46 - Spinal tract Pathways

45 - Lymph nodes of Neck

*The lymph nodes of the neck can be divided into six levels within the defined anatomic triangles. These groups and the areas that they drain are particularly important when locating and working up a "neck mass" or possible malignancy. The groups and drainage areas are as follows:

I--Submental and submandibular nodes
II--Upper jugulodigastric group
III--Middle jugular nodes (draining the nasopharynx and oropharynx, oral cavity, hypopharynx, larynx.
IV--Inferior jugular nodes draining the hypopharynx, subglottic larynx, thyroid, and esophagus.
V-- Posterior triangle group
VI--Anterior compartment group
---------------------------------------------------

*Here are a few questions related to the neck lymph nodes, try answering them :

1q: Lymph nodes metastases from oropharyngeal cancers most commonly occur at ?
a. Level I
b. Level II
c. Level III
d. Level IV
e. Level V

answer b. Level II.(subdigastric nodes)

2q:  Which of the following are the level III lymph nodes of the neck ?
a. Upper jugular chain nodes
b. Middle jugular chain nodes
c. Lower jugular chain nodes
d. Posterior triangle nodes
e. Submental nodes

answer b. Middle jugular chain nodes.

3q: A lymph node that is inferior to the cricoid, superior to the clavicle and deep to the sternocleidomastoid muscle (SCM) in what level ?
a. Level I
b. Level II
c. Level III
d. Level IV

answer d. Level IV.


*These questions have been taken from Page 126 of the Schwartz's principles of surgery (8th ed) - self-assesment and review .

44 - Coronary sinus

*The coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the myocardium of the heart.
*It is present in humans and other animals.
*The coronary sinus opens into the auricle, between the inferior vena cava and the auriculo-ventricular opening.
*It returns the blood from the substance of the heart, and is protected by a semicircular fold of the lining membrane of the auricle, the coronary valve. ( valve of Thebesius).
*The sinus, before entering the auricle, is considerably dilated - nearly to the size of the end of the little finger.
*Its wall is partly muscular, and at its junction with the great coronary vein is somewhat constricted and furnished with a valve consisting of two unequal segments.

*It is located in the right atrium and runs transversely in the groove between the left atrium and ventricle on the posterior surface of the heart.
*The coronary sinus orifice (opening) is just superior to the septal leaflet of the tricuspid valve.
*The coronary sinus orifice is also known as the ostium of the coronary sinus, and is guarded by the Thebesian valve.

*It receives blood mainly from the small, middle, great and oblique cardiac veins.
*It also receives blood from the left marginal vein and the left posterior ventricular vein.
*The anterior cardiac veins drain directly into the right atrium. (Some small veins drain into any of the four chambers of the heart.)
*It drains into the right atrium on the posterior, inferior surface, medial to the inferior vena cava opening.

43 - Adductor canal (Subsartorial/Hunter's canal)

*The adductor canal (Subsartorial/Hunter’s canal) is an aponeurotic tunnel in the middle third of the thigh, extending from the apex of the femoral triangle to the opening in the Adductor magnus, the Adductor hiatus.

*It courses between the anterior compartment of thigh and the medial compartment of thigh, and has the following boundaries:

1. anterolaterally - the Vastus medialis.
2. posterior - the Adductor longus. It is covered in by a strong aponeurosis which extends from the Vastus medialis, across the femoral vessels to the Adductor longus and magnus.

Lying on the aponeurosis is the Sartorius muscle.

*The canal contains the femoral artery, femoral vein, and branches of the femoral nerve (specifically, the saphenous nerve, and the nerve to the Vastus medialis).

*Named after JOHN HUNTER.

42 - Uterine artery

*The uterine artery arises from the anterior trunk of the internal iliac artery(hypogastric artery) .
*Its course is at first downwards and forwards until it reaches the parametrium when it turns medially towards the uterus.
*It reaches the uterus at the level of the internal os, where it turns upwards, at right angles, and follows a spiral course along the lateral border of the uterus to the region of the uterine cornu.
*Here it sends a branch to supply the fallopian tube and ends by anastomosing with the ovarian artery.
*The tortuosity is lost when the uterus enlarges during pregnancy.
*During the vertical part of its course it sends branches which run transversely and pass into the myometrium. These are called the arcuate arteries.
*From these arcuate arteries, a series of radial arteries arise, almost at right angles.
*These radial arteries reach the basal layers of the endometrium, where they are termed as the basal arteries.
*From these are derived the terminal spiral and straight arterioles of the endometrium.
*THE LEAST VASCULAR PART OF THE UTERUS IS THE MIDLINE.

*The branches of the uterine artery are :
1. Ureteric artery
2. Descending vaginal artery- These unite to form the anterior and posterior azygos artery of the vagina. This is of great importance during the Total hysterectomy.
3. Circular cervical
4. Arcuate -- radial -- basal -- spiral and straight arterioles of the functional layer of the endometrium.
5. Anastomotic branch with the ovarian artery

*The relation of the uterine artery to the ureter is of great importance.
*The uterine artery crosses above the ureter in the parametrium where it gives off an important ureteric branch to that structure.
*The artery runs transversely while the ureter runs approximately anteroposteriorly through the ureteric canal of the parametrium.

*The ovarian artery is derived from the AORTA.

41 - Venous sinuses of Brain

40 - Pelvic diaphragm

The pelvic floor or pelvic diaphragm is composed of muscle fibers of the levator ani, the coccygeus(ishciococcygeus), and associated connective tissue which span the area underneath the pelvis. The pelvic diaphragm is a muscular partition formed by the levatores ani and coccygei, with which may be included the parietal pelvic fascia on their upper and lower aspects. The pelvic floor separates the pelvic cavity above from the perineal region (including perineum) below.

The right and left levator ani lie almost horizontally in the floor of the pelvis, separated by a narrow gap that transmits the urethra, vagina, and anal canal. The levator ani is usually considered in three parts: pubococcygeus, puborectalis, and iliococcygeus. The pubococcygeus, the main part of the levator, runs backward from the body of the pubis toward the coccyx and may be damaged during parturition. Some fibers are inserted into the prostate, urethra, and vagina. The right and left puborectalis unite behind the anorectal junction to form a muscular sling . Some regard them as a part of the sphincter ani externus. The iliococcygeus, the most posterior part of the levator ani, is often poorly developed.

The coccygeus(ischiococcygeus), situated behind the levator ani and frequently tendinous as much as muscular, extends from the ischial spine to the lateral margin of the sacrum and coccyx.

The pelvic cavity of the true pelvis has the pelvic floor as its inferior border (and the pelvic brim as its superior border.) The perineum has the pelvic floor as its superior border.

Some sources do not consider "pelvic floor" and "pelvic diaphragm" to be identical, with the "diaphragm" consisting of only the levator ani and coccygeus, while the "floor" also includes the perineal membrane and deep perineal pouch. However, other sources include the fascia as part of the diaphragm. In practice, the two terms are often used interchangeably.

Inferiorly, the pelvic floor extends into the anal triangle.

39 - Urogenital diaphragm

Most of the support of the perineum is provided by the pelvic and urogenital diaphragms.


The urogenital diaphragm is external to the pelvic diaphragm and includes the triangular area between the ischial tuberosities and the symphysis. The urogenital diaphragm is made up of the deep transverse perineal muscles, the constrictor of the urethra, and the internal and external fascial coverings (perineal membrane).

38 - Perineal body

The perineal body (or central tendon of perineum) is a pyramidal fibromuscular mass in the middle line of the perineum at the junction between the urogenital triangle and the anal triangle . It is found in both males and females. In males, it is found between the bulb of penis and the anus; in females, is found between the vagina and anus, and about 1.25 cm in front of the latter.

The perineal body is essential for the integrity of the pelvic floor, particularly in females. Its rupture during delivery leads to widening of the gap between the anterior free borders of levator ani muscle of both sides, thus predisposing the woman to prolapse of the uterus, rectum, or even the urinary bladder.

At this point, the following muscles converge and are attached:

* External anal sphincter 
* Fibers from external urinary sphincter
* Superficial transverse perineal muscle
* Deep transverse perineal muscle
* Anterior fibers of the levator ani 
* Bulbospongiosus

37 - Muscles of Perineum/Urogenital region

SUPERFICIAL MUSCLES OF PERINEUM :
1. Superficial Transverse perinei
2. Bulbospongiosus (Bulbocavernosus in older textbooks)
3. Ischiocavernosus

DEEP MUSCLES OF PERINEUM :
1. Deep Transverse Perinei
2. Sphincter urethrae

37 - Skull Foramina

1. Anterior Palatine Foramen
2. Palatine Process of Maxilla
3. Palatine
4. Greater Palatine Foramen
5. Lesser Palatine Foramen
6. Pterygoid Processes of Sphenoid
7. Zygomatic Process
8. Squamous Part of Temporal Bone
9. Mandibular Fossa
10. Styloid Process
11. Stylomastoid Foramen
12. Mastoid Process
13. Mastoid Foramen
14. Superior Nuchal Line
15. External Occipital Protruberance
16. Median Nuchal Line
17. Inferior Nuchal Line
18. Foramen Magnum
19. Condyloid Canal
20. Occipital Condyle
21. Hypoglossal Canal
22. Jugular Foramen
23. Carotid Canal
24. Foramen Spinosum
25. Foramen Ovale
26. Foramen Lacerum
27. Vomer
28. Transverse Palatine Suture
29. Median Palatine Suture

View this page to read about the structures that pass through each of these foramina. 

36 - Musculocutaneous nerve

PATH OF THE NERVE :

The musculocutaneous nerve arises from the lateral cord of the brachial plexus, opposite the lower border of the Pectoralis minor, its fibers being derived from C5, C6, C7.

It penetrates the Coracobrachialis muscle and passes obliquely between the Biceps brachii and the Brachialis, to the lateral side of the arm; a little above the elbow it pierces the deep fascia lateral to the tendon of the Biceps brachii and is continued into the forearm as the lateral antebrachial cutaneous nerve.

In its course through the arm it innervates the Coracobrachialis, Biceps brachii, and the greater part of the Brachialis.

* The branch to the Coracobrachialis is given off from the nerve close to its origin, and in some instances as a separate filament from the lateral cord of the plexus; it is derived from the seventh, cervical nerve.

* The branches to the Biceps brachii and Brachialis are given off after the musculocutaneous has pierced the Coracobrachialis; that supplying the Brachialis gives a filament to the elbow-joint.

* The nerve also sends a small branch to the bone, which enters the nutrient foramen with the accompanying artery.

IRREGULARITIES : 

The musculocutaneous nerve presents frequent irregularities.

It may adhere for some distance to the median and then pass outward, beneath the Biceps brachii, instead of through the Coracobrachialis.

Some of the fibers of the median may run for some distance in the musculocutaneous and then leave it to join their proper trunk; less frequently the reverse is the case, and the median sends a branch to join the musculocutaneous.

The nerve may pass under the Coracobrachialis or through the Biceps brachii.

Occasionally it gives a filament to the Pronator teres, and it supplies the dorsal surface of the thumb when the superficial branch of the radial nerve is absent.

DAMAGE : 

Although rare, the musculocutaneous n. can be affected through compression due to hypertrophy or entrapment between the biceps aponeurosis & brachialis fascia or it may be injured through stretch as occurs in dislocations & sometimes in surgery.

Isolated injury, causes weakness of elbow flexion & supination of the forearm.

A discrete sensory disturbance is present on the radial side of the forearm.

The nerve is usually involved in an upper brachial plexus palsy

Injury can occur before entering the coracobrachialis due to dislocation or apparently due to stretch due to throwing injury

Heavy backpacks can cause damage to the upper trunk of the brachial plexus – dysfunction can be severe & prolonged with similar injury as occurs with Erb's palsy from breech deliveries. Early detection is important – the combination of time, avoidance of wearing a backpack, and strengthening of the shoulder muscles will probably be effective.

Distal to the coracobrachialis, the MC cause appears to be weight lifting – either through compression due to hypertrophy or entrapment between the biceps & brachialis, the nerve may lead to a painless loss of muscle strength in flexion & supination of the forearm. Initial treatment should include avoidance of biceps curls or other biceps exercises.

Images courtesy : wikipedia .

35 - Renal corpuscle ( Glomerulus ) Microscopic anatomy

A – Renal corpuscle
B – Proximal tubule
C – Distal convoluted tubule
D – Juxtaglomerular apparatus
1. Basement membrane (Basal lamina)
2. Bowman's capsule – parietal layer
3. Bowman's capsule – visceral layer
3a. Pedicels (podocytes)
3b. Podocyte

4. Bowman's space (urinary space)
5a. Mesangium – Intraglomerular cell
5b. Mesangium – Extraglomerular cell
6. Granular cells (Juxtaglomerular cells)
7. Macula densa
8. Myocytes (smooth muscle)
9. Afferent arteriole
10. Glomerulus Capillaries
11. Efferent arteriole

I loved this picture so much, i had to put it here . It beautifully depicts the whole microscopic anatomy of the Renal corpuscle including the glomerulus with podocytes, juxtaglomerular cells , macula densa etc .

NOTE : I am not the original author of this image . Michał Komorniczak, Polish wikipedist is the author of this image and the whole credit goes to him .

33 - Nerve supply of the Tongue

Motor supply :

All the intrinsic muscles, except the palatoglossus are supplied by the hypoglossal nerve. the palatoglossus is supplied by the cranial part of accessory nerve through the pharyngeal plexus .

Sensory supply :

Anterior 2/3rd of the tongue - lingual nerve is the nerve of general sensation and the chordatympani is the nerve of taste for the anterior two-thirds of the tongue .

Posterior 2/3rd of tongue - the glossopharyngeal nerve is the nerve for both general sensation and taste sensation for the posterior 1/3rd of the tongue .

The posterior most part of the tongue is supplied by the vagus nerve through the internal laryngeal branch .

32 - Hemivertebrae

*First read this question that appeared in the May 2006 AIIMS Medical Postgraduation Entrance Examination .


Q: Lumbar hemivertebra results due to the abnormal development of ?


a. dorsal sclerotome
b. intermediate cell mass
c. notochord
d. ventral sclerotome

answer d. ventral sclerotome

Now after you have seen the answer, u have to know what hemivertebra actually means .


The congenital vertebral anomalies are classified based on failure of formation, failure of segmentation and a combination of the two (mixed) (Fig. 1). The most common type of failure of formation anomaly is a hemivertebra. This is where a portion of the vertebra is missing resulting in a small, triangular shaped "half vertebra" or hemivertebra. Hemivertebrae can be subclassified based on their relationship to the adjacent spine (segmented, semisegmented, nonsegmented).

When several vertebral segments fail to separate bilaterally, a block vertebra results producing fused vertebral bones. Unilateral unsegmented vertebral bars are caused by the failure of segmentation only on the left or right side of the spine.

Fig. 1. Diagrammatic representation of classification system of congenital scoliosis. (A) Failures of formation; various types of hemivertebrae (semisegmented, fully segmented, wedge vertebra). (B) Failures of segmentation; block vertebra, unsegmented bar. (C) Mixed; combination of hemivertebra and unsegmented bar.




Now that you know what hemivertebra means lets see what sclerotome actually means . look at the figure below .

In the figure above ,somites are arranged in pairs alongside the neural tube(light orange) and notochord (blue). Each somite is composed of a dermatome (light purple), myotome (light brown), and sclerotome (dark yellow). The ectoderm lies above and the endoderm below. Now see the picture below which demonstrates the formation of the vertebrae. 

 The above figure shows that the sclerotomes present in the somites proceed dorsally over the neural tube to form dorsal somites and the sclerotomes which proceed ventrally below the neural tube form the ventral somites .

The dorsal somites form the dorsal part of the vertebrae and the ventral somites form the ventral part of the vertebrae . the neural tube forms the spinal cord .


AND A DEFECT IN THE FORMATION OF VENTRAL SOMITES LEADS TO THE FORMATION OF LUMBAR HEMIVERTEBRAE .

31 - Facial nerve subdivisions and functions

Subdivisions and Functions of the Facial Nerve.

Facial Nerve Subdivision	Function
Branchial motor	Muscles of facial expression
	Posterior belly of digastric muscle
	Stylohyoid muscle
	Stapedius muscle
Visceral motor	Salivation—lacrimal, submandibular, and sublingual
	Nasal mucosa or mucous membrane
General sensory	Sensory to auricular concha
	External auditory canal
	Tympanic membrane
Special sensory	Chorda tympani nerve—taste to anterior two-thirds of the tongue

30 - PGI Chandigarh December 2002 Anatomy Mcqs with answers

1q: which of the following are draining channels of cavernous sinus ?
a. inferior petrosal sinus
b. inferior ophthalmic vein
c. sphenoparietal sinus
d. middle cerebral vein
e. superior ophthalmic vein

answer a , e . inferior petrosal sinus drains into internal jugular vein and superior ophthalmic vein drains into facial vein

2q: Recurrent laryngeal nerve has the following course in neck ?
a. it passes anterior to inferior thyroid artery
b. it passes through sternomastoid
c. it passes between branches of inferior thyroid vessels
d. it passes posterior to inferior thyroid vessels
e. it is superficial to inferior constrictor muscle

answer a , c , d .

3q: blood supply of lungs are ?
a. pulmonary artery
b. pulmonary vein
c. bronchial artery
d. intercostal artery
e. internal thoracic artery

answer a , b , c . pulmonary artery , pulmonary vein and bronchial artery

4q: true statements about esophageal hiatus are ?
a. lies between two crura of diaphragm
b. lies at the level of D12 vertebra
c. vagus nerve passes through it
d. lie in right crura of diaphragm
e. thoracic duct passes through it

answer c , d . vagus nerve passes through esophageal hiatus and lies in the right crura of diaphragm

5q: blood supply of great toe are ?
a. dorsalis pedis artery
b. lateral plantar artery
c. metacarpal artery
d. posterior tibial artery
e. medial plantar artery

answer a , e . dorsalis pedis artery and medial plantar artery .

6q: median nerve injury at elbow affects ?
a. adduction of the thumb
b. flexion at DIP joints of 2nd finger
c. flexion of PIP of third finger
d. flexion at 1st and 2nd DP fingers
e. flexion of MCP joints except thumbs

answer a , b , c , d .

7q: at the time of birth which of the following ossification centres are seen ?
a. lower end of femur
b. upper end of humerus
c. calcaneum
d. upper end of tibia
e. head of humerus

answer a , c . lower end of femur and calcaneum

8q: primordial germ cells develop from ?
a. neural crest
b. splanchnic mesoderm
c. genital ridge
d. yolk sac
e. somatic mesoderm

answer d . yolk sac

9q: blood supply of little’s area are ?
a. greater palatine artery
b. septal branch of superior labial artery
c. anterior ethmoidal artery
d. septal branch of sphenopalatine artery
e. nasal branch of sphenopalatine artery

answer a , b , c , d .

29 - AIIMS November 2004 anatomy mcqs with answers

1q: a posteriorly perforating ulcer in the pyloric antrum of the stomach is likely to produce initial localized peritonitis or abscess formation in the ?


a. greater sac
b. left subhepatic and hepatorenal spaces ( pouch of Morrison )
c. omental bursa
d. right subphrenic space

answer c . omental bursa

2q: knowledge of the segmental cutaneous innervation of the skin of the lower extremity is important in determining the level of the intervertebral disk disease . thus S1 nerve root irritation will result in pain located along the ?


a. anterior aspect of the thigh
b. medial aspect of the thigh
c. anteromedial aspect of the leg
d. lateral side of foot

answer d . lateral side of foot

3q: which one of the following extraocular muscles is served by a contralateral brain stem nucleus ?


a. superior rectus
b. medial rectus
c. inferior oblique
d. inferior rectus

answer a . superior rectus

4q: all of the following are characteristic of a bronchopulmonary segment except ?


a. it is surgically resectable
b. it is named according to the segmental bronchus supplying it
c. it is drained by intersegmental branch of pulmonary vein
d. it is the largest subdivision of a lobe

answer c . it is drained by intersegmental branch of pulmonary vein

5q: injury to the common peroneal nerve at the lateral aspect of head of fibula results in all of the following except ?


a. weakness of ankle dorsi-flexion
b. foot drop
c. loss of ankle reflex
d. sensory impairment on lateral aspect of leg extending to the dorsum of foot

answer c . loss of ankle reflex

6q: the mesentery of small intestine, along its attachment to the posterior abdominal wall, crosses all of the following structures except ?


a. left gonadal vessels
b. third part of duodenum
c. aorta
d. right ureter

answer a . left gonadal vessels

7q: venous drainage from neurohypophysis is routed through all of the following except ?


a. portal vessels to adenohypophysis
b. superior hypophyseal veins to ventricular tanycytes
c. inferior hypophyseal veins to dural venous sinuses
d. capillaries to median eminence and hypothalamus

answer b . superior hypophyseal veins to ventricular tanycytes

8q: all of the following muscles undergo paralysis after injury to C5 and C6 spinal nerves except ?


a. biceps
b. coracobrachialis
c. brachialis
d. brachioradialis

answer b . coracobrachialis

9q: a 59 year old man complains of recurrent attacks of pain in the region of left shoulder radiating to sternum and the pit of stomach . the attacks of pain came at lengthy intervals until the last two days when it became continuous . the physician diagnosed it as angina pectoris . in this case the pain pathway from the heart is carried by ?


a. superior cervical cardiac nerve
b. middle and inferior cervical cardiac nerve
c. thoracic splanchnic nerve
d. vagus

answer b . middle and inferior cervical cardiac nerve

28 - AIIMS November 2005 anatomy mcqs with answers

1q: all of the following statements about the splenic artery are true except that it ?


a. has a tortuous course
b. is a branch of coeliac trunk
c. has branches that anastomose freely within spleen
d. supplies the greater curvature of stomach

answer c . has branches that anastomose freely within spleen is a wrong statement because within the spleen it divides repeatedly to form successfully the straight vessels called pencilli, ellipsoids and arterial capillaries

2q: which of the following among axillary lymph nodes is a terminal group ?


a. pectoral
b. central
c. lateral
d. apical

answer d . apical . the apical group of axillary lymph nodes is the terminal group of axillary lymph node as it receives efferent lymph vessels from all the other axillary nodes

3q: the vertebral artery traverses all of the following except ?


a. foramen magnum
b. subarachnoid space
c. intervertebral foramen
d. foramen transversorium

answer c . intervertebral foramen

4q: all of the following structures pass through the superior aperture of thorax except ?


a. right recurrent laryngeal nerve
b. left common carotid artery
c. left sympathetic trunk
d. thoracic duct

answer a . right recurrent laryngeal nerve

5q: all of the following statements about the vagus nerve are true except that it ?


a. supplies heart and lung
b. carries postganglionic parasympathetic fibers
c. innervates right two third of transverse colon
d. stimulates peristalsis and relaxes sphincters

answer b . carries postganglionic parasympathetic fibers

6q: the narrowest part of the ureter is at the ?


a. uretero - pelvic junction
b. hiac vessel crossing
c. pelvic ureter
d. uretero – vesical junction

answer d . uretero – vesical junction. It is the anatomical location where the ureter joins the urinary bladder

27 - flexor retinaculum mcqs

1q: a 16 years old girl failed in her final examination. Disgusted with life, she cut across the front of the wrist at the flexor retinaculum, she was rushed to hospital . the surgeon noticed that cut was superficial . all the following structures would have been damaged except ?

a. ulnar nerve
b. median nerve
c. palmar cutaneous branch of median nerve
d. superficial branch of radial artery

answer b . median nerve

explanation : median nerve would escape injury in a superficial cut as it lies deep to the flexor retinaculum . here is a list of structures which pass superficial and deep to flexor retinaculum .

structures lying superficial to flexor retinaculum of hand are :

1. ulnar nerve
2. ulnar vessels
3. palmar cutaneous branch of ulnar nerve
4. palmar cutaneous branch of median nerve
5. Palmaris longus tendon

Structures lying deep to flexor retinaculum of hand are :

1. median nerve
2. ulnar bursa
3. radial bursa
4. tendons like flexor digitorum profundus, flexor digitorum superficialis, flexor pollicis longus and flexor carpi radialis .

This question was asked in the november 2002 AIIMS paper . 

26 - ulnar nerve anatomy part 2

MUSCULAR BRANCHES AND INNERVATION :  the ulnar nerve and its branches innervate the following muscles in the forearm and hand:

An articular branch that passes to the elbow joint while the ulnar nerve is passing between the olecranon and medial epicondyle of the humerus.

 In the forearm, via the muscular branches of ulnar nerve:

 1. Flexor carpi ulnaris

2. Flexor digitorum profundus (medial half)

 In the hand, via the deep branch of ulnar nerve:

 1. Hypothenar muscles

2. Opponens digiti minimi

3. Abductor digiti minimi

4. Flexor digiti minimi brevis

5. Adductor pollicis

6. The third and fourth lumbrical muscles

7. Dorsal interossei

8. Palmar interossei

 

In the hand, via the superficial branch of ulnar nerve:

 1. Palmaris brevis

 CUTANEOUS INNERVATION : the ulnar nerve also provides sensory innervation to the part of the hand corresponding to the fourth and fifth digits:

 1. Palmar branch of ulnar nerve - anterior

2. Dorsal branch of ulnar nerve – posterior

 ULNAR NERVE ENTRAPMENT : the ulnar nerve can be trapped or pinched in various ways as it proceeds down the arm from the brachial plexus to the ring and middle fingers. One common cause is cubital tunnelsyndrome, where the tunnel runs the inner outside side of the elbow. Pinching of the nerve often causes tingling symptoms in the little and ring fingers. In some cases moderate to severe pain is experienced from pinching this nerve. Often such pins and needles sensations can be caused by sleeping wrongly on your arm, or by cycling for extended periods of time, but sometimes the problems last for days. In severe cases, surgery is performed to move the nerve.

25 - ulnar nerve anatomy part 1

INTRODUCTION:  In human anatomy, the ulnar nerve is a nerve which runs near the ulna bone. The ulnar nerve is the largest unprotected nerve in the human body (meaning, unprotected by muscle or bone), and the only unprotected nerve that does not serve a purely sensory function (those nerves specifically meant to perceive changes in the environment, such as nerves in the skin). This nerve is directly connected to the little finger, and the adjacent half of the ring finger, supplying the palmar side of these fingers, including both front and back of the tips, perhaps as far back as the fingernail beds.

Aggravation of this nerve is commonly referred to as hitting one's "funny bone." this name is thought to be a (conscious or subconscious)pun, based on the sound resemblance between words "humerus" and "humourous" .

COURSE IN ARM : The ulnar nerve comes from the medial cord of the brachial plexus, and runs inferior on the posterior and medial (posteromedial) aspects of the humerus down the arm, going behind the medial epicondyle, through the cubital tunnel, at the elbow (where it is exposed for a few centimeters, just above the joint). Because of the mild pain and tingling throughout the forearm associated with an inadvertent impact of the nerve at this point, it is usually called the funny bone. (it may also have to do with its location relative to the humerus, as the name "humerus" is a homophone to the word "humourous").

 COURSE IN FOREARM : It enters the anterior (flexor/front) compartment of the forearm through the two heads of flexor carpi ulnaris and runs alongside the ulna. There it supplies one and a half muscles (flexor carpi ulnaris & medial half of flexor digitorum profundus). It soon joins with the ulnar artery, and the two travel inferiorly together, deep to the flexor carpi ulnaris muscle.

 Here it gives off the following branches: 

 1. Muscular branches of ulnar nerve

2. Palmar branch of ulnar nerve

3. Dorsal branch of ulnar nerve

COURSE IN HAND :  After it travels down the ulna, the ulnar nerve enters the palm of the hand. Unlike the median nerve which travels below the flexor retinaculum of the hand and through the carpal tunnel, the ulnar nerve and artery pass superficial to the flexor retinaculum via the ulnar canal.

 Here it gives off the following branches: 

 1. Superficial branch of ulnar nerve

2. Deep branch of ulnar nerve