09/03/2021 [muscles of the hand, muscles of the forearm, stomach physiology, Korsakoff syndrome, narcolepsy] Flashcards
What can the muscles on the hand be divided into? [2]
Extrinsic muscles: anterior/posterior of the forearm, control crude movements and produce forceful grip
Intrinsic muscles: fine motor functions of the hand
Name the thenar muscles of the hand
- Opponens pollicis
- Abductor pollicis brevis
- Flexor pollicis brevis
What do the thenar muscles produce? And what innervates them?
Produce the thenar eminence of the hand.
The median nerve innervates them.
Attachments, actions, location and innervation of the opponens pollicis
The largest of the thenar muscle underlies the other two:
- attachment: tubercle of the trapezium, associated flexor retinaculum. Inserts into the lateral margin of the metacarpal of the thumb [i.e. the first metacarpal]
- action: opposes the thumb, by medially rotating and flexing the metacarpal on the trapezium
Attachment, action, location and innervation of the abductor pollicis brevis
This muscle is found anteriorly to the opponens pollicis and proximal to the flexor pollicis brevis.
Attachments: Originates from the tubercles of the scaphoid and trapezium, and from the associated flexor retinaculum. Attaches to lateral side of proximal phalanx of the thumb.
Actions: Abducts the thumb.
Innervation: Median nerve
Flexor pollicis brevis
The most distal of the thenar muscles.
Attachments: Originates from the tubercle of the trapezium and from the associated flexor retinaculum. Attaches to the base of the proximal phalanx of the thumb.
Actions: Flexes the metacarpophalangeal (MCP) joint of the thumb.
Innervation: Median nerve. The deep head is innervated by the deep branch of the ulnar nerve
What do thh hypothenar muscles produce? And what is their innervation?
The hypothenar muscles produce the hypothenar eminence – a muscular protrusion on the medial side of the palm, at the base of the little finger. These muscles are similar to the thenar muscles in both name and organisation.
The ulnar nerve innervates the muscles of the hypothenar eminence
Location, attachment, action and innervation of the opponens digiti minimi
The opponens digit minimi lies deep to the other hypothenar muscles.
Attachments: Originates from the hook of hamate and associated flexor retinaculum, inserts into the medial margin of metacarpal V.
Actions: It rotates the metacarpal of the little finger towards the palm, producing opposition.
Innervation: Ulnar nerve
Abductor digiti minimi
The most superficial of the hypothenar muscles.
Attachments: Originates from the pisiform and the tendon of the flexor carpi ulnaris. It attaches to the base of the proximal phalanx of the little finger.
Actions: Abducts the little finger.
Innervation: Ulnar nerve
Flexor digiti minimi brevis
This muscle lies laterally to the abductor digiti minimi.
Attachments: Originates from the hook of hamate and adjacent flexor retinaculum, and inserts into the base of the proximal phalanx of the little finger.
Actions: Flexes the MCP joint of the little finger.
Innervation: Ulnar nerve
What can denervation of the lumbrical muscles lead to?
Ulnar claw and hand of benediction
Location, attachment, actions and innervation of the lumbricals
Attachments: Each lumbrical originates from a tendon of the flexor digitorum profundus. They pass dorsally and laterally around each finger, and inserts into the extensor hood.
Actions: Flexion at the MCP joint and extension at the interphalangeal (IP) joints of each digit.
Innervation: The lateral two lumbricals (of the index and middle fingers) are innervated by the median nerve. The medial two lumbricals (of the little and ring fingers) are innervated by the ulnar nerve.
Names of the four lumbricals
I [unipennate], II [unipennate], III [bipennate], IV [bipennate]
Location and action of the interossei
The interossei muscles are located between the metacarpals. They can be divided into two groups: the dorsal and palmar interossei.
In addition to their actions of abduction (dorsal interossei) and adduction (palmar interossei) of the fingers, the interossei also assist the lumbricals in flexion at the MCP joints and extension at the IP joints
Location, attachment, action and innervation of the dorsal interossei
The most superficial of all dorsal muscles, these can be palpated on the dorsum of the hand. There are four dorsal interossei muscles.
Attachments: Each interossei originates from the lateral and medial surfaces of the metacarpals. They attach into the extensor hood and proximal phalanx of each finger.
Actions: Abduct the fingers at the MCP joint.
Innervation: Ulnar nerve
Palmar interossei
These are located anteriorly on the hand. There are three palmar interossei muscles – although some texts report a fourth muscle at the base of the proximal phalanx of the thumb.
Attachments: Each interossei originates from a medial or lateral surface of a metacarpal, and attaches into the extensor hood and proximal phalanx of same finger.
Actions: Adducts the fingers at the MCP joint.
Innervation: Ulnar nerve
What are the two other muscles of the pal that are not lumricals/interossei and do not fit into the hypothenar/thenar compartments
Palmaris brevis
Adductor brevis
Location, attachments, actions, innervation of the palmaris brevis
This is a small, thin muscle, found very superficially in the subcutaneous tissue of the hypothenar eminence.
Attachments: Originates from the palmar aponeurosis and flexor retinaculum, attaches to the dermis of the skin on the medial margin of the hand.
Actions: Wrinkles the skin of the hypothenar eminence and deepens the curvature of the hand, improving grip.
Innervation: Ulnar nerve
Location, attachments, innervation of the adductor pollicis
This is large triangular muscle with two heads. The radial artery passes anteriorly through the space between the two heads, forming the deep palmar arch.
Attachments: One head originates from metacarpal III. The other head originates from the capitate and adjacent areas of metacarpals II and III. Both attach into the base of the proximal phalanx of the thumb.
Actions: Adductor of the thumb.
Innervation: Ulnar nerve
What is the action of the lumbricals on the IPJ?
Extension
In the general, what is the action of the muscles of the anterior compartment fo the forearm?
Flexion at the wrist and fingers, and pronation.
how are the muscles divided in the anterior compartment?
Superficial, intermediate and deep.
Muscles of the superficial compartment
Flexor carpi ulnaris, palmaris longus, flexor carpi radilais and pronator teres.
Where do the muscles of the superficial compartment arise from?
Medial epicondyle of the humerus
Attachment, actions and innervation of the flexor carpi ulnaris
Attachments: Originates from the medial epicondyle with the other superficial flexors. It also has a long origin from the ulna. It passes into the wrist and attaches to the pisiform carpal bone.
Actions: Flexion and adduction at the wrist.
Innervation: Ulnar nerve
Palmaris longus
Attachments: Originates from the medial epicondyle, attaches to the flexor retinaculum of the wrist.
Actions: Flexion at the wrist.
Innervation: Median nerve.
Where is the palmaris longus? And, how common is it missing in the population?
This muscle is absent in about 15% of the population.
Dissection Tip: Just distal to the wrist, if you reflect back the palmaris longus, you will find the median nerve immediately underneath it
Flexor carpi radialis
Attachments: Originates from the medial epicondyle, attaches to the base of metacarpals II and III.
Actions: Flexion and abduction at the wrist.
Innervation: Median nerve
Pronator teres [incl. location]
The lateral border of the pronator teres forms the medial border of the cubital fossa, an anatomical triangle located over the elbow.
Attachments: It has two origins, one from the medial epicondyle, and the other from the coronoid process of the ulna. It attaches laterally to the mid-shaft of the radius.
Actions: Pronation of the forearm.
Innervation: Median nerve
Which muscle is in the intermediate compartment of the forearm?
The flexor digitorum superficialis is the only muscle of the intermediate compartment. It can sometimes be classed as a superficial muscle, but in most individuals, it lies between the deep and superficial muscle layers.
Why is the flexor digitorum superficialis a good anatomical landmark?
The muscle is a good anatomical landmark in the forearm – the median nerve and ulnar artery pass between its two heads, and then travel posteriorly.
Attachments, actions and innervations of the flexor digitorum superficials
Attachments: It has two heads – one originates from the medial epicondyle of the humerus, the other from the radius. The muscle splits into four tendons at the wrist, which travel through the carpal tunnel, and attaches to the middle phalanges of the four fingers.
Actions: Flexes the metacarpophalangeal joints and proximal interphalangeal joints at the 4 fingers, and flexes at the wrist.
Innervation: Median nerve
What are the three muscles in the deep compartment of the forearm?
Flexor digitorum profundus, flexor pollicis longus, pronator quadratus
Location, attachments, actions and innervations of the flexor digitorum profundus
Attachments: Originates from the ulna and associated interosseous membrane. At the wrist, it splits into four tendons, that pass through the carpal tunnel and attach to the distal phalanges of the four fingers.
Actions: It is the only muscle that can flex the distal interphalangeal joints of the fingers. It also flexes at metacarpophalangeal joints and at the wrist.
Innervation: The medial half (acts on the little and ring fingers) is innervated by the ulnar nerve. The lateral half (acts on the middle and index fingers) is innervated by the anterior interosseous branch of the median nerve.
Flexor pollicis longus
This muscle lies laterally to the FDP.
Attachments: Originates from the anterior surface of the radius and surrounding interosseous membrane. Attaches to the base of the distal phalanx of the thumb.
Actions: Flexes the interphalangeal joint and metacarpophalangeal joint of the thumb.
Innervation: Median nerve (anterior interosseous branch)
Pronator quadratus
A square shaped muscle found deep to the tendons of the FDP and FPL.
Attachments: Originates from the anterior surface of the ulna and attaches to the anterior surface of the radius.
Actions: Pronates the forearm.
Innervation: Median nerve (anterior interosseous branch).
Which nerve innervates the flexor carpi ulnaris?
Ulnar nerve
pH of the stomach
1.5-3.5
Where is HCl produced int eh stomach?
Parietal cells
Reaction to produce HCl [4]
Water and CO2 [in parietal cell] -> carbonic acid [H2CO3] + carbonic anhydrase -> H+ + HCO3-
H+ then transported into the stomach lumen via H+ -K+ ATPase ion pump [using ATP and K+].
The bicarbonate ion is transported out of the cell into the blood via a transporter protein called anion exchanger which transports the bicarbonate ion out the cell in exchange for a chloride ion (Cl–). This chloride ion is then transported into the stomach lumen via a chloride channel.
This results in both hydrogen and chloride ions being present within the stomach lumen. Their opposing charges leads to them associating with each other to form hydrochloric acid (HCl)