Palm

Identify the intrinsic muscles of the palm; be able to describe their positions and relationships relative to one another, their actions and innervations: Opponens digiti minimi

Position: Deep to the abductor digiti minimi and flexor digiti minimi brevis in the hypothenar compartment (eminence) Action: Oppose the little finger to the thumb Innervation: Deep branch of the ulnar nerve

Identify the intrinsic muscles of the palm; be able to describe their positions and relationships relative to one another, their actions and innervations: Flexor digiti minimi brevis

Position: Lateral-most muscle of the hypothenar eminence (compartment) Action: Flex the 5th digit Innervation: Deep branch of the ulnar nerve

Identify the intrinsic muscles of the palm; be able to describe their positions and relationships relative to one another, their actions and innervations: Abductor pollicis brevis

Position: Lateral-most muscle of the thenar eminence (compartment) Action: abduct the thumb Innervation: Recurrent branch of median nerve

Identify the intrinsic muscles of the palm; be able to describe their positions and relationships relative to one another, their actions and innervations: Opponens pollicis

Position: Lies deep to abductor pollicis brevis and flexor pollicis brevis in the thenar eminence (compartment) Action: Oppose the thumb to the little finger Innervation: Recurrent branch of median nerve

Identify the intrinsic muscles of the palm; be able to describe their positions and relationships relative to one another, their actions and innervations: Adductor pollicis

Position: Lies in the adductor compartment, and travels transversely across the first and second interosseus spaces to the proximal phalanx of the thumb Action: Adduction of the thumb, flexion of the thumb Innervation: Deep branch of the ulnar nerve

Identify the intrinsic muscles of the palm; be able to describe their positions and relationships relative to one another, their actions and innervations: Lumbricals (4)

Position: Located in the superficial midpalmar/central compartment; they originate on the sides of the flexor digitorum profundus tendons and insert upon the extensor hoods. No direct attachment to bone. Action: Flexion at the MCP joints and extension at the PIP and DIP joints. This is due to the position of the extensor hood posterior to PIP and DIP but anterior to MCP. The "lumbrical salute" Innervation: 2 medial-most lumbricals by the deep branch of the ulnar nerve. 2 lateral-most lumbricals by the common digital branches of the median nerve.

Identify the intrinsic muscles of the palm; be able to describe their positions and relationships relative to one another, their actions and innervations: Abductor digiti minimi

Position: Medial-most muscle of the hypothenar eminence (compartment) Action: Abduct the 5th digit Innervation: Deep branch of the ulnar nerve

Identify the intrinsic muscles of the palm; be able to describe their positions and relationships relative to one another, their actions and innervations: Flexor pollicis brevis

Position: Medial-most muscle of the thenar eminence (compartment) Action: Flex the thumb at the carpometacarpal and metacarpophalangeal joints Innervation: Recurrent branch of median nerve

Identify the intrinsic muscles of the palm; be able to describe their positions and relationships relative to one another, their actions and innervations: Dorsal interossei (4)

Position: Originate on metacarpals 1-5; insert on extensor hoods and radial side of proximal phalanges of digits 2 and 3, and ulnar side of digits 3 and 4 Action: Abduct digits 2, 3, 4 Innervation: Deep branch of the ulnar nerve

Identify the intrinsic muscles of the palm; be able to describe their positions and relationships relative to one another, their actions and innervations: Palmar interossei (3)

Position: Originate on metacarpals 2, 4, and 5, and insert on the extensor hoods and ulnar side of proximal phalanx on digit 2, and radial side of proximal phalanges of digits 4 and 5 (Deep mid- palmar, i.e. central, compartment) Action: Adduct digits 2, 4, and 5 PAD = Palmar ADducts Innervation: Deep branch of the ulnar nerve

How do you know where an injury occurred with the medial branch?

Prior to entering tunnel median n. gives off its palmar br. The palmar branch supplies cutaneous sensation to the skin of the middle palm Thus if palm is numb, then know it occurred proximally to branch coming off. If palm sensation remains, you know the injury is distal to the palmar branch.

Describe the location and function of the palmar aponeurosis

The palmar aponeurosis is the thickened fascia of the palm that blends with the flexor retinaculum and palmaris longus tendon. It overlies the long flexor tendons and divides the palm into compartments. It splits distally into four longitudinal digital bands that extend into the fingers, joining the fibrous digital sheaths which anchor the long flexor tendons against the phalanges. The purpose of the aponeurosis is to protect the palm; to compartmentalize the palm; and the anchor the long flexor tendons. The palmar aponeurosis is tensed by either palmaris longus or palmaris brevis (both muscles are variable in occurrence).

What occurs with trauma to the median nerve?

Vulnerable to injury due to superficial position. Severing this nerve results in loss of function of the thenar eminence muscles and 2 lumbricals. The thenar eminence atrophies and only functions of flexion-extension remain -- "ape - hand" deformity Carpal tunnel CAN get to this phase.