: smaller and anteromedial
* the pars vascularis: larger and posterolateral

Pars nervosa

The pars nervosa is the anteromedial portion of the jugular foramen and is smaller than the larger, posterolateral pars vascularis. It contains:

* inferior petrosal sinus
* glossopharyngeal cranial nerve (CN IX)

The inferior petrosal sinus drains the cavernous sinus and courses in the petro-occipital fissure adjacent to the clivus prior to its exit through the pars nervosa and subsequent drainage into the jugular vein beneath the foramen.

The glossopharyngeal nerve yields a tympanic branch (Jacobson`s nerve) which reaches and supplies the middle ear along with the inferior tympanic artery via the inferior tympanic canaliculus which is occasionally seen at CT in cross section at the level of the carotico-jugular spine.

Pars vascularis

The pars vascularis is the posterolateral portion of the jugular foramen and is larger than the smaller anteromedial portion termed the pars nervosa. It contains:

* jugular bulb: a venous expansion between the endocranial sigmoid sinus and the exocranial jugular vein
* vagus cranial nerve (CN X)
* spinal accessory cranial nerve (CN XI).

The vagus nerve yields an auricular branch (Arnold nerve) via the mastoid canaliculus on the lateral wall of the foramen adjacent to the mastoid segment of the facial nerve.
Ligament:Elbow:Collateral ligaments

Lateral Side of Elbow Joint

* Lateral collateral ligament complex
	+ Radial collateral ligament
		- Triangular shaped
		- Apex is on the lateral epicondyle
		- Base blends with anular ligament around radial head
		- Lies deep to overlying common extensor tendon
		- Provides origin for the superficial head of supinator muscle
	+ Lateral UCL
		- Thin ligament
		- Provides restraint to posterolateral instability of radial head
		- Origin: Lateral epicondyle, blending with posterior aspect of origin of RCL
		- Insertion: Supinator crest of lateral side of proximal ulna
		- Courses posterior to radial head, partially blending with anular ligament
	+ Anular ligament
		- Attached to anterior and posterior aspects of radial notch of ulna
		- Forms a ring or collar around radial head
		- Anterior attachment becomes taut in supination
		- Posterior attachment becomes taut in extreme pronation
		- Provides origin for superficial head of supinator muscle
	+ Accessory lateral collateral ligament
		- Anatomically inconstant
		- Origin: Anterior inferior aspect of anular ligament
		- Insertion: Supinator crest of ulna, blending with insertion of lateral UCL
		- Stabilizes anular ligament during varus stress

Medial Side of Elbow Joint

* Ulnar (medial) collateral ligament
	+ Restraint against valgus stress
	+ Triangular shaped
	+ Origin: Inferior surface of medial epicondyle
	+ Insertion: Coronoid and olecranon portions of ulna
	+ Composed of three bands
		- Anterior: Functionally most important, extends from medial epicondyle of humerus to sublime tubercle of coronoid process
		- Posterior: Functionally less important but maintains reciprocal tautness with anterior band, extends from medial epicondyle to olecranon
		- Transverse: Functionally unimportant, forms base of triangle between anterior and posterior bands
	+ Lies deep to common flexor tendon

Proximal Radio-Ulnar Joint

* Anular ligament
* Quadrate ligament
	+ Thin fibrous band
	+ Origin: Lateral side of ulna, distal to radial notch
	+ Insertion: Medial side of radial neck, distal to anular ligament
	+ Stabilizes proximal radio-ulnar joint in full supination
* Oblique cord
	+ Anatomically inconstant
	+ Origin: Lateral side of ulna, distal to tuberosity
	+ Insertion: Medial side of radius, distal to tuberosity
Abdomen:Radiological spaces:Lesser sac

The **lesser sac**or **omental bursa**is a cavity found with the abdomen and is part of the peritoneal cavity.

* formed from the space between the greater and lesser omentum
* part of the peritoneal cavity that lies posterior to stomach and lesser omentum.
* communicates with greater sac via epiploic foramen (of Winslow)

Boundaries

* anterior wall
	+ peritoneum of lesser omentum
	+ posterior surface of stomach
	+ anterior two layers of greater omentum
	+ caudate lobe of the liver
* posterior wall
	+ peritoneum that covers the diaphragm, pancreas, left kidney and adrenal gland, and duodenum
	+ to the left by splenorenal and gastrospelic ligaments and right by epiploic foramen

Epiploic foramen boundaries:

superior: caudate lobe of liver

inferior: D1 duodenum

anterior: portal triad in the lesser omentum (DAVE)

poster: peritoneum covering IVC
Joints:Joints of the foot:Subtalar & talocalcaneonavicular joints

The **talocalcaneal joint**,also called the **subtalar joint**, is a plane synovial joint important and complex joint in the hindfoot that allows articulation of the talus and calcaneus. It allows inversion and eversion of the foot.

There are three articulating facets between the talus and the calcaneus, delineated as the anterior, middle and posterior facets.

* **anterior:** head of talus with anterior facet of calcaneus; small articulation in size, just lateral to medial facet
* **middle:**medial (sustentacular) facet of talus with the middle facet at the sustentaculum tali of the calcaneus

* **posterior:**posterior facet of talus with posterior facet of calcaneus; largest articulation in size. Separated from the others by the tarsal canal.

Ligaments and membranes

The main ligament of the joint is the interosseous talocalcaneal ligament, a thick, strong band of two partially joined fibers that bind the talus and calcaneus. It runs through the sinus tarsi, a canal between the articulations of the two bones.

There are four additional ligaments that form weaker connections between the talus and calcaneus.

* anterior talocalcaneal ligament (or anterior interosseous ligament): attaches at the neck of the talus on the front and lateral surfaces to the superior calcaneus.
* posterior talocalcaneal: ligament extends from the lateral tubercle of the talus to the upper medial calcaneus.
* lateral talocalcaneal ligament: connects from the lateral talus under the fibular facet to the lateral calcaneus, and runs parallel to the calcaneofibular ligament.
* medial talocalcaneal ligament: extends from the medial tubercle of the talus to the sustentaculum tali on the medial surface of the calcaneus.

A synovial membrane lines the capsule of the joint, and the joint is wrapped in a capsule of short fibers that are continuous with the talocalconeonavicular and calcaneocuboid joints of the foot.

Relations:

* anterior: tarsal bones
* posterior: calcaneal tendon
* medial: tarsal canal with its contents
* lateral: fibularis tendons

Blood supply:

* arterial - anterior tibial, posterior tibial and fibular arteries. Forms an anastomosis around the subtalar joint giving off the sinus tarsi artery that pass through the sinus tarsi.

Nerve supply:

* deep peroneal, medial and lateral plantar nerves
Abdomen:Visceral arteries:Adrenals

Each (left and right) **superior suprarenal artery** is a branch of the inferior phrenic arteryon that side of the body. The left and right phrenic arteries supply the diaphragm, and come off the aorta.

The **middle suprarenal arteries** arise from the abdominal aorta at the level of L1. Right middle suprarenal artery passes behind the IVC.

The **inferior suprarenal arteries** usually originate at the trunk of the renal artery before its terminal division, and usually present substantially different diameters corresponding to the age variable. The suprarenal arteries irrigate the suprarenal gland parenchyma, the ureter, and the surrounding cellular tissue and muscles.
Arterial structures:Pelvis:Ovarian artery

The **ovarian artery**is a paired structure and are the main gonadal artery in females.

Origin

The ovarian artery arises anterolaterally from the aorta just inferior to the renal arteries and superior to the inferior mesenteric artery.

Course

Descends caudally in the retroperitoneum on psoas major with the gonadal vein andureter. Passes into the pelvis anterior to the iliac vessels. In the pelvis it takes a medial path through the suspensory towards the uterus. Anastomoses with the ovarian branch of the uterine artery at the uterus.

Supplies

* ovary
* Fallopian tube
* uterus

Variant anatomy

In 20%, they arise from the renal arteries. Uncommonly may arise from adrenal, lumbar or internal iliac arteries.
Muscles:Foot:Flexor hallucis brevis

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

Origin: cuboid and lateral cuneiform and tendon of tibialis posterior

Insertion: medial and lateral sides of the proximal phalanx of great toe

Nerve: medial plantar nerve

Action: flexion of proximal phalanx of big toe

- the belly of the muscle splits into two parts and hence two sites of insertion
Arterial structure:Brachial:Profunda brachii artery

The largest branch of the brachial artery. It leaves through the lower triangular space (border shaft of humerus, long head of triceps and teres major) and run in the radial groove with the radial nerve.

- supplies triceps and gives nutrient artery to the humerus.

- divides into two terminal branches, (and joins anastomosis around the elbow). The middle collateral that descends in the medial head of the triceps and the radial collateral that courses through the lateral intermuscular septum accompanying the radial nerve
Bone: Hip Bone, Femur, and Patella: Epiphyses(sites, dates of appearances)

Hip pattern of ossification

* 3 primary centers: Ischium, ilium, pubis (start in fetus)
	+ Joined by triradiate cartilage; matures 15-16 y/o
* 5 secondary centers: Iliac crest, anterior inferior iliac spine, ischial tuberosity, pubis, ASIS

Still separate at birth, gradually close over. Aged 18 the acetabulum is completely ossified. The whole hip bone does not ossify until between 20 and 25.

Femur - ossified from 5 centres.

* Shaft (7 weeks in utero)
* Head (4-6 months)
* Greater trochanter (2-4 years)
* Lesser trochanter (10-12 years)
* Femoral condyles (9 months in utero).
* All bones fully united 16-20 years.

Patella - Single centre.

* Begins aged 2 - 3, but up to 6 years. Completes by puberty.
Muscle:Pelvis:Obturator internus

Obturator internus is a pelvic muscle that is attached to the medial surface of the obturator membrane and pass through the lesser sciatic foramen to reach the gluteal region. The fibers converge and end in four or five tendinous bands, which are reflected at a right angle over the grooved surface of the ischium between its spine and tuberosity. It functions to help laterally rotate femur with hip extension and abduct femur with hip flexion

Origin: pelvic surface of the obturator membrane/foramen, the ischial and pubic ramus of the foramen.

Insertion: greater trochanter of the proximal femur. The insertion is a single flattened tendon that pass across the capsule of the hip joint and receives attachment from superior/inferior gemellus.

Innervation: The internal obturator muscle is also innervated by the nerve to internal obturator (L5, S1).

A bursa, narrow and elongated in form, is usually found between the tendon and the capsule of the hip-joint; it occasionally communicates with the bursa between the tendon and the ischium.

The muscle is covered with strong membrane, the obturator fascia. The tendinous arch slopes across the fascia.
Muscles:Deep fascia:Plantar aponeurosis

Layers of dense collegen fibres at the sole of the foot

Origin: medial process of the calcaneus

Insertion: divides into five individual bands that inserts into each of the toes

- it is covered at the level of the distal metatarsal heads by superficial transverse metatarsal ligaments

- septa extend from the edges and attaches to the 1st and 5th metatarsal (these separate the abductors from the flexor digitorum brevis)
Joint:Joints of the shoulder girdle:Sternoclavicular joint

The **sternoclavicular joint** is a diarthrodial synovial articulation between the medial clavicle, manubrium and the first costal cartilage that joins the upper limb with the axial skeleton.

Articulation

There are two non-congruent articular surfaces forming a saddle-type joint between the medial clavicle and the clavicular notch of the sternum.

The articular surfaces are covered with fibrocartilage, thicker on the clavicle than sternum (rather than hyaline cartilage is in most other synovial joints). The joint space is divided by an flat and circular articular disc which is thicker peripherally., also made of fibrocartilage.

Fibrous capsule

This is thickened in front and behind but above and below it is more loose

Ligaments

Because of the non-congruent articular facets much the joint stability comes from surrounding ligaments:

* **anterior sternoclavicular ligament:** broad and attached above to the anterosuperior aspect of the clavicle. It passes inferomedially to the upper anterior aspect of the manubrium and the first costal cartilage
* **posterior sternoclavicular ligament:** weaker band posterior to the joint from the clavicle to the back of the upper manubrium
* **interclavicular ligament:** between superomedial ends of the clavicles. Continuous above with deep cervical fascia and unites the superior aspects of the clavicles
* **costoclavicular ligament:** inverted cone that is short and flattened. Joins the upper surface of the first rib with the inferior clavicular surface.

Special structures

* **articular disc**
	+ flat and oval in shape
	+ attached to the joint capsule anteriorly and posteriorly, first costal cartilage inferiorly and the clavicle superiorly

Relations

* anteriorly: sternocleidomastoid muscle
* posteriorly: sternohyoid muscle, sternothyroid muscle, brachiocephalic veins, origin of the great vessels

Blood supply

* arterial: internal thoracic and suprascapular arteries

Nerve supply

* medial supraclavicular and subclavian nerves

Variant anatomy

* ~2.5% of the population have an inferior facet for articulation with the first rib
* perforation of the articular disc, meaning the joint recesses are in communication
Abdomen:Ligament:Inguinal ligament and associated structures

The **inguinal ligament** (or **Poupart's ligament**) is a fibrous band extending from the anterior superior iliac spine to the pubic tubercule. It is an important anatomical landmark and denotes the transition of the pelvis to the lower limb.

The inguinal ligament is formed by the lower border of the aponeurosis of the external oblique muscle, which is thickened and folded on itself. Its lateral half runs obliquely, while the medial half is almost horizontal.

Attachments

* from medial end of the inguinal ligament, some fibres pass posteriorly to attach to the superior pubic ramus forming the triangular **lacunar ligament** (**of Gimbernat**). The crescenteric free lateral edge for the lacunar ligament is the medial margin o the femoral rings.
* fibres that run with the lacunar ligament continue to pass more laterally to attach to the pecten pubis forming **pectineal ligament** (**of Cooper**).
* superior fibres run past the pubic tubercle, behind the spermatic cord, to fuse with those of the contralateral external oblique aponeurosis forming the **reflected inguinal ligament**

 The upper surface of the ligament gives origin to the cremaster muscle from its medial part, internal oblique muscle from the lateral two-thirds and transversus abdominis muscle from its lateral one-third.

The ligament is continuous with the fascia lata of the thigh and the upper grooved surface forms the floor of the inguinal canal.

Relations

The **retroinguinal passage** or **subinguinal space** is formed deep to the inguinal ligament and contains a number a structures as they pass from the pelvis to the lower limb:

* deep circumflex iliac artery (laterally)
* iliopsoas muscle
* femoral vein
* femoral artery
* femoral nerve
* lymphatic channels draining inguinal lymph nodes
Cranial vault: Bones:Parietal

The parietal bone is a paired, irregular, quadrilateral skull bone that forms the sides and roof of the cranium.

The parietal bone has four borders, four angles, and external/internal surfaces.

Borders include: frontal, sagittal, occipital (half of lambdoid suture), and squamous temporal.

Angles include: sphenoid, mastoid, occipital, and frontal.

The external surface is convex and smooth. It features:

* parietal eminence
* superior temporal line for attachment of temporalis fascia
* inferior temporal lines for attachment of temporalis muscle
* parietal foramen contains an emissary vein to superior sagittal sinus

The internal surface is concave and features:

* groove for middle meningeal vessels
* groove above: forms sagittal sulcus

##### Articulations

The parietal bone articulates with five other bones: the frontal, sphenoid, temporal, occipital, and contralateral parietal bone.
Abdomen:Hollow viscus:Caecum

The **caecum** is the first part of the large bowel and lies in the right lower quadrant of the abdomen.

Blind-ending sac of bowel that lies below the ileocaecal valve. The caecum measures 6cm in length and can have a maximum diameter of 9 cm. The appendix typically arises from the posteromedial surface, 2 cm inferior to the ileocaecal valve.

* Covered in peritoneum, except posteriorly where it has a layer of loose connective tissue and it has a variable mesentery.
* Two peritoneal folds on either side of the posterior wall of the caecum forms the retrocaecal recess where the appendix can lie.
* The superior margin of the caecum is defined by the ileocaecal ostium.
	+ Upper and lower flaps consisting smooth muscle protrude into the lumen around the ostium forming the ileocaecal valve.
	+ Its competence (or lack of) is often shown by contrast reflux into the terminal ileum.

Relations

* anterior - parietal peritoneum, anterior abdominal wall and loops of small bowel
* posterior - iliacus muscle, psoas muscle, femoral nerve, lateral cutaneous nerve of the thigh and variably appendix
* medial - ileocaecal valve and terminal ileum
* superior - ascending colon
* inferior - lateral third of the inguinal ligament

Blood supply

* arterial supply - anterior and posterior caecal arteries from colic artery, a branch of ileocolic artery from superior mesenteric artery
* venous return - similar named to artery to the superior mesenteric vein

Nerve supply

* sympathetic supply via superior mesenteric plexus
* parasympathetic supply via pelvic splanchnic nerves (from S2 - S4)

Lymphatic supply

Lymph travels with the arterial supply to paracolic lymph nodes, which drain to the superior mesenteric group.

Variant anatomy

* subhepatic caecum - failure of the caecum to migrate to its typical position during midgut rotation in embryogenesis
* azygosed caecum
* caecum and appendix in left lower quadrant
* mobile caecum
	+ right colonic mesentery fails the fuse to the lateral peritoneum
	+ occurs in ~15% of the population
Abdomen:Muscles:Posterior abdominal muscles and fasciae

**Posterior abdominal wall** is made up by a floor of muscles. The five lumbar vertebra along with the IVC and aorta project forward in midline, leaving two pairs of paravertebral gutters. These are floored by the psoas and quadratus lumborum and below the iliac crest and iliacus muscle. The crura and adjacent parts of diaphragm also involved.

**Psoas muscle** (discussed in a different section)

The **quadratus lumborum muscle** is an irregular quadrilateral flat muscle that forms part of the posterior abdominal wall. It lies between the psoas and the transversus abdominis. Its action is the extension and lateral flexion of vertebral column; fixes 12th rib during inspiration to stabilise the diaphragm.

it is covered anteriorly by the lumbar fascia. At L1, a thickening of this fascia passes to the 12th rib, constitute the lateral arcuate ligament.

Origin: medial half of inferior margins of 12th ribs and upper four lumbar transverse processes

insertion: iliolumbar ligament and internal rim of iliac crest

Anterior relations:

* colon
* kidney
* psoas muscle (major and minor)
* diaphragm
* subcostal, ilioinguinal and iliohypogastric nerves

innervation:

- ventral rami of the 12th thoracic nerve

- L1-L4 spinal nerves

Blood supply

* branches of the lumbar arteries
* the arteria lumbalis ima
* the lumbar branch of the iliolumbar artery
* branches of the subcostal artery

Variant anatomy

The number and extent of attachments to the last rib vary.

**Lumbar fascia** is the lumbar part of the thoracolumbar fascia. Three layers of fascia enclose two muscular compartments.

The anterior layer covers the quadratus lumborum, and extends from the front of the iliolumbar ligament/iliac crest to the lower border of the twelfth rib. Medially it is attached to the transverse process and laterally, it blends with the middle layer and gives origin to the transversus abdominis and internal oblique.

The middle layer covers the erector spinae muscles anteriorly, extend from the iliolumbar ligament to the 12th rib as well. medially it is attached to the lumbar transverse process and laterally its blends with both anterior and posterior layers,.

The posterior layer lies over the erector spinae on the posterior aspect and attached medially to the spinous processes. It extends from the posterior part of the iliac crest and sacrum up to the 12th rib and further up to all the angles of the ribs, which is the thoracic part of the thoracolumbar fascia.
Anatomy of the Neck (Non-Spinal)

**Anatomy**

Laryngeal divisions: supraglottic, glottic and subglottic
Vestibule, ventricle/sinus
Pyriform recess/sinus/fossa | Fibromuscular structures & folds
Circular
*Superior constrictor & components*
*Middle constrictor*
*Inferior constrictor & components* | Longitudinal
*Stylopharyngeus*
*Palatopharyngeus*
Rosenmüller fossa | Boundaries
Relations
Masticator space
Parotid space
Submandibular & sublingual spaces
Retropharyngeal space
Masseter muscle
*Medial pterygoid*
*Lateral pterygoid*
*Pterygopalatine fossa*
*Palatine plates*
*Contents*
Foramen ovale
Nerves
*Mandibular n. & branches*
*Maxillary n. & branches*
*Pterygopalatine ganglion*
Vessels
*Maxillary artery & branches*
*Deep maxillary vein*
*Genioglossus*
*Mylohyoid*
*Hyoglossus*
Hyoid bone
Mylohyoid sling
Lingual artery, nerve and chorda tympani
Facial artery & vein
Hypoglossal & glossopharyngeal nerves
Lymphatic drainage | Other Muscles
*Geniohyoid*
*Intrinsic muscles*
*Styloglossus*
*Palatoglossus*
Vertebral artery in the neck
Topography,relations with scaleni anterior and medius
External carotid artery and its head branches
Internal jugular vein
Carotid body
Nerves
*Glossopharyngeal*
*Vagus*
*Accessory*
*Hypoglossal* | Jugular tributaries
Carotid sympathetic plexus
*Superficial cervical chain*
*Spinal accessory chain*
*Deep cervical chain*
*Jugulo-digastric and juguloomohyoid, Virchow nodes*
*Retropharyngeal nodes*
Cross sections (horizontal sections) of the neck at all vertebral levels
Median section (Mid-sagittal section) of the neck
Cerebellum:Neocerebellum

The **neocerebellum** is the lateral zone of each hemisphere of the cerebellum. It receives input exclusively from the cerebral cortex (especially the parietal lobe) via the pontine nuclei (forming cortico-ponto-cerebellar pathways), and sends output mainly to the ventrolateral thalamus (in turn connected to motor areas of the premotor cortex and primary motor area of the cerebral cortex) and to the red nucleus.

It is thought to be involved in planning movement that is about to occur.
Abdomen:Arterial:Parietal branches

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.

The **lumbar arteries** are arteries located in the lower back or lumbar region. The lumbar arteries are in parallel with the intercostals.

* They are usually four in number on either side, and arise from the back of the aorta, opposite the bodies of the upper four lumbar vertebrae.
* A fifth pair, small in size, is occasionally present: they arise from the middle sacral artery.

Course:

* They run laterally and backward on the bodies of the lumbar vertebrae, behind the sympathetic trunk, to the intervals between the adjacent transverse processes, and are then continued into the abdominal wall.
* The arteries of the right side pass behind the inferior vena cava, and the upper two on each side run behind the corresponding crus of the diaphragm.
* The arteries of both sides pass beneath the tendinous arches which give origin to the psoas major, and are then continued behind this muscle and the lumbar plexus.
* They cross the quadratus lumborum, the upper three arteries running behind, the last usually in front of the muscle.
* At the lateral border of the quadratus lumborum they pierce the posterior aponeurosis of the transversus abdominis and are carried forward between this muscle and the internal oblique.
* They anastomose with the lower intercostal, the subcostal, the iliolumbar, the deep iliac circumflex, and the inferior epigastric arteries.

The **inferior phrenic arteries** (**IPA**) are the first branches of the abdominal aorta. These are paired branches of the abdominal aorta/coeliac trunk supplying the diaphragm. Its importance lies in that the right IPA is the most common extrahepatic arterial supply of hepatocellular carcinoma.

* **origin:** abdominal aorta or coeliac trunk at the level of T12-L2
* **course:** superiorly in retroperitoneal fat in close relation to the diaphragmatic crura. The left artery pass behind the oesophagus and the right behind the IVC.
* **branches:** anterior, posterior, superior, and middle suprarenal branches
* **supply:** diaphragm, inferior vena cava, oesophagus, liver (segments II, III, VII - bare area)

#### Variant anatomy

* may arise from renal arteries, left gastric artery, hepatic artery, superior mesenteric artery or spermatic artery.
Mandible:Condyle, neck, ramus & body

Condylar Process

* thicker than the coronoid process. It is convex anteroposteriorly and side to side, and extends farther on the posterior than on the anterior surface
* consists of two portions - condyle and neck
* condylar neck is flattened from front to back; lateral pterygoid muscle inserts into it on the pterygoid fovea. Posteriorly the TMJ joint capsule is attached. The auriculoptemporal nerve and maxillary artery and vein cross the medial aspect of the neck, lying between it and the sphenomandibular ligament.
* The condyle is marked convex and projects beyond the neck with articular surface for articulation with the articular disk of the temporomandibular joint (TMJ)
Ligaments:Knee joint:Patellar retinacula

**Medial Retinaculum Complex**

* Medial stabilizer of patellofemoral joint
* Extends from patella to vastus medialis
* Medial retinacular complex divided into superior, mid, and inferior portions, which blend into one another
	+ Superior:
		- VMO: Muscular slip of vastus medialis; arises either from adductor magnus tendon or from adductor tubercle
		- Medial patellofemoral ligament: arises from adductor tubercle adjacent to MCL origin and inserts at medial border of patella
	+ Mid portion: Thin fibers of superficial MCL fascia
	+ Inferior
		- Patellotibial ligament arises from tibia at level of insertion of gracilis and semitendinosus
		- Patellotibial ligament inserts on inferior aspect patella and patellar tendon
		- Medial patellomeniscal ligament lies deep to patellotibial ligament

**Lateral Retinaculum**

* Lateral stabilizer of patellofemoral joint
* Extends from patella to vastus lateralis
* 3 layers
	+ I (superficial): Iliotibial tract and its anterior expansion, supplemented posteriorly by superficial portion of biceps femoris and its anterior expansion
	+ II (mid): Retinaculum of quadriceps (vastus lateralis)
	+ III (deep): Lateral part of joint capsule
Cerebral sulci:Calcarine sulcus

The **calcarine sulcus** (or **calcarine fissure**) is an anatomical landmark located at the caudal end of the medial surface of the brain.

The calcarine sulcus begins near the occipital pole in two converging rami and runs forward toward the splenium of the corpus callosum, where it is joined at an acute angle by the medial part of the parieto-occipital sulcus. The anterior part of this sulcus gives rise to the prominence of the calcar avis in the posterior cornu of the lateral ventricle.

Function

The calcarine sulcus is where the primary visual cortex (V1) is concentrated. The central visual field is located in the posterior portion of the calcarine sulcus and the peripheral visual field in the anterior portion.
3. Ventricular system

The **ventricular system** in the brain is composed of CSF-filled ventricles and their connecting foraminae. They are continuous with the central spinal canal.

* two lateral ventricles
* third ventricle
* fourth ventricle

The interconnections between the ventricles occurs through the following:

* interventricular foramen (of Monro): lateral to third
* cerebral aqueduct (of Sylvius): third to fourth
* median aperture (of Magendie): fourth to cisterna magna
* two lateral apertures (of Luschka): fourth to the cerebellopontine angle

Both the cisterna magna and the cistern of the great cerebral vein are in the subarachnoid space. This space is continuous with the subarachnoid space around the cord down to the level of the cauda equina.
Cranial nerve systems:Accessory nucleus & n.

Accessory nerve is a motor cranial nerve that supplies the trapezius and SCM.

Origin:

Two distinct nuclear origins

* Bulbar (cranial) motor fibers originate in lower nucleus ambiguus
* Spinal motor fibers originate from spinal nucleus of accessory nerve which is a narrow column of cells along lateral aspect of anterior horn from C1 to C5

Intra-Axial Segment

* Bulbar fibers course anterolaterally to exit lateral medulla in postolivary sulcus inferior to CN9 & 10
* Spinal nerve fibers emerge from lateral aspect of cervical spinal cord between anterior & posterior roots. Fibers combine forming a bundle that ascends entering skull base via foramen magnum

Cisternal Segment

* Bulbar portion travels anterolaterally through basal cistern together with CN9 & 10
* Bulbar & spinal portions join together within lateral basal cistern

Skull Base Segment

* Passes through posterior pars vascularis portion of jugular foramen
	+ Vagus nerve (CN10) & jugular bulb are also in pars vascularis

Extracranial Segment

* Combined CN11 exits jugular foramen into carotid space
* Fibers from bulbar portion which arose within nucleus ambiguus transfer to vagus nerve
	+ Travels via CN10 to supply muscles of pharynx & larynx
		- Larynx: Except cricothyroid muscle via recurrent laryngeal nerve
		- Pharynx: Superior constrictor & soft palate via pharyngeal plexus
* Fibers from spinal portion remain in extracranial CN11
	+ Diverges posterolaterally from carotid space
	+ Runs back and descends obliquely behind diagastric and stylohyoid muscle
	+ Descend along medial aspect of sternocleidomastoid muscle
	+ Innervates sternomastoid muscle
	+ Continues across floor of posterior cervical space in cervical neck
	+ Terminate in & innervate trapezius muscle
Arterial:Femoral:Popliteal

The **popliteal artery** represents the direct continuation of the superficial femoral artery in the popliteal fossa as the vessel courses posteriorly behind the knee.

#### Summary

* **origin:** continuation of the superficial femoral artery
* **main branch:** anterior tibial artery
* **termination:** continues as the tibioperoneal trunk
* **supply:** knee, lower leg and foot

#### Variant anatomy

Variants in popliteal branching pattern 1, 2:

* ~90% of the population displays the typical branching pattern of bifurcation into anterior tibial artery and tibioperoneal trunk
* ~10% have variant branching pattern:
	+ hypoplastic infrapopliteal vessels ~4% (range 1.0-6.8%)
	+ high origin of anterior tibial artery ~2.5% (range 0.5-4.5%)
	+ trifurcation (no tibioperoneal trunk) ~2% (range 1.5-3.2%)
	+ high origin posterior tibial artery ~1%
7. Carotid sheath

**The carotid sheath**

The carotid sheath is a deep fascia layer that extends from the base of the skull to the arch of the aorta.

Relations

* Superiorly it is attached to the margin of the carotid canal and the jugular fossa.
* Inferiorly: aortic arch
* Medially the pharynx.
* Laterally the deepest part of the parotid glands separated by the styloid process with its three muscles.
* Anteriorly the temporal fossa.
* Posteriorly the sympathetic cervical trunk on the prevertebral fascia.

Content:

* The internal carotid artery
* Internal jugular vein
* Last four cranial nerves

**Carotid space**:

* Location: Posterior to parapharyngeal space in suprahyoid region; and lateral to visceral space and retropharyngeal space in infrahyoid region.
* Fascia: All 3 layers, deep cervical fascia
* Importance: CN10 & carotid here; squamous cell carcinoma nodes along superficial margin
Larynx:Pyriform recess/sinus/fossa

**Piriform sinus**  is a recess on either sides of the laryngeal orifice. It is bounded medially by the aryepiglottic fold, laterally by the thyroid cartilage and thyrohyoid membrane. The fossae are involved in speech.

Relations:

- Deep to the mucous membrane of the piriform fossa lie the recurrent laryngeal nerve and internal laryngeal nerve, a branch of the superior laryngeal nerve.[1] The internal laryngeal nerve supplies sensation to the area, and it may become damaged if the mucous membrane is inadvertently punctured.

The piriform fossa is a common place for food to become trapped.
Meninges:Middle meningeal artery

The **middle meningeal artery** branches off the first part of the maxillary artery. It passes vertically through the roots of the auricotemporal nerve and enters the middle cranial fossa via the foramen spinosum. Here it gives off two branches - superior tympanic branch and ganglionic branch - before dividing into anterior and posterior divisions.

**Anterior division of the middle meningeal artery:** runs anterolaterally through the middle cranial fossa on the greater wing of sphenoid before coursing superiorly, often grooving the bone, and passes under the pterion before giving its terminal branches over the upper parietal bone.

**Posterior division of the middle meningeal artery:** runs horizontally posteriorly over the squamous part of the temporal bone to gives its terminal branches over the lower parietal bone.
Meninges:Arachnoid mater (in general)

The **arachnoid mater** forms the middle layer of the meninges and together with the pia mater is sometimes referred to as the **leptomeninges**.

* thin impermeable membrane comes into direct contact with the dura mater but easily separated
* separated from the pia mater by a CSF filled space known as the subarachnoid space.

Extent:

* continuous with the spinal arachnoid mater through the foramen magnum.
* extends to the superior surface of the pituitary fossa but does not envelop the pituitary gland.
* exits the cranium as part of the optic nerve-sheath complex
* Arachnoid villi/granulations: endothelial-lined extensions of arachnoid and SAS into dural sinus that return CSF to the blood.

It does not enter the sulci or fissures except at the great longitudinal fissure between the cerebral hemispheres.

Subarachnoid Space

* CSF-filled space contained between arachnoid (outer wall), pia (inner wall)
* Contains traversing arteries, veins
* Numerous sheet-like filiform trabeculae extend across SAS from arachnoid to pia, forming bridging chordae coated by leptomeningeal cells that are continuous with pia, inner arachnoid

**Arachnoid cisterns:** spaces between the base of the brain and the base of the skull due incongruent contours between the two.

* cisterna magna: largest, occupies the angle between the undersurface of the cerebellum and the posterior surface of the medulla.
* pontine cistern
* interpeduncular cistern: lie between the dorsum sellae of the sphenoid and the cerebral peduncles., roofed by the third ventricle.
Natsuki Hanae

**Natsuki Hanae** es el Seiyū de *Kratz* nacido el 26 de junio de 1991 en la Prefectura de Kanagawa, Japón.

## Trivia

* Natsuki Hanae es conocido por Inaho Kaiduka en Aldnoah.Zero, Kousei Arima en Shigatsu wa Kimi no Uso, Ken Kaneki en Tokyo Ghoul, Hikari Sakishima en Nagi no Asukara, y Kimi Haimura en Dansai Bunri no Crime Edge.
Ligaments:Hip:Inguinal ligament

The **inguinal ligament** (or **Poupart's ligament**) is a fibrous band extending from the anterior superior iliac spine to the pubic tubercule. It is an important anatomical landmark and denotes the transition of the pelvis to the lower limb.

Gross anatomy

The inguinal ligament is formed by the lower border of the aponeurosis of the external oblique muscle, which is thickened and folded on itself. Its lateral half runs obliquely, while the medial half is almost horizontal.

Attachments

The inguinal ligament arises from the anterior iliac spine and attaches to the pubic tubercle although there are some fibres which attach elsewhere as extensions or reflections of the inguinal ligament:

* some fibres pass posteriorly to attach to lateral part of pubic tubercle forming the **lacunar ligament** (**of Gimbernat**)
* fibres that run with the lacunar ligament continue to pass more laterally to attach to the pecten pubis forming **pectineal ligament** (**of Cooper**)
* superior fibres run past the pubic tubercle to fuse with those of the contralateral external oblique aponeurosis forming the **reflected inguinal ligament**

The upper surface of the ligament gives origin to the cremaster muscle from its medial part, internal oblique muscle from the  lateral two-thirds and transversus abdominis muscle from its lateral one-third.

The ligament is continuous with the fascia lata of the thigh and the upper grooved surface forms the floor of the inguinal canal.

Relations

The **subinguinal space** is formed deep to the inguinal ligament and contains a number a structures as they pass from the pelvis to the lower limb:

* deep circumflex iliac artery (laterally)
* iliopsoas muscle
* femoral nerve
* femoral artery and vein
* lymphatic channels draining inguinal lymph nodes
Cranial nerve systems:Abducens nucleus & n.

CN6 is a pure motor nerve which supplies the lateral rectus.

Origin:

Abducens nucleus

* Paired CN6 nuclei located in pontine tegmentum near midline
	+ Found just anterior to fourth ventricle in the lower pons

Intra-Axial Segment

* Abducens nerve axons course anteroinferiorly through pontine tegmentum
* Emerges from anterior brainstem near midline through groove between pons and pyramid of medulla oblongata (bulbopontine sulcus)

Cisternal Segment

* CN6 ascends anterosuperiorly in prepontine cistern and penetrates the dura to enter to Dorello canal.
* It is either posterior or anterior to anterior inferior cerebellar artery

Interdural Segment

* Abducen nerve passes over the clivus, arching forward over the the ridge of the petrous temporal bone in the Dorello canal, following the basilar plexus. It then pierces inner (cerebral) layer dura mater to its entrance into cavernous sinus.

Cavernous Segment

* CN6 courses anteriorly within cavernous sinus
	+ Abducens nerve is only cranial nerve to lie within cavernous sinus
	+ Cranial nerves 3, 4, V1 and V2 are all embedded within lateral wall of cavernous sinus
* Within cavernous sinus CN6 runs along inferolateral aspect of cavernous internal carotid artery

Extracranial (Intra-Orbital) Segment

* CN6 enters orbit through superior orbital fissure together with CN3 and CN4
* Passes through annulus of Zinn
* Supplies motor innervation to lateral rectus muscle
Bone: Tibia and Fibula: Epiphyses (sites, dates of appearance)

**Tibia**

The tibia is ossified from three centers; one for the body and one for either extremity. Ossification begins in the center of the body, about the seventh week of fetal life, and gradually extends toward the extremities.

The center for the upper epiphysis appears before or shortly after birth at close to 34 weeks gestation; it is flattened in form, and has a thin tongue-shaped process in front, which forms the tuberosity; that for the lower epiphysis appears in the second year.

The lower epiphysis fuses with the tibial shaft at about the eighteenth, and the upper one fuses about the twentieth year.

Two additional centers occasionally exist, one for the tongue-shaped process of the upper epiphysis, which forms the tuberosity, and one for the medial malleolus.

**Fibula**

The fibula is ossified from *three* centers, one for the shaft, and one for either end. Ossification begins in the body about the eighth week of fetal life, and extends toward the extremities. At birth the ends are cartilaginous.

Ossification commences in the lower end in the second year, and in the upper about the fourth year. The lower epiphysis, the first to ossify, unites with the body about the twentieth year; the upper epiphysis joins about the twenty-fifth year.
Abdomen:Arterial:Inferior and superior epigastric arteries

The **superior epigastric artery** is one of two terminal branches of the internal thoracic artery with the other being the musculophrenic artery.

The superior epigastric artery originates at the level of the sixth or seventh costal cartilage. It descends to the anterior abdominal wall, crossing the diaphragm in the interval between the sternal and the costal parts of the muscle. Here it lies anterior to the transverse abdominis muscle and perforates the rectus abdominis muscle.

The superior epigastric artery anastomoses with the inferior epigastric artery, which is a branch of the external iliac artery, providing an important alternate blood supply if the aorta becomes occluded..

Branches

Branches of the superior epigastric artery perforate the rectus sheath and supply the skin of the abdomen