Back and Upper Limb lab session

The Back

Vertebral region: runs as a band over the vertebral column
Scapular region: is the area over the scapula
Auscultatory triangle or triangle of auscultation
Infrascapular region: is the area between the scapular region and the lumbar region
Lumbar region. Loin
Lumbar (Petit’s) triangle: is the triangle above the iliac crest between the margins of the latissimus dorsi and the external abdominal oblique
Sacral region lies over the sacrum
Coccygeal foveola

Regions of the dorsum.

Percent distribution of human body (it is useful especially during the wound examination, and it helps describe their largeness, extensiveness).

Percent distribution of human body. A. anterior view, B. posterior view, C. hand.

Fascia is a sheet of fibrous tissue that encloses muscle or groups of muscles. It serves as a divider between several layers. Fascia also envelops the body beneath the skin.

The fascia of the back is called thoracolumbar fascia which coveres the muscles of the back. Thoracolumbar fascia forms the canal (invests all intrinsic muscle of the back) with the vertebral column and posterior, external surfaces of the ribs. It is divided into the following layers:

The posterior layer or the superficial layer covers the superficial group of the muscles of the back. The posterior layer covers the sacral region, it then ascends and makes an origin for the latissimus dorsi and posterior inferior serratus. In the cervical region it separates the trapezius from the splenius capitis. Superficial layer becomes thinner and forms the nuchal fascia. Posterior layer of the thoracolumbar fascia is attached to the spinous processes.

The anterior layer or quadratus lumborum fascia isthe deep part of the thoracolumbar fascia. It covers the quadratus lumborum. Anterior layer is attached to the costal (transverse) processes and separates the intrinsic back muscle from the muscles of the ventrolateral body wall.

The middle layer between the erector spinae (in the posterior) and the quadratus lumborum (in the front).

The posterior and middle layers unite at the lateral surface of the erector spinae and later joined (at the lateral surface of quadratus lumborum) by the anterior layer to form the aponeurosis (origin) of transverses abdominis.

Thoracolumbar fascia.

Nuchal fascia (fascia nuchae) is the continuation of the posterior or superficial layer of thoracolumbar fascia. In the middle of the nuchal fascia lies the nuchal ligament.

This group of muscles is concerned with the upper limb, movements of the vertebral column and they are called extrinsic or superficial muscles of the back.

Muscles of the back.

The trapezius has the following parts:

descending part or superior part
transverse part or middle part
ascending part or inferior part

Attachment place: the externaloccipital protuberance, superior nuchal line, ligamentum nuchae and the spinous processes of the vertebrae C7 to T12 and also the trapezius inserts into the lateral part of the clavicule, acromion and the spine of the scapula.
Action: superior part: elevation of scapula, middle part: retraction of scapula, inferior part: depression of scapula. When the superior and inferior parts act together they rotate the latelar part of the scapula upward and elevate the upper limb above the head.
Nerve supply: CN XI – the accessory nerve and cervical nerves C3-C4.
Arterial supply: superficial branch of transverse cervical artery, acromial branch of suprascapular artery, dorsal branches of posterior intercostals arteries.

Attachment place on thespinous processes of T6 to T12 LV, thoracolumbar fascia, 1/3 of the iliac crest, ribs (9^th – 12^th), and the intertubercular groove of humerus.
Action: adduction, extention and medial rotation of the arm, and depression of the shoulder
Nerve supply: the thoracodorsal nerve (C6-C8, the short branch of the brachial plexus)

Clinical comments

The latissimus dorsi is the accessory muscle of inspiration. The latissimus dorsi is a very important muscle during forced expiration and coughing and is also known as the COUGHING MUSCLE.

The back of the hand can cover the buttock when the arm is rotated medially (as far as possible). The latissimus dorsi is also called DRESS COAT POCKET.

Attachment place: the medial margin of the scapula from the superior angle to the spine of the scapula and it arises from the transverse process of the cervical vertebrae (C1-C4)
Action: elevation of the scapula, medial rotation of the inferior angle of scapula
Nerve supply: the dorsal scapular nerve (C4-C5) is a short branch of the brachial plexus, anterior rami of C3-C4.

Attachment place: the ligamentum nuchae, spinous processes of C7 to T1 (minor) and T2-T5 vertebrae (major) and they insert into the medial margin of the scapula
Action: retraction of the scapula toward the vertebral column, presses the scapula to the thoracic wall
Nerve supply: the dorsal scapular nerve (C4-C5).

Attachment place: the ribs 9^th-12^th and it arises from the thoracolumbar fascia from the spinous processes of 12^th thoracic to 1^st – 3^rd lumbar vertebrae.
Action: depresses the ribs 9^th – 12^th
Nerve supply: intercostals nerves (T9-T12)

Attachment place: the ribs 2^nd – 5^thand it arises from the spinous processes of C6-C7 and Th1-Th2
Action: elevates the 2^nd – 5^th ribs
Nerve supply: intercostal nerves (T1-T4 or T2-T5)

Clinical comments

Serratus posterior inferior is an accessory muscle of inspiration.

The flow chart of the back muscles and their innervation.

The muscles of the back proper are the intrinsic muscles of the back. They are called the erector spinae. It includes all the muscles innervated by the dorsal rami of the spinal nerves. This muscles form two longitudinal columns which lie lateral to the spinous processes in the osteofibrous canal. This canal is formed by thoracolumbar fascia (posterolateral limit), transverse (costal) processes and spinous processes.

Erector spinae is divided into:

The sacrospinales consist of the iliocostalis which is subdivided into the:

Lumbar part or iliocostalis lumborum lateral division of lumbar erector spinae. It arises from the sacrum, external lip of the iliac crest and thoracolumbar fascia and inserts into the costal processes of the lumbar vertebrae and the 6^th-9^th ribs.

Thoracic part or iliocostalis thoracis arises from the lower six (12^th-6^th) to the upper six (6^th-1^st) ribs.

Iliocostalis cervicis arises from the 6^th-3^rd ribs to transverse processes of the 6^th-4^th cervical vertebrae.

Nerve supply: all are innervated by dorsal rami of spinal nerves (C4-L3)

Longissimus is subdivided into:

Longissimus lumborum or lumbar part is the medial division of lumbar erector spinae.
Longissimus thoracis
Longissimus cervicis
Longissimus capitis

Nerve supply: all are innervated by dorsal rami of spinal nerves (C2-L5).

Spinalis is divided into:

Spinalis thoracis
Spinalis cervicis
Spinalis capitis

Nerve supply: all are innervated by dorsal rami of spinal nerves (C2-Th10).

The erector spinae forms three columns which are attached inferiorly by the common origin to the iliac crest, posterior aspect of the sacrum, sacroiliac ligament, lumbar spinous processes – lateral column- (iliocostalis) Intermediate is inserted in the angles of the ribs (longissimus). Medial column (spinalis) is inserted in transverse processes of thoracic and cervical vertebrae, mastoid process, spinous processes of upper thoracic vertebrae

Action: When the action takes places at the same time on both side, extension of the head and vertebral column is possible. However, acting alone – flexion to the same side is possible.

Spinotransversales consist of:

splenius capitis arise from the spinous processes of C4-Th3 and inserts on the mastoid process of the temporal bones and lateral parts of the linea nuchae located superiorly on the occipital bone.
splenius cervicis arise from the spinous processes of Th6-Th3 and inserts on the transverse processes of C1-C3.

Origin: inferior part of lig. nuchae, spinous processes of T1 to T6 vertebrae
Insertion: mastoid process, superior nuchal line, transverse processes of vertebrae C1 to C4
Action: acting pair – extension of head and neck, acting alone – flexion. When action is initiated by the muscles located on that side, rotation of the head to the same side is possible. When in unison (on both sides at the same time) flexion of the head to the posterior.
Nerve supply: cervical nerves. All are innervated by dorsal rami of spinal nerves (C1-C5(C8)).

Transversospinales consist of:

semispinalis is subdivided into:

Semispinalis thoracis
Semispinalis cervicis
Semispinalis capitis

Nerves: all are innervated by dorsal rami of spinal nerves (Th4-Th6, C3-C6, C1-C5).

Nerves: all are innervated by dorsal rami of spinal nerves (C3-S4).

Rotatores are subdivided into:

Rotatores cervicis
Rotatores thoracis
Rotatores lumborum

Nerves: all are innervated by dorsal rami of spinal nerves (Th1-Th11).

Interspinales consist of:

Interspinales cervicis
Interspinales thoracis
Interspinales lumborum

Nerves: all are innervated by the dorsal rami of spinal nerves (C4-L3).

Intertransversarii lie lateral to the interspinales. They consist of:

Intertransversarii laterales lumborum
Intertransversarii mediales lumborum

Nerves: all are innervated by dorsal rami of spinal nerves (C1-C6).

Intertransversarii thoracis
Intertransversarii posteriores cervicissubdivided into:
- Medial part
- Lateral part

Nerves: all are innervated by dorsal rami of spinal nerves (L1-L4).

Intertransversarii anteriores cervicis

Nerves: all are innervated by dorsal rami of spinal nerves (C4-L3).

Longissimus is subdivided into:

Longissimus lumborum or lumbar part is the medial division of lumbar erector spinae.
Longissimus thoracis
Longissimus cervicis
Longissimus capitis

Nerve supply: all are innervated by dorsal rami of spinal nerves (C2-L5).

Spinalis is divided into:

Spinalis thoracis
Spinalis cervicis
Spinalis capitis

Nerve supply: all are innervated by dorsal rami of spinal nerves (C2-Th10).

Action: When the action takes places at the same time on both side, extension of the head and vertebral column is possible. However, acting alone – flexion to the same side is possible.

The Topographical Elements of the Back

The auscultatory triangle or triangle of auscultation is formed by:

Lateral border of trapezius – medial limit
Medial border of scapula – lateral limit
Superior border of latissimus dorsi – inferior limit
Floor is formed by rhomboid major

The auscultatory triangle.

Clinical comments

The auscultatory triangle is the largest in position with the upper limbs above the head, the 6^th intercostal spaces become available for auscultation (the superior segments of the lower lobes of the lungs).

The left triangle is so named because the drip of the ingested fluids into the cardia of the stomach could be heard through it and timed in cases of oesophageal obstruction.

The lumbar triangle or inferior lumbar space is formed by:

Lateral border of latissimus dorsi – medial limit
Posterior margin of external oblique – lateral limit
Iliac crest – inferior limit

The lumbar triangle.

Clinical comments

It is a weak area at the back. Through the superior lumbar triangle abscesses and/or herniation may occur.

The superior lumbar space or triangle is formed by:

the 12^th rib and serratus posterior inferior – superior limit
the erector spinae – medial limit
the internal oblique – lateral limit

The muscles of the shoulder girdle.

Clinical comments

Through the superior lumbar triangle abscesses or herniation may occur.

The Shoulder Girdle

The deltoid fascia covers deltoid muscle and continues inferiorly as a brachial fascia.

The axillary fascia is a continuation of the pectoral fascia. The axillary fascia continues posteriorly as a posterior thoracic fascia and distally as a brachial fascia.

The clavicopectoral fascia is a strong fibrous sheet, located posterior to the clavicular part of the pectoralis major and covers the axillary vessels and nerves.

Muscles of the shoulder girdle and foramina.

The scapular muscles (extends from scapula to the humerus): 6 in number.

Deltoid consist of three functional parts, all of which have the same distal attachment (deltoid tuberosity of humerus). All these parts are innervated by the axillary nerve (from posterior cord).
anterior: clavicular part attached into the lateral 1/3 of anterior surface of clavicle. Its action is flexion and medial rotation of arm.
middle: acromial part inserts into the lateral border of acromion

Action: abduction of arm

posterior: spinal part inserts into the inferior lip of crest of the scapula

Action: extension and lateral rotation of the arm

Supraspinatus inserts into the supraspinatus fossa and the highest part of greater tubercle of the humerus.

Action: abduction of arm.
Nerves: the suprascapular nerve (short branch from the brachial plexus).

Infraspinatus inserts into the infraspinatus fossa and themiddle part of greater tubercle of the humerus.

Action: lateral rotation
Nerves: just like the supraspinatus -the suprascapular nerve (short branch from the brachial plexus).

Teres minor inserts into the lateral margin of the infraspinatus fossa and the lower part of greater tubercle of the humerus.

Action: lateral rotation.
Nerves: the axillary nerve.

Teres major inserts into the dorsal surface of inferior angle of scapula and into the crest of lesser tubercle of the humerus.

Action: protraction and upward rotation of the scapula, also fixation of the scapula to chest wall.
Nerves: lower subscapular nerve (short branch from the brachial plexus).

Subscapularis inserts into the subscapular fossa and the lesser tubercle of the humerus.

Action: medial rotation of arm.
Nerves: upper and lower subscapular nerves (C5-C8).

Clinical comments

The subscapularis is particulary a strong medial rotator of the arm. Paralysis of this muscle gives the maximal lateral rotation.

Subscapularis, teres major and latissimus dorsi are inserted on the lesser tubercle and crest of lesser tubercle of the humerus.

Muscles, which are associated with the head and surgical neck of the humerus are called the “rotator-cuff” musculature. (the supraspinatus, the infraspinatus, the teres minor, the subscapularis)

Attachments of the shoulder girdle muscles.

The rotator cuff.

The Spinal Nerve

The spinal nerve consists of:

ventral root – motor, sympathetic, and preganglionic fibres.
dorsal root – sensitive.

Structure of the typival spinal nerve.

Localisation of the spinal nerve.

The spinal nerve has five following branches:

ventral primary ramus: a mixture of motor and sensory fibers – communicate to form plexuses, except in the thoracic region.
dorsal primary ramus: a mixture of motor and sensory fibers that divide into medial and lateral branches (without plexuses).
white ramus communicating: sympathetic preganglionic fibers.
grey ramus communicating: sympathetic postganglionic fibers.
meningeal branch: sensitive.

The Brachial Plexus

The brachial plexus extends from the neck into the axilla and is formed by the union of the ventral rami of nerves C5-C8 also by the contribution of T1.

The brachial plexus divides into two parts:

Supraclavicular part of the brachial plexus (consists of rami and trunks with their branches) is situated in the posterior triangle of the neck ,between the anterior and posterior scalenus muscles.

Infraclavicular part consists of cords and their branches and is located in the axilla.

Ventral rami from C5 and C6 unite to form the superior trunk, which is also known as the upper trunk.
Ventral ramus of C7 forms the middle trunk.
Ventral rami of C8 and T1 form the inferior trunk, which is also known as the lower trunk.

Each trunk divides into anterior and posterior divisions.

The anterior divisions of all trunks supply the anterior part (flexors) and the posterior divisions supply the posterior (extensor) part of the upper limb.

All divisions form three cords:

Posterior cord is created by the three posterior divisions of the trunks.
Anterior division of the inferior trunk continues as a medial cord.
Anterior divisions of the superior and middle trunks form the lateral cord.

Each cord of the brachial plexus divides into long nerves:

Posterior cord terminates as an axillary and radial nerve.
Medial cord divides into the ulnar nerve, medial root of the median nerve, and two cutaneous nerves: medial brachial cutaneous nerve and antebrachial cutaneus nerve.
Lateral cord divides into the musculocutaneous nerve and lateral root of the median nerve.
Short nerves of the brachial plexus arises from the supraclavicular and also from the infraclavicular part.

The dorsal scapular nerve pierces the scalenus medius muscle, and then descends to supply the levator scapulae muscle and rhomboid muscles.

The long thoracic nerve descends on the lateral thoracic wall and supplies the serratus anterior muscle.

The subclavius nerve descends posteriorly to the clavicle and supplies the subclavius muscle.

The suprascapular nerve arises from the inferior trunk, passes laterally through the scapular notch and supplies the supraspinatus and infraspinatus muscles.

Lateral pectoral nerve arises from the lateral cord, and passes medially to the medial pectoral nerve and innervates the pectoral major muscle

The medial pectoral nerve arises from the medial cord, but passes laterally to the lateral pectoral nerve. Both nerves supply the pectoral muscles.

The brachial plexus.

The Blood and the Lymph Vessels of the Shoulder Girdle

The axillary artery:

Origin: It begins at the external margin of the first rib as a continuation of the subclavian artery.
End: It ends at the external margin of the teres major muscle.
Course: During its course through the axilla it is situated on the medial side of the humerus, behind the pectoral minor muscle and on the lateral side of the axillary vein. The pectoral minor muscle divides the axillary artery into three parts.

Branches of the axillary artery:

The first part is located between the lateral border of the first rib and the superior margin of the pectoralis minor muscle. Just only one branch arises from this part. It is the superior thoracic artery.

The second part lies behind the pectoralis minor muscle and ends on the lower margin of this muscle. This part gives off two branches:

Thoracoacromial artery arises as a short trunk and subdivides into four branches: acromial, deltoid, pectoral and clavicular.
Lateral thoracic artery supplies both pectoral muscles and descends on the anterolateral thoracic wall.

The third part extends to the inferior end of the axillary artery and gives off three branches:

Subscapular artery, (large branch) descends along the lateral border of the subscapular muscle and divides into two branches: the circumflex artery (supplies muscles on the dorsal surface of the scapula) and thoracodorsal artery (supplies the latissimus dorsi muscle)
Anterior and posterior circumflex humeral arteries arise at the same level and the first one passes anteriorly around the humerus. However, the second one runs posteriorly through the quadrangular space (with axillary nerve) and anatomise with the first one. Both of them supply surrounding muscles.

Triangular and quadrangular spaces.

All veins which are situated superficially to the fascia are called superficial veins. All veins which lie under the fascia, are called deep veins.

The superficial veins of the upper limb create two main veins, which are located: on the middle side of the limb (basilic vein) and on the lateral side (cephalic vein).

The basilic vein arises from the dorsal venous network of the hand, runs upwards on the medial side of the forearm to the cubital fossa ,where is joined by the medial cubital vein, then continues a general course until the first-third of the arm, where it pierces the brachial fascia to join the one of two brachial veins or even the axilary vein in some cases.

The cephalic vein arises also from dorsal venous network of the hand, but crosses the anatomical snuff box, runs on the lateral side of the forearm and arm, continues through the deep fascia in the deltopectoral triangle and joins the axillary vein. It is connected with the cubital vein in the cubital fossa. About 60% people have different configuration of superficial veins in the cubital fossa.

The basilic and cephalic veins are connected with the anterior median vein by the median (intermediate) cephalic vein and the median (intermediate) basilic vein. The anterior median veinruns on anterior surface of the forearm.

In the cubital fossa the superficial veins form a network which varies from person to person.

Clinical comments

The cubital network of superficial veins (sometimes the dorsal venous network of the hand) are usually used for injection of drugs, that should be injected into the vein.

The axillary vein: located on the medial side of the axillary artery. It begins at the level of the inferior margin of the pectoralis major muscle as a continuation of the brachial vein and ends on the external margin of the first rib. The subclavian vein is a continuation of this vein. The axillary vein is joined by the cephalic vein in the deltopectoral triangle.

The axillary lymph nodes (20-30) are arranged in five principal groups:

The lateral axillary lymph nodes lie on the lateral wall of the axillary cavity, medially to the axillary vein and drain lymph from the medial part of the upper limb.

The subscapular axillary lymph nodes are situated near the posterior axillary fold and receives lymph from the posterior aspect of the thoracic wall and scapular region.

The pectoral axillary lymph nodes are located on the medial wall of the axilla in association with the lateral thoracic artery and drain lymph from anterior thoracic wall and lateral part of the breast.

The central axillary lymph nodes are situated near base of the axilla and axillary artery and receive lymph from other groups of axillary nodes except the apical group.

The apical axillary lymph nodes lie at the apex of the axilla and receive lymph from all four groups. The efferent vessels of these nodes unite to form the subclavian lymphatic trunk.

The Topographical Elements

Borders:
- Superior border: the clavicle.
- Medial border: the pectoralis major muscle.
- Lateral border: the deltoid muscle.
Contents:
- The cephalic vein.

Borders:
- Superior border: Teres minor muscle.
- Inferior border: Teres major muscle.
- Lateral border: Long head of the triceps brachi.
Contents:
- The circumflex scapular artery.

Borders:
- Superior border: teres minor muscle and subscapularis muscle.
- Inferior border: teres major muscle.
- Lateral border: humerus – surgical neck. Corcobrachial muscle.
- Medial border: long head of the triceps brachi.
Contents:
- Posterior circumflex humeral artery.
- Axillary nerve.

The axilla is a pyramidal space at the junction of the arm with the thorax, which is bordered by four walls with a clear perspective of its apex and base. It is the pathway for the large nerves and vessels of the upper limb.

Apex of the axilla.

Walls of the axilla.

Borders:

The base is formed by the skin with hair.
The anterior wall is formed by the pectoral muscles.
The posterior wall contains the subscapularis, teres major and latissimus dorsi muscles.
The medial wall is formed by the seratus anterior muscle which covers the thoracic wall from lateral.
The lateral wall contains the neck of the humerus and coracobrachial muscle.

The Arm

Deltoid region

Anterior region of arm or anterior surface of arm
Posterior region of arm or posterior surface of arm
- lateral bicipital groove or radial bicipital groove
- medial bicipital groove or ulnar bicipital groove

Anterior region of elbow or anterior surface of elbow
- cubital fossa
Posterior region of elbow or posterior surface of elbow

Anterior region of forearm or anterior surface of forearm
Posterior region of forearm or posterior surface of forearm
Lateral border or radial border
Medial border or ulnar border

Wrist or region of wrist
Dorsum of hand or dorsal region of hand
Palm of hand or palmar region of hand

Regions of the upper limb, anterior view.

The brachial fascia is a continuation of the deltoid and axillary fascia. Distally it becomes fascia of the forearm. The brachial fascia forms two intermuscular septa on the arm:

Medial intermuscular septum of the arm
- Origin: end of the coracobrachial muscle
- Insertion: medial epicondyle of the humerus
Lateral intermuscular septum of the arm
- Origin: deltoid tuberosity of the humerus
- Insertion: lateral epicondyle of the humerus

These septas divide the arm into two compartments:

Anterior (flexor) compartment of arm
Posterior (extensor) compartment of arm

Muscles of the arm (musculi brachii) divided into two groups:

Muscles of the anterior group of the arm.

The anterior group formes the following muscles:

The biceps brachii muscle(musculus biceps brachii) has two heads:

Long head
- Origin: supraglenoid tubercle..
Short head
- Origin: coracoid process of scapula.
Insertion (both heads): both tuberosity of radius.
Action (both heads): flexion and adduction of the forearm. Flexion and supination of the forearm.

Origin: coracoid process of scapula.
Insertion: middle third part of the humerus: medial border.
Action: flexion & adduction of the arm.

Origin: distal half of the anterior surface of humerus.
Insertion: tuberosity of ulna.
Action: flexion of forearm (the elbow joint).

Practical tips

The short head of biceps, the coracobrachialis and the pectoralis minor all are attached into the coracoid process of scapula.

Muscles of the anterior group of arm. Section through the arm.

Muscles of the arm, located posteriorly.

The posterior group (extensors) – innervated by radial nerve.

Origin (long head): infraglenoid tubercle of scapula
Origin (medial head): distal part of the posterior surface of the humerus
Origin (lateral head): proximal part of the posterior surface of the humerus
Insertion (all heads): olecranon
Action: Extension and adduction of arm. Extension of forearm.

Anconeus muscle

Articularis cubitis muscle

Muscles of the arm, located posteriorly. Section through the arm.

The musculocutaneous nerve is a branch of the lateral cord of the brachial plexus, passes through the coracobrachialis muscle, then continues distally between the biceps brachii and brachialis muscles. It pierces the antebrachial fascia and becomes the lateral antebrachial cutaneous nerve. The musculocutaneous nerve supplies all the flexor muscles of the arm.

The radial nerve – terminal branch from posterior cord, runs downward with the deep brachial artery in the radial groove, pierces the lateral brachial intermuscular septum, then lies between the brachialis and brachoradialis muscles. It supplies all extensor muscles and skin on the posterior part of the arm.

Relations of the radial nerve.

The median nerve (nervus medialis)is formed by the union of the lateral root from the lateral cord and a medial root from the medial cord of the brachial plexus. It descends to the cubital fossa with the brachial artery, medial to the humerus and does not give off any branches tn the arm.

The ulnar nerve (UN) – as the terminal, long branch from the medial cord, C8-Th1 passes distally and to the back through the medial intermuscular septum. It descends with the superior collateral ulnar artery. It turns around the medial epicondyle, where it lies superficially and is easily palpable. It has no branches on the arm.

Relations of the ulnar nerve.

Muscles innervation of the arm.

The axillary and the radial nerves of the arm.

Innervation of the skin on the arm.

Skin of the arm is supplied:

Medially: the medial brachial cutaneous nerve – from medial cord.
Posteriorly (lower part): cutaneous branch from the radial nerve – from the posterior cord.
Laterally and posteriorly: lateral brachial cutaneous nerve from axillary nerve – from the posterior cord.

Practical tips

The ulnar nerve has lack the branches on the level of the upper arm.

The brachial artery descends as a continuation of the axillary artery. Begins at the inferior border of the pectoralis major muscle and ends in the cubital fossa, where it divides into two terminal branches. It is situated medial to the humerus, descends with the median nerve and gives off the following branches:

The deep brachial artery: largest branch, accompanies the radial nerve and descends in the radial groove of the humerus. It divides into terminal branches:

middle collateral artery
radial collateral artery, which gives off:
- anterior branch
- posterior branch

Both these branches (anterior, and posterior) supply the arterial anastomoses around the elbow.

Relations of the recurrent and collateral arteries. Anterior view of the arterial anastomoses of elbow joint.

The superior collateral ulnar artery – accompanies the ulnar nerve, runs downward and joins the arterial anastomoses around the elbow.

The inferior collateralulnar artery – arises from brachial artery below the superior ulnar artery, also runs downwards and divides into two terminal branches:

Anterior branch
Posterior branch

These branches also supply the arterial anastomoses around the elbow.

Relations of the recurrent and collateral arteries. Posterior view of the arterial anastomoses of the elbow joint.

Unnamed muscular branches

Terminal branches of brachial artery (ends in the cubital cavity):

Radial artery
Ulnar artery

Two brachial veins accompany the brachial artery and these veins receive blood from two radial veins and two ulnar veins and from one of two main superficial veins of upper limb – the basilic vein, which pierces brachial fascia in the one third of the medial side of the arm and joins one of the brachial veins.

Two main superficial veins pass along the medial and lateral sides of the forearm and arm. On the anterior surface of the cubital region they are connected by the is also joined by the arterial median vein of the forearm.

The forearm

The forearm is enclosed in a sheath of antebrachial fascia. The fascia sheath is partially made by interosseus membrane. Fascia attaches to posterior border of ulna and it contains intermuscular septa which divide forearm into compartments, which contain groups of muscles and vessels.

There are three main fibroosseus compartments:

anterior: for flexors
lateral: for lateral extensors
posterior: for dorsal extensors

The deep fascia forms the flexor retinaculum,which stretches across the front of the wrist and the extensor retinaculum which stretches across the back of the wrist. The flexor retinaculum converts the concave anterior surface of the carpus into a carpal tunnel for passage of tendons of flexor muscles (four tendons of flexor digitorum superficialis, four tendons of the flexor digitorum profundus, one of the flexor carpi ulnaris and one of flexor carpi radialis).

Muscles of the forearm are divided into three groups:

The superficial group of the flexors of the forearm contains four muscles and all of them arise from the medial epicondyle of the humerus (also partly origin of the flexor digitorum superficialis: middle group) as a common flexor attachment.

The pronator teres muscle has two heads of the proximal attachment, which units next and between them passes the median nerve; brachial artery divides into radial and ulnar arteries on muscle and radial artery passes above muscle, ulnar artery passes below muscle.

Proximal insertion (humeral head): medial intermuscular septum, medial epicondyle.
Proximal insertion (ulnar head): ulnar head coronoid process of ulna.
Distal Insertion: tuberosity of the radius.
Action: pronation and flexion of the forearm.
Nerve supply: median nerve.

The flexor carpi radialis muscle with tendon of this muscle passes the radial artery and superficial branch of radial artery.

Proximal Insertion: antebrachial fascia.
Distal Insertion: bases of the 2nd and 3rd metacarpal.
Action: flexion and pronation of the forearm, flexion and abduction of the hand.
Nerve supply: median nerve.

The palmaris longus muscle. It’s tendon passes superficially to the flexor retinaculum.

Proximal Insertion: antebrachial fascia.
Distal Insertion: transversal carpal ligament, palmar aponeurosis.
Action: flexion of the hand and forearm and pronation of forearm.
Nerve supply: median nerve.

The flexor carpi ulnaris muscle has two heads and his tendon is a good guide for ulnar artery and nerve.

Proximal Insertion (Humeral head): medial epicondyle and antebrachial fascia.
Proximal Insertion (Ulnar head): antebrachial fascia, posterior side of olecranon and posterior border of ulna.
Distal Insertion: Pisiform.
Action: Flexion of the hand, adduction of the hand.
Nerves: Ulnar nerve.

The intermediate group of the flexors of the forearm muscles contains just only one muscle:

The flexor digitorum superficialis muscle, which has also two heads and gives rise to four tendons; median nerve and ulnar vessels pass below this muscle.

Proximal Insertion (humeroulnar head): medial epicondyle and coronoid process.
Proximal Insertion (radial head): proximal end of radius.
Distal Insertion: sides of the 2nd phalanx of four fingers.
Action: flexion of proximal and middle phalanxes and hand.
Nerves: median nerve.

The deep group of forearm muscles contains three muscles:

Proximal Insertion: 2/3 of upper anteromedial part ulna and interooseus membrane; it divides into four parts and end in four tendons. Each tendon passes through a division in the corresponding tendon of the superficialis muscle into the base of the distal phalanges.
Distal Insertion: bases of terminal phalanges of four fingers.
Action: flexion of terminal phalanges and hand, adduction of hand.
Nerves: radial part – median nerve, ulnar part – ulnar nerve.

The flexor pollicus longus muscle radial artery and vein lies on this muscle.

Proximal Insertion: anterior side of radius, medial epicondyle and interosseus membrane.
Distal Insertion:base of distal phalanx of thumb.
Action: flexion of the thumb, flexion and abduction of hand.
Nerves: anterior interosseus nerve of forearm.

Proximal Insertion: ¼ of anterior and posterior part of distal ulna.
Distal Insertion: ¼ of anterior and posterior part of distal radius.
Action: pronation of the hand.
Nerves: anterior interosseus nerve of forearm.

The superficial group of the dorsal antebrachial muscles – superficial extensors of the forearm. All muscles of that group are attached to the lateral epicondyle by the common tendon, also all of them are supplied by the radial nerve.

The brachioradialis muscle. Along tendon of that muscle passes the superficial part of the radial nerve with radial vessels.

Proximal Insertion: lateral part of humerus, lateral intermuscular septum.
Distal Insertion: radial styloid process.
Action: flexion of the forearm.

Proximal Insertion: lateral epicondyle and lateral intermuscular septum.
Distal Insertion: dorsal base of the 2nd metacarpal.
Action: extension and abduction of the hand, flexion of forearm.

Proximal Insertion: lateral epicondyle and antebrachial fascia.
Distal Insertion: dorsal base of the 3nd metacarpal (styloid process).
Action: extension of the hand.

Proximal Insertion supinator crest, radial collateral ligament, annular ligament and lateral epicondyle.
Distal Insertion: tuberosity of the radius, oblique line of radius.
Action: supination of the hand and forearm.

Proximal Insertion: lateral epicondyle, radial collateral ligament, annular ligament and antebrachial fascia.
Distal Insertion: dorsal surface mid. base of distal phalanges of four fingers.
Action: extension of the phalanges and hand and abduction of phalanges.

Proximal Insertion: lateral epicondyle.
Distal Insertion: dorsal aponeurosis, proximal phalanx of little finger.
Action: extension and adduction of the little finger.

Proximal Insertion: lateral epicondyle,radial collateral ligament, antebrachial fascia, posterior part of ulna.
Distal Insertion: base of 5th metacarpal.
Action: extension and abduction of the hand.

Proximal Insertion: lateral epicondyle and radial collateral ligament.
Distal Insertion: olecranon.
Action: extension of the forearm.

The deep group of the dorsal antebrachial muscles contains five muscles, which are supplied by the deep branch of the radial nerve.

Proximal Insertion: interosseus membrane, dorsal surfaces of radius and ulna.
Distal Insertion: lateral side of base of first metacarpal and trapezium.
Action: abduction and flexion of the thumb and hand.

Proximal Insertion: ateral side of dorsal surface of ulna and intermuscular membrane.
Distal Insertion: base of distal phalanx of the thumb.
Action: extension of distal phalanx of the thumb, adduction of the hand.

Proximal Insertion: dorsal radius, interosseus membrane.
Distal Insertion: base of proximal phalanx of the thumb.
Action: extension of the first phalanx of the thumb, abduction of the hand and thumb.

Proximal Insertion: dorsal ulna, interosseus membrane.
Distal Insertion: tendon of extensor digitorum communis, index finger.
Action: extension and abduction of index, helps extend hand.

The cubital fossa (fossa cubitalis) is a triangular shaped area and it is bounded by:

superiorly: imaginary line between the epicondyles of the humerus, brachialis and biceps brachii divide cubital fossa in lateral and medial parts.
medially: the pronator teres muscle.
laterally: the brachioradialis muscle, extensor carpi radialis longus, extensor carpi radialis brevis
the floor of the cubital fossa is formed by brachialis and suppinator muscles.
the roof is formed by fascia and bicipital aponeurosis – cubital fascia, part of antebrachial fascia.

Contents:

The biceps tendon
Brachial artey and it’s terminal branches – radial artery, ulnar artery
Brachial vein
Median nerve
Radial nerve
Radial collateral artery

The flexor retinaculum forms a tough band of carpal tunnel, it closes carpal groove and projects from the medial (ulnar side) carpal bones (pisiform and hamate) to the lateral carpal bones (scaphoid and trapezium). The retinaculum crosses superficial to the tendons of flexor digitorum superficial muscle and median nerve to separate these structures from the tendon of palmaris longus muscle (superficial and central in position) and ulnar nerve and ulnar vessels, which are situated between superficial and deep layer of the flexor retinaculum. The latter structures are sandwiched between the retinaculum (deep to them) and the superficially placed palmar carpal ligament.

Contents:

Ten tendons of the flexores muscles
The median nerve

The extensor retinaculum: crosses from styloid process of ulna to pisiform and triquetrum.The extensor tendons are arranged in one row which circumscribes the distal extremity of the radius and ulna. The extensor retinaculum covers the superficial (external) aspect of the extensor tendons and under that retinaculum we can identify six separate tunels for the passage of the long extensor tendons. Each tunel is lined with a synowial sheath.

Intertendinous connections are transverse and oblique fibres which are present between tendons of extensor digitorum muscle. Usually there are three intertendinous connections.

Flexor and extensor retinaculums form canals for muscles and blood vessels. Tendons of muscles are surrounded by carpal tendinous sheath.

There are following ones:

Palmar carpal tendinous sheath: tendinous sheath of flexor ollicis longus, tendinous sheath of flexor carpi radialis, common flexor sheath.

Dorsal carpal tendinous sheath: tendinous sheath of abductor longus and extensor pollicis brevis, tendinous sheath of extensors carpi radials, tendinous sheath of extensor pollicis longus, tendinous sheath of extensor digitorum and extensor indicis, tendinous sheath of extensor minimi brevis, tendinous sheath of extensor carpi ulnaris.

Fibrous sheaths of digits of hand: anular part of fibrous sheath, cruciform part of fibrous sheath.

Synovial sheaths of digits of hand: vincula tendinum (long vinculum, short vinculum).

The hand

The antebrachial fascia continues distally as a fascia of the hand. The fascia of the palm is thin over the thena and hypothenar eminences, but is thick in the middle part where forms palmar aponeurosis, triangular in shape. The fascia divides hand into compartments, which contain the separate groups of muscles. Septums which divide muscles are called palmar radial and palmar ulnar septums.

Fascia consist of four parts:

deep palmar fascia of hand
deep dorsal fascia of hand
superficial dorsal fascia of hand
superficial palmar fascia of hand, which forms in central part palmar aponeurosis.It forms superficial transverse metacarpal ligaments (between II – V fingers) and transverse fasciculi (proximally to ligaments between II – V fingers).

Muscles of the hand are divided into three groups:

Proximal Insertion (superficial head): flexor retinaculum.
Proximal Insertion (deep head): carpal groove.
Distal Insertion: base of 1st phalanx of 1st finger.
Action: flexes, abducts and adducts the thumb, also opposites thumb.
Nerves: superficial head – median nerve deep head – ulnar nerve.

Proximal Insertion: flexor retinaculum, trapezium, scaphoid.
Distal Insertion: lateral side of base of proximal phalanx of thumb.
Action: abducts, opposits and flexes thumb.
Nerves: median nerve.

Proximal Insertion: flexor retinaculum.
Distal Insertion: radial side of 1st metacarpal.
Action: abducts, flexes and rotates the metacarpal of thumb.

Proximal Insertion (oblique head): capitate, bases of 2nd and 3rd metacarpals.
Proximal Insertion (transverse head): third metacarpal.
Distal Insertion: medial side of base of 1st phalanx, sesamoid bone,on metacarpophalangeal joint of thumb.
Action: adducts thumb.
Nerves: ulnar nerve.

The hypothenar muscles (All are inervated by the ulnar nerve).

Proximal Insertion: flexor retinaculum, palmar aponeurosis.
Distal Insertion: skin,medial border of the palm.
Action: wrinkles skin.

Proximal Insertion: pisiform, flexor retinaculum, pisohamatum ligament.
Distal Insertion: medial side base of 1st phalanx of small finger.
Action: abducts small finger, flexes first phalanx, extend interphalangeal joint.

Proximal Insertion: hamulus of hamate, flexor retinaculum.
Distal Insertion: medial side base of 1st phalanx of small finger.
Action: flexes first phalanx of small finger.

Proximal Insertion: hamulus of hamate, flexor retinaculum.
Distal Insertion: medial side, shaft of 5th metacarpal.
Action: opponens 5th finger, also flexes, abducts and rotates.

The intermediate muscles are subdivided into two groups:

The lumbricales muscles are four small, fleshy fasciculi, which are associated with tendons of the digitorum profundus. These two radial muscles arise from the lateral side of the tendons of the digitorum profundus and two ulnar muscles attach to medial and lateral sides of neighbouring tendons of digitorum profundus. Each tendon passes on anterior surface of deep transverse metacarpal ligaments and attachs to the radial side of the corresponding proximal phalanx of II – V fingers.

Action: flex the metacarpophalangeal joints and extends the two distal phalanges.
Nerves: 1st and 2nd by branches of median 3rd and 4th by branches of ulnar nerve.

The interossei muscles are subdivided into palmar and dorsal group. All interossei are innervated by branches from the ulnar nerve.

Three muscles, which attach to proximal insertion and then pass on posterior surface of deep transverse metacarpal ligaments and attachs to distal insertion.

Origin (1^st): medial side of 2nd metacarpal.
Origin (2^nd): lateral side of 4nd metacarpal.
Origin (3^rd): lateral side of 5th metacarpal.
Inserion (1st): medial side of metacarpophalangeal joints and extensor expansions.
Inserion (2nd and 3rd): lateral sides of metacarpophalangeal joints and extensor expansions
Action: all adduct fingers: 2nd, 4th and 5th into third finger, and flex the metacarpophalangeal joints, and extends the two distal phalanges.

Four muscles, which attach to proximal insertion and then pass on posterior surface of deep transverse metacarpal ligaments and attachs to distal insertion.

Origin: each adajcent sides of two metacarpal bones I – V
Insertion (1st and 2nd): medial sides of metacarpophalangeal joints and extensor expansions of II and III
Insertion (3rd and 4th): lateral sides and extensor expansions of medial sides of III and IV
Action: abduct fingers and flex the metacarpophalangeal joints and extends the two distal phalanges.

The flow chart of the muscles of the hand.

Innervation of the forearm and hand

Median nerve leaves the cubital fossa between heads of the pronator teres muscle and descends between two flexores digitorum (superficial and profundus), then it passes between flexor carpi radialis and palmaris longus On the wrist lies more superficial ,but under flexor retinaculum.

On forearm it gives off:

The anterior interosseus nerve it supplies deep flexor muscles, interosseus membrane, radiocarpal joint, wrist joints.
Muscular branches which supply all antebrachial flexores except the medial half of the flexor digitorum profundus and the flexor carpi ulnaris.
Palmar branch which divides in lateral and medial branches and supplies skin of palm and skin over thenar.

Next it passes under the carpal tunel and divides into terminal branches:

Branch to thenar muscles.
Common palmar digital nerves three muscles which divide in two or three proper palmar digital nerves:
- Common palmar digital nerve of first finger: it supplies first lumbricale muscle and part of palm skin, palmar side of thumb and radial side of index.
- Common palmar digital nerve of second finger: it supplies second lumbricale muscle and skin on ulnar side of index and radial side of medius.
- Common palmar digital nerve of third finger: it supplies often third lumbricale muscle and skin on ulnar side of medius and radial side of ring, it has communicating branch with ulnar nerve.

Clinical comments

When the median nerve is damaged, if the patient tries to make a fist, the index and partly the middle finger tend to remain stright, while the ring and the little fingers flex – blessing hand.

Ulnar nerve (nervus ulnaris) turns around the medial epicondyle of humerus passes between two heads of the flexor carpi ulnaris and runs downwards under that muscle and then between flexor carpi ulnaris and flexor digitorum profundus with the ulnar artery, and medially to it. It supplies part of the elbow joint ,the medial half of the flexor digitorum profundus and the flexor carpi ulnaris.

It gives off on forearm:

Muscular branches to the medial half of the flexor digitorum profundus and the flexor carpi ulnari
Nerve for ulnar artery.
Dorsal branch which subdives in usually five dorsal digital nerves and supply skin on proximal and middle phalanges of minimus and ring and radial side of medius.

After giving off dorsal branch the ulnar nerve change name in palmar branch, and terminates dividing into two terminal branches:

Deep branch: supplies the hypothenar, 3rd and 4th lumbricales, interossei muscles, also adductor pollicis and deep head of flexor pollicis brevis.
Superficial branch: suddivides into:
- Common palmar digital nerve of IV finger – subdivide in proper digital nerves
  which supply lateral side of minimus and medial side of ring.
- Proper palmar digital nerve of medial part V finger. Proper digital nerves supply skin palmar surface and dorsal surface over middle and distal phalanges.

Clinical comments

The ulnar nerve injury gives the characteristic apperance of the hand is known as claw-hand. Usually this nerve is damaged or is compressed when the elbow hits a hard surface, because is covered only by fascia and skin (when turn round the medial epicondyle).

Radial nerve divides in the cubital fossa into two branches:

Superficial branch continues generally course of the radial nerve and descends under tendon of the brachioradialis muscle. In the distal part of the forearm that branch pierces the posterior deep fascia and runs to the hand. There supplies the skin on dorsal surface on thumb and 2nd finger and lateral half of the 3rd finger exept distal parts of these fingers.

It gives off:

Dorsal digital nerves – five nerves which supply both sides of thumb index and lateral side of medius (they supply dorsal surface of these fingers ver proximal and middle phalanges).
Communicating branch with ulnar erves.

Deep branch passes through the suppinator muscle, turn around lateral side of the radius and supplies posterior muscles of the forearm.

It gives off:

posterior interosseus nerve of forearm.
muscular branches for extensors and sometimes to lateral group of extensors.

Before dividing into distal branches radial nerve gives off posterior cutaneous nerve of forearm.

Medially: by the medial antebrachial cutaneus nerve, from medial cord of brachial plexus
Laterally: by lateral antebrachial cutaneus nerve, from musculocutaneus nerve
Posteriorly: by posterior cutaneus nerve of of forearm, from radial nerve

Arterial supply of the forearm and hand

Radial artery is the smaller terminal branch of the brachial artery. It crosses lateraly under the bicipital aponeurosis, and next descends with the superficial branch of radial nerve under tendon of the brachioradialis muscle. Near the wrist it lies superficialy just under the fascia and skin.

Clinical comments

In that point we can measure the pulse rate, becouse the radial artery can be compresed against the distsal end of the radius. Remember, don’t used the pulb of the thumb to measure the puls rate, because you can interpreted yours pulse rate as a patient’s.

Then radial artery turns dorsaly and passes under the tendons of the abductor pollicis longus and extensor pollicis brevis muscles.It crosses the anatomical snuff-box (bordered by the abductor pollicis longus and extensor pollicis brevis muscles lateraly and by the extensor pollicis longus medialy) and there can be palpated too. At the end it finishes as deep palmar arch.

The anatomical snuffbox.

The radial artery gives off following branches:

The radial recurrent artery, which ascends to supply the arterial anastomoses around the elbow.
The superficial palmar branch anastomoses with the ulnar artery to form the superficial palmar arch.
The palmar and dorsal carpal branches to the palmar and dorsal carpal arches.
Princeps pollicis artery, which divides into two or three branches for palmar side of the thumb and lateral side of the index finger.
First metacarpal dorsal artery, which divides next into two dorsal digital arteries.

Ulnar artery is the lager one of two terminal branches of the brachial artery, runs downwards between flexor digitorum superficialis and flexor digitorum profundus with the ulnar nerve. Then it passes along lateral border of flexor carpi ulnaris. It passes on the wrist superficialy to the flexor retinaculum, laterally to pisiform and forms superficial palmar arch.

It gives off following branches:

The ulnar recurrent artery, which subdivide into anterior and posterior branches and anastomoses with the other arterial anastomoses around the elbow.
The common interosseus artery: arises in the cubbital fossa and divides into two branches:
- anterior interosseus artery which passes anteriorly to the membrane and supplies the pronator quadratus.
- posterior interosseus arteries. which sends branch to arterial anastomoses around the elbow, which is called the recurrent interosseus artery and descends posteriorly to the membrane, supplies extensores muscles.
The palmar and dorsal carpal branches to the palmar and dorsal carpal arches.
The deep branch of the ulnar artery anastomoses with the radial artery to forms the deep palmar arch.

Descending branches:

Inferior ulnar collateral artery (anterior and posterior branch).
Superior ulnar collateral artery.
Collateral radial artery (anterior and posterior branch).
Collateral medial artery, branch from deep brachial artery.

Ascending branches:

Recurent radial artery (anterior and posterior branch).
Recurent ulnar artery (anterior and posterior branch).
Recurent interosseus artery.

The superficial palmar arch is situated distally and superficially to the deep arch. It is formed by the junction of ulnar artery with the superficial branch of the radial artery. It gives rise to three common palmar digital arteries for II-IV fingers. Each of common palmar arteries next subdivides into a pair of proper palmar digital arteries, which pass along lateral and medial palmar margins to the pulp of each finger.

The deep palmar arch is formed by the junction of the radial artery with the deep branch of the ulnar artery. It is situated on the bases of the metacarpal bones. It gives off the palmar metacarpal arteries, which join the common palmar digital arteries just before their subdividions into the proper palmar digital arteries. The palmar metacarpal arteries gives off the perforating branches (anterior and posterior) which anastomoses with the dorsal metacarpal arteries.

Dorsal carpal arterial arch is formed by:

Dorsal carpal branch from the ulnar artery
Dorsal carpal branch from the radial artery
Terminal branch of the anterior interosseus artery
Terminal branch of the posterior interosseus artery

Dorsal carpal arterial arch is located on the dorsum of the hand and gives off the common dorsal metacarpal arteries (from dorsal carpal arch) and they recives perforanting branches, which anastomoses with the palmar metacarpal arteries. Each of the common dorsal metacarpal arteries divides into two proper dorsal digital arteries, which pass along dorsal margins of II – V fingers and terminate at the level of the distal interphalanx joints. Medial side of thumb and lateral side of index are supplied by princeps pollicis artery The skin of the dorsal surface of the distal phalanx is supplied by the small branches from the proper palmar digital arteries.

Palmar carpal arterial arch Is formed by:

Palmar carpal branch from the radial artery.
Palmar carpal branch from the ulnar artery.
Terminal branch of the anterior interosseus artery.
Recurent branches from the deep palmar arch.

Venous drainage of the forearm and hand

The cephalic and the basilic veins take origin from the dorsal venosus arch and partly also, first one, from the cephalic vein of the thumb (vena cephalica pollicis), which is called the lateral marginal vein (vena marginalis lateralis). The basilic vein recives blood also from the basilic vein of the fifth finger (vena basilica digiti minimi), which is also called the medial marginal vein (vena marginalis medialis).

Following superficial veins are present on the forearm:

cephalic vein of forearm
basilic vein of forearm
median cubital vein
median antebrachial vein

Deep veins on the forearm acompanies arteries. Usually two veins accompany the same named artery. On the hand the superficial and deep palmar arterial arches are acompanied by venae comitantes. Palmar metacarpal veins, which unit to form a deep palmar venosus arch.