Axillary and Median Nerve
Musculoskeletal block - Anatomy - lecture 6
Editing file Color guide : Only in boys slides in Blue Objectives Only in girls slides in Purple important in Red By the end of the lecture, students should be able to: Doctor note in Green Extra information in Grey ✓ Describe the origin, course, relations, branches and distribution of the axillary & median nerves
✓ Describe the common causes and effects of injury to the axillary and median nerves Brachial plexus
Remember To Drink Cold Beer Axillary Nerve
Origin Course Branches
(C 5 & 6) - It passes inferiorly and Posterior cord of laterally along the brachial plexus. posterior wall of the axilla to exit. أي ﻋﺻب ﻧﺎﺧذه ﻻزم ﻧﻌرف ﻣن أي ﻗطﻊ ﻣن اﻟﺳﺑﺎﯾﻧل ﻛورد ﺟﺎء ، ﻷن أي ﺿرر ﯾﺻﯾر ﻓﯾﮭم ھو أﯾﺿﺎً راح ﯾﺗﺄﺛر.
-Then, it passes posteriorly (Motor) (Sensory) around the surgical neck of to the deltoid and superior lateral cutaneous the humerus. teres minor nerve of arm that loops muscles. around the posterior -It is accompanied by the margin of the deltoid posterior muscle to innervate skin in circumflex humeral artery. that region. Axillary Nerve
Lesions affects The axillary nerve is usually injured due to:
● Fracture of surgical neck of the humerus
Motor: Sensory: ● Downward 1- Impaired abduction of the shoulder (15-90˚) Loss of dislocation of the Note: the patient CANNOT raise his arm over 30˚. sensation shoulder joint 2- Paralysis of the deltoid and teres minor over the lateral muscles side of the (The paralyzed deltoid wastes rapidly proximal part As the deltoid atrophies, the rounded contour of the of the arm. ● Compression from shoulder is flattened compared to the uninjured the incorrect use side). of crutches Median Nerve
Origin
(C5,6,7, 8, T1)
The median nerve is formed anterior to the third part of the axillary artery by the union of lateral and medial roots
• The lateral root (C5,6&7), arises from the lateral cord of the brachial plexus. • The medial root (C8 & T1), arises from the medial cord of the brachial plexus. originating from the lateral and medial cords of the brachial plexus. Note: Axillary artery is named Brachial artery when it reaches the arm Median Nerve
In the arm Note that
It enters the arm from the axilla at the ● The median nerve has NO inferior margin of the teres major major branches in the arm muscle. or axilla, but a branch to It passes vertically down the medial Brachial artery side of the arm in the anterior one of the muscles of the compartment and is related to the forearms, the (Pronator brachial artery throughout its course: Teres), this branch may ● In proximal regions (In upper 1⁄2 of the originate from the nerve arm), it lies immediately lateral to the immediately proximal to brachial artery. the elbow joint. ● In more distal regions (In the middle of the arm), it crosses the medial side of the brachial artery. ● In the lower 1⁄2 it descends on the medial side of the brachial artery. ● It descends anterior to the elbow joint. Note: Flexor retinaculum is a fibrous tissue: Retinaculum = Deep fascia flexor = in the middle Median Nerve
Median nerve passes into the The median nerve continues into the forearm anterior to the elbow hand by passing deep to the flexor joint(between the 2 heads of retinaculum. It innervates: pronator teres) where it branches innervates most ● Three thenar eminence muscles of the muscles in the anterior associated with the thumb. compartment of the forearm (6.5 ● Lateral two lumbrical muscles muscles) Except the: associated with movement of ● Flexor Carpi Ulnaris the index and middle finger. ● the medial half of the Flexor ● Skin over the palmar surface of Digitorum Profundus the lateral three and one- half (which are innervated by the digits and over the lateral side ulnar nerve). of the palm and middle of the wrist. (The lateral 2/3rd of the palm of the hand.) Median Nerve Lesions
Injury of the median nerve at different levels causes different syndromes - In the arm and forearm the median nerve is usually not injured by trauma, why ? Because of its relatively deep position.
Sites of damage Serious effects
Loss of opposition of the Loss of sensation: thumb: from the thumb and lateral 3½ In the carpal tunnel (deep The delicate pincer- like action fingers & lateral ⅔ of the palm. in the flexor retinaculum) is not possible. اﺧﻄﺮ ﺷﻲ ﻻن ﻣﺎ ﻓﻲ ﻋﻀﻠﺔ ﺛﺎﻧﯿﺔ ﺗﺴﻮي ﻧﻔﺲ اﻟﺤﺮﻛﺔ أو ﻋﺼﺐ ﺛﺎﻧﻲ ﯾﻌﻮض
At the wrist above the flexor retinaculum
In the elbow region (supracondylar fracture of the humerus) Lesion About Motor Sensory and tropic
● Loss of pronation. Sensory: ● Hand is kept in supine position. Loss of sensation from: ● Wrist shows weak flexion, and ● The radial side ⅔ of the ulnar deviation. (cause there is no muscle to antagonise the action of the ulnaris) palm. ● Loss of flexion on the ● Palmar aspect of the interphalangeal joints of the lateral 3½ fingers. Damaged in supracondylar fracture of index and middle fingers. ● Distal part of the dorsal Median humerus ● Weak flexion of ring and little surface of the lateral 3½ Nerve Muscles affected are: fingers. ● Thumb is adducted (cause the fingers. Lesion in ● Pronator muscles of the forearm (they adductor muscle is not supplied by the median nerve) and laterally rotated, with the Elbow will always be supinated) ● All long flexors of the wrist and loss of flexion of terminal Region phalanx and loss of opposition. fingers except flexor carpi ulnaris ● Wasting of thenar eminence. and medial half of flexor ● Hand looks flattened and “apelike”,and presents an Trophic Changes: digitorum profundus inability to flex the three most ● Dry and scaly skin radial digits when asked to make a fist. ● Easily cracking nails Supinator ● Atrophy of the pulp of The index and Flex.Dig. Pronator teres Superficialis middle fingers are the fingers extended because of Wasting of Flex.carpi the antagonist radialis thenar eminence muscle Extra Flex.pol.long us Flex.carpi ulnaris Lesion About Motor Sensory Often injured by penetrating wounds (stab Thenar muscles are Sensory: Loss of sensation from: wounds or broken glass) of the forearm. paralyzed and atrophy (ﻟﻤﺎ اﻟﺸﺨﺺ ﯾﺤﺎول ﯾﻨﺘﺤﺮ) Median Nerve happens with time so that ● The radial side of the palm. the thenar eminence ● Palmar aspect of the lateral Lesion at the NOTE: You have to know each deformity and becomes flattened. 3½ fingers. Wrist the muscles/nerves involved. ● Distal part of the dorsal Opposition and abduction surface of the lateral 3½ of thumb are lost, and fingers. thumb and lateral two
fingers are arrested in Trophic Changes: adduction and hyperextension position. ● Dry and scaly skin ● Easily cracking nails “Apelike hand” ● Atrophy of the pulp of the fingers
are the same as in the elbow region injuries. Median Nerve The most common neurological problem Weak motor function of Burning pain or ‘pins Lesion associated with the median nerve is the thumb, index & middle and needles’ along the deep in flexor compression beneath the flexor retinaculum distribution of median nerve to fingers. lateral 3½ fingers. retinaculum at the wrist. “Carpal Tunnel The symptoms first appear as sensory but Syndrome” No sensory changes over the palm when it progresses further the motor as the palmar cutaneous branch is symptoms appear. given before the median nerve enters the carpal tunnel. most common in postmenopausal women SUMMARY MCQs
Question 1: The median nerve continues into the hand by passing deep to the? Question 5: Loss of pronation is a motor effect of: A. Flexor retinaculum A. Median nerve injury in elbow B. Brachialis B. Median nerve injury at the wrist C. Coracobrachialis C. Axillary nerve injury D. Extensor digitorum longus D. Median nerve injury in the carpal tunnel Question 2: The median nerve originate from: Question 6: A patient complaining of pins and needles sensation along the medial side of A. Lateral cord the upper limb and the 3 lateral fingers, that would indicate: B. Medial cord A.Median Nerve Lesion in the Elbow Region C. Both B & A B. Carpal tunnel syndrome D. Posterior cord C. Surgical neck fracture Question 3: Which one of the following is a sensory supply of the median nerve? D.Median Nerve Lesion at the wrist A. 3 thenar Muscles B. 3 hypothenar Muscles SAQ C. Palmer lateral 3 and a half digit D. Palmer medial 1 and a half digit Question 1: One of the trophic changes in Median Nerve Lesion in the Elbow Question 4: A physician examined an X ray and saw that the patient had a Region? fracture in the surgical neck, which nerve will he be worried about? Dry and scaly skin A. brachial B. Radial Question 2: Where are the axillary motor branches located? C. Musculocutaneous In the deltoid and teres minor muscles. D. Axillary Answers: Q1.A- Q2.C -Q3.C -Q4.D- Q5.A- Q6.B Team members
Girls team : Boys team:
● Ajeed Al Rashoud ● Khalid AL-Dossari ● Taif Alotaibi ● Naif Al-Dossari ● Noura Al Turki ● Faisal Alqifari ● Amirah Al-Zahrani ● Salman Alagla ● Alhanouf Al-haluli Special thank for ● Ziyad Al-jofan ● Sara Al-Abdulkarem ● Suhail Basuhail ● Rawan Al Zayed Anatomy team 436 ● Ali Aldawood ● Reema Al Masoud ● Khalid Nagshabandi ● Renad Al Haqbani ● Mohammed Al-huqbani ● Nouf Al Humaidhi ● Jehad Alorainy ● Fay Al Buqami ● Khalid AlKhani ● Jude Al Khalifah ● Omar Alammari ● Nouf Al Hussaini ● Alwateen Al Balawi ● Rahaf Al Shabri ● Danah Al Halees Team leaders ● Haifa Al Waily ● Rema Al Mutawa ● Abdulrahman Shadid ● Amirah Al Dakhilallah Good luck ● Ateen Almutairi ● Maha Al Nahdi ● Renad Al Mutawa Give us your feedback: ● Ghaida Al Braithen ● Reham Yousef =This lecture done by