recursal/Fanatic-Fandom huggingface dataset:
Extra ocular muscles

**Extra-ocular muscles**

**Introduction**

6 muscles which work in concert to direct gaze.

**Gross**
anatomy

Thin sheets of muscle attaching between the orbit
then piercing through Tenon’s capsule to insert onto the eye usually on the coronal
equator of the eyeball. 4 rectus muscles and 2 oblique muscles.

**Attachments**

Rectus muscles – superior, inferior, medial and
lateral. All attach to a fibrous ring in the apex of the orbit (superior and
medial also arise from dural sheath of optic nerve) then diverge as they run
forward at insert into the eyeball at four points as indicated by their names. Produce
elevation, depression, medial and lateral deviation respectively.

Superior oblique – Attaches at apex of orbit
(sphenoid), then runs medially to a hook (troclea) at the superomedial part of
the orbit, then turns through an acute angle to insert onto the eye. Produces inwards
rotation and elevation/medial deviation.

Inferior oblique – Attaches to the anteromedial
part of the orbit (maxilla) and passes laterally to the inferolateral part of
the eye posterior to the coronal equator. Produces outwards rotation.

**Blood supply**

Branches of ophthalmic artery – either directly or
via ciliary arteries (2 each except lateral rectus)

Superior and inferior ophthalmic arteries –
superior and inferior parts of the orbit respectively. Superior passes through
superior orbital fissure to drain into cavernous sinus. Inferior passes through
superior or inferior orbital fissure and may join pterygoid plexus before
draining into the cavernous sinus or drain directly into the superior ophthalmic
vein.

**Nerve supply**

Oculomotor nerve (all except lateral rectus [abducens]
and superior oblique [troclea])

**Lymphatic**
drainage

Contentious. May drain via facial lymphatics:
eyelid pre- and post-tarsal plexusesto medial and lateral groups. Medial – sup/deep
submandibular nodes and lateral to sup/deep parotid and preauricicular then all
to sup/deep cervical then to either R internal jugular or to thoracic duct.

**Variant**
anatomy

Varying
number of ciliary arteries

Infraorbital
artery may supply inferior rectus and inferior oblique
Intracranial cavity (extra axial): Middle cranial fossa:Superior orbital fissure

The **superior orbital fissure** is the communication between the cavernous sinus and the apex of the orbit. It is straddled by the tendinous ring which is the common origin of the four rectus muscles (extraocular muscles).

Through the fissure (from superior to inferior) pass:

1. lacrimal nerve (a branch of the ophthalmic nerve)
2. frontal nerve (a branch of the ophthalmic nerve)
3. superior ophthalmic vein
4. trochlear nerve (CN IV)
5. superior division of the oculomotor nerve (CN III)
6. nasociliary nerve (a branch of the ophthalmic nerve)
7. inferior division of the oculomotor nerve (CN III)
8. abducens nerve (CN VI)

"Lazy French Tarts Sit Nakedly In Anticipation"
Cranial vault: Bones:Frontal

The frontal bone is a skull bone that contributes to the cranial vault. It contributes to form part of the anterior cranial fossa.

The frontal bone has two portions

* vertical portion (squama): has external/internal surfaces
* horizontal portion (orbital): has superior/inferior surfaces

External surface of the vertical portion features:

* frontal/metopic suture
* frontal eminence (tuber frontale)
* superciliary arches which join to form the glabella
* supraorbital margin
* supraorbital notch/foramen containing supraorbital vessels / nerve
* zygomatic process laterally
* upper and lower temporal lines run backwards and are the sites of attachment for the temporalis fascia and temporalis muscle, respectively
* nasal part features the nasal notch, nasion (middle of frontonasal suture), and nasal process (sharp spine, forms part of nasal septum)

Internal surface of the vertical portion features:

* sagittal sulcus: vertical groove which lodges superior sagittal sinus
* frontal crest: ridge, formed from edges of sulcus that gives attachment to the superior sagittal sulcus
* foramen caecum: small notch, converted into foramen, emissary vein from nose
* groove for anterior meningeal artery (branch of anterior ethmoidal artery)

The horizontal portion is composed of two thin, orbital plates separated by the ethmoidal notch.

Internal surface of the horizontal portion is smooth and concave. It features:

* lacrimal fossa; lateral shallow depression for lacrimal gland
* fovea trochlearis / trochlear spine near nasal part, for attachment of cartilaginous pulley for superior oblique muscle

Superior surface of the horizontal portion is convex and contains depressions for convolutions. It features:

* frontal sinuses, frontonasal duct empties into middle meatus
* anterior and posterior ethmoidal canals

##### Articulations

The frontal bone articulates with twelve bones. Unpaired (1) bones include: ethmoid and sphenoid. Paired bones (2) include: nasals, maxillae, lacrimals, parietals, and zygomatic bones.

#### Variant anatomy

* persistent metopic suture
* hypoplasia/aplasia of the frontal sinus(es)
Ligament:Coracoclavicular ligament

The **coracoclavicular ligament**, fan-shaped, is the major stabilising factor of the acromioclavicular joint.

The coracoclavicular ligament can be divided into two parts, the more medial conoid ligament and trapezoid ligament.

* **conoid ligament**
	+ origin: knuckle of the coracoid process of the scapula
	+ runs upward, forming an inverted cone as it widely attaches to the undersurface of the clavicle (around the conoid tubercle)
* **trapezoid ligament**
	+ origin: trapezoid ridge on the coracoid process of the scapula
	+ runs laterally and horizontally, attaching to the underside of the clavicle (to the similarly named, trapezoid ridge)
Arterial:Femoral:Dorsalis pedis

**Arterial supply to the foot**can be divided into plantar and dorsal components.

Plantar arterial supply

**Medial plantar artery**

* *origin:* branch off the posterior tibial artery
* smaller calibre vessel
* *course:* supplies the medial side of the foot, passing between abductor hallucis and flexor digitorum brevis.
* *supply:* provides the arterial digital supply to the big toe
	+ gives off cutaneous branches that perforate the plantar aponeurosis between abductor hallucis and flexor digitorum brevis

**Lateral plantar artery**

* *origin:* branch off the posterior tibial artery
* larger calibre vessel
* *course:* crosses the sole obliquely towards the base of the fifth metatarsal bone between FDB and abductor digiti minimi. Continues as a deep trunk to form the plantar arch
	+ gives off cutaneous branches that perforate the plantar aponeurosis
	+ gives off a superficial branch that follows its respective nerve

**Plantar arch**

* anastomosis of the lateral plantar artery and dorsalis pedis artery
* only arterial plantar arch in the foot
* Course:
	+ lies in the neurovascular plane between the first and second anatomical layers
	+ travels across the bases of the fourth, third, and second metatarsals
	+ joins the dorsalis pedis artery in the proximal part of the first intermetatarsal space

**Plantar metatarsal arteries**

* there are four metatarsal arteries
* branch off the plantar arch
* supply the four clefts and digits
* anastomose with the dorsal metatarsal arteries via perforating arteries

Dorsal arterial supply

**Dorsalis pedis artery**

* continuation of the anterior tibial artery
* Course:
	+ starts between the malleoli, over the lower end of the tibia
	+ runs lateral to extensor hallucis longus
	+ runs to the base of the first intermetatarsal space, where its deep branch joins the plantar arch
* Branches
	+ medial tarsal artery
	+ lateral tarsal artery (which supply the tarsal bones)
	+ arcuate artery more distally (gives off 3 lateralmost dorsal metatarsal arteries)
	+ Lateral and arcuate artery passes over the tarsal and metatarsal bones and converge
* continues as the first dorsal metatarsal artery

**Dorsal metatarsal artery**

* 1st artery is the continuation of the dorsalis pedis artery and supplies the first cleft and the medial side of the dorsum of the great toe

* lateral three metatarsal arteries branches off the arcuate artery
	+ travel in the lateral three interdigital spaces
	+ give off a proximal and distal perforating branches that communicate with the plantar metatarsal arteries of the plantar arch
	+ continues into the toes as dorsal digital arteries
Bone:Carpal bones:Articular surfaces

Scaphoid: boat shaped bone and forms the radial portion of the carpal tunnel.  It is important for stability and movement at the wrist and may be fractured after a fall onto a hyper-extended hand. Scaphoid fracture may be radiologically occult in the acute setting and may result in avascular necrosis

Lunate: semilunar bone. Convex proximal facet for the radius. It articulates with the scaphoid, capitate and triquetrum. Most commonly dislocated and displaced anteriorly. This can cause compression of the median nerve in the carpel tunnel.

Triquetral: oval surface on palmar surface for the pisiform. Proximally it is smooth for the articulation with the capsule and disc of the wrist joint. Distally the triquentral articulates with the hamate and lunate.

Pisiform: flat surface for articulation with the triquentrium

Trapezium: articulates with the trapezoid and scaphoid. Distally it has a saddle shaped articular surface for the thumb metacarpal.

Trapezoid: wedged between the trapezium and capitates. Articulates with the scaphoid and index finger metacarpal.

Capitate: largest carpal bone, lies between the hamate, trapezoid and scaphoid. Articulates with the base of the middle and tiny part of ring finger.

Hamate: wedge shaped. Proximally the edge articulates with the lunate. The base articulates with the fourth and fifth metacarpals.
Bone:Radius and ulna:Epiphyses (sites, dates of appearance/fusion)

RADIUS

The radius ossifies from three centres.

* Shaft - 8th week
* upper epiphysis 15 years
* lower epiphysis at 20 years.

A fourth centrer sometimes appears in the tuberosity in the 14/15th year.

ULNA

The ulna ossifies from four main centres.

* Shaft - 8th week
* Distal end - 5-6 years
* proximal trochlea 9-10 years
* proximal/distal epiphysis 14-16 years and 17/18 respectively.
Intracranial cavity (extra axial): Posterior cranial fossa:Occipital bone

The**occipital bone** is a trapezoid skull bone that contributes to the posteroinferior part of the cranial vault. It is pierced by the foramen magnum, permitting communication from the cranial cavity to the vertebral canal

The occipital bone is composed of four parts:

* squamous part: external/internal surfaces
* basilar part (basiocciput): lower/upper surfaces
* lateral (jugular) parts (two): under/upper surfaces

SQUAMOUS PART: curved, expanded plate located behind the foramen magnum.

The external surface of the squamous part features:

* external occipital protuberance
* highest nuchal line
* superior nuchal line: occipitalis, trapezius, sternocleidomastoid, splenius capitis
* inferior nuchal line: rectus capitis posterior major and minor
* median nuchal line: attachment of ligamentum nuchae
* attachment of posterior atlanto-occipital membrane

The internal surface of the squamous part features:

* cruciate eminence divide region into four fossa; the upper two contain the occipital lobes while the lower two contain the cerebellar hemispheres
* internal occipital tuberosity at intersection
* sagittal sulcus for superior sagittal sulcus, falx cerebri attaches to margins
* internal occipital crest gives attachment to falx cerebelli
* transverse grooves hold transverse sinuses

BASILAR PART: quadrilateral piece in front of the foramen magnum.

The lower surface of the basilar part features:

* pharyngeal tubercle: attachment to fibrous raphe of pharynx
* either side of middle line: longus capitis, and rectus capitis anterior
* anterior atlanto-occipital membrane

The upper surface of the basilar part features:

* clivus has a broad, shallow groove, for medulla oblongata
* lateral grooves for the inferior petrosal sinus

JUGULAR PART:

* occipital condyles: articulate with atlas, egg shaped, permitting nodding and lateral flexion, but not rotation
* hypoglossal canal: at base of occipital condyles
* condylar fossa: behind condyle, receives posterior margin of superior facet of atlas, can be perforated by condyloid canal which contains an emissary vein from the transverse sinus
* jugular process, excavated in front by jugular notch, forming posterior part ofjugular foramen

The upper surface of the lateral part features

* jugular tubercle: overlies hypoglossal canal, sometimes crossed by oblique groove for CN 9, 10, 11

Articulations

The occipital bone articulates with 6 bones. Unpaired (one) bones include the sphenoid and atlas. Paired (two) bones include the parietals (lambdoid suture) and temporal (mastoid/petrous parts) bones.
Arterial supply to brain:Anterior communicating artery (AComA)

The **anterior communicating artery (ACOM)** arises from the anterior cerebral artery and acts as an anastomosis between the left and right anterior cerebral circulation. It is about 4mm in length and demarcates the junction between the A1 and A2 segments of the anterior cerebral artery.

Branches: Additionally, it gives off numerous small branches which go on to supply:

* cingulate gyrus
* anterior columns of the fornix
* optic chiasm
* lamina terminalis
* hypothalamus
* para-olfactory areas

Normal variants

* ACOM duplication - incidence 18%
* ACOM fenestration - incidence ~15%
* ACA trifurcation arising from the ACOM - incidence ~7.5%
* absent ACOM - incidence 5% (surgical dissection)
Abdomen:Muscles:Rectus abdominis and fascias

The **rectus abdominis** muscle is strap-like in appearance and forms part of the anterior abdominal wall and is enclosed by the rectus sheath. It has two heads. The muscle supports abdominal viscera, compression of the abdomen, trunk movement. There are three tendinous intersection in the muscle that divide the muscle into segments, which are often incomplete posteriorly. It is divided into two halves by the **linea alba.**

* The linea alba is a strong midline fibrous structure, from the xiphoid process above to the pubic symphysis. It is formed by the interlacing fibres of aponeuroses of the oblique and transverse abdominal muscles. Umbilicus is a defect in the linea alba where the fetal vessels pass.

Origin: medial head from the pubic symphysis and lateral head from the pubic crest.

Insertion: xiphisternum and 5th-to-7th costal cartilages

Blood supply

* **Intercostal artery:** lower six
* **Superior epigastric artery:** terminal branch of internal thoracic
* **Inferior epigastric artery:** lie on the posterior surface of the rectus muscle
* Venous drainage if by veins of similar names.

Lymph drainage

* Region above umbilicus drain to pectoral group
* Region below umbilcius drain to superficial inguinal nodes

Nerve supply

* **Intercostal nerves T7-T12:** pass from intercostal spaces into the abdominal wall between internal oblique and transversus muscles and run in this neurvascular plane to enter the sheath by piercing the posterior layer of the internal oblique aponeurosis, into the rectus muscle. It then becomes anterior cutaneous nerves.

The **pyramidalis** muscle arise from the body of the pubic and the symphysis between rectus abdominis and its sheath. It converges with its fellow into the linea alba.

The **rectus sheath** encloses the rectus abdominis and pyramidalis muscles. It is composed of the aponeurosis of the internal oblique splitting anteriorly and posteriorly at the sides of the rectus muscle (termed semilunar line) The external oblique aponeurosis fuses with the anterior layer to form the anterior layer of the sheath. The transversus aponeurosis fuses with posterior layer to form the posterior layer of the sheath.

Only the middle segment of the rectus abdominis is completely enclosed, with the posterior sheath lacking in parts of the superior and inferior segments:

* superior to the costal margin the internal and transverse aponeuroses are deficient because they either do not extend beyond . Only external oblique aponeurosis exist.
* inferiorly to the arcuate line, all three muscle layer aponeurosis pass in front of the rectus muscle.

Content:

* rectus and pyramidalis
* lower six thoracic nerve
* posterior intercostal vessels
* superior and inferior epigastric vessel
Bone:Radius and ulna:Joint capsular attachments

ULNA

Proximal end:
The anterior border of the elbow joint capsule attaches to the proximal olecranon surface. The capsule and tendon of the triceps is attaches to the posterior surface. These may be separated by a bursa.
The posterior and oblique bands of the ulnar collateral ligament attaches to the medial surface of the olecranon
The annular ligament is attached to the anterior rim of the radial notch and the posterior margin of the notch.
Key gyri:Hippocampus & components

## **Hippocampus**

* Curved structure on medial aspect of temporal lobe.
* Location: lies in the huppocampal sulcus, immediately below the floor of the temporal horn of the lateral ventricles.
* Consists of two interlocking "U-shaped" gray matter structures
	+ Hippocampus proper (Ammon horn) forms more superolateral, upside-down U
	+ Dentate gyrus forms inferomedial U
* Has three anatomic subdivisions
	+ Head (pes hippocampus): Most anterior part, oriented transversely; has 3-4 digitations on superior surface. Posterior to amydala.
	+ Body: Cylindrical, oriented parasagittally
	+ Tail: Most posterior portion; narrows then curves around splenium to form indusium griseum above corpus callosum (CC)

**Ammon horn (hippocampus proper)**

* Subdivided into four zones (based on histology of main cell layers)
	+ CA1 (Sommer sector): Small pyramidal cells (most vulnerable; commonly affected by anoxia, mesial temporal sclerosis)
	+ CA2: Narrow, dense band of large pyramidal cells ("resistant sector")
	+ CA3: Wide loose band of large pyramidal cells
	+ CA4 (end-folium): Loosely structured inner zone, enveloped by dentate gyrus
* Blends laterally into subiculum
	+ Subiculum forms transition to neocortex of parahippocampal gyrus (entorhinal cortex)
* Covered by layer of efferent fibers, the alveus
	+ Alveus borders temporal horn of lateral ventricle ventricle
	+ Forms fimbria from crus of fornix
Key conditions formatting

**Definition**

**Clinical presentation**

**Pathology**

 ***\* Where it occurs***

 ***\* Complications***

 ***\* Epidemiology***

 ***\* Differential diagnosis***

**Radiology**

 ***\* Modality/Technique***

 ***\* Associated conditions***

 ***\* Features***

 ***\* Artefacts***

 ***\* Pitfalls***

 ***\* Clinical Impacts***

 ***\* Sensitivity/specificity***

**Management plan & communications**

**Relevant anatomy**

**Further reading**
Ligament:Shoulder:Coracohumeral ligament

The **coracohumeral ligament** (**CHL**) is a strong supportive ligament of the shoulder joint. It reinforces the rotator interval.

* originates from the coracoid process base (lateral surface)
* runs laterally across the glenohumeral capsule
* attaches to the margin of the greater and lesser tuberosities of the humerus, and along the transverse ligament bridging the bicipital groove
Femoral

The **arterial supply of the lower limbs** is via vessels arising from the external iliac artery.

The common femoral artery (CFA) is the direct continuation of the external iliac artery. It begins at the level of the inguinal ligament. It terminates as it gives off the profunda femoris and continues as the superficial femoral artery (SFA).

Branches of CFA:

* superficial epigastric artery
* superficial circumflex iliac artery
* superficial external pudendal artery
* deep external pudendal artery

SFA provides dominant in-line arterial supply in thigh

* Courses through the femoral triangle beneath sartorius, anterior to femoral vein
* Exits adductor canal at adductor hiatus, becomes popliteal artery
* Multiple muscular branches; supreme geniculate (medial) branch is largest

The popliteal artery is the direct continuation of the SFA in the adductor canal. The popliteal artery terminates into the anterior tibial artery and the tibioperoneal trunk.

The anterior tibial artery passes through the interosseous membrane to reach the anterior compartment of the leg. It continues to the dorsum of the foot as the dorsalis pedis artery.

The tibioperoneal trunk divides into the posterior tibial and peroneal arteries. The posterior tibial artery passes downwards and behind the medial malleolus. It divides into medial and lateral plantar arteries.

Normal variant

* CFA trifurcate into SFA, profunda femoris and LCFA
* CFA arise from internal iliac artery
* Femoral artery give off Medial and lateral circumflex artery
* 10% high bifurcation of CFA at femoral head
* Double SFA
Abdomen:Radiological spaces:Anterior pararenal spaces

The **anterior pararenal space** is the portion of the retroperitoneum that lies between the posterior surface of the parietal peritoneum and the anterior reflection of the perirenal fascia. It contains the duodenum, pancreas and retroperitoneal segments of the ascending and descending colon. It also contains the roots of the small bowel mesentery and transverse mesocolon.

Medially, the space is in continuity with the opposite side. There is a paucity of fat within the compartment and therefore, is it difficult to identify on CT or MRI in patients with no additional pathology.

When fluid collects within the anterior pararenal space it becomes easier to identify on CT or MRI. Additionally, because the perirenal fascia is bilaminated, fluid in the compartment can dissect between the anterior and posterior fascia and sit behind the kidney.

Fluid extends throughout the space until it reaches its boundaries:

* **medially**- there is continuity with the other side although in most cases, fluid will lateralize to the side of pathology
* **laterally**-the compartment is limited as the lateroconal fascia and parietal peritoneum merge
* **superiorly**- fluid may extend to the dome of the diaphragm immediately posterior to the oesophagus and phrenicoesophageal ligament
* **inferiorly**- fluid may extend to the iliac fossa, from there into the pelvis and potentially to the rectus sheath, around the round ligament or vas deferens and even into the femoral sheath

Additionally, fluid can dissect along ligaments and mesenteries to lie in the subperitoneal space, e.g. gastrosplenic ligament, transverse mesocolon and greater omentum.
Arterial structures:Pelvis: Superior and inferior gluteal arteries

The **superior gluteal artery** is the largest branch of the internal iliac artery. It is a short artery which runs backward *between the lumbosacral trunk and S1*, and, passing out of the pelvis above the *upper border of the piriformis muscle*, immediately divides into a superficial and a deep branch.

Within the pelvis it gives off a few branches to the iliacus, piriformis, and obturator internus muscles.

Superficial branch

The superficial branch enters the deep surface of the gluteus maximus, and divides into numerous branches, some of which supply the muscle and anastomose with the inferior gluteal artery, while others perforate its tendinous origin, and supply the integument covering the posterior surface of the sacrum, anastomosing with the posterior branches of the lateral sacral arteries.

Deep branch

The deep branch lies under the gluteus medius and almost immediately subdivides into two.

Of these, the superior division, continuing the original course of the vessel, passes along the upper border of the gluteus minimus to the anterior superior spine of the ilium (ASIS), anastomosing with the deep iliac circumflex artery and the ascending branch of the lateral femoral circumflex artery.

The inferior division crosses the gluteus minimus obliquely to the greater trochanter, distributing branches to the gluteal muscles and anastomoses with the lateral femoral circumflex artery.

Some branches pierce the gluteus minimus and supply the hip-joint.

The **inferior gluteal artery** (**sciatic artery**), the smaller of the two terminal branches of the anterior trunk of the internal iliac artery, is distributed chiefly to the buttock and back of the thigh.

It passes down on the sacral plexus of nerves and the piriformis muscle, behind the internal pudendal artery, to the lower part of the greater sciatic foramen, through which it escapes from the pelvis between the piriformis and coccygeus.

It then descends in the interval between the greater trochanter of the femur and tuberosity of the ischium, accompanied by the sciatic and posterior femoral cutaneous nerves, and covered by the gluteus maximus, and is continued down the back of the thigh, supplying the skin.
Arterial structures:Pelvis:Vaginal artery

The **vaginal artery** is an artery in females that supplies blood to the vagina and the base of the bladder and is a branch of the internal iliac artery.

It descends to the vagina, supplying its mucous membrane. It can send branches to the bulb of the vestibule, the fundus of the bladder, and the contiguous part of the rectum.

The vaginal artery is frequently represented by two or three branches.
Arterial:Femoral:Peroneal

**Fibular artery** (also known as the **peroneal artery**) supplies blood to the lateral compartment of the leg. It arises from the tibial-fibular trunk.

It runs runs distally in fibrous canal between FHL and TP, just medial to the fibula. It supplies a perforating branch to both the lateral and anterior compartments of the leg; it also provides a nutrient artery to the fibula. It ends by dividing into perforating branch whch pierces the interosseous membrane to enter the extensor compartment and lateral calcaneal branch.

The fibular artery is accompanied by small veins (venae comitantes) known as fibular veins.

Branches

Communication branch to anterior tibial artery.

Perforating branch to anterior lateral malleolar artery.

A calcaneal branch to the lateral part of the calcaneus.

Nutrient artery to fibula

Supplies

Calf muscles and peroneal muscles
Facial bones:Palatine

The **palatine bone** isa bone of the facial skeleton, forms the hard palate along with the axilla.

Structure

Located between the maxilla and the pterygoid process of the sphenoid bone.

It contributes to the walls of three cavities: the floor and lateral wall of the nasal cavity, the roof of the mouth, and the floor of the orbit; it enters into the formation of two fossae, the pterygopalatine and pterygoid fossae; and one fissure, the inferior orbital fissure.

	+ horizontal plate: articulate with each other at the posterior part of the median palatine suture and forms the posterior portion of the hard palate and nasal floor.
	+ perpendicular plate
* Three processes
	+ the pyramidal process, which is directed backward and lateral from the junction of the two parts, and
	+ the orbital process
	+ sphenoidal process: surmount the vertical part, and are separated by a deep notch, the sphenopalatine notch.

Articulations:

the sphenoid, ethmoid, maxilla, inferior nasal concha, vomer and opposite palatine.

Foramina:

* The larger greater palatine foramen is located in the posterolateral region of each of the palatine bones, usually at the apex of the maxillary third molar. The greater palatine foramen transmits the greater palatine nerve and blood vessels.
* The smaller, the lesser palatine foramen, transmits the lesser palatine nerve and blood vessels to the soft palate and tonsils.
* Sphenopalatine foramen, transmits the sphenopalatine artery
Muscle/Group:Forearm:Extensor compartment deep layer:Supinator

**Supinator**

* Has two heads of origin
* Origin of humeral head: Lateral epicondyle, radial collateral ligament, anular ligament
* Origin of ulnar head: Supinator fossa of ulna (anterior) and supinator crest of ulna (posterior)
* Insertion: Lateral side of proximal radial shaft
* Innervation: Deep branch of radial nerve
* Action: Supinates forearm
Joints:Ankle:Fibrous capsule

The capsule encloses the ankle joint and is lined with synovium.

It attaches to the articular margins of all 3 bones except for anteriorly on the talus where it is fixed in front of the articular margin on the neck of the talus. Posteriorly over the tibia the capsule is attached to the posterior tibiofibular ligament.

The synovial membrane is attached to the articular margin of the talus and clothes the intracapsular part of the talar neck. Elsewhere it attaches to the articular margins and lines the inside of the capsule.
Bone:Clavicle, scapula and humerus:Attachments of ligaments

CLAVICLE

   The **sternal end** articulates with the clavicular notch of the manubrium. Ligament attachments are:

* fibrous capsule joint all around
* articular disc superoposteriorly
* interclavicular ligament superiorly
* The **shaft** forms the base for several attachment of ligaments.
* in its medial two thirds, on the inferior surface, an oval impression allows attachment of costoclavicular ligament
* in its lateral one thirds, on the inferior surface, a ridge trapezoid line and tubercle, the conoid tubercle is attachment for trapezoid and conoid part of the coracoclavicular ligament.

The **acromial end** articulates with the acromion process of the scapula. It gives attachment for the joint capsule.

SCAPULA

The coracoid process

* at the apex gives attachment of the conoid ligament
* proximal to the tip a line gives attachment of the trapezoid ligament
* the lateral margin gives base to coracoacromial ligament
* inferior surface gives corocohumeral ligament

The glenoid cavity

* anterior rim: the superior/middle/inferior glenohumeral ligaments

HUMERUS

* Lateral supracondylar ridge - the lateral intermuscular septum
* Medial supracondylar ridge - medial intermuscular septum
* Lateral epicondyle - radial collateral ligament
* Medial epicondyle - ulnar collateral ligament
Infratemporal fossa:Medial pterygoid

Medial pyteroid is a muscle of mastication with two heads. The action is pulling of the angle of the mandible upwards, forwards and medially (in chewing). The two heads arise from either side of the lateral pterygoid plate, fuses at its edge and pass down and backwards at 45 degrees to the mandible.

Origin: larger deep head arises from the medial surface of the lateral pyteroid plate, and smaller superficial head arises for the tuberosity of the maxilla and pyramidal process of the palatine bone

Insertion: medial aspect of the angle of mandible.

Nerve: medial pterygoid nerve from mandibular nerve
Muscle/Group:Shoulder (Pectoral):Triceps (brachii)

**Triceps muscle, long head**

* Origin: Infraglenoid tubercle of scapula
* Insertion: Proximal olecranon and deep fascia of arm after joining with lateral and medial heads
* Nerve supply: Radial nerve
* Blood supply: Deep brachial artery branches
* Action: Elbow extension, adducts humerus when arm is extended

**Triceps muscle, lateral head**

* Origin: Posterior and lateral humeral shaft, lateral intermuscular septum
* Insertion: Proximal olecranon and deep fascia of arm after joining with long and medial heads
* Nerve supply: Radial nerve
* Blood supply: Deep brachial artery branches
* Action: Elbow extension

**Triceps muscle, medial head**

* Origin: Posterior humeral shaft from teres major insertion to near trochlea, medial intermuscular septum
* Insertion: Proximal olecranon and deep fascia of arm after joining with lateral and long heads
* Nerve supply: Radial & branches of ulnar nerve
* Blood supply: Deep brachial artery branches
* Action: Elbow extension
* Variants, triceps muscle: Fourth head from medial humerus, slip termed the dorso-epitrochlearis extending between triceps and latissimus dorsi
Infratemporal fossa:Lateral pterygoid

Lateral pterygoid is a two-headed muscle of mastication. The two heads converge and fuse into a short thick tendon before insertion into the neck of the mandible. Upper fibers pass back into the capsule and the articular disc of the TMJ. Its action is drawing on the condyle and the disc of the TMJ forward from the mandibular fossa forward into the articular eminence.

Origin: upper head from the roof of the infratemporal fossa, lower head from the lateral surface of the lateral pterygoid plate.

Insertion: pterygoid fovea on the front of the neck of the mandible.

Nerve: lateral pterygoid branch from the anterior division of the mandibular nerve
Larynx:Laryngeal cartilages

Respiratory organ that lies between the pharynx and trachea, and functions for phonation and protection of airway. It lies at C4-C6 vertebrate, below the hyoid bone.

Cartilages are:

* Thyroid cartilage: Largest laryngeal cartilage; "shields" larynx
	+ 2 anterior laminae meet anteriorly at acute angle
	+ Superior thyroid notch at anterior superior aspect
	+ Superior cornua are elongated & narrow; attach to thyrohyoid ligament
	+ Inferior cornua short & thick; articulate with sides of cricoid cartilage (cricothyroid joint)
* Cricoid cartilage: Only complete ring in endolarynx; provides structural integrity
	+ 2 portions: Posterior lamina & anterior arch
	+ "Signet ring" band anterior & "signet" posterior
	+ Lower border of cricoid cartilage is junction between larynx above & trachea below
* Epiglottis
* Arytenoid cartilage: Paired pyramidal cartilages that sit atop posterior cricoid cartilage
	+ Vocal & muscular processes are at level of TVC
	+ Vocal processes: Anterior projections of arytenoids where posterior margins of TVC attach
* Corniculate cartilage: Rests on top of superior process of arytenoid cartilage, within AE folds
* Cuneifrm
Intracranial cavity (extra axial): Posterior cranial fossa:Internal auditory meatus with CN VII & VIII

Internal acoustic meatus is a 1cm long canal running laterally in the petrous temporal bone (lateral to the foramen magnum).

   Contains cranial nerves VII and VIII, and the labyrinthine artery, as they pass towards the inner ear. There is a seperate opening for each structure laterally.

Content:

* Vestibulocochlear nerve (CN8): CPA-IAC cistern
	+ Components
		- Vestibular (balance) & cochlear (hearing) portions
	+ Cochlear nerve portion, CN8 course
		- Leaves spiral ganglion as auditory axons
		- Travels as cochlear nerve in anterior-inferior quadrant of IAC
		- Joins SVN & IVN at porus acusticus to become CN8 bundle in CPA cistern
		- Crosses CPA cistern as posterior nerve bundle to enter brainstem at pontomedullary junction
		- Enters brainstem and bifurcates to synapse with both dorsal & ventral cochlear nuclei
	+ CN7 & CN8 orientation in IAC cistern
		- "Seven-up, coke down" useful pneumonic
		- CN7 anterosuperior; cochlear nerve anteroinferior
		- SVN posterosuperior; IVN posteroinferior in IAC
* Facial nerve (CN7): CPA-IAC cistern
	+ Root exit zone in pontomedullary junction
	+ Travels anterior to CN8 in CPA cistern
	+ Anterosuperior in IAC cistern
* AICA loop
	+ Arises from basilar artery then rises into IAC
	+ Continues in IAC as internal auditory artery (IAA)
	+ May mimic cranial nerve on high-resolution T2
	+ IAA supplies 3 branches to inner ear
* Other structures in internal acoustic meatus cistern
	+ Crista falciformis (horizontal crest): Horizontal bony projection from IAC fundus
	+ Vertical crest (Bill's bar): Vertical bony ridge in superior portion of IAC fundus
	+ Cochlear nerve canal: IAC outlet for cochlear nerve to cochlea
	+ Macula cribrosa: Perforated bone between IAC & vestibule of inner ear
Arterial supply to brain:Posterior cerebral artery (PCA), segments & branches

The **posterior cerebral arteries (PCA)**are the terminal branches of the basilar artery. It curls back around the cerebral peduncle and pass above the tentorium, to supply the occipital lobes and posteromedial temporal lobes.

   The PCA is divided into four segments:

* **P1 (mesencephalic):** from it origin at the termination of the basilar artery to posterior communicating artery (PCOM), within interpeduncular cistern. Perforating branches arise from P1.
* **P2 (ambient):** from the PCOM around the cerebral peduncle above occulomotor, divided into P2A (anterior) and P2P (posterior) sub-segments.  P2A is within crural cistern which then bridges to the P2P segment in ambient cistern (thus ambient segment)
* **P3:** quadrigeminal segment (within the quadrigeminal cistern) extends posteromedially from level of quadrigeminal plate
* **P4:** cortical segment (e.g. calcarine artery, within the calcarine fissure) arise from distal PCA at or just before reaching calcarine fissure

Vascular Territory

* Penetrating branches: Midbrain, thalami, posterior limb of internal capsule, optic tract
* Ventricular/choroidal branches: Choroid plexus of third/lateral ventricles, parts of thalami, posterior commissure, cerebral peduncles
* Splenial branches: Posterior body and splenium of corpus callosum
* Cortical branches: Posterior 1/3 of medial hemisphere surface; most of inferior temporal lobe, most of occipital lobe (including visual cortex)

Branches

* **P1:**
	+ Posterior thalamoperforating arteries: pass posterosuperiorly in interpeduncular fossa and enter undersurface of midbrain
* **P2:**
	+ Thalamogeniculate arteries: pass posteromedially into midbrain
	+ Peduncular perforating arteries: pass directly into cerebral peduncles
	+ *Medial/lateral posterior choroidal branches*: pass around medial geniculate body to reach the posterior part of the inferior horn of the lateral ventricle to supply the choroid plexus
	+ PCOM:
		- anterior thalamoperforator

* **P4:**
	+ Two terminal trunks
		- Lateral: posterior temporal arteries supplies the posterior part of the temporal lobe
		- Medial: medial occipital artery, divide into calcarine artery and parieto-occipital artery, splenial artery

Variant anatomy

* PCA fenestration: rare
* foetal origin of PCA from the PCOM: unilateral incidence 10%, bilateral incidence 8%
* Persistent carotid-basilar anastomoses
	+ PCAs supplied by persistent trigeminal artery or proatlantal intersegmental artery
Muscle/Group:Shoulder (Pectoral):Coracobrachialis

**Coracobrachialis muscle**

* Origin: Coracoid process tip, in common with and medial to short head biceps tendon
* Insertion: Medial surface of humeral mid shaft, between brachialis and triceps muscle origins
* Nerve supply: Musculocutaneous nerve, perforates muscle
* Blood supply: Brachial artery, muscular branches
* Action: Flexes and adducts shoulder, supports humeral head in glenoid
* Variants: Bony head extending to medial epicondyle, short head extending to lesser tuberosity
Cerebral aqueduct

The **cerebral aqueduct (of Sylvius)** is the structure within the brainstem that connects the third ventricle to the fourth. It is located within the midbrain, surrounded by periacqueductal grey matter (PAG) with the tectum of midbrain located posteriorly and the tegmentum anteriorly.

It is filled with CSF and its obstruction leads to obstructive hydrocephalus with dilatation of the lateral and third ventricles only.
Bone:Carpal bones:Ossification

The carpal bones are cartilaginous at birth. The capitates ossifies first at 1 year, the pisiform is the last at 10 years. The other carpel bones ossify according to size.
Capitate: 2nd month
Hamate: 3rd month
Triquetrium: 3rd year
Lunate, scaphoid, trapezium, trapezoid: 4th and 5th years
Pisiform: 9th year
Muscle/Group:Forearm:Flexor compartment superficial layer:Flexor carpi radialis

Flexor carpi radialis is a flexor and radial abductor of the wrist. It passes through the forearm, becomes a long tendon that runs through its own compartment in the carpal tunnel lying on a groove of the trapezium and into the metacarpals. The radial artery lies lateral to the tendon, the median nerve is medial to it.

Origin: common origin

Insertion: the bases of the second and third metacarpals

Nerve: median nerve (C6, C7)
Infratemporal fossa:Pterygopalatine fossa

The **pterygopalatine fossa (PPF)** is a small bony space of the deep face with a shape of an inverted pyramid between the maxillary bone, the pterygoid process and the orbital apex. It is important as a neurovascular crossroad of the nasal cavity, masticator space, orbit, oral cavity and middle crania fossa.

At the anterior end of the medial wall of the infratemporal fossa, the lateral plate is separated from the maxilla by the pterygomaxillary fissure which passes into the pterygoapalatine fossa.

Borders

* **medial**- perpendicular plate palatine bone
* **lateral** - narrowing to pterygomaxillary fissure
* **anterior**- posterior wall of maxillary sinus
* **posterior**- medial and lateral pterygoid plates; inferior aspect of lesser wing of sphenoid bone
* **roof** - inferior orbital fissure and apex of the orbit.
* **floor** - narrowing to palatine canals. The palatine bone articulates with the lateral pterygoid plate.

Communications

* **medially** - communicates with the nasal cavity via the sphenopalatine foramen, which transmits the sphenopalatine artery and the posterior superior nasal nerve
* **laterally**-  infratemporal fossa via the pterygomaxillary fissure
* **anteriorly**- communicates with the orbit via the inferior orbital fissure
* **posteriorly and superiorly** - communicates with the Meckel cave and cavernous sinus (of the middle cranial fossa) via the foramen rotundum
* **posteriorly and inferiorly** - communicates with the middle cranial fossa via the vidian canal, which transmits the Vidian nerve
* **inferiorly** - communicates with the palate via the greater and lesser palatine canals

Contents

* pterygopalatine ganglion
* third part of the maxillary and its branches - sphenopalatine/greater palatine/posterior superior alvolar/pharyngeal/artery of pterygoid canal
* maxillary division of trigeminal nerve (V2) - enters via foramen rotundum
* nerve of the pterygoid canal
Joint:Elbow joint:Articular surfaces

Elbow is a hinge synovial joint between the lower end of humerus and the upper ends of the radius and ulnar.

Articulation surface

- the capitulum (portion of a sphere) that articulates with upper concave surface of head of radius

- the trochlea, grooved surface, and articulates with the trochlea notch of the ulnar (connecting the prominences of coronoid process and olecranon)

Two fossae above the articulation surface. The anterior receives the coronoid process and head of radius in full flexion and posterior receives olecranon in full extension.

Medially, the trochlea is limited by a sharp ridge whereas laterally, the articular surface blends with the capitulum and is continuous. This together with the obliquiity of the ulnar shaft to the trochlea notch contribute to the "carrying angle".
Cranial vault: Bones:Layers of skull

Skull (28 separate bones, mostly connected by fibrous sutures)

* Cranium has several parts
	+ Calvarial vault
	+ Cranial base
	+ Facial skeleton
* Calvarial vault composed of several bones
	+ Frontal bone
	+ Paired parietal bones
	+ Squamous occipital bone
	+ Paired squamous temporal bones
* Three major serrated fibrous joints (sutures) connect bones of vault
	+ Coronal suture
	+ Sagittal suture
	+ Lambdoid suture
* Outer, inner tables
	+ Two thin plates of compact cortical bone
	+ Separated by diploic space (cancellous bone containing marrow)
* Endocranial surface
	+ Lined by outer (periosteal) layer of dura
	+ Grooved by vascular furrows
	+ May have areas of focal thinning (arachnoid granulations), foramina (emissary veins)

Anatomical variance:

* Hyperostosis of frontalis interna - benign overgrowth of frontal bone.
* Accessory sutures- common in parietal and occipital bones, (zigzag pattern merge with adjacent suture, differentiate from fractures).
* Metopic suture – calvarial suture in the midline through the frontal bone from the nasion to the bregma.
* Intrasutural bone - segments of bone, frequently found around lambdoid sutures, should not be more than 10.
* Bathrocephaly (outward bulge of occipiital squamosal)
* Prominent external occipital protuberance
* Accessory fontanelles, i.e.  parietal fontanelles
* Small parietal foramina - foramen situated on the posterior aspect of the parietal bone near the sagittal suture. It transmits the emissary veins draining to superior sagittal sinus and occasionally a branch of the occipital artery
Infratemporal Fossa

The infratemporal fossa is the skeletal space beneath the base of the skull and the side wall of the pharynx and the ramus of the mandible. Should not be confused with parapharyngeal space which is a fascial bounded space.

**Boundaries:**

- medially: lateral pterygoid plate in front, and superior constrictor (pharynx) and tensor palati muscle behind.

- laterally: ramus of the mandible and coronoid process

- anteriorly: posterior surface of the maxilla, ending above as the infra-orbital fissure

- posteriorly: articular eminence of the temporal bone, styloid process and carotid sheath

- roof: greater wing of the sphenoid (with foramen oval and foramen spinosum) and squamous part of the temporal bone in front of the articular eminence

- floor: medial pteryoid attached to the mandible

**Content:**

- muscles: medial and lateral pterygoid

- artery: maxillary artery and its branches (middle meningeal/inferior alveolar/deep temporal/buccal)

- vein: pterygoid venous plexus

- nerve: mandibular nerve (its sensory and motor branches), chorda tympani nerve, superior alveolar branches of the maxillary nerve
Anatomy of the Pelvis

**Anatomy**

Pubic symphysis
Sacrospinous ligament
Superior, middle and inferior rectal arteries
Internal pudendal artery
Uterine artery
Median sacral artery  |  Superior and inferior gluteal arteries
Obturator artery
Vaginal artery  | Umbilical artery
Superior and inferior vesical arteries
Ovarian artery
Lumbosacral trunk
Sciatic nerve
Pudendal nerve
Obturator nerve
Cauda equina  | Superior & inferior gluteal nerves
Hypogastric nerves
Inferior hypogastric plexus
Pelvic splanchnic nerves (parasympathetic)
Rectouterine & rectovesical pouches  | Superficial and deep perineal pouches
Ischioanal fossae
Bladder and urethra (male and female)
Uterus
Uterine tubes & broad ligament
Ovaries
Vagina
Pelvic ureters
Prostate
Ductus deferens and spermatic cord
External genitalia (male and female)
Basal CSF cisterns:Quadrigeminal cistern

The **quadrigeminal cistern** is one of the subarachnoid cisterns.

It is located between the splenium of the corpus callosum and the superior surface of the cerebellum and extends from the third ventricle to the great cerebral vein.

1. The great cerebral vein.
2. The posterior pericallosal arteries.
3. superior cerebellar arteries and branches
4. posterior cerebral arteries and branches
5. Fourth nerve
Arterial structures:Pelvis:Internal pudendal artery

The **internal pudendal artery** is an artery that branches off the internal iliac artery, providing blood to the external genitalia.

Course:

* It exits the pelvic cavity through the greater sciatic foramen, inferior to the piriformis muscle, to enter the gluteal region.
* It then curves around the sacrospinous ligament to enter the perineum through the lesser sciatic foramen.
* It reaches the deep perineal pouch, and travels through the pudendal canal (anteroposteriorly) with the internal pudendal veins and the pudendal nerve.

Branches